Copyright 2017, Richard J. Roper

Evaluation of the In-furrow Nematicide Velum Total for

Management of Meloidogyne inconita in Cotton

by

Richard J. Roper, B.S.

A Thesis

In

Crop Science

Submitted to the Graduate Faculty

of Texas Tech University in

Partial Fulfillment of

the Requirements for

the Degree of

MASTER OF SCIENCE

Approved

Dr. Jason Woodward

Chair of Committee

Dr. Glen Ritchie

Dr. Kenny Melton

Dr. Jackie Smith

Dr. Mark Sheridan

Dean of the Graduate School

May, 2017

Copyright 2017, Richard J. Roper

Texas Tech University, Richard J. Roper, May 2017

ii

ACKNOWLEDGMENTS

I thank Dr. Jason Woodward for the opportunity to conduct this research, for

the guidance in carrying it out, and for always encouraging me to be a better scientist.

I would like to thank my committee members for their time, comments, and revisions

that helped sharpen this manuscript. Dr. Glen Ritchie for his assistance with statistics,

Dr. Kenny Melton for his knowledge of the cotton industry, and Dr. Jackie Smith for

his economic expertise. I would like to thank Bayer CropScience, Plains Cotton

Growers, and Texas A&M AgriLife Extension Service for providing funding for this

project. I would also like to thank Debrah Dobitz, Bobby Rodriguez, and Ira Yates for

their technical support, as well as fellow graduate student Xiaoxiao Liu for her

invaluable assistance and support throughout this study. I thank my family, my wife,

Courtney, and my son, Soren, for all their support and understanding throughout this

endeavor.


iii

TABLE OF CONTENTS

ACKNOWLEDGEMENTS .................................................................................................. ii

ABSTRACT ..................................................................................................................... iv

LIST OF TABLES ............................................................................................................ vi

I. INTRODUCTION ........................................................................................................... 1

II. LITERATURE REVIEW ............................................................................................... 3

Distribution of Meloidogyne incognita in west Texas ....................................... 4

Disease symptoms .............................................................................................. 5

Lifecycle of Meloidogyne incognita .................................................................. 6

Resistance to Meloidogyne incognita................................................................. 8

Granular nematicicde aldicarb ........................................................................... 9

Seed treatment nematicides .............................................................................. 10

In-furrow nematicide Velum® Total ................................................................ 12

III. MATERIALS AND METHODS ................................................................................. 14

Field experiments ............................................................................................. 14

Evaluations ....................................................................................................... 15

Harvest ............................................................................................................. 16

Economic analysis ............................................................................................ 17

Data analysis .................................................................................................... 17

IV. RESULTS AND DISCUSSION ................................................................................... 18

Plant population ............................................................................................... 18

Plant height ...................................................................................................... 19

Late season plant measurements ...................................................................... 20

Harvest ............................................................................................................. 21

Fiber quality ..................................................................................................... 22

Economic analysis ............................................................................................ 24

V. SUMMARY AND CONCLUSIONS ............................................................................... 42

LITERATURE CITED ..................................................................................................... 45

APPENDIX ..................................................................................................................... 51


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ABSTRACT

Root-knot nematodes (Meloidogyne incognita) are the most destructive of the

plant-parasitic nematodes in the High Plains. In this region, approximately 50% of

irrigated fields are infested and yield losses of up to 25% have been reported. Prior to

2011, the granular nematicide aldicarb, was the most widely used chemical treatment;

however, it is no longer commercially available for use. New chemical management

options are necessary to reduce crop losses due to M. incognita. Velum® Total, the

primary product being evaluated in this study, is a novel fungicide/nematicide,

fluopyram, plus the insecticide, imidacloprid. Field experiments were conducted in

2015 and 2016 to evaluate combinations of in-furrow applications of Velum® Total,

cultivars that vary in their response to M. incognita, and the seed treatment nematicide

Aeris® in fields with varying levels of M. incognita.

There were no negative effects from either in-furrow or seed treatment

nematicides on stand establishment or early season plant growth. Differences in stand,

plant height, yield, fiber quality parameters, loan value, and net returns above variable

cost (NRAVC) were observed between cultivars. Yields were greatest for Stoneville

4946GLB2 and lowest for FiberMax 1900GLT at 1756 and 1628 kg/ha, respectively.

Use of the seed treatment nematicide was of limited effectiveness and caused a

decrease in NRAVC at two of the five locations.

Overall, applications of Velum® Total increased lint yields under high

nematode pressure conditions. The highest rate increased lint yields by 167 kg/ha and


v

the moderate rate numerically increased yield by 109 kg/ha, over the control. NRAVC

was numerically decreased $32 per hectare at the high rate compared to the moderate

rate in the high nematode pressure location. This corresponds to the significant

decrease at two other locations and another numerical decrease at a fourth location.

All of which indicates that the moderate rate application was more profitable than the

highest rate application. Results from these studies suggest that cultivar selection is

the most effective means of managing root-knot nematodes in cotton. Velum® Total is

a viable management option in fields severely infested with M. incognita.


vi

LIST OF TABLES

4.1 Monthly rainfall (mm) distribution for the years 2015 and 2016

and the 30 year average for locations in west Texas ........................................ 27

4.2 Main and fixed effects of in-furrow nematicide application, resistant

cultivar use, and seed treatment nematicide ..................................................... 28

4.3 Stand establishment as affected by in-furrow nematicide rates,

cultivar and seed treatment nematicide use ...................................................... 30

4.4 Plant height as affected by in-furrow nematicide rates,

cultivar and use of seed treatment nematicide ................................................. 31

4.5 Node number as affected by in-furrow nematicide rates,

cultivar and seed treatment nematicide use ...................................................... 32

4.6 Percent open boll as affected by in-furrow nematicide rates, cultivar

and seed treatment nematicide use ................................................................... 33

4.7 Lint yield as affected by in-furrow nematicide rates, cultivar and seed

treatment nematicide use .................................................................................. 34

4.8 Seed yield as affected by in-furrow nematicide rates, cultivar and seed

treatment nematicide use .................................................................................. 35

4.9 Fiber quality by HVI at TTU Research Farm 2015 as affected

by in-furrow nematicide rates, cultivar and seed treatment

nematicide use .................................................................................................. 36

4.10 Fiber quality by HVI at Lubbock Co. location 2015 as affected


nematicide use .................................................................................................. 37

4.11 Fiber quality by HVI at TTU Research Farm 2016 as affected


nematicide use .................................................................................................. 38

4.12 Fiber quality by HVI at Lubbock Co. location 2016 as affected


nematicide use .................................................................................................. 39


vii

4.13 Fiber quality by HVI at Yoakum Co. location 2016 as affected


nematicide use .................................................................................................. 40

4.14 Net returns above variable costs as affected by in-furrow nematicide

rates, cultivar and seed treatment nematicide use ............................................ 41

A.1 Variable Costs assessed in dollars per hectare 2015 and 2016 ........................ 52

A.2 Net returns above variable costs (NRAVC) meansa as affected by in-furrow

nematicideb rates, cultivarc and seed treatment nematicided use

(With calculated gin means for color and leaf grades) .................................... 53

A.3 P-values of main and fixed effects of in-furrow nematicide application,

resistant cultivar use, and seed treatment nematicide use ................................ 54


1

CHAPTER I

INTRODUCTION

In the High Plains region of west Texas, cotton is the primary regional crop,

and a considerable amount of the United States and Texas cotton production occurs in

the region. The economic importance of this fiber and oilseed crop cannot be

overstated, as it provides vital commerce and employment for many rural communities

in the High Plains.

Of the many threats to the cotton industry, plant-parasitic nematodes are a

serious concern. The root-knot nematode, Meloidogyne incognita, is the most

destructive of the plant-parasitic nematodes in the High Plains and approximately 50%

of irrigated fields in the region are infested (Orr and Robinson, 1984; Starr et al.,

1993; Wheeler et al., 2000; Woodward et al., 2014). If left untreated, crop losses

could be as high as 10% to 25% and can easily lead to reduced profit margins

(Kirkpatrick and Sasser, 1984, Wheeler et al., 2000). The presence of other

pathogens, such as the Fusarium oxysporum f. sp. vasinfectum or Verticillium dahliae,

can also greatly increase crop losses through a synergistic effect with M. incognita

(Wheeler et al., 2013). If plants are already affected by M. incognita, the presence of

other pathogens can tip the precarious balance of tolerance in the cotton plant. These

stressors are compounded with the addition of drought stress, thus nematode control is


2

especially vital during periods of regional drought, also as in the case of the High

Plains, in semi-arid climates.

Many strategies, of varying effectiveness, are available to combat M. incognita

such as the use of partially resistant cultivars, rotation with non-host crops,

fumigation, chemical and biological seed treatments, as well as at-plant and in-season

chemical applications. Of these, the use of partially resistant cultivars and chemical

control options are the preferred methods due to effectiveness and ease of use. In the

High Plains, the granular nematicide aldicarb (Temik® 15G, Bayer CropScience,

Research Triangle Park, NC), was historically the most widely used chemical

treatment. In 2011, the manufacturer voluntarily removed the product from the market

because of potential health and environmental concerns. While generic formulations

of aldicarb have recently been made available, such products are not being marketed

to cotton production regions on the Southwestern United States. The void, left by the

unavailability of aldicarb, in chemical treatment options limits the tools available in

controlling M. incognita populations.

New chemical management options are necessary to reduce crop losses due to

M. incognita. Velum® Total, the main product being evaluated in this study, is a novel

fungicide/nematicide, fluopyram, plus the insecticide, imidacloprid, that causes the

immobilization and eventual death of nematodes by preventing cellular energy from

being transferred in the mitochondria. The purpose of this study is to evaluate

combinations of treatment strategies in fields with varying levels of M. incognita.

Texas Tech University, Richard J. Roper, May, 2017

3

CHAPTER II

LITERATURE REVIEW

Cotton (Gossypium hirsutum L.) is an economically important fiber and oilseed

crop in many parts of the world. It is grown annually in more than seventy countries

and is the single most important fiber crop worldwide, with 30.6 million hectares

harvested globally and a production of 21.3 million metric tons in the 2015/16

Country Marketing Year (USDA-WAP). The potential of value-added processing in

cotton is expansive, allowing for multiple agronomic inputs (Basra, 1999).

One of the most damaging and widespread pathogens of cotton is the Southern

root-knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood. This pest is

found in all cotton-producing regions of the U.S. and is considered the most

widespread nematode parasite for the crop (Thomas and Kirkpatrick, 2001).

Considerable yield losses are possible from M. incognita infestations and cotton fiber

quality can be affected (Davis et al., 2014; Kirkpatrick and Sasser, 1984, Powell,

1971). Meloidogyne incognita is the most destructive of the Meloidogyne spp., which

are the most damaging plant-parasitic nematodes throughout the U.S. Cotton Belt with

approximately double the yield loss attributed to M. incognita as to all other cotton

crop nematode parasites (Koenning et al., 2004). In 2014, Texas produced 1.3 million

metric tons of cotton with crop losses totaled at 9.7% (126,000 metric tons), 4%

(52,000 metric tons) lost due to plant-pathogenic nematodes, 2.0% (26,000 metric


4

tons) were incurred by Meloidogyne spp. (National Cotton Council Disease Database,

Beltwide Cotton Disease Loss Estimate Committee).

Fields infested with M. incognita have historically been managed using

chemical management strategies; the primary management strategy has been the at-

planting application of the granular nematicide aldicarb (Wrather et al., 2002).

Because second-stage juveniles and eggs overwinter in underground plant remains,

increasing the following season’s inoculum load, nematode populations increase

exponentially year over year in untreated cotton monocultures (Jeger et al., 1993).

Distribution of Meloidogyne incognita in west Texas

Meloidogyne incognita parasitizes more than 2,000 species of plants including

various crop and weed species (Davis and Webster, 2008; Mitkowski, 2003; Sasser,

1980). In general, M. incognita prefers coarse soil types because the particle size

allows for increased ease of mobility through the substrate. Coarse soil types, which

are often nutrient deficient and have low water holding capacity, multiply the impact

of M. incognita. The increased stress and resulting damage to the plant is more

consequential because M. incognita diverts the already scarce resources available to

the plant for its own use (Khalilian et al., 2001 and 2002).

It is projected that M. incognita infests 40-57% of cotton acreage in the

Southern High Plains of West Texas (Orr and Robinson, 1984; Starr et al., 1993;

Wheeler et al., 2000; Woodward et al., 2014). The distribution of nematodes in fields

is often inconsistent, causing irregular patches of damage (Beltwide Cotton Nematode


5

Survey and Education Committee, 2003). The amount and size of these patches can

vary, ranging from small and limited in number to large and widely dispersed

throughout the field (Wrather, 2002).

Disease symptoms

Plants infected by M. incognita show a general loss of vigor. Aboveground

symptoms associated with infections include suppressed plant growth, stunting,

nutritional deficiency, chlorosis and temporary wilting during the heat of the day.

Belowground symptoms of M. incognita infections include a less developed root

system and the presence of galls (Thomas and Kirkpatrick, 2001). Early in their

development, affected plants show mild to severely reduced developmental rates,

depending on the severity of the infestation and the resistance level of the cultivar.

Throughout early to mid-development cracks can occur in the root epidermis, caused

by both juvenile burrowing and gall formation, which allow entrance for other

pathogens (Shepard and Huck, 1989). According to Lu et al. (2014), cotton plants

infected by M. incognita have been associated with reduced leaf chlorophyll content.

Mature affected plants exhibit chlorosis in the canopy because of the formation of

galls by M. incognita, which diverts and blocks the flow of nutrients. In some severe

cases, plants may die before reaching maturity (Kirkpatrick et al., 1995).

Severity of signs and symptoms from M. incognita infestation vary depending

on the availability of water and nutrients. Damage from plant-parasitic nematodes on

the shoot system of plants is not unique. It is characterized by stunting of the plant


6

and leaf chlorosis. The only unique aspect of infection by M. incognita is the galling

on the roots. Root system symptoms caused by M. incognita in cotton are potentially

much more diagnostic than shoot system symptoms. Often, visible galls or “knots”

appear on infected cotton roots (Bridge and Page, 1980). These knots are infected root

tissue, caused by the establishment of a feeding site leading the formation of giant

cells, and can be found on both the tap-root and the lateral roots. The unimpeded flow

of water and nutrients from the roots are very important to the cotton plant, even a few

galls on the tap-root and lateral roots can disrupt the regular flow of water and

nutrients to the leaves and bolls, thus significantly impairing the yield (Lu et al., 2014;

Pettigrew, 2001 and 2004).

Lifecycle of Meloidogyne incognita

There are four known races of M. incognita; populations are separated using

the results of host response on Deltapine 16 cotton and NC 95 tobacco. Race 1 does

not reproduce on cotton or resistant tobacco. Race 2 reproduces on "root-knot

resistant" NC 95 tobacco. Race 3 reproduces on Deltapine 16 cotton. Populations that

attack both cotton and tobacco are designated as Race 4. None of the four races attack

peanuts (Taylor and Sasser, 1978).

In cotton, races 3 and 4 are the parasitic races of importance. The root knot

nematode life cycle is comprised of four juvenile stages with the first-stage juvenile

(J1) molting inside the egg and after hatching, the second-stage juvenile (J2) emerges

from the egg and locates a host via chemotaxis, penetrating just behind the root tip and


7

migrate toward where the developing vascular tissue differentiates, once there, they

establish a permanent feeding site becoming sedentary, resulting in the characteristic

galling of root tissue (Starr, 1998). After ten to fourteen days feeding, the J2 molts to

a third-stage juvenile (J3), followed by the fourth-stage juvenile (J4) after four to six

days. The J3 and J4 stages do not feed. Females reinitiate feeding and begin egg

production five to seven days following the final molt and are capable of producing as

many as seven hundred and fifty eggs (Starr, 1998). Meloidogyne incognita

reproduction is by parthenogenesis resulting in clonal progeny. Since the vermiform

males are not involved in reproduction, they exit the root after the final molt (Starr,

1998). The eggs are deposited into a gelatinous matrix (the egg masses) that ruptures

the root epidermis. Both eggs and J2 contribute to overwinter survival, with the J2

being the primary inoculum in the spring (Jeger et al., 1993).

Plant-parasitic nematodes use a stylet, a needle or straw-like structure located

anteriorly at the head, which is inserted into a host cell to acquire nutrients by sucking

out the contents (Veech, 1990). Mature female root-knot nematodes are sedentary

endo-parasites, which establish permanent feeding sites via the formation of giant cells

resulting in root galling. While feeding, females inject protein factors that trigger a

hijacking of the cellular machinery in the cells adjacent to the feeding site (Hussey,

1985; Huang, C.S., 1985). The giant cells (also called nurse cells) associated with

each feeding site provide nutrients for the juvenile and they enlarge as the nematode

feeds (Starr, 1998).


8

Resistance to Meloidogyne incognita

While nematodes have developed numerous strategies to successfully

parasitize their hosts, plants have an array of defenses against pathogen infection.

Genes of certain cotton cultivars confer tolerance or resistance against M. incognita

infection. Tolerance refers to the response of a host plant to infection (i.e. degree of

damage) usually in reference to yield suppression; whereas, resistance describes the

effect of the plant on the nematode’s ability to reproduce (Davis, 2007).

Tolerance implies that the host has endurance and withstands stress better than

a host that is not tolerant. A cultivar has “true tolerance” of a plant disease if it is

susceptible to infection and supports the same pathogen load as another cultivar, but

has significantly better yield and quality, or if it supports significantly more of the

pathogen as another cultivar with the same yield and quality (Davis, 2007; Politowski

and Browning, 1978; Schafer, 1971).

Resistance and susceptibility, in relation to plant-parasitic nematodes, are the

terms used to describe the plant’s effect on the nematode’s reproductive ability this

resistance therefore allows certain cultivars to withstand infection, either by limiting

root penetration (i.e. fewer nematodes burrowing in equals fewer galls) or mitigating

the damage caused per infection (i.e. smaller galls, less disruption to the flow of water

and nutrients through roots, and fewer eggs deposited). This resistance of the plant to

infection decreases nematode reproduction overall as the numbers dwindle year after

year with fewer inoculum being available to reinfect the following year’s crop (Davis


9

and Kemerait, 2009). Cotton breeders utilize two sources of root-knot nematode

resistance, one found in the Auburn 623 RNR germplasm line and the other in the

cultivar Acala NemX (Davis, 2007; Davis and May, 2003; Shepherd and Huck, 1989).

Other general plant defense strategies include: developing thicker root

epidermis, changing composition of cell walls, hyperactive controlled cell death

(apoptosis), systemic acquired resistance (SAR) which results in enhanced defense

mechanisms in plants, the use of reactive oxygen species (ROS), and other host

responses (i.e. auxins, pathogen-associated molecular patterns PAMPs) (Bellafiore,

2008; Huang, J. S. 1985).

In the absence of aldicarb, the most cost-effective method for growers in semi-

arid climates, to reduce root-knot nematode population densities in heavily infested

fields, has been to use partially resistant cultivars and crop rotation (Wheeler et al.,

2014).

Granular nematicicde aldicarb

Aldicarb is a systemic nematicide that has the ability to translocate from the

root system to leaves after application, which made it effective against a number of

insect pests as well. The overall yield response of aldicarb in the presence of M.

incognita, in a 7-year study performed in Texas, was an increase, which averaged 3 to

5% over the untreated check (Wheeler et al., 2013). In a similar study in Alabama,

use of aldicarb improved yield by 10%, in the presence of Fusarium wilt/Meloidogyne

incognita complex (Wheeler et al., 2013). Aldicarb allowed for increased profitability


10

from cotton monocultures, both by inhibiting nematodes early season after planting

and thereby preventing them from feeding and causing damage to seedlings; also

because it was shown to increase root system development which allowed for a higher

carrying capacity of nematodes (Wheeler et al., 2013; Reddy et al., 1997). Aldicarb is

being phased out of use through a voluntary agreement between the manufacturer and

the EPA due to potential environmental and health concerns. Toxicological studies

have revealed, that high levels of exposure to aldicarb had the potential to cause

various effects such as sweating, nausea, dizziness and blurred vision, abdominal pain,

vomiting, and diarrhea in humans (EPA, 2010). In addition, aldicarb was found to be

highly toxic to small mammals with a LD50 at 0.5 mg/kg to 1.5 mg/kg and birds at a

LD50 ranging from 1.78 mg/kg to 5.34 mg/kg. It was also found to be moderately

toxic to fish at an LC of 8.8 mg/L in rainbow trout and 1.5 mg/L in bluegill sunfish

(Anonymous, 1996). Before it was discontinued, producers preferred to use aldicarb

for nematode control because of its cost effectiveness and efficacy. This phase out of

aldicarb necessitates a new management strategy for M. incognita.

Seed treatment nematicides

Seed treatment nematicides, such as abamectin (Avicta®, Syngenta) and

thiodicarb (one component of the seed treatment, Aeris®, Bayer CropScience), come

pre-applied to the seed coat. This reduces the risk to the applicator compared to the

use of aldicarb; however, seed treatment nematicides have a lower level of nematode

control and yield response than aldicarb (Wheeler et al., 2013).


11

Abamectin is an insecticide and nematicide, developed by Merck and Co., Inc.

in 1975 (Campbell, 2012). Due to the low solubility of abamectin it is best used as a

seed treatment; however, much of the product stays on the seed coat. Thus, the

benefits of abamectin diminish as the root system develops, resulting in variable and

limited effectiveness against M. incognita (Faske and Starr, 2006 & 2007; Monfort et

al., 2006). Additionally, abamectin demonstrates limited foliar translocation, a high

affinity to bind soil particles, and rapid decomposition in soil and sunlight (Faske,

2009). Due to these factors, the release of abamectin for use as a commercial

nematicide was delayed (Putter et al., 1981; Wislocki et al., 1989). Abamectin is

currently the active ingredient in the Avicta® line of products by Syngenta. According

to Wheeler et al. (2013), the increase in cotton yield for Avicta® over an untreated

check without environmental variables included was 0.8% and with the inclusion of

average high temperature in August was 1.9%.

Thiodicarb was introduced by Bayer CropScience in 2007, and combined with

the insecticide imidacloprid, as part of the commercially applied seed treatment Aeris®

used to ward off nematodes and insects in the early stages of seedling development

(Hall et al. 2007; Riggs et al. 2007). In a study conducted over seven years in West

Texas, the cotton yield increases for Aeris® and Avicta® were statistically

indistinguishable from each other as they both had 0.8% and 1.9% yield increases over

the nontreated control without and with environmental variables included, respectively

(Wheeler et al., 2013).


12

In-furrow nematicide Velum® Total

Velum® Total consists of fluopyram, referred to as a broad-spectrum fungicide

with nematicidal activity, and the insecticide imidacloprid. Velum® Total is labeled

for use against aphids, plant bugs, thrips, whiteflies, and nematodes and is also being

evaluated for management of some soilborne fungi (Faske and Hurd, 2015).

Fluopyram is a nonselective nematicide that affects through contact and

ingestion both plant-parasitic and free-living nematodes. Fluopyram inhibits Complex

II of the respiratory chain in mitochondria resulting in the immobility and death of

nematodes (Bayer CropScience, 2015). Fluopyram has limited xylem movement,

which indicates that direct contact is needed for nematode suppression unlike systemic

nematicides like aldicarb. Fluopyram shows promising activity against plant-parasitic

nematodes in preliminary laboratory and field reports (Faske and Hurd, 2015).

Research on tomato shows that concentrations of fluopyram of 5.18 µg/ml (for 2-hr

EC50) and 1.18 µg/ml (for 24-hr EC50), similar to that of aldicarb and abamectin, are

sufficient to inhibit infection and ensure paralysis of M. incognita (Faske and Hurd,

2015).

Testing Velum® Total for economic feasibility is an important step in the

identification of new and needed management strategies for M. incognita in cotton.

This study will assess the effects of Velum® Total on cotton stand count, plant height,

yield, and fiber quality in combination with susceptible and partially resistant cotton

cultivars and seed applied nematicides. New chemical management options are


13

necessary to reduce crop losses due to M. incognita. The purpose of this study is to

evaluate combinations of treatment strategies in fields with varying levels of M.

incognita.


14

CHAPTER III

MATERIALS AND METHODS

Field experiments

Field experiments were conducted in 2015 and 2016 to evaluate combinations

of in-furrow applications of Velum® Total, cultivars that vary in their response to M.

incognita and seed treatment nematicides. Trials were conducted at the Texas Tech

University Quaker Research Farm (Lat: 33.5992, Lon: -101.9092), the field was

comprised of two soil types: Amarillo-Urban land complex and Acuff-Urban land

complex; two grower locations in Lubbock County, the planting location near the

Lubbock Country Club (Lat: 33.6333, Lon: -101.8511) has an Amarillo fine sandy

loam soil, the location off North Quaker (Lat: 33.6717, Lon: -101.8997) has two soil

types, Amarillo fine sandy loam and Estacado clay loam; and one location in Yoakum

County (Lat: 33.0258, Lon: -102.6564), the planting location has two soil types,

Patricia and Amarillo loamy fine sands.

Nematode pressure varied by location and relative risk was assessed based on

soil sampling and/or field history from previous years. All management practices

other than nematode control were based on Texas A&M AgriLife Extension

recommendations or at the discretion of the cooperating producer.

The experimental design was a randomized complete block with treatments assigned

in split-split-split plot arrangement and four replications. The whole-plot factor was


15

in-furrow nematicide rate, the sub-plot factor was cotton cultivar and the sub-sub-plot

factor was nematicide seed treatment. In-furrow nematicide treatments consisted of

Velum® Total applied at 0, 0.731, 1.023, and 1.315 liters per hectare. The cultivars

evaluated were FiberMax 1900GLT, an earlier maturing susceptible cultivar,

FiberMax 2011GT, an earlier maturing resistant cultivar, FiberMax 2484B2F, a

medium maturing susceptible cultivar and Stoneville 4946GLB2, a medium maturing

resistant cultivar.

Experimental units (plots) were comprised of two rows 10.67 m in length on

1.02 m centers. Cotton was planted between 5 and 20 May at a density of 129,058

seed per hectare using John Deere MaxEmerge 1700 vacuum planter. Seed placement

was at a depth of approximately 35 mm, depending on soil moisture. The planter was

modified to allow Velum® Total to be sprayed by a CO2 pressurized sprayer calibrated

to deliver 48.6 liter/hectare. The spray solution was directed into the soil furrow

opening before the seed was dropped. All cultivars were treated with the standard

cotton seed treatment, which consists of a base fungicide and insecticide. Lots were

later divided and treated with the Aeris® Seed Applied System which contains

imidacloprid and thiodicarb an insecticide and nematicide respectively.

Evaluations

Stand counts were measured approximately 40 days after planting by visually

counting the total number of cotton plants that emerged from each plot. Plant heights

and total nodes were recorded approximately 70 days after planting. Ten plants from


16

each plot, five from each row, were chosen at random and measured from the

cotyledon to the apical meristem. Vigor ratings were conducted approximately 30 and

60 days after planting by visual estimates of plant size, tissue health and wilted

appearance. Plots were compared to the producer’s commercial cultivar adjacent to

the trial plots. The plots were evaluated on a scale of 1 to 5, with the producer’s

commercial cultivar being the average, 3 rating.

In 2016, open boll evaluations were conducted approximately 120 days after

planting by randomly selecting a 0.915 m length from each row (total of 1.83 m per

plot), counting the total bolls and the number of open bolls. Using these data, a

percentage of open bolls was calculated (%open boll = #open bolls/total bolls).

Harvest

Plots were harvested in late October through mid-November. Harvesting was

done with two-row commercial cotton harvest equipment, either an International 95, a

John Deere 484, or a John Deere 7460 depending on the year and location, with all

plots at a single location harvested by the same equipment. All harvesters were

equipped with a digital mounted scale system. Cotton samples (~800g) were obtained

from each plot and were ginned at the Texas A&M AgriLife Research and Extension

Center in Lubbock. Lint turnout percentages were calculated for each plot. Sub-

samples of lint (~150g) were collected following the ginning process and submitted to

the Texas Tech Fiber and Biopolymer Research Institute for fiber quality using High

Volume Instrumentation.


17

Economic analysis

Fiber quality parameters were used to calculate loan price values according to

industry standards (Anonymous, 2015a). Color and leaf grades were set to base values

of 41-1 and 4, respectively. The base cotton price, which requires that lint meet

certain quality criteria, was $1.145/kg. Deductions and premiums were assessed for

fiber quality according to the Commodity Credit Corporation Loan Premium and

Discount Schedule (Anonymous, 2015b and 2016b). Net returns above variable costs

were assessed by deducting seed cost and technology fees (Anonymous, 2016a),

accounting for cotton seed value ($227 per metric ton), ginning costs ($0.074 per kg),

and bagging and ties ($0.071 per kg) (Table 4.14).

Data analysis

Data analysis was performed with SAS version 9.4 (SAS Institute, Research

Triangle Park, NC). Analysis of variance (ANOVA) was run using the general linear

model (GLM) followed by Fisher’s Protected Least Significant Difference (LSD).

Main and fixed effects are presented in Table 4.2. Significance is at P=0.05 unless

otherwise stated.


18

CHAPTER IV

RESULTS AND DISCUSSION

Significant location-by-in-furrow nematicide and location-by-cultivar

interactions were observed for most parameters, therefore, data were presented by

trial. Locations to conduct trials were chosen based on previous classification of

nematode pressure. The TTU Research Farm has no history of M. incognita, while the

Lubbock Co. locations have been classified as having moderate nematode pressure,

and the Yoakum Co. site has high nematode pressure. While rainfall totals at planting

varied among locations, adequate moisture was available to ensure stand establishment

and activate nematicide treatments (Table 4.1). In 2016, cool soil temperatures

occurred in mid-May as a result of a cold front that moved into the region (Figure 4.1).

Plant population

Stand establishment varied across the five locations, averaging 84.4, 71.5,

41.7, 64.6, and 61.9% for TTU Research Farm in 2015, Lubbock County 2015, TTU

Research Farm 2016, Lubbock County 2016 and Yoakum County 2016, respectively

(Table 4.3). Stand was not influenced by the application of an in-furrow nematicide.

No phytotoxicity symptoms related to emergence or the appearance of deformed

seedlings were observed for in-furrow nematicide treatments or seed treatment

nematicides (data not shown). The addition of a seed treatment nematicide did not

improve stands over the base fungicide treatment. Differences in emergence among


19

cultivars were highly significant, where stands were greatest for FiberMax 2484B2F

and lowest for Stoneville 4946GLB2 at four of the five locations. Differences in stand

between the two years could be explained by environmental conditions after planting

(Table 4.1). More precipitation fell in 2015 than in 2016. In 2015, there was heavy

rain May through July with very dry weather in August and September. Increased

precipitation in October encouraged late vegetative growth, which caused some

problems during harvest. In 2016, less precipitation prior to planting would have led

to higher soil temperatures, coupled with a cold front including precipitation following

planting, likely accounts for the main differences in stand emergence between years

(personal observation).

Plant height

There was no effect of in-furrow nematicide application on plant height in any

trial among the two years (Table 4.4). Plant heights varied by location and averaged

between 47.9 and 70.9 cm for the Yoakum County 2016 and Lubbock County 2016

locations, respectively. Differences in plant height between these two locations may

have been attributed to management practices such as irrigation and fertility (data not

shown). As could be expected, plant height differences between cultivars were found

to be significant at most locations (P≤0.09), where heights were greatest for Stoneville

4946GLB2 (59.0 cm) and lowest for FiberMax 2484B2F (54.9 cm).


20

Late season plant measurements

The number of nodes, total bolls and open bolls was assessed in the three trials

conducted in 2016. The means across all treatments for each location’s total number

of nodes averaged 15.5, 16.7, and 14.6 for TTU Research Farm 2016, Lubbock

County 2016 and Yoakum County 2016, respectively (Table 4.5). Overall, node

development was lowest at the Yoakum County 2016 location where nematode

pressure was highest. In general, the application of an in-furrow nematicide had no

effect on node development at two locations; whereas, slight differences were

observed at the TTU Research Farm. The addition of a seed treatment nematicide did

not affect node development. Differences in node development among cultivars were

highly significant, where nodes were greatest for FiberMax 1900GLT and lowest for

FiberMax 2011GT.

The number of open bolls was used to assess earliness and location means

ranged from 23.9 to 59.4% for Lubbock County and TTU Research Farm, respectively

(Table 4.6). The application of an in-furrow nematicide significantly affected percent

open boll (P≤0.08). Overall, the application of Velum® Total improved percent open

boll over the non-treated control, and this trend was more pronounced as nematode

pressure increased. The addition of the seed treatment nematicide did not affect

percent open boll over the base fungicide treatment. Differences in percent open boll

among cultivars were highly significant at the Lubbock County and Yoakum County

locations. FiberMax 2011GT exhibited the highest percent open boll followed by


21

FiberMax 1900GLT, Stoneville 4946GLB2 and FiberMax 2484B2F. These results

reflect the relative maturity of these cultivars and support designations described by

the manufacturer. Differences in vigor were observed by cultivar early to midseason;

however, no correlation with yield was found (data not shown).

Harvest

Lint yields varied across all five locations, with location means ranging from

1351 kg/ha at the Lubbock County location during 2015 to 2411 kg/ha at the Lubbock

County location in 2016 (Table 4.7). The application of an in-furrow nematicide had

no effect on lint yield at four of the five locations; however, at the highest nematode

pressure location, the application of Velum® Total at the two highest rates increased

yields. Yields for plots treated with the seed treatment nematicide and the base

fungicide treatment were similar at all locations. Differences in lint yield among

cultivars was highly significant at four out of five locations, where lint yields were

greatest for Stoneville 4946GLB2, with 1756 kg/ha, and lowest for FiberMax

1900GLT, with 1628 kg/ha. Seed yields were unaffected by in-furrow nematicide

application or seed treatment nematicide use except at the Yoakum County location,

where the higher in-furrow nematicide application rates had increases of 200 and 150

kg over the non-treated control (Table 4.12). Cultivar was the driving force behind

seed yield at all locations, with certain cultivars doing better in differing environments

than others, and management practices impacting how successful cultivars performed.


22

Fiber quality

No differences in micronaire were observed among the four in-furrow

nematicide treatments (Tables 4.9, 4.10, 4.12, 4.13), except at the TTU Research Farm

in 2016 (Table 4.11). At this location, micronaire was slightly higher for plots

receiving Velum® Total compared to the non-treated control. Likewise, all fiber

quality parameters were similar between the base fungicide and the nematicide seed

treatment (Tables 4.9-4.13). Management practices were identical at the TTU

Research Farm between years. Micronaire was slightly higher in 2016 (4.77 units)

compared to 2015 (4.59 units), which could have resulted from heat units accumulated

later in the growing season (data not shown).

Differences in most all fiber quality parameters were observed among cultivars

at all locations, except uniformity at the 2016 Lubbock Co. location (Tables 4.9-4.13).

Micronaire values at the TTU Research Farm ranged from 4.44 to 4.72 units in 2015

and 4.40 to 5.03 units in 2016 for FiberMax 2484B2F and Stoneville 4946GLB2,

respectively (Tables 4.9 and 4.10). As such, micronaire values for all cultivars in

2015 were in the base range of the CCC Loan Premium and Discount Schedule

(Anonymous, 2015a). Micronaire values for FiberMax 1900GLT, FiberMax 2011GT

and FiberMax 2484B2F were in the premium range, whereas, Stoneville 4946GLB2

received a high micronaire discount in 2016 at the Yoakum County location, but was

in the base range at the Texas Tech Research Farm and the Lubbock County locations.

Average micronaire values for the two Lubbock Co. locations equaled 3.78 and 3.95


23

units in 2015 and 2016, respectively (Tables 4.9 and 4.10). Both values are within the

premium range on the CCC Loan Premium and Discount Schedule. FiberMax

2484B2F had the lowest micronaire in both years; whereas, micronaire values for

other cultivars were more variable. In contrast, micronaire averaged 5.02 units at the

Yoakum Co. location (Table 4.13). Micronaire values for FiberMax 2011GT and

FiberMax 2484B2F were in the base range, whereas, FiberMax 1900GLT and

Stoneville 4946GLB2 received high micronaire deductions.

A consistent trend was observed, where FiberMax 2484B2F had the longest

fiber length across all five trials at 1.21 inches, with a low of 1.18 inches at the

Lubbock County location in 2015 and a high of 1.24 inches at the TTU Research Farm

in 2016 (Tables 4.9-4.13). Stoneville 4946GLB2 had the shortest fiber length at 1.16

inches with a low of 1.15 inches in 2016 and a high of 1.19 inches at the TTU

Research Farm in 2015.

FiberMax 1900GLT had the highest strength overall at 32.90 g/tex, with a low

of 31.45 g/tex at the Lubbock County location in 2016 and a high of 34.18 g/tex at the

Yoakum County location in 2016. Stoneville 4946GLB2 had the lowest fiber strength

overall at 31.65 g/tex with a low of 29.74 g/tex at the Lubbock county location in 2016

and a high of 32.96 g/tex at the Yoakum County location in 2016. All cultivars except

for FiberMax 2011GT, had their highest fiber strength averages at the Yoakum County

2016 location. Fiber strength decreased overall from 2015 to 2016 averaging 0.65


24

units lower at the two locations in 2016 that corresponded to locations in 2015 (Tables

4.9-4.13).

Uniformity was not impacted by in-furrow or seed treatment nematicides

except at the 2016 Lubbock Co. location where the application of in-furrow

nematicide slightly increased uniformity (Tables 4.9-4.13). Fiber uniformity was

different among cultivar at all locations, but the 2016 Lubbock Co. location.

Stoneville 4946GLB2 had the highest uniformity overall at 82.69%, with a low of

81.98% at the Lubbock Co. location in 2015 and a high of 83.33% at the TTU

Research Farm in 2015. FiberMax 2011GT had the lowest uniformity at 82.27% with

a low of 81.82% at the Lubbock Co. location in 2015 and a high of 82.81% at the TTU

Research Farm in 2015. While differences were observed between these four fiber

quality parameters, overall mean values were within the premium range.

Economic analysis

Loan value, a product of fiber quality, was unaffected by in-furrow nematicide

treatment rate or seed treatment nematicide in 2015 (Tables 4.9-4.10). In 2016, loan

value was affected by the in-furrow nematicide where all rates decreased loan value in

the low nematode pressure location, only the highest rate decreased loan value at the

moderate nematode pressure location, and the two highest rates increased loan value at

the high nematode pressure location (Tables 4.11-4.13). Cultivars resulted in the

greatest differences in loan value with ranges from $1.276/kg (FiberMax 1900GLT,

Yoakum County location 2016) to $1.350/kg (FiberMax 2484B2F, TTU Research


25

Farm 2015). FiberMax 2484B2F had the highest loan value averaging $1.344/kg. At

three out of five locations, Stoneville 4946GLB2 had the lowest loan value and

averaged the lowest at $1.320/kg.

Applications of the in-furrow nematicide treatment numerically trended to

have increased net returns above variable costs (NRAVC) in the high nematode

pressure field but were not statistically different. At the moderate nematode pressure

locations in-furrow nematicide application numerically trended to decrease NRAVC

but was not statistically significant except at the highest application rate at the

Lubbock County location in 2015. Application of the in-furrow nematicide treatment

resulted in a numerical trend to decrease NRAVC in the low nematode pressure

locations but not statistically lower except at the Tech Research Farm in 2016 (Table

4.14). The seed treatment nematicide seemed to be of limited use in all fields

especially a disadvantage in the low nematode pressure locations. Differences in

NRAVC were significant for cultivars at three out of five locations, with a similar

trend occurring at the other two locations. The cultivar with the highest NRAVC was

Stoneville 4946GLB2 averaged across all trial locations at $2381/ha having a profit of

$121/ha advantage over FiberMax 2011GT which had $2260/ha, $162/ha over

FiberMax 2484B2F which had $2219/ha, and $221/ha advantage over FiberMax

1900GLT which had the lowest average return of $2160/ha across all trial locations

and was the lowest at four of the five locations (Table 4.14).


26

Figure 1. Soil temperature during May 2016 at the Texas Tech University Quaker

Research Farm.

0

5

10

15

20

25

30

Soil Temperature, °C (10 cm)


27

Table 4.1 Monthly rainfall (mm) distribution for the years 2015 and 2016 and the 30 year average for locations in

west Texasa,b

Month

-----------2015----------- -----------------------2016---------------------- -----30-yr avg -----

Lubbock

Co.

TTU

Farm

Lubbock

Co.

TTU

Farm

Yoakum

Co. Lubbock

-------------------------------------------------------- mm -------------------------------------------------------

January 35 42 12 13 6 17

February 1 2 9 5 11 23

March 18 17 4 4 0 32

April 37 46 19 26 34 38

May 154 285 83 133 62 64

June 120 63 22 68 34 85

July 128 105 38 8 27 57

August 16 4 107 125 220 52

September 25 16 70 54 77 82

October 164 129 4 26 18 43

November 27 23 16 16 87 25

December 20 19 13 16 12 22

Annual total 744 751 397 494 588 487

a Abbreviations: avg, average; mm, millimeters; yr, year.

b Thirty year average reported by National Weather Service 2016.


28

Velum® = Velum® Total

SeedTrt = Seed Treatment = Base or Aeris®

Cultivar = ST 4946GLB2, FM 2011GT, FM 2484B2F, FM 1900GLT

*, **, *** are significant at p-value = 0.05, 0.01, and the 0.001 levels respectively. NS = not significant.

Table 4.2 Main and fixed effects of in-furrow nematicide application, resistant

cultivar use, and seed treatment nematicide use

Variable, location

Velum®

Total Cultivar

Velum® by

Cultivar SeedTrt

Velum®

by

SeedTrt

Cultivar

by

SeedTrt

Stand

Yoakum Co. 2016 * * NS NS NS NS

Lubbock Co. 2015 NS * NS NS NS *

Lubbock Co. 2016 NS *** * NS NS **

TTU Farm 2015 NS ** NS NS NS ***

TTU Farm 2016 * * NS NS NS NS

Plant Height

Yoakum Co. 2016 NS *** NS NS NS NS

Lubbock Co. 2015 NS NS NS NS NS NS

Lubbock Co. 2016 NS *** NS NS NS NS

TTU Farm 2015 NS NS NS NS NS NS

TTU Farm 2016 * *** NS NS NS NS

Node


Lubbock Co. 2016 NS * NS NS NS NS

TTU Farm 2016 ** *** NS NS NS NS

Lint Yield

Yoakum Co. 2016 ** *** NS NS NS NS

Lubbock Co. 2015 NS ** NS NS NS NS

Lubbock Co. 2016 NS * NS NS * *


TTU Farm 2016 NS * NS * NS NS

Loan Value


Lubbock Co. 2015 NS ** NS NS NS NS


TTU Farm 2015 NS *** NS NS NS NS


NRAVC


Lubbock Co. 2015 * *** NS * NS NS

Lubbock Co. 2016 NS NS NS NS NS NS

TTU Farm 2015 NS NS NS NS * NS

TTU Farm 2016 ** ** NS * NS NS


29

Velum® = Velum® Total,

SeedTrt = Seed Treatment = Base or Aeris®,

Cultivar = ST 4946GLB2, FM 2011GT, FM 2484B2F, FM 1900GLT

*, **, *** are significant at p-value = 0.05, 0.01, and the 0.001 levels respectively. NS = not significant.

Table 4.2 Continued.

Variable, location

Velum®

Total Cultivar

Velum®

by

Cultivar

Seed

Treatment

Velum® by

SeedTrt

Cultivar

by

SeedTrt

Percent Open Bolls

Yoakum Co. 2016 ** *** NS NS NS NS

Lubbock Co. 2016 ** *** NS NS NS NS


Micronaire


Lubbock Co. 2015 NS *** * NS NS NS


TTU Farm 2015 NS *** NS NS NS *

TTU Farm 2016 ** *** * NS NS NS

Length




TTU Farm 2015 NS *** NS NS NS *

TTU Farm 2016 NS *** NS NS * NS

Strength






Uniformity


Lubbock Co. 2015 NS * NS NS NS NS

Lubbock Co. 2016 * NS NS NS NS NS

TTU Farm 2015 NS ** NS NS NS NS

TTU Farm 2016 NS * NS NS NS NS


30

Table 4.3 Stand establishmenta as affected by in-furrow nematicideb rates, cultivarc and seed treatment

nematicided use

Factor, level

TTU Farm

2015

Lubbock

Co. 2015

TTU Farm

2016

Lubbock Co.

2016

Yoakum Co.

2016 In-furrow nematicide

0 85.4 a 73.2 a 37.9 a 65.4 a 56.8 a

0.7 82.9 a 68.6 a 41.1 a 63.9 a 61.4 a

1.0 83.6 a 72.9 a 45.0 a 63.2 a 65.0 a

1.3 85.7 a 71.4 a 42.9 a 65.7 a 64.3 a

p-value 0.4883 0.5870 0.4558 0.8805 0.1653

Cultivar

ST 4946GLB2 81.4 c 69.3 b 40.0 b 61.4 b 63.6 a

FM 2011GT 83.9 bc 70.4 b 40.4 b 59.6 b 63.6 a

FM 2484B2F 86.8 a 76.1 a 45.7 a 67.9 a 56.8 b

FM 1900GLT 85.4 ab 70.7 b 40.4 b 69.6 a 65.4 a

p-value 0.0012 0.0256 0.0286 0.0007 0.0070

Nematicide seed treatment

No 83.9 a 72.5 a 42.9 a 64.6 a 62.1 a

Yes 84.6 a 70.7 a 40.4 a 64.6 a 61.8 a

p-value 0.4440 0.3326 0.1395 1.0000 0.8981 a Stand establishment means represented by percent of stand emergence. b Velum® Total, liters per hectare.

c Stoneville 4946GLB2, FiberMax 2011GT, FiberMax 2484B2F, FiberMax 1900GLT.

d Aeris® Seed Treatment system.

Means with the same letter are not significantly different according to Fisher’s Protected LSD.


31

Table 4.4 Plant heighta as affected by in-furrow nematicideb rates, cultivarc and seed treatment

nematicided use

Factor, level

TTU Farm

2015

Lubbock Co.

2015

TTU

Farm 2016

Lubbock Co.

2016

Yoakum

Co. 2016 In-furrow nematicide - - - - - - - - - - - - - - - - - - - - - - - - - - - cm - - - - - - - - - - - - - - - - - - - - - - - - - - -

0 56.1 a 50.3 a 56.9 a 71.1 a 47.2 a

0.7 57.2 a 51.8 a 58.4 a 71.1 a 47.8 a

1.0 57.2 a 51.6 a 56.4 a 70.1 a 48.3 a

1.3 55.1 a 50.0 a 55.4 a 71.4 a 48.5 a

p-value 0.8843 0.8428 0.5324 0.9011 0.6689

Cultivar

ST 4946GLB2 57.9 a 50.5 ab 59.2 a 76.5 a 50.8 a

FM 2011GT 56.4 a 51.6 ab 54.1 c 67.8 c 47.0 bc

FM 2484B2F 54.6 a 49.0 b 55.9 b 69.1 bc 46.0 c

FM 1900GLT 56.6 a 52.1 a 58.2 a 70.6 b 48.3 b

p-value 0.3399 0.0898 <0.0001 <0.0001 <0.0001


No 56.1 a 50.8 a 57.2 a 70.9 a 48.0 a

Yes 56.6 a 51.1 a 56.6 a 71.1 a 47.8 a

p-value 0.7401 0.8703 0.2652 0.4551 0.4830 a Plant height means expressed in centimeters. b Velum® Total, liters per hectare.





32

Table 4.5 Node number as affected by in-furrow nematicidea rates,

cultivarb and seed treatmentc nematicide use

Factor, level

TTU Farm

2016

Lubbock Co.

2016

Yoakum

Co. 2016

In-furrow nematicide

0 15.52 ab 16.72 a 14.55 a

0.7 15.88 a 16.68 a 14.67 a

1.0 15.11 c 16.63 a 14.51 a

1.3 15.48 bc 16.65 a 14.52 a

p-value 0.0014 0.9450 0.6756

Cultivar

ST 4946GLB2 15.09 c 16.72 a 14.35 b

FM 2011GT 15.32 bc 16.39 b 14.19 b

FM 2484B2F 15.68 ab 16.66 ab 14.83 a

FM 1900GLT 15.89 a 16.91 a 14.88 a

p-value 0.0002 0.0150 <0.0001


No 15.51 a 16.66 a 14.65 a

Yes 15.49 a 16.68 a 14.48 a

p-value 0.8800 0.8898 0.0892

Node development determined by means of ten plants measured per plot and means of

each replicate per trial location. a Velum® Total, liters per hectare.

b Stoneville 4946GLB2, FiberMax 2011GT, FiberMax 2484B2F, FiberMax 1900GLT.

c Aeris® Seed Treatment system.

Means with the same letter are not significantly different according to Fisher’s Protected

LSD.


33

Table 4.6 Percent open bolla as affected by in-furrow nematicideb

rates, cultivarc and seed treatment nematicided use

Factor, level

TTU Farm

2016

Lubbock Co.

2016

Yoakum

Co. 2016


0 53.4 b 19.7 c 27.9 c

0.7 61.9 a 26.0 ab 35.7 ab

1.0 61.8 a 20.9 bc 29.7 bc

1.3 60.6 ab 29.0 a 40.7 a

p-value 0.0756 0.0034 0.0036

Cultivar

ST 4946GLB2 59.6 a 19.8 c 27.7 c

FM 2011GT 63.1 a 36.6 a 50.0 a

FM 2484B2F 55.5 a 11.6 d 17.1 d

FM 1900GLT 59.5 a 27.5 b 39.3 b

p-value 0.2420 <0.0001 <0.0001


No 60.6 a 22.9 a 32.3 a

Yes 58.2 a 24.9 a 34.7 a

p-value 0.3453 0.3198 0.3643 a Percent open boll means calculated by (%open boll = #open bolls/total bolls). b Velum® Total, liters per hectare.



Means with the same letter are not significantly different according to Fisher’s Protected

LSD.


34

Table 4.7 Lint yielda as affected by in-furrow nematicideb rates, cultivarc and seed treatment nematicided

use

Factor, level

TTU Farm

2015

Lubbock

Co. 2015

TTU Farm

2016

Lubbock

Co. 2016

Yoakum Co.

2016


0 1399 a 1361 ab 1561 a 2386 a 1486 b

0.7 1462 a 1313 b 1608 a 2447 a 1490 b

1.0 1494 a 1425 a 1543 a 2363 a 1595 ab

1.3 1468 a 1303 b 1498 a 2447 a 1653 a

p-value 0.7941 0.0911 0.3413 0.7535 0.0093

Cultivar

ST 4946GLB2 1525 a 1366 ab 1633 a 2463 ab 1793 a

FM 2011GT 1512 a 1468 a 1483 b 2286 b 1477 b

FM 2484B2F 1359 a 1315 bc 1641 a 2323 b 1525 b

FM 1900GLT 1429 a 1256 c 1455 b 2573 a 1430 b

p-value 0.2873 0.0012 0.0023 0.0141 <0.0001


No 1444 a 1348 a 1602 a 2441 a 1525 a

Yes 1468 a 1353 a 1504 b 2381 a 1586 a

p-value 0.7247 0.8805 0.0255 0.3935 0.1702 a Lint yield means presented in kilogram/hectare. b Velum® Total, liters per hectare.





35

Table 4.8 Seed yielda as affected by in-furrow nematicideb rates, cultivarc and seed treatment nematicided

use

Factor, level

TTU Farm

2015

Lubbock

Co. 2015

TTU Farm

2016

Lubbock

Co. 2016

Yoakum Co.


0 2130 a 1806 ab 1921 ab 3410 a 2060 b

0.7 2151 a 1876 a 1851 b 3426 a 2124 ab

1.0 2245 a 1804 ab 2009 a 3331 a 2260 a

1.3 2169 a 1733 b 1837 b 3393 a 2227 a

p-value 0.8703 0.2568 0.0889 0.9048 0.0672

Cultivar

ST 4946GLB2 2256 a 1917 a 1963 ab 3411 ab 2613 a

FM 2011GT 2223 a 1700 c 2007 a 3332 b 1964 b

FM 2484B2F 2091 a 1854 ab 1820 b 3265 b 2097 b

FM 1900GLT 2127 a 1748 bc 1828 b 3552 a 1996 b

p-value 0.6329 0.0116 0.0269 0.1833 <0.0001


No 2173 a 1870 a 1913 a 3417 a 2134 a

Yes 2175 a 1740 b 1897 a 3363 a 2201 a

p-value 0.9830 0.0110 0.7660 0.5711 0.2570 a Seed yield means presented in kilogram/hectare. b Velum® Total, liters per hectare.





36

Table 4.9 Fiber qualitya by HVI at TTU Research Farm 2015 as affected by in-furrow nematicideb


Factor, level Micronaire

Length

(inches)

Strength

(g/tex)

Uniformity

(%)

Loan value

($/kg) In-furrow nematicide

0 4.55 a 1.20 a 32.74 a 82.91 a 1.35 a

0.7 4.57 a 1.21 a 33.05 a 82.99 a 1.34 a

1.0 4.59 a 1.20 a 32.76 a 83.11 a 1.35 a

1.3 4.63 a 1.20 a 33.02 a 83.01 a 1.35 a

p-value 0.4902 0.7799 0.5000 0.6927 0.2227

Cultivar

ST 4946GLB2 4.72 a 1.19 b 32.73 b 83.33 a 1.34 b

FM 2011GT 4.58 b 1.19 b 32.49 b 82.81 b 1.35 a

FM 2484B2F 4.44 c 1.22 a 32.75 b 82.82 b 1.35 a

FM 1900GLT 4.61 ab 1.19 b 33.59 a 83.07 ab 1.35 a

p-value <0.0001 0.0001 0.0004 0.0059 0.0054


No 4.59 a 1.20 a 32.95 a 82.93 a 1.35 a

Yes 4.59 a 1.20 a 32.84 a 83.08 a 1.35 a

p-value 0.9011 1.0000 0.5632 0.2037 0.2481 a Fiber quality determined by High Volume Instrumentation (HVI) at the Texas Tech Fiber and Biopolymers Research Institute.

Loan value determined by using the 2016 CCC Loan Schedule with a standard color and leaf grade of 41-1 and 4, respectively. b Velum® Total, liters per hectare.





37

Table 4.10 Fiber qualitya by HVI at Lubbock Co. location 2015 as affected by in-furrow nematicideb



Length

(inches)

Strength

(g/tex)

Uniformity

(%)

Loan value


0 3.75 a 1.16 a 31.37 a 81.78 a 1.34 a

0.7 3.86 a 1.17 a 31.30 a 81.78 a 1.35 a

1.0 3.75 a 1.17 a 31.26 a 81.81 a 1.34 a

1.3 3.78 a 1.17 a 31.40 a 81.62 a 1.34 a

p-value 0.1011 0.9096 0.9202 0.6745 0.2213

Cultivar

ST 4946GLB2 3.74 b 1.15 b 31.10 bc 81.98 a 1.35 a

FM 2011GT 3.98 a 1.15 b 30.84 c 81.82 a 1.34 a

FM 2484B2F 3.70 b 1.18 a 31.35 b 81.44 b 1.34 a

FM 1900GLT 3.72 b 1.18 a 32.04 a 81.76 ab 1.34 b

p-value <0.0001 <0.0001 <0.0001 0.0176 0.3345


No 3.77 a 1.17 a 31.30 a 81.75 a 1.34 a

Yes 3.79 a 1.16 a 31.37 a 81.75 a 1.35 a







38

Table 4.11 Fiber qualitya by HVI at TTU Research Farm 2016 as affected by in-furrow nematicideb rates,

cultivarc and seed treatment nematicided use


Length

(inches)

Strength

(g/tex)

Uniformity

(%)

Loan value


0 4.68 c 1.20 a 32.16 a 82.71 a 1.34 a

0.7 4.82 ab 1.20 a 32.49 a 82.90 a 1.32 b

1.0 4.85 a 1.19 a 32.20 a 82.61 a 1.32 b

1.3 4.73 bc 1.19 a 32.16 a 82.98 a 1.32 b

p-value 0.0049 0.4016 0.6823 0.2209 0.0432

Cultivar

ST 4946GLB2 5.03 a 1.15 d 31.73 b 83.02 a 1.29 c

FM 2011GT 4.80 b 1.17 c 32.25 b 82.56 b 1.34 ab

FM 2484B2F 4.40 c 1.24 a 31.80 b 82.64 ab 1.35 a

FM 1900GLT 4.84 b 1.22 b 33.24 a 82.98 a 1.33 b

p-value <0.0001 <0.0001 <0.0001 0.0442 <0.0001


No 4.78 a 1.20 a 32.31 a 82.88 a 1.32 a

Yes 4.76 a 1.19 a 32.20 a 82.72 a 1.33 a







39

Table 4.12 Fiber qualitya by HVI at Lubbock Co. location 2016 as affected by in-furrow nematicideb rates,



Length

(inches)

Strength

(g/tex)

Uniformity

(%)

Loan value


0 3.94 a 1.21 a 30.62 a 82.18 b 1.34 a

0.7 4.02 a 1.21 a 30.47 a 82.45 ab 1.34 a

1.0 3.89 a 1.22 a 30.97 a 82.68 a 1.34 a

1.3 3.95 a 1.20 a 30.34 a 82.00 b 1.33 b

p-value 0.5589 0.0928 0.3671 0.0361 0.0007

Cultivar

ST 4946GLB2 4.10 a 1.18 c 29.74 c 82.48 a 1.34 a

FM 2011GT 3.99 a 1.20 b 30.90 ab 82.33 a 1.35 a

FM 2484B2F 3.72 b 1.23 a 30.35 bc 82.13 a 1.33 b

FM 1900GLT 3.98 a 1.22 ab 31.45 a 82.37 a 1.34 a

p-value 0.0008 <0.0001 0.0003 0.5405 0.0003


No 3.94 a 1.21 a 30.57 a 82.30 a 1.339 a

Yes 3.96 a 1.21 a 30.63 a 82.35 a 1.341 a







40

Table 4.13 Fiber qualitya by HVI at Yoakum Co. location 2016 as affected by in-furrow nematicideb rates,



Length

(inches)

Strength

(g/tex)

Uniformity

(%)

Loan value


0 5.02 a 1.16 a 33.08 a 82.17 a 1.30 b

0.7 5.05 a 1.15 a 32.92 a 82.57 a 1.29 b

1.0 4.99 a 1.17 a 33.22 a 82.61 a 1.31 a

1.3 5.03 a 1.16 a 33.16 a 82.57 a 1.30 ab

p-value 0.7838 0.1719 0.8167 0.0952 0.0076

Cultivar

ST 4946GLB2 5.11 ab 1.13 c 32.96 b 82.66 a 1.28 b

FM 2011GT 4.99 b 1.13 c 32.25 c 81.85 b 1.30 b

FM 2484B2F 4.77 c 1.20 a 32.98 b 82.40 a 1.35 a

FM 1900GLT 5.21 a 1.18 b 34.18 a 82.75 a 1.28 b

p-value <0.0001 <0.0001 <0.0001 0.0001 <0.0001


No 5.04 a 1.16 a 33.01 a 82.43 a 1.30 a

Yes 5.00 a 1.16 a 33.18 a 82.40 a 1.30 a







41

Table 4.14 Net returns above variable costsa as affected by in-furrow nematicideb rates, cultivarc and seed

treatment nematicided use

Factor, level

TTU Farm

2015

Lubbock

Co. 2015

TTU Farm

2016

Lubbock

Co. 2016

Yoakum Co.


0 2145 a 1877 a 1806 a 3544 a 2039 a

0.7 2112 a 1793 ab 1782 a 3521 a 2038 a

1.0 2209 a 1881 a 1743 a 3397 a 2201 a

1.3 2101 a 1700 b 1619 b 3417 a 2169 a

p-value 0.9073 0.0168 0.0154 0.6874 0.1411

Cultivar

ST 4946GLB2 2217 a 1888 a 1800 a 3491 a 2508 a

FM 2011GT 2228 a 1901 a 1722 ab 3453 a 1995 bc

FM 2484B2F 2075 a 1774 ab 1799 a 3345 a 2104 b

FM 1900GLT 2047 a 1689 b 1629 b 3591 a 1842 c

p-value 0.5608 0.0032 0.0200 0.4215 <0.0001


No 2155 a 1848 a 1802 a 3508 a 2106 a

Yes 2129 a 1778 b 1673 b 3432 a 2119 a

p-value 0.8232 0.1208 0.0037 0.4647 0.8375 a Net returns above variable costs presented in dollars/hectare and include seed value. Variable costs included: seed costs, technology

fees, ginning costs and bag/tie fees. b Velum® Total, liters per hectare.





42

CHAPTER V

SUMMARY AND CONCLUSIONS

Neither the application of Velum® Total nor the use of Aeris® affected stand

establishment at any location; however, differences in stand were observed among

cultivars (Table 4.3). No in-season injury was observed following Velum® Total

applications in either year. Likewise, no injury was observed with Aeris® in 2015;

however, a difference in uniformity was observed between the base seed treatment and

Aeris® at all locations in 2016 and was evident through early bloom. Despite visual

differences, plant heights were unaffected by seed treatment and were similar for all

in-furrow nematicide rates. Differences in height were observed between cultivars,

but were more in response to management tactics than nematode damage.

Growth and development was assessed at all locations in 2016. A slight

difference in the total number of nodes was observed among in-furrow nematicide

applications at one location; however, no variances were observed between the two

seed treatments. Differences in the total number of nodes were observed among

cultivars, which is characteristic of growth habit. No differences in the total number

of bolls were observed for any factors at any location. When assessing the percentage

of open bolls, which can be used to estimate maturity, differences were observed

among cultivars and in-furrow nematicides, but not seed treatments. FiberMax


43

2011GT and FiberMax 1900GLT consistently exhibited a higher percentage of open

bolls than Stoneville 4946GLB2 and FiberMax 2484B2F, which correlates with the

relative maturity classification of each cultivar. Applications of Velum® Total

increased the percentage of open bolls at all locations. Higher application rates tended

to increase the percentage of open bolls. The greatest difference occurred between the

non-treated control and the highest rate where nematode pressure was greatest.

Lint yields varied by location and in general, resistant cultivars outperformed

non-resistant cultivars in high nematode pressure locations and non-resistant cultivars

outperformed resistant cultivars in low nematode pressure locations with a few

exceptions. Stoneville 4946GLB2 a resistant cultivar, in most cases, outperformed the

other cultivars in lint yield and averaged the highest yield with all locations totaled.

Overall, fiber quality was not affected by in-furrow or seed treatment

nematicides (Tables 4.9-4.13). Fiber quality varied by cultivar with resistant cultivars

having, in general, slightly lower loan values. While differences were observed

between fiber quality parameters, mean values generally were within the premium

range. While Stoneville 4946GLB2 had lower fiber quality overall it made up any

loan value discount in higher lint yield. This is seen in the NRAVC where across all

five locations Stoneville 4946GLB2 averaged $160 above the second highest return

FiberMax 2484B2F and $307 above the lowest return FiberMax 1900GLT (Table

4.14).


44

Results from this study indicate that Velum® Total, when used at

recommended rates, has no negative effects on early season crop growth or

development nor yield. In low nematode pressure fields, results indicate the use of

Velum® Total is not profitable. For the application of Velum® Total in moderate

fields to be cost effective, producers need to consider the variance of nematode

distribution in fields and take multiple samples to determine what specific areas are

infested. High-pressure areas in moderate fields would likely see increased profit

from site-specific applications of Velum® Total. Scouting observations throughout the

growing season can help better identify areas that would benefit from the application

of Velum® Total. These benefits should be weighed with other nematode

management considerations for maximized yield potential. The results support that

Velum® Total positively impacts yield in high nematode pressure fields. There was a

direct correlation between Velum® Total application rate and lint yield in the high

nematode pressure field. In low and moderate nematode pressure fields, the use of the

1.3 liter/ha application rate is not as cost efficient as the 1.0 liter/ha rate.

While the partially resistant cultivars used in this study have slightly lower

fiber quality compared to non-resistant cultivars, the increased yield of resistant

cultivars outweighs any penalties that may be imposed from their lower fiber quality.

Stoneville 4946GLB2 had superior performance overall, especially in higher root knot

nematode pressure fields.


45

CHAPTER VI

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51

APPENDIX I

*Seed cost evaluated at 129,058 seed/hectare.

Seed treatment consisted of either Base fungicide treatment or Base + Aeris® nematicide seed treatment

Table A.1 Variable Costs assessed in dollars per hectare 2015 and 2016

Seed cost* Seed

tech

Seed

treatment

Velum® Total

(L/ha)

Ginning

costs

Bagging

and ties

Cultivar 2015 2016 Base Aeris® 0 0.73 1.02 1.32 $/kg $/kg

FM 1900GLT 209.02 206.08 NA 0 25.75 0 46.70 65.38 84.07 0.07 0.08

FM 2011GT 170.25 170.25 NA 0 25.75 0 46.70 65.38 84.07 0.07 0.08

FM 2484B2F 99.80 99.80 100.92 0 25.75 0 46.70 65.38 84.07 0.07 0.08

ST 4946GLB2 162.64 162.64 43.27 0 25.75 0 46.70 65.38 84.07 0.07 0.08


52

.Table A.2 Net returns above variable costsa as affected by in-furrow nematicideb rates, cultivarc and seed

treatment nematicided use (With calculated gin means for color and leaf grades)

Factor, level

TTU Farm

2015

Lubbock

Co. 2015

TTU Farm

2016

Lubbock

Co. 2016

Yoakum Co.


0 2290 a 2118 a 2147 a 4021 a 2295 a

0.7 2215 a 2054 a 2088 a 3923 a 2324 a

1.0 2382 a 2113 a 2110 a 3835 a 2481 a

1.3 2252 a 1921 b 1932 b 3891 a 2414 a

p-value 0.7875 0.0117 0.0066 0.7407 0.2277

Cultivar

ST 4946GLB2 2378 a 2157 a 2144 a 3966 a 2859 a

FM 2011GT 2384 a 2119 a 2092 a 3840 a 2190 c

FM 2484B2F 2277 a 2038 a 2126 a 3855 a 2411 b

FM 1900GLT 2100 a 1891 b 1915 b 4011 a 2055 c

p-value 0.3083 0.0006 0.0019 0.6994 <0.0001


No 2307 a 2098 a 2128 a 3974 a 2360 a

Yes 2263 a 2005 b 2010 b 3862 a 2397 a

p-value 0.7154 0.0491 0.0107 0.3727 0.6024 a Net returns above variable costs means presented in dollars/hectare and include seed value. Variable costs included: seed costs,

technology fees, ginning costs and bag/tie fees. b Velum® Total, liters per hectare.





53

Velum® = Velum® Total, SeedTrt = Seed Treatment = Base or Aeris®, Cultivar = ST 4946GLB2, FM

2011GT, FM 2484B2F, FM 1900GLT

*, **, *** are significant at p-value = 0.05, 0.01, and 0.001 levels respectively.

Table A.3 P-values of main and fixed effects of in-furrow nematicide

application, resistant cultivar use, and seed treatment nematicide use

Variable, location

Velum®

Total Cultivar

Velum®

x

Cultivar

SeedTrt

Velum®

x

SeedTrt

Cultivar

x

SeedTrt

Stand

Yoakum Co. 2016 0.02* 0.01* 0.40 0.93 0.46 0.55

Lubbock Co. 2015 0.24 0.03* 0.34 0.34 0.28 0.01*

Lubbock Co. 2016 0.72 0.00*** 0.05* 1.00 0.67 0.00**

TTU Farm 2015 0.09 0.00** 0.59 0.47 0.75 0.00***

TTU Farm 2016 0.02* 0.05* 0.56 0.17 0.68 0.06

Plant Height

Yoakum Co. 2016 0.33 0.00*** 0.37 0.63 0.45 0.26

Lubbock Co. 2015 0.49 0.12 0.35 0.89 0.64 0.87

Lubbock Co. 2016 0.62 0.00*** 0.65 0.65 0.79 0.82

TTU Farm 2015 0.70 0.41 1.00 0.76 0.32 0.94

TTU Farm 2016 0.01* 0.00*** 0.45 0.47 0.92 0.66

Node

Yoakum Co. 2016 0.68 0.00*** 0.45 0.09 0.32 0.23

Lubbock Co. 2016 0.95 0.02* 0.69 0.89 0.57 0.71

TTU Farm 2016 0.00** 0.00*** 0.66 0.88 0.08 0.34

Lint Yield

Yoakum Co. 2016 0.01** 0.00*** 0.54 0.14 0.79 0.17

Lubbock Co. 2015 0.09 0.00** 0.89 0.88 0.47 0.42

Lubbock Co. 2016 0.75 0.01* 0.10 0.39 0.02* 0.05*

TTU Farm 2015 0.79 0.29 0.99 0.72 0.08 0.77

TTU Farm 2016 0.34 0.00* 0.94 0.03* 0.92 0.22

Loan Value

Yoakum Co. 2016 0.15 0.00*** 0.15 0.09 0.09 0.10

Lubbock Co. 2015 0.83 0.00** 0.31 0.14 0.41 0.77

Lubbock Co. 2016 0.79 0.00*** 0.21 0.77 0.18 0.33

TTU Farm 2015 0.39 0.00*** 0.79 0.58 0.35 0.49

TTU Farm 2016 0.06 0.00*** 0.18 0.34 0.70 0.71

NRAVC

Yoakum Co. 2016 0.23 0.00*** 0.75 0.60 0.83 0.22

Lubbock Co. 2015 0.01* 0.00*** 0.98 0.05* 0.37 0.52

Lubbock Co. 2016 0.74 0.70 0.17 0.37 0.23 0.18

TTU Farm 2015 0.79 0.31 1.00 0.72 0.02* 0.88

TTU Farm 2016 0.01** 0.00** 0.99 0.01* 0.74 0.27


54

Velum® = Velum® Total, SeedTrt = Seed Treatment = Base or Aeris®, Cultivar = ST 4946GLB2, FM

2011GT, FM 2484B2F, FM 1900GLT

*, **, *** are significant at p-value = 0.05, 0.01, and 0.001 levels respectively.

Table A.3 Continued

Variable, location

Velum®

Total Cultivar

Velum® x

Cultivar SeedTrt

Velum®

x

SeedTrt

Cultivar

x

SeedTrt

Percent Open

Bolls

Yoakum Co. 2016 0.00** 0.00*** 0.56 0.36 0.84 0.78

Lubbock Co. 2016 0.00** 0.00*** 0.50 0.32 0.86 0.78

TTU Farm 2016 0.08 0.24 0.41 0.35 0.32 0.71

Micronaire

Yoakum Co. 2016 0.78 0.00*** 0.78 0.42 0.69 0.43

Lubbock Co. 2015 0.10 0.00*** 0.04* 0.55 0.30 0.65

Lubbock Co. 2016 0.56 0.00*** 0.09 0.62 0.57 0.40

TTU Farm 2015 0.49 0.00*** 0.55 0.90 0.42 0.02*

TTU Farm 2016 0.00** 0.00*** 0.03* 0.49 0.76 0.49

Length

Yoakum Co. 2016 0.17 0.00*** 0.57 0.35 0.48 0.81

Lubbock Co. 2015 0.91 0.00*** 0.15 0.19 0.71 0.33

Lubbock Co. 2016 0.09 0.00*** 0.66 0.57 0.90 0.39

TTU Farm 2015 0.78 0.00*** 0.77 1.00 0.43 0.02*

TTU Farm 2016 0.40 0.00*** 0.16 0.55 0.04* 1.00

Strength

Yoakum Co. 2016 0.82 0.00*** 0.34 0.46 0.29 0.66

Lubbock Co. 2015 0.92 0.00*** 0.24 0.64 0.19 0.48

Lubbock Co. 2016 0.37 0.00*** 0.45 0.77 0.56 0.66

TTU Farm 2015 0.50 0.00*** 0.62 0.56 0.53 0.38

TTU Farm 2016 0.68 0.00*** 0.19 0.60 0.96 0.07

Uniformity

Yoakum Co. 2016 0.10 0.00*** 0.23 0.81 0.99 0.53

Lubbock Co. 2015 0.67 0.02* 0.23 0.99 0.70 0.91

Lubbock Co. 2016 0.04* 0.54 0.22 0.69 0.82 0.86

TTU Farm 2015 0.69 0.01** 0.19 0.20 0.36 0.15

TTU Farm 2016 0.22 0.04* 0.25 0.32 0.23 0.05