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NY Weekly Field Crop Pest Report, 2005

June 2, 2005 Volume 4 Number 7

1. View from the Field

2. A Soybean Seed Rot and Seedling Blight

3. Black Cutworm In Corn

4. Wireworms in Corn?

5. How “Grubby” are Your Corn Fields?

6. Growing Degree Days in NYS

7. Clipboard Checklist

8. Contact Information

View From The Field

Eastern NYS

Ken Wise

Western NYS

Julie Stavisky

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I’ve seen several 1st & 2nd and a few 3rd instar alfalfa weevil larvae this week at the Valatie research farm. Tip feeding was at about 10 percent. The winter grains looked great.

At the SUNY Cobleskill Farm there was alfalfa weevil in the 1st and 2nd larval instars. They are feeding second cutting alfalfa and tip feeding was at 10 to 20 percent. I have not discovered any potato leafhoppers in alfalfa yet this year on any farm.

In the southern tier, corn that was planted in mid-May is up and growing. As Nate Herendeen (NWNY Team) and others have observed in other locations, corn is not very green yet. There were no significant stand reductions from insects, although we did track down a renegade wireworm larva. The growers there, like elsewhere in the state, are becoming increasingly concerned about damage to corn stands from geese. Stay tuned for more details next week.

Throughout the Finger Lakes region, at least half of the alfalfa fields I’ve observed have been cut. We’re going to have to watch the new growth carefully for alfalfa weevil.

Nancy Glazier (NWNY Team) and I observed soybean aphids on buckthorn plants at the Cornell research farm in Aurora. They were not the winged forms, so they might be staying put for a while before they head for soybean plants.

Soybean Seed Rots and Seedling Blight

Ken Wise, NYS IPM

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Many different organisms cause seed rot and seedling blights. Most of these organisms are soil-borne and a few are seed-borne. Most seed rots and seedling blights proliferate in poorly drained, cold (less than 58 degrees) and wet soils.

Seed Rot: Many times the infected seed will not germinate. If the seed does germinate the radicle will become infected and rot. The rot can be tan, brown, gray or black and the seed or radicle will appear wet and mushy. Some of the organisms that infect seed are Pythium, Fusarium, and Rhizoctonia.

Seedling blight: It is difficult to determine which pathogen causes seedling blight in any one field. Many times it can be a complex of Pythium, Rhizoctonia and Phytophtora. Pythium can cause the seedlings to have a wet, rotted appearance, while Phytophtora generally appears as a dry, dark rot on the roots. Sunken, reddish-brown lesions on the hypocotyls are most likely a Rhizoctonia infection. The Rhizoctonia lesions are small when they first appear. As these lesionsgrow they cangirdle the stem, causing the soybean plant to die. If the Rhizoctoniainfected seedlings do not kick the bucket the infection will weaken the stem and may cause the plant to lodge after the pods form.

Black Cutworm in Corn

Julie Stavisky, NYS IPM

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Are we likely to have severe cutworm problems this year? Many of the insects that migrate northwards have not been observed so far this spring. Our neighbors in the Midwest, including Ohio and Indiana, have seen very low numbers of adult cutworms in traps. Visit our online publication, Black Cutworm in Field Corn to review the scouting and management procedures.

Wireworms in your corn?

Ken Wise, NYS IPM

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Wireworms are the larval forms of click beetles. Adults are brown to black, bullet-shaped, hard-shelled beetles, about 1.5” long. The larvae are hard, smooth, slender, yellow to reddish-brown, wire-like worms varying from .5” to 1.5” long. Wireworm can be a problem in 1st year corn after sod but, depending on the species, may continue for 2 - 6 years. Wireworms feed on seed and roots of corn. Symptoms are hollowed-out seed at germination and missing, wilted, or stunted seedlings. If losses due to wireworm are severe, consider practicality of replanting (disk and treat the field with a soil insecticide at replanting). For more information checkout Early Season Insect Pests of Corn.

How “Grubby” are your corn fields?

Ken Wise, NYS IPM

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White grubs are the larval forms of Japanese beetles, May or June beetles, or European chafers which are all types of scarab beetles. White grubs are thick, white soft-bodied larvae about 1/4" to 1" long, and curl into a C-shape when disturbed. White grubs are normally a problem in 1st year corn after sod, feeding on the roots of corn plants. Symptoms are gaps in cornrows at time of emergence and wilted, or stunted seedlings. There are no control measures for white grub and they are seldom an economic problem in New York field corn production. For more information checkout Early Season Insect Pests of Corn.

Growing Degree Days in NYS

Keith Waldron, NYS IPM

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March 1 - May 31, 2005

Location

Base 48 F

Base 50 F

Batavia

246 

184

Chazy

122.6*

79.3*

Clifton Park

372.8* 

281.6*

Geneva

248.4*

183*

Ithaca

215

153.8

Mexico

187.6*

133.2*

Prattsburg

193.8

140.9

*Missing data
Source: http://newa.nysaes.cornell.edu/base5005.htm

Clipboard Checklist

Keith Waldron, NYS IPM

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General:
-Update field records: variety, planting date/rate, pesticides used,
nutrient inputs including manure, other important field observations, etc.
-Is hay harvesting equipment ready to go?
-Note any repairs to corn planters, other spring machinery, and
harvesting equipment as they are cleaned and lubricated.
- Repair forage harvest equipment as needed

Pest Monitoring Priorities:
Alfalfa:

-alfalfa weevil, weevil cocoons present?, weeds, crown rot, leaf spot diseases

Small Grain Cereals:
-Winter Wheat: Cereal leaf beetle, virus diseases, weeds, powdery mildew
-Spring Grains: Cereal leaf beetle, seedling diseases, weeds

Field Corn:
-Monitor corn for weeds, note presence of triazine resistant annual
broadleaf weeds. Cultivate or treat if necessary.
-Check corn emergence, take stand counts/plant populations, check for signs of damping off / seedling blights, seed corn maggot

Contact Information

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Julie Stavisky:IPM Area Educator, Livestock and Field Crops, Western NY
Phone: (315) 331-8415
Fax: (315) 331-8411
Email: js38@cornell.edu

Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Phone: (315) 787 - 2432
Fax: (315) 787-2360
Email: jkw5@cornell.edu

Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock
Phone: (518) 434-1690
Fax: (518) 426-3316
Email: klw24@cornell.edu