View
0
Download
0
Category
Preview:
Citation preview
Wheat Diseases and Their Control in a No-till Management System
Bob Hunger
Extension Wheat Pathologist
Oklahoma State University
Low- or no-till affects impacts disease incidence/severity via increased residue
on soil surface that affects pathogen inoculum and/or alters the soil
environment (moisture/temperature)
Photo credit: Oklahoma Conservation Commission
The Disease Triangle
Courtesy of J.P. Damicone
Some Diseases – No or little effect
Courtesy Dr. Stephen Harrison, LSU
Stripe rust Loose smut
Common bunt WSMV
Leaf rust
Courtesy Dr. Jeff Edwards, OkSU
WSBM & WSSMV
Aphids:Barley Yellow Dwarf Virus
Aphids:BYDV Decreased disease Increased residue is less attractive to aphids
Photo credit: extension.entm.purdue.edu
ROOT DISEASES Strawbreaker foot/root rot is decreased due
to residue inhibiting spore dispersal to seedlings
Strawbreaker foot root (eyespot)
ROOT DISEASES Dryland root rot is decreased because the soil
environment becomes more cool and moist
Dryland root rot caused by Fusarium
Courtesy of Dr. B. Bowden, USDA-ARS, Manhattan, KS
ROOT DISEASES Sharp eyespot (Rhizoctonia root rot) and
Pythium root rot are increased due to the soil environment becoming more cool/moist &
inoculum is increased
Sharp eyespot caused by Rhizoctonia
Poor seedling stand due to Pythium root rot
Take-all root rot is increased because the soil environment becomes more cool/moist & inoculum is increased
Take all root rot
% GC 14 DAP
% GC 31 DAP
% GC 45 DAP0
10
20
30
40
50
60
70
80
90
Effect of seed treatments on ground cover in Oklahoma in 2009
Drs. Jeff Edwards & Hunger, OkSU
% G
rou
nd
co
ver
*
*
Kingfisher 2008
Cherokee 20080
10
20
30
40
50
60
70
UntreatedRaxil
Gaucho XT
Yield response to Raxil and Gaucho seed treatments in Oklahoma in 2008
Dr. Jeff Edwards, OkSU
Yie
ld (
bu
/acre)
*
Powdery mildew
Foliar Diseases: Powdery Mildew
Powdery mildew
Increased disease Increases pathogen inoculum
FOLIAR DISEASES Septoria leaf & Stagonospora glume blotch
Septoria leaf & Stagonospora glume blotch
Increased disease Increased pathogen inoculum
Septoria leaf blotch – note “pycnidia” (black specks) Stagonospora glume blotch
Foliar Diseases Tan Spot
Resting bodies on straw Lesions on leaves
Tan spot Increased disease Increases pathogen inoculum
Fungicide applied
No fungicide0
10
20
30
40
50
60
70
Percentage (%) tan spot severity as affected by management practices,
cultivars, & fungicide
Carignano, et al. 2008. Agron. J. 100:145-153
2145 = Susceptible Overley = moderately resistant
% t
an
sp
ot
severit
y
Crop Rotation is helpful with No-till
• If do not rotate crops in a no-till system, there likely will be problems over time with tan spot, septoria, powdery mildew, etc
•Even with rotation, a disease such as Fusarium head blight can occur in a wheat-corn rotation
Fusarium head blight (aka scab) Photo credit: Oklahoma Conservation Commission
Plow
Chisel
No-till
0
200
400
600
800
1000
1200
1400
1600
Effect of wheat-sorghum rotation on tan spot severity
Bockus & Claassen. 1992. Agron. J. 100:145-153 A
UD
PC
m
easu
re o
f t
an
sp
ot
severit
y)
Plow
Chisel
No-till
0
5
10
15
20
25
30
35
40
Effect of wheat-sorghum rotation on wheat yield
Bockus & Claassen. 1992. Agron. J. 100:145-153
Wh
eat
yie
ld (
bu
/acre)
Wheat Foliar Fungicides in Oklahoma (Not all are yet labeled for use on wheat)
Rate PHIA Product (oz/A) (days/GS) TRIAZOLE Tilt – Syngenta 4 10.5 Alto – Syngenta 3.0-5.5 30 Folicur – Bayer CropScience 4 30 Prosaro – Bayer CropScience 6.5-8.2 30 STROBILURIN Headline - BASF 6.0-9.0 10.5 Evito – Arysta LifeScience 2-4 40 Aproach – DuPont 6-12 45, 14, 7/10.5 straw, hay, forage MIXTURES Quilt - Syngenta 14 45/10.5 Quilt Xcel - Syngenta 10.5-14 30 Stratego – Bayer CropScience 10 35 Stratego YLD – Bayer CropScience 4 35 TwinLine – BASF 7-9 30/10.5 Priaxor – BASF ?? ?? PYRAZOLE – AMIDE &/or MIXED Vertisan - DuPont ?? ?? APHI = pre-harvest interval; number of days required between last application & harvest
This information is provided only as a guide. It is the responsibility of the pesticide applicator by law to read and follow all current label directions. No endorsement is intended for products listed, nor is criticism meant for products not listed.
Generics are available for Tilt and Folicur
Split Application of a Fungicide – on
spring wheat in North Dakota
Yield increases of 2-7 bushels IF environment favorable for disease; greater return if have wheat stubble present and the it is a susceptible variety
Dr. Marsha McMullen, North Dakota St. Univ
Split Application of a Fungicide
4-5 leaf
Stage =
Feekes 2
Tillering
stage
Dr. Marsha McMullen, North Dakota St. Univ
0
10
20
30
40
50
60
70
80
PM
LR
Wheat Disease Control with Fungicides - 2011
Fungicides -applied on 16-Mar* (GS 6), 05-Apr** (GS9), & 12-Apr (GS 10.1) -PM rated on 01-Apr; LR rated on 19-May
Dis
eas
e S
eve
rity
(%
) P
M=p
ow
de
ry m
ildew
L
R=l
eaf
ru
st
A A A
A A A
B
B
B
B
B B
B
A
A
B
48
50
52
54
56
58
60
62
64
66
Yield
TW
2011 Wheat Disease Control using Fungicides Y
ield
(b
u/A
) &
te
st w
eig
ht
(lb
/bu
)
Fungicides applied on 16-Mar* (GS 6), 05-Apr** (GS 9) and 12-Apr (GS10.1) BUT for Hdline FB Twinline, it was a half rate of Twinline
A
A A A
A
For TW – no differences between fungicides
B B
B
Summary of Effects of Tillage on Wheat Diseases
•No- or low-till increases residue that affects disease by:
-increasing pathogen inoculum
-altering the soil environment (cooler, more moist soil)
•Rotate crops and have a plan for the rotation
-generally a rotation to a legume is best
•Consider reactions of varieties to diseases
-e.g., a variety with some resistance to tan spot, septoria, etc.
•Use a seed treatment to help stand establishment
•Use fungicide to help with foliar disease control,
especially in continuous wheat
Recommended