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Eastern New York Field Crops Pest Report, 2003

For 8/8/03:

Alfalfa

General Crop Condition
Alfalfa was 12 to 16 inches at the SUNY Cobleskill farm this week (August 5).

Potato Leafhopper
Some of the TAg field scouts are reporting that potato leafhopper infestations declined this week. This might be from the heavy rain and thunderstorms we have been having. A heavy rain or thunderstorm can reduce a population of potato leafhoppers in an alfalfa field. You really need to check the infestation after a heavy rain or thunderstorm to make sure.

For more information, see Potato Leafhopper on Alfalfa Management Guide, 302k pdf file

Picture of potato leafhopper

Field Corn

General Crop Condition
Field corn at the SUNY Cobleskill farm was starting to pollinate this week (August 5).

Corn Rootworm
A few counties have reported fields over threshold for corn rootworm (CRW). Some of the corn plants have the classic goose neck symptoms of corn rootworm feeding.

Scouting Tip
Remember, when taking beetle counts you are monitoring to assess the potential that CRW's will lay enough eggs in the field to cause damage to next year's corn crop. Taking beetle counts is important but make sure you stop to check a portion of the female western CRW's for the actual presence of eggs. Squeeze the abdomens of the yellow and black striped CRWs and look for the small yellow - white eggs. It takes CRW about three weeks from the time the adult beetles emerge from the soil and mate until the time the females are gravid. In this time period you may find high CRW numbers in a field but since the females are not yet capable of laying eggs they are not causing an economic problem. This is the reasoning behind sampling the same field 2-3 times before making the management decision. Being pollen feeders and highly mobile, CRW's may relocate to another pollinating field during the 3 week period. Comparing the two types of fields, the second field is at greater risk from subsequent CRW damage since females (and their eggs) will have matured and are ready for deposit.

When is the best time to control corn rootworm if a field exceeds the action threshold?

  • The following year!

    If there is a field over the action threshold what are the options for control next season?

  • The best option to control corn rootworm is crop rotation. Corn after corn is prime habitat for corn rootworm and will increase infestations from year to year.

  • Crop rotation is not always possible so ....... The second management option is the use of a soil-applied insecticide at planting. To select an insecticide registered for corn rootworm, please consult the Cornell Guide for Integrated Field Crop Management.

  • Additional CRW management technologies may be available for use during the 2004. Check with your seed supplier about the availability of CRW insecticide treated seed and / or CRW active Bt hybrids

How to Monitor for Corn Rootworm

Barley

Powdery mildew
Franklin County reports a very heavy infection of powdery mildew on malting barley. Powdery mildew appears as a dusty white to gray coating over leaf surfaces.

Powdery Mildew Fact Sheet

Picture of Powdery Mildew on Barley

Soybeans

Soybean Aphid
High populations of soybean aphids, in excess of 1000 per plant, have been reported in some soybean fields in central NY. If anyone in Eastern York is scouting soybeans and discovers soybean aphids I would like to report the levels you might be observing in fields.

Sclerotinia stem rot/white mold
As soybean fields continue growing and canopies begin to close keep on the lookout for sclerotinia stem rot/white mold caused by Sclerotinia sclerotiorum. Field symptoms include isolated patches of stunted, yellow or lodged plants. A fluffy white mycelium can be found on the lower stem and surrounding ground. Small black pellet-like sclerotia may also be present on or in affected stems or on the mycelium. Affected stems will be soft and mushy at infection site.

See next week's report for fall weed considerations!

Do you know the number of growing degree-days in your region today?
Check this website: NEW YORK GROWING DEGREE-DAY TRACKER
(Base Temp. 50F)

Contributors to this week's pest report!
Jeff Miller (Oneida County)
Beth Spaugh (Clinton County)
David Norton (TAg Scout: Chenango, Fulton, Montgomery, Herkimer, Otsego, Madison, Oneida Counties)
Kevin Ganoe (Chenango, Fulton, Montgomery, Herkimer, Otsego Counties)
Richard Gast (TAg Scout: Franklin County)
Jonathan Wisbeski (Orange County)
Keith Waldron (NYS Field Crops and Livestock IPM Coordinator)
Ken Wise (Eastern New York)

Happy Scouting!
Ken Wise