Disease Management in No-till Wheat...

Dr. Bob HungerState Extension Wheat Pathologist

405‐744‐[email protected]

Department of Entomology & Plant Pathology

127 Noble Research CtrOklahoma State University

Bob HungerExtension Wheat PathologistOklahoma State University

Disease Management in No-till Wheat Systems





• Regulatory; quarantine, inspections, etc• Physical; temperature, radiation, etc• Biological; use one organism to control another

• Genetic; genetic resistance• Cultural; planting date, crop rotation,

tillage/residue management• Chemical; seed treatments to facilitate

stand establishment & foliar fungicides to help protect existing yield potential

Many methods are available to manage wheat diseases





Disease Control - Genetic Resistance

Soilborne mosaic resistant

Soilborne mosaic susceptible





Disease Control – CulturalPlanting Date

Late planted wheat

Early planted wheat – total loss due to

wheat streak mosaic & high plains

C. Rush, Texas A&M





No-till 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





Effect from No-till & Increased ResidueTan spot – Septoria – Powdery mildew





Some Diseases – No or little effect

Leaf rust

Loose smut

WSBM & WSSMV

WSMVCommon bunt

Courtesy Dr. Jeff Edwards, OkSU

Stripe rust

Courtesy Guy Padgett, LSU





Photo credit: extension.entm.purdue.edu

No-till (high residue) decreases incidence/severity of some diseases such as barley yellow dwarf

Increased residue is less attractive to

aphids that transmit BYDV





Strawbreaker foot/root rot (eyespot) is decreased due to residue inhibiting spore

dispersal to seedlings





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 DISEASESSharp 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 Pythiumroot rot





Sharp eyespot caused by Rhizoctonia Poor seedling stand due to Pythium root rot

Sharp eyespot (Rhizoctonia root rot) and Pythium root rot are increased due to the soil

environment becoming more cool/moist & inoculum is increased





Take-all root rot is increased because the soil environment becomes more

cool/moist & inoculum is increased





Effect of seed treatments on ground cover in Oklahoma in 2009

% GC 14 DAP% GC 31 DAP

% GC 45 DAP0

102030405060708090

% G

rou

nd

cov

er

Drs. Jeff Edwards & Hunger, OkSU





Yield response to Raxil and Gaucho seed treatments in Oklahoma in 2008

Kingfisher 2008

Cherokee 20080

20

40

60

80

Untreated RaxilGaucho

XT

Yie

ld (

bu

/ac

re)

Dr. Jeff Edwards, OkSU





Powdery mildew, tan spot, and Septoria are increased because inoculum from wheat residue

Powdery mildewSeptoria leaf

blotch

Tan spot





Tan spot severity as affected by management practices, cultivars, & fungicide

Fungicide appliedNo fungicide

0

20

40

60

80

2145 = SusceptibleOverley = Moderately Resis

% t

an s

pot

sev

erit

yCarignano, et al. 2008. Agron. J. 100:145-153





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)





Wheat-Sorghum Rotation Affects Tan Spot Severity

Plow

Chisel

No-till

0200400600800

1000120014001600

AU

DP

C

mea

sure

of

tan

sp

ot s

ever

ity)

Bockus & Claassen. 1992. Agron. J. 100:145-153





Wheat-Sorghum Rotation Affect on Yield

Plow

Chisel

No-till

05

10152025303540

Wh

eat

yiel

d (

bu

/ac

re)

Bockus & Claassen. 1992. Agron. J. 100:145-153

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 10.5Alto – Syngenta 3.0-5.5 30Folicur – Bayer CropScience 4 30Prosaro – Bayer CropScience 6.5-8.2 30

STROBILURINHeadline - BASF 6.0-9.0 10.5Evito – Arysta LifeScience 2-4 40Aproach – DuPont 6-12 45, 14, 7/10.5

straw, hay, forage

MIXTURESQuilt - Syngenta 14 45/10.5Quilt Xcel - Syngenta 10.5-14 30Stratego – Bayer CropScience 10 35Stratego YLD – Bayer CropScience 4 35TwinLine – BASF 7-9 30/10.5Priaxor – BASF ?? ??

PYRAZOLE – AMIDE &/or MIXEDVertisan - 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





Effect from No-till & Increased ResidueTan spot – Septoria – Powdery mildew

Split Application of a Fungicide – on spring wheat in North Dakota

Yield increases of 2-7 bushels IF environmentfavorable 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 leafStage = Feekes 2

Tillering stage

Dr. Marsha McMullen, North Dakota St. Univ





0

20

40

60

80

100

120

No Fung Avg 4 SA Avg 20 others

PMLR32DAALR38 DAA

Disease Severity

(%)

PM=p

owde

ry m

ildew

LR=

leaf ru

st

2015 Split Application Fungicide for WheatDisease Control

‐Fungicides applied on 10‐Apr (GS 10)‐PM rated on 29‐Apr‐LR read on 12‐May (32DAA) and 18‐May (38DAA)





0

10

20

30

40

50

60

70

80

90

100

No fungicide Avg 4 SA Avg 20 others

YieldTW

2015 Split Application Fungicide for Wheat Yield & TW

Yield (bu/A) & TW (lb/bu

)‐TW no difference between SA & boot‐Yield from SA treatments averaged 8% greater





YearApplication

typeYield (bu/ac)

TW (lb/bu) Yield increase

2015Split applcn (4) 88 59.8

8%Other (20) 81 59.6

2014Split applcn (4) 57 59.3

7%Other (17) 53 57.9

2013Split applcn (3) 88 61.7

1%Other (17) 87 61.2

Increase in Yield & TW from Split Fungicide Application





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 manage foliar diseases, especially

in continuous wheat

Disease Management in No-till Wheat...

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