102

What’s New

New NPM Program Publications ................................ 102

Crops

Vegetable Crop Update 8/27/13 .................................. 102

Late Planted Drought Stricken Soybean as a Forage?...Check

the Label First ............................................................ 102

A Guide to Making Soybean Silage ............................ 102

Video on Late Season Drought Stress in Soybean ....... 104

Plant Disease

Late Season Soybean Disease Update – 8/27/13 .......... 104

Plant Disease Diagnostic Clinic (PDDC) Summary ..... 106

New Video: White Mold in Soybean .......................... 106

New NPM Program Publications

The UW Nutrient and Pest Management (NPM) Program has

just released two new card-style publications. The first contains the UW price-adjusted nitrogen guidelines for wheat. The

second card shows the interpretive categories for soil test

phosphorus (P) and potassium (K). The cards are excerpts from

the UW-Extension publication Nutrient Application Guidelines

for Field, Vegetable, and Fruit Crops in Wisconsin (A2809) - –

specifically tables 6.2, 7.1 and 7.2.

Copies of these and other NPM Program publications are

available free of charge. To place an order, contact NPM at

npm@hort.wisc.edu or 608-265-2660. NPM Program

publications are also available for viewing and download at

http://ipcm.wisc.edu/.

To view these new publications scroll down to the end of this newsletter.

Vegetable Crop Update 8/27/13

The 18th issue of the Vegetable Crop Update is now

available. This issue contains an invitation to growers to

observe and rank potato varieties from fresh market trial at

HARS-SRF as well as early and late blight updates. Click here

to view this issue.

Late Planted Drought Stricken Soybean as a Forage?...Check the Label First

Shawn Conley, Soybean and Wheat Extension Specialist

Severe alfalfa winterkill coupled with late soybean plantings

followed by dry conditions have growers considering chopping

their soybean as a forage. Before you even consider this option

make sure you check the label of the pesticides applied to the

crop before you grease the chopper.

Let's start with the herbicides first. In short, outside of

glyphosate (14 to 25 day, depending upon timing/use)

and a handful of pre's and posts (please refer to Table

3-3 in A3646, Pest Management is WI Field Crops) most soybean herbicides are listed as "not permitted"

for forage use.

Next, many common insecticides used for soybean

aphid management implicitly state "Do NOT graze or

feed treated forage or straw to livestock" (please refer

to Table 3-8 in A3646, Pest Management is WI Field

Crops)

Lastly, fungicide labels are as equally exclusive with

pre-harvest intervals ranging from 14 days to "Do

NOT graze or feed soybean forage or hay" (please

refer to Table 3-12 in A3646, Pest Management is WI Field Crops) .

If you somehow pass the gauntlet of "Do not" or "Not

Permitted" and the forage value is greater than the grain value

then the highest protein and yields are obtained from soybean

harvested at the R6 to R7 growth stage. Harvesting soybeans

for forage between the R1 and R5 stage will result in a very

high quality silage, but dry matter yields will be reduced

significantly. Forage quality will be reduced from R5 soybean

forward if a conditioning process is used during harvest as

conditioning will cause significant seed shattering. For

additional information please refer to Soybeans for Hay or Silage.

A Guide to Making Soybean Silage

Dan Undersander, Professor, Kevin Jarek, Tom Anderson,

NickSchneider, and Lee Milligan, Extension Educators,

University of Wisconsin, Madison 53706

Corresponding author: Dan Undersander. djunders@wisc.edu

Undersander, D., Jarek, K., Anderson, T., Schneider, N., and

Milligan, L. 2007. A guide tomaking soybean silage. Online.

Forage and Grazinglands doi:10.1094/FG-2007-0119-01-

MG

Volume 20 Number 25 - - - University of Wisconsin Crop Manager - - - August 29, 2013

103

Adverse weather such as drought or early frost sometimes

raises the issue of harvesting soybean fields for forage due to

forage shortage and/or low yield grain yield potential of the

soybean crop. Soybean forage can be harvested as either silage

or hay. Harvesting as hay requires much longer field drying

times, increases shattering losses, and can be very dusty. No

information was found concerning production and feeding of

soybean silage. Therefore, eight farmers who had made

soybean silage in Wisconsin during the fall of 2005 were

surveyed and the silage was sampled for analysis. Following

are recommendations for making soybean silage as reflected by the farmer experience.

Soybean should be harvested for silage at the R3 stage [when

one of the four top nodes with a fully developed leaf has a 3/16

inch long pod (1)] for dairy animals.

It is possible to harvest as late as R7 stage (one pod on main

stem has reached mature color; 50% of leaves yellow;

physiological maturity, no more dry matter accumulation).

Yield at the later stage is increased compared to R3 and R4

stages and plant dry matter is near to that required for ensiling

(2,3,5). While overall forage quality at the R7 is similar to the

R3 or R4 stage and to alfalfa, the plant is significantly different

as far as the animal is concerned. The R3 and R4 stage soybean have high forage quality from green leaves and much more

digestible stems. The R7 stage soybean has high forage quality

because of seeds in the pods while having fewer leaves and

much lower quality stems. Therefore, seed shatter during

harvesting at the R7 stage, resulting in loss of forage quality,

is a significant issue. Secondly, the high oil content of the

beans at the R7 stage may cause erratic fermentation in the

silo, reducing palatability and forage intake. Most of the

farmers surveyed had harvested the forage at the R3 to R4

stage.

Standing soybean forage at the R3 to R4 stage was generally at about 80% moisture and needed to be mowed and wilted to

dry down to 65% moisture for ensiling (Table 1). Farmers were

able to mow and condition with their standard

mower/conditioners, though they often needed to go

slower than normal. Farmers also noted that flail

conditioners caused more damage to the soybean than

roller conditioners. Drying time to 65% moisture

generally took 2 to 3 days in the late fall.

Forage yield averaged 1.5 ton/acre, ranging from 1.0 to 2.25

ton/acre. This is significantly less than many published reports

but reasonable when the soybean is stressed from drought or

late planting. Silage was made in oxygen limiting silos, plastic bags, and bunkers. Forage should be chopped with a 3/8-inch

theoretical length of cut for good packing. Silage produced by

the farmers surveyed was generally in the correct moisture

range (Table 1) and fermented well. Forage quality was similar

to alfalfa haylage as reported by others when soybean is

harvested at the R3 stage (2,4).

Some farmers mixed the soybean silage with other crops

including 3rd crop alfalfa, corn silage, sorghum-sudangrass,

and triticale. Alfalfa mixed with the soybean silage had no

effect on forage quality. Sorghum-sudangrass, corn silage,

and triticale all lowered the quality of the silage by reducing

crude protein content and increasing fiber content (data not

presented).

The farmer has the choice of mixing forages when ensiling

or ensiling forages separately and mixing them when feeding.

Forages should only be mixed at ensiling if the mixture will

have better fermentation characteristics (proper moisture, better

substrate for bacteria, etc.) than either silage alone. When

forages are mixed at ensiling, often one is not at the optimum

stage for ensiling which reduces overall silage quality and/or

yield. Further, ensiling the two forages separately, gives the

operator has more flexibility balancing the ration according to

needs of the animals being fed and quality of the ensiled

material.

Farmers generally fed the soybean silage as 15 to 20% of the ration. They were asked how animals consumed and performed

on soybean silage. Of the farms surveyed (Table 2), in only one

case was feed intake decreased. Thus, while soybean silage is

less palatable than alfalfa or corn silage, it can be used as

a significant portion of the ration without influencing animal

intake. There was no problem with sorting stems from leaves,

likely due to the fine chop used. Most importantly, in no case

was there any discernable difference in performance when

animals were fed soybean silage. Dairy cows are particularly

sensitive to their ration, so feeding soybean silage to other

category of animals should be no problem in a balanced ration. Some reports of feed intake problems may have been caused

by ensiling soybean at later stages, when high oil content from

the seed may have affected palatability.

In summary, making soybean silage may be a good

opportunity for farmers short of forage due to drought. The

following recommendations will provide successful soybean

silage experience:

Talk to your crop insurance adjuster before harvesting

any insured soybeans for forage to make sure that all

requirements for insurance are met.

Make sure any herbicides used on the soybeans are

cleared for feeding to cattle.

104

Harvest soybeans at R3 stage, when one of the four

top nodes with a fully-developed leaf has a 3/16-inch-

long pod.

Wilt forage to 35% dry matter before ensiling. Note:

producers felt soybean whole-plant moisture was

difficult to judge in the field, therefore testing is well

worth the expense.

Chop at 3/8-inch theoretical length of cut, pack well,

and seal in airtight, covered pile, tube, bunker, or

vertical silo.

Literature Cited

1. Fehr, W. R., and Caviness, C. E. 1977. Stages of soybean

development. Spec. Rep. 80. Iowa Agric. Home Econ. Exp.

Stn. Iowa State Univ., Ames.

2. Hintz, R., Albrecht, K. A., and Oplinger, E. S. 1992. Yield

and quality of soybean forage as affected by cultivar and

management practices. Agron. J. 84:795-798.

3. Munoz, A. E., Holt, E. C., and Weaver, R. W. 1983. Yield

and quality of soybean hay as influenced by stage of growth

and plant density. Agron J. 75:1457-148

4. Seiter, S., Altermose, C. E., Davis, M. H. 2004. Forage

soybean yield and quality responses to plant density and row distance. Agron J. 96:966-970.

5. Willard, C. J. 1925. The time of harvesting soybean for hay

and seed. Agron J. 17:157-168. Forage

Video on Late Season Drought Stress in Soybean

Shawn Conley, Soybean and Wheat Extension Specialist

Common issues growers may have concerning soybean yield

when affected by drought during late season growth are discuss

by Wisconsin State Soybean and Wheat Extension Specialist

Dr. Shawn Conley. In an R6 field, Shawn gives tips on what to

look for and harvest options when lack of precipitation is

severe.

Late Season Soybean Disease Update – August 27, 2013

Damon Smith, Field Crops Extension Pathologist, University

of Wisconsin-Madison

Several diseases have been popping up in soybean fields around the state over the past couple of weeks. White mold

(a.k.a. Sclerotinia stem rot) has become apparent in various

fields, along with the appearance of Sudden death syndrome,

and Phytophthora root and stem rot of soybean.

Wilting and plant death as a result of Sclerotinia stem rot.

Photo Credit: Craig Grau.

Got White Mold?…Revenge Sprays Don’t Pay

Now that symptoms of white mold are readily apparent in

many fields, questions have been flooding in about scouting

and spraying a fungicide. Scouting at this point only helps the grower/consultant make a record of where white mold is found,

so that good management decisions can be made it that field

the next time a soybean crop is planted there. At R4 and later

growth stages it is too late to spray for white mold.

Recent research published among the North Central Region

soybean pathologists show that the best time to apply a

fungicide is at R1 followed by the next best timing being at

R3. After R3 success declines rapidly. Remember too that the

“curative” ability of fungicides is very misleading. No

fungicide will “cure” any infection. Many of these simply

inhibit spore germination or disrupt mycelial development and don’t kill the fungus. Also, now that soybean canopies are

very thick it is very hard to get the fungicide down under the

canopy in contact with the fungus. All fungicides labeled for

soybean are contact fungicides (no movement into plant), local

penetrants (limited movement into the plant), or acropetal

penentrants that move only upward in the plant. Therefore, the

expectation of applying a fungicide to the upper foliage and it

moving down to the crown of the plant is

unreasonable. Earlier this season I published an disease

profile on white mold (pdf). View the profile to find a

summary of control recommendations along with other helpful

105

informational links. You can learn more about fungicides,

fungicide mobility, and fungicide mode of action by visiting

the Field Crop Fungicide page.

Interveinal necrosis and chlorosis of foliage are typical of

sudden death syndrome, and look similar to foliar symptoms of

brown stem rot.

Sudden death…That Sounds Bad

Actually it isn’t as sudden as the name sounds. Sudden

death syndrome (SDS) is actually a slow death, if death

actually occurs. SDS is caused by the fungus Fusarium

virguliforme. This fungus infects soybean roots very early in

the growing season and causes a root rot. It also produces a

toxin that is translocated up the vascular system of the plant,

which causes the characteristic interveinal (between veins) yellowing and browning of leaves. This symptom looks very

similar to Brown stem rot (BSR); so foliar symptoms alone

can’t be used to distinguish SDS from BSR. Plants should be

pulled and the roots and internal stem should be

inspected. Rotted root systems with NO BROWNING OF

THE PITH indicate SDS. Intact roots systems WITH

BROWNING OF THE PITH indicate BSR. Under extreme

cases of SDS leaves can curl and plants can wilt and

die. Conditions that favor SDS include high yield

environments and cool wet growing seasons, like we have had

this season.

Management for SDS is purely preventative. Resistant or

moderately resistant varieties should be planted in fields with a

history of SDS. Also, delaying planting a bit might also help

reduce the severity of SDS. No fungicide will be effective

against SDS and spraying a fungicide is not

recommended. Scouting is encouraged to make record of

where SDS was found in order to make SDS-management

decisions for future soybean crops.

To learn more about SDS, read or download the new UWEX

fact sheet on Sudden Death Syndrome.

Brown discoloration of a soybean stem as a result of infection by Phytophthora sojae. Photo Credit: Craig Grau.

Phytophthora Root and Stem Rot…Now That is a Funny

Name

While it can be a tongue twister to say, it can be a problem in

soybean fields in Wisconsin. Some fields have been identified

this season with Phytophthora root and stem rot caused by

Phytophthora sojae along with several fields where root rot

was observed on plants as a result of infection by a newly

described Phytophthora species, Phytophthora sansomeana

(see an earlier article about P. sansomeana). The Wisconsin

Department of Agriculture, Trade and Consumer Protection,

Plant Industry Bureau Laboratory recently completed a survey of 52 soybean fields around the state. In that survey P. sojae

was identified in 7 fields, while 5 fields were identified with P.

sansomeana. No Phytophthora was detected in the other 40

fields (See Map).

2013 DATCP Soybean Seedling Root Rot Survey. Data

courtesy of Anette Phibbs, Wisconsin DATCP.

In a similar survey performed in my laboratory we have also

found Phytophthora species causing root and stem rot on

soybeans only occasionally this season. This isn’t to say that

there aren’t fields with bad cases of Phytophthora root and

106

Follow us on

stem rot, but those fields will likely occur infrequently this

season.

Phytophthora root and stem rot is favored by saturated soil

and cool to moderate temperatures (58 F – 77 F). Fields that

are not well drained are more prone to the

disease. Management is purely preventative by choosing

varieties with resistance to P. sojae. There are several races of

P. sojae so it is important to choose a variety that has

resistance to the primary races in Wisconsin. Varieties with

the RPS 1K form of resistance work well in many fields in

Wisconsin. No foliar fungicides are effective against Phytophthora root and stem rot. However, fungicide seed

treatments can help reduce infection early in the season. Also

improving water drainage can help reduce damage by

Phytophthora species.

To learn more about Phytophthora root and stem rot in

Wisconsin, visit our Phytopthora root and stem rot of

soybean page, or download the new UWEX fact sheet on

Phytopthora (pdf).

Plant Disease Diagnostic Clinic (PDDC) Summary

Brian Hudelson, Ann Joy, Erin DeWinter and Joyce Wu, Plant

Disease Diagnostics Clinic

The PDDC receives samples of many plant and soil samples

from around the state. The following diseases/disorders have

been identified at the PDDC from August 17, 2013 through

August 23, 2013.

Plant/Sample Type, Disease/Disorder, Pathogen, County

FIELD CROPS,

Corn, Common Rust, Puccinia sorghi, Dane

Soybean, Dicamba Injury, None, Waupaca

Soybean, Root Rot, Pythium sp., Fusarium spp., Dodge, Fond

du Lac, Lafayette, Marathon, St. Croix

Soybean, Sudden Death Syndrome, Fusarium solani, Dodge

Soybean, Target Spot, Corynespora cassiicola, Fond du Lac

FORAGE CROPS,

Alfalfa, Aphanomyces Root Rot, Aphanomyces euteiches,

Dane

Alfalfa, Crown Rot, Fusarium spp., Dane

Alfalfa, Phytophthora Root Rot, Phytophthora sp., Dane

Alfalfa, Pythium Root Rot, Pythium sp., Dane

FRUIT CROPS,

Apple, Root/Crown Rot, Fusarium sp., Waukesha

Apple, Sphaeropsis Canker, Sphaeropsis sp., Waukesha

Cherry, Cherry Leaf Spot, Blumeriella jaapii, Shawano

Cherry, Powdery Mildew, Podosphaera clandestina, Shawano

Raspberry, Root/Crown Rot, Phytophthora sp., Dane

VEGETABLES,

Sweet Corn, Eyespot, Aureobasidium zeae, Green Lake

Tomato, Fusarium Wilt, Fusarium oxysporum, Will (IL)

Tomato, Late Blight, Phytophthora infestans, Sauk

For additional information on plant diseases and their control,

visit the PDDC website at pddc.wisc.edu.

New Video: White Mold in Soybean

Dr. Damon smith talks about white mold of soybean. For

every 10% increase in incidence of white mold, there can be up

to a 5 bushel per acre loss in yield. This makes white mold an important disease of soybean in the North Central soybean

growing region. The discussion here includes how to identify

white mold, details of the disease cycle, and how to manage the

disease. For more information about white mold visit the

Soybean Plant Health Topics webpage

at http://fyi.uwex.edu/fieldcroppathology/soybean_pests_diseas

es/ and scroll down to the “White Mold” section.

N:Wheat Price Ratio TablePrice of Wheat ($/bu wheat)

6.00 6.25 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75 9.00

Price

of N

($/lb

N)

0.450.500.550.600.650.700.750.800.850.900.951.00 Pr

ice of

N =

[$/to

n fer

tilize

r N x

(100

/ %

N in

ferti

lizer

)] / 2

000

0.050

0.075

0.100

0.125

This publication is available from the Nutrient and Pest Management (NPM) Program. web (ipcm.wisc.edu); phone (608) 265-2660; email (npm@hort.wisc.edu). NPM

The University of Wisconsin’s nitrogen (N) fertilizer guidelines for wheat allow growers to determine N application rates that provide maximum economic returns based on the cost of N and an antici-pated wheat price. To get an N rate for wheat, you must know the field’s soil group, previous crop and N:Wheat price ratio. For wheat following corn on loamy (sandy loam or finer textured) soils, the N rate can be further refined if a preplant soil nitrate test (PPNT) is collected. These guidelines (see other side of card) also provide a range of profitable N rates that are within $1/acre of the maximum return rate. For more information, see UWEX publication A2809 Nutrient Application Guidelines for Field, Vegetable, and Fruit Crops in Wisconsin.

ADDITIONAL GUIDELINES (see other side for specific guidelines): � When wheat follows a forage legume or leguminous vegetable, use the N rate for wheat following corn with a PPNT

less than or equal to 50 lb N/a and take the legume credit. � Manure N credits must be subtracted from the N rates. � No N is required on organic soils. � If 100% of the N will come from organic sources, use the top end of the range. � Reduce N rates by 10 lb N/a for spring wheat on all soils.

Funding provided by the Wisconsin Dept. of Agriculture, Trade & Consumer Protection. I-07-2013-2M

N:Wheat Price Ratio (see table on other side to determine ratios)

0.050 0.075 0.100 0.125

Soil Group Previous Crop PPNT (lb NO3- N/a) lbs N/acre (total to apply)11 On loamy soils with < 2% organic

matter, add 30 lb N/a to all rates. On soils with more than 10% organic matter, reduce rates by 30 lb N/a.

2 If the PPNT is < 50 lb N/a, use the top end of the profitable range; if the PPNT is 51 to 100 lb N/a, use the bottom end of the profitable range; if the PPNT is > 100 lb/a, no additional N is needed.

See other side for more guidelines.

LOAMY

Corn < 50 or no PPNT 75 70 60 5565 ------- 85 55 ------- 80 50 ------- 70 40 -------- 65

51 to 100 45 40 35 3035 ------- 55 30 ------- 50 25 ------- 40 20 -------- 35

> 100 0 0 0 00 ------- 0 0 ------- 0 0 ------- 0 0 -------- 0

Soybean, small grain All results2 or no PPNT 55 50 45 4045 ------- 65 40 ------- 60 35 ------- 50 35 ------- 45

SANDY All crops PPNT is not recommended on sandy (sand and loamy sand) soils.

105 100 90 8595 ------- 115 95 ------- 110 80 ------- 100 70 -------- 95

University of Wisconsin Nitrogen Guidelines for Wheat

Soil group

Soil test category

Very low (VL) Low (L) Optimum (O) High (H)Very high

(VH)Excessively

high (EH)

-------------------------------------------------- soil test K (ppm) ---------------------------------------------------

demand level 1: Corn grain, Soybean, Clover, Small grains (but not wheat), Grasses, Oilseed crops, Pasture

Loamy < 70 70–100 101–130 131–160 161–190 > 190

Sandy, Organic < 45 45–65 66–90 91–130 — > 130

demand level 2: Alfalfa, Corn silage, Wheat, Beans, Sweet Corn, Peas, Fruits

Loamy < 90 90–110 111–140 141–170 171–240 > 240

Sandy, Organic < 50 50–80 81–120 121–160 161–200 > 200

demand level 3: Tomato, Pepper, Brassicas, Leafy greens, Root, Vine, and Truck crops

Loamy < 80 80–140 141–200 201–220 221–240 > 240

Sandy, Organic < 50 50–100 101–150 151–165 166–180 > 180

demand level 4: Potato

Loamy < 80 80–120 121–170 171–190 191–220 > 220

Sandy, Organic < 70 70–100 101–130 131–160 161–190 > 190

To determine your soil test potassium (K) category:1) Choose the highest demanding crop in your rotation.2) Choose the soil group for the predominant soil in the field.3) Find your soil test category by using the analysis number for potassium from your soil test results.

This card can help you determine your soil test categories, which you will need when using the University of Wisconsin’s recommendations for P2O5 and K2O fertilizer ap-plication rates; there are different application rates for each of the soil test categories.

To get started, you will need your soil test results for P and K in parts per million (ppm) from a Wisconsin DATCP certified soil testing lab along with information about your crops and soils.

The goal of the UW soil testing and nutrient appli-cations guidelines pro-gram is to maintain soil test levels near optimum. This ensures maximum

If the desired crop is not listed on the table or you are unsure of your soil group, consult UWEX publication A2809 Nutrient Application Guidelines for Field, Vegetable, and Fruit Crops in Wisconsin’s tables 4.1 and 4.2.

Funding for this publication was provided by the Wisconsin Department of Agriculture, Trade & Consumer Protection (DATCP).

Soil group

Soil test category

Very low (VL) Low (L) Optimum (O) High (H)Excessively

high (EH)

----------------------------------------------soil test P (ppm)-----------------------------------------------

demand level 1: Corn grain, Soybean, Clover, Small grains (but not wheat), Grasses, Oilseed crops, Pasture

Loamy < 10 10–15 16–20 21–30 > 30

Sandy, Organic < 12 12–22 23–32 33–42 > 42

demand level 2: Alfalfa, Corn silage, Wheat, Beans, Sweet Corn, Peas, Fruits

Loamy < 12 12–17 18–25 26–35 > 35

Sandy, Organic < 18 18–25 26–37 38–55 > 55

demand level 3: Tomato, Pepper, Brassicas, Leafy greens, Root, Vine, and Truck crops

Loamy < 15 15–30 31–45 46–75 > 75

Sandy, Organic < 18 18–35 36–50 51–80 > 80

demand level 4: Potato

Loamy < 100 100–160 161–200 > 200

Sandy, Organic < 30 30–60 61–90 91–120 > 120

To determine your soil test phosphorus (P) category:1) Choose the highest demanding crop in your rotation.2) Choose the soil group for the predominant soil in the field.3) Find your soil test category by using the analysis number for phosphorus from your soil test results.

If the desired crop is not listed on the table or you are unsure of your soil group, consult UWEX publication A2809 Nutrient Application Guidelines for Field, Vegetable, and Fruit Crops in Wisconsin’s tables 4.1 and 4.2.

economic yield and pro-vides flexibility in nutrient management planning.

For soils that test greater than optimum, the objective of the nutrient application guidelines is to rely on the soil to supply the bulk of the nutrients needed for crop growth and to reduce the soil test level to optimum.

For soils that test less than optimum, the objective is to build-up soil test levels to the optimum category.

I-07-2013-2MNPM

This publication is available from the Nutrient and Pest Management (NPM) program.

web: ipcm.wisc.edu

phone: (608) 265-2660

email: npm@hort.wisc.edu