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Corn flea beetle and Stewart's wilt predictions for 2008

Mike Hoffmann & Jeffrey Gardner, Dept. of Entomology, Cornell University, Ithaca.

John Gibbons, Ontario Co.  CCE,

Keith Eggleston, Northeast Regional Climate Center

Stewart's wilt is an important disease of sweet corn in New York.  The disease is caused by a bacterial pathogen that is vectored almost exclusively by the corn flea beetle.  The bacteria overwinter in the gut of adult flea beetles.  In the spring, beetles infest early plantings of corn and transmit the pathogen to the plant by feeding and defecating on leaves.  Stewart's wilt is characterized by development of conspicuous streaks on the leaves and stalk due to plugging of vascular tissue.  Early wilt infections cause reduction of yield in susceptible varieties by reducing stands due to death or stunting of infected seedlings.  Seedlings, which survive early infections, remain stunted, tassel prematurely, and frequently produce no ears or nubbins.  Disease severity is aggravated by high temperatures, which causes faster development and movement of the bacteria through the infected plants.

Corn flea beetles spend the winter as adults near the soil surface in grassy areas in and around cornfields.  Severe winter temperatures can kill most of the population and result in a very low incidence of Stewart's wilt disease the following summer.  Thus, a winter temperature index is used to predict the likelihood of Stewart's wilt problems.  One forecast uses the number of months with mean temperatures above 24°F for December, January, and February.  The Stewart's wilt index (likelihood of wilt problems) is as follows:

Iowa State method

Number of months ³ 24°< F

Predicted risk

<0

Negligible

<1

Low to moderate

<2

Moderate to high

<3

High

   

2008 forecast:

The winter of 2007-2008 was generally mild, and the Iowa model predicts moderate to high risk throughout much of NY.  Risk maps can be accessed at http://www.nrcc.cornell.edu/grass/stewart_maps.html. The model does not account for the number of beetles entering the winter, the number of surviving beetles that actually carry the pathogen, or the effect of varietal susceptibility.  Despite these knowledge gaps the model has done well in predicting relative incidence of Stewart’s wilt.

Management options for Stewart's wilt disease control include:

1) planting resistant varieties

2) planting with treated seed for susceptible varieties

3) applying a foliar insecticide spray if needed to protect seedling corn.

Tabulated risk of Stewart’s wilt for many locations in NY:

     

Average °F

     

Station

County

Dec

Jan

Feb

IA Count

Risk

ADDISON

STEUBEN

29.0

27.8

24.5

3

High

ALBANY

ALBANY

27.8

27.6

26.2

3

High

Albion

ORLEANS

29.4

29.9

25.3

3

High

ALCOVE DAM

ALBANY

26.6

25.4

25.9

3

High

ANGELICA

ALLEGANY

26.5

26.1

22.5

2

Moderate to high

Appleton

NIAGARA

31.1

32.1

25.6

3

High

Arkport

STEUBEN

28.3

27.9

24.1

3

High

AUBURN

CAYUGA

28.3

27.8

25.8

3

High

BAINBRIDGE

CHENANGO

26.4

25.7

24.2

3

High

Batavia

GENESEE

27.9

28.5

23.6

2

Moderate to high

BATH

STEUBEN

28.2

27.3

23.8

2

Moderate to high

BINGHAMTON

BROOME

27.3

27.2

24.2

3

High

BLOOMINGBURG

SULLIVAN

29.4

29.3

28.7

3

High

BOONVILLE

ONEIDA

21.0

21.7

18.7

0

Negligible

Branchport

YATES

28.6

28.2

24.1

3

High

     

Average °F

     

Station

County

Dec

Jan

Feb

IA Count

Risk

BRIDGEHAMPTON

SUFFOLK

35.4

33.9

35.0

3

High

BUFFALO

ERIE

29.3

29.7

25.1

3

High

CANTON

ST. LAWRENCE

21.3

23.5

19.2

0

Negligible

CARMEL

PUTNAM

29.4

28.4

28.5

3

High

CHEMUNG

CHEMUNG

28.3

26.5

24.2

3

High

COBLESKILL

SCHOHARIE

25.7

26.2

24.5

3

High

CONKLINGVILLE

SARATOGA

26.3

22.9

22.4

1

Low to moderate

COOPERSTOWN

OTSEGO

26.2

25.9

23.9

2

Moderate to high

CORNING

STEUBEN

25.9

25.2

21.3

2

Moderate to high

DANSVILLE

LIVINGSTON

29.7

29.0

26.1

3

High

DELHI

DELAWARE

25.4

23.7

23.5

1

Low to moderate

DELTA DAM

ONEIDA

26.0

25.5

21.6

2

Moderate to high

Dresden

YATES

27.3

25

25

3

High

DUNKIRK

CHAUTAUQUA

32.0

31.2

27.0

3

High

EAST JEWETT

GREENE

25.1

23.2

23.3

1

Low to moderate

EAST SIDNEY

DELAWARE

26.3

25.0

24.4

3

High

Elba

GENESEE

26.5

27.2

26.1

3

High

ELLENBURG DEPOT

CLINTON

19.7

21.1

19.0

0

Negligible

ELMIRA

CHEMUNG

28.5

28.3

25.3

3

High

FARMINGDALE

SUFFOLK

36.4

34.5

34.9

3

High

FRANKLINVILLE

CATTARAUGUS

26.1

25.1

21.8

2

Moderate to high

Fredonia

CHAUTAUQUA

32

31

22.6

2

Moderate to high

Freeville

TOMPKINS

28.8

28.7

26.5

3

High

Friend

YATES

28.6

28.5

23.1

2

Moderate to high

FULTON OSWEGO

OSWEGO

27.6

28.2

24.3

3

High

Gainesville

WYOMING

26.8

26.4

25.1

3

High

Geneva

ONTARIO

28.8

29.2

22.4

3

High

GLENS FALLS

WARREN

24.9

22.2

21.8

1

Low to moderate

GRIFFISS AFB

ONEIDA

25.9

26.5

24.1

3

High

Groveland

LIVINGSTON

29.7

30

25.5

3

High

HIGHMARKET

LEWIS

18.7

19.2

16.0

0

Negligible

Himrod

YATES

30.3

30.3

25.8

3

High

HONEOYE

ONTARIO

29.0

28.6

25.4

3

High

HOOKER

LEWIS

22.6

23.5

19.8

0

Negligible

HORNELL

STEUBEN

26.3

25.4

23.5

2

Moderate to high

INDIAN LAKE

HAMILTON

21.0

20.5

17.9

0

Negligible

ISLIP

SUFFOLK

35.1

33.8

34.0

3

High

Ithaca

TOMPKINS

29.1

28.2

26.5

3

High

JAMESTOWN

CHAUTAUQUA

29.0

27.5

23.7

2

Moderate to high

Lansing

TOMPKINS

30.2

30.1

24.6

3

High

LANSING MANOR

SCHOHARIE

27.3

27.9

26.4

3

High

LITTLE FALLS

HERKIMER

26.1

25.2

22.4

2

Moderate to high

LOCKE

CAUYGA

24.5

24.0

23.0

2

Moderate to high

Lockport

NIAGARA

30.3

30.6

26.4

3

High

LOWVILLE

LEWIS

22.9

23.4

18.6

0

Negligible

MALONE

FRANKLIN

19.5

22.0

18.9

0

Negligible

MASSENA

OTSEGO

20.3

21.3

18.0

0

Negligible

MECKLENBURG

SCHUYLER

26.7

26.7

23.2

2

Moderate to high

MONTGOMERY

ORANGE

30.1

29.1

27.7

3

High

MORRISVILLE

MADISON

24.6

24.8

22.3

2

Moderate to high

NEW ALBION

CATTARAUGUS

26.9

25.2

21.8

2

Moderate to high

NEWCOMB

ESSEX

19.6

18.1

16.8

0

Negligible

NORWICH

CHENANGO

25.8

26.2

24.1

3

High

     

Average °F

     

Station

County

Dec

Jan

Feb

IA Count

Risk

OCEANSIDE

NASSAU

36.1

35.0

35.1

3

High

OLD FORGE

HERKIMER

21.8

21.4

17.5

0

Negligible

OLEAN

CATTARAUGUS

28.4

27.7

24.2

3

High

ONEONTA

OTSEGO

28.6

28.7

26.6

3

High

Pavilion

GENESEE

26.4

27.6

25.6

3

High

PENN YAN

YATES

29.7

28.9

26.4

3

High

PISECO

HAMILTON

22.2

19.1

16.9

0

Negligible

PLATTSBURGH

CLINTON

23.3

23.3

21.7

0

Negligible

Potter

YATES

28.3

28.5

23.5

3

High

POUGHKEEPSIE

DUTCHESS

32.1

30.8

30.5

3

High

Prattsburg

STEUBEN

26.9

26.7

25.1

3

High

Pulteney

STEUBEN

28.3

28.7

23.1

2

Moderate to high

Red Hook

DUTCHESS

31.3

30.3

24.4

3

High

RHINEBECK

DUTCHESS

28.4

26.5

27.3

3

High

ROCHESTER

MONROE

29.3

30.4

26.4

3

High

SARANAC

FRANKLIN

18.6

18.5

15.4

0

Negligible

Scriba

OSWEGO

26.8

28.6

28.8

3

High

SHERBURNE

CHENANGO

26.2

25.7

24.7

3

High

BROOKHAVEN

CHENANGO

35.4

33.4

33.6

3

High

SLIDE MTN

ULSTER

23.8

22.9

22.7

0

Negligible

Sodus

WAYNE

28.2

28.8

25.1

3

High

STUYVESANT

COLUMBIA

28.3

28.0

27.4

3

High

SYRACUSE

ONONDAGA

27.9

29.5

25.7

3

High

THURSTON

STEUBEN

28.3

27.3

23.4

2

Moderate to high

TROY

RENSSELAER

28.4

29.3

27.0

3

High

TUPPER LAKE

FRANKLIN

19.5

21.1

16.0

0

Negligible

WALES

ERIE

27.2

26.8

22.6

2

Moderate to high

WARSAW

WYOMING

25.3

24.2

20.5

2

Moderate to high

WATERTOWN

JEFFERSON

25.2

27.0

20.8

2

Moderate to high

WAVERLY

TIOGA

29.8

29.0

25.9

3

High

Wayland

STEUBEN

27.7

27.6

23.9

2

Moderate to high

WELLSVILLE

ALLEGANY

27.6

26.4

22.8

2

Moderate to high

WELLSVILLE

ALLEGANY

29.0

28.0

24.6

3

High

WEST POINT

ORANGE

32.5

31.1

30.8

3

High

WESTCHESTER

WESTCHESTER

33.4

32.9

32.2

3

High

WHITEHALL

WASHINGTON

18.9

23.4

22.4

0

Negligible

WHITNEY POINT

BROOME

26.6

27.0

24.2

3

High

Williamson

WAYNE

29.2

29.9

25.8

3

High

YOUNGSTOWN

NIAGARA

30.4

30.2

25.6

3

High

* Stations in lower case represent Network for Environment and Weather Awareness (NEWA) stations.