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Eastern New York Field Crops Pest Report, 2002

For 6/24/02:

Alfalfa

Alfalfa Weevil: SUNY Cobleskill alfalfa fields were 6 to 20 inches tall. Alfalfa weevil tip feeding ranged from 40 to 60% percent on re-growth in 5 fields (June 20). While one of these fields was over threshold, larvae were starting to pupate. The 4th instar larvae spins a fibrous pea-sized net cocoon and then transforms itself into pupae. Cocoons can be found on the plant where you see leaves pulled together. Open these leaf bundles up and you can often find the cocoon. When pupation begins this means tip feeding will soon end. If there is a mixture of larval sizes, watch and monitor the field closely because the smaller larvae will pupate later that the larger ones.

Jeff Miller (Oneida County) reports a field over threshold for alfalfa weevil (June 19).

Check out our on-line publication, IPM for Alfalfa Weevil. 1.2 Mb pdf file

Potato Leafhopper: I found low to moderate levels of potato leafhopper in 6 alfalfa fields at the SUNY Cobleskill farm this week (June 20).

Check out our on-line publication, Potato Leafhopper Management in Alfalfa

Damsel Bugs: I found several damsel bugs while looking for potato leafhopper this week (June 20). Damsel Bugs eat small eggs of insects as well as aphids and mites in many crops. This insect uses a needle like mouth-part to insert into its prey and suck out the insides. They are slender, often yellowish-brown and about 8 -12 mm (3/8 to 1/2 inch) long. The wings lie flat across the back, crossing at the tips. The abdomen is slightly swollen and the body tapers toward a narrow, elongated head. The adult female inserts white eggs into the stem of the plant --only the egg cap shows. Damsel Bug nymphs resemble wingless adults in shape and color. Be a little careful with damsel bugs because they are predators and can give a painful bite to big and small alike.

Grass & Pasture

True Armyworm: Lisa Fields, (Schoharie County) and Kevin Ganoe (Chenango, Fulton, Herkimer, Montgomery and Otsego Counties) report low to moderate captures of true armyworm moths (June 19 and 21).

Aaron Gabriel, (Washington County) reports finding a few armyworms in grass fields. He has not seen damage to grasses (June 19).

Last week's Mystery Larvae Revealed: The pictures I sent with last week's report were SAWFLY larvae found in a hay field. Sawfly is not an economic pest in grasses. Jeff Miller (Oneida County) found the larvae and provided the pictures. See attached photos.

Field Corn

Black Cutworm: Aaron Gabriel, (Washington County) reports significant cutworm damage in field corn (June 19).

For more information on Black Cutworm in Field Corn, check out our on-line publication (912k pdf file).

Seed Corn Maggot: Aaron Gabriel, (Washington County): As Aaron states, ;seed corn maggot took out almost every seedling in one part of a cornfield where manure was applied more heavily than the rest of the field. Seed corn maggot is attracted to heavily manured fields and fields with high organic matter. What percent of your growers used a seed treatment when planting corn this season?

For more information on ;Early Season Field Corn Insect Pests check out our on-line publication http://www.nysipm.cornell.edu/publications/early_insects.pdf

Yellow Nutsedge: There were large infestations of Yellow Nutsedge in several cornfields at the SUNY Cobleskill farm (June 2O). So is yellow nutsedge a grass? No, it is sedge!
Grasses have narrow leaves with parallel veins, one cotyledon, stem is round or flattened and hollow, while a sedge has narrow leaves with parallel veins, one cotyledon, stems triangular, and are solid inside. If you look at nutsedge roots you can generally find little tubers called nutlets. A good rule of thumb is: Sedges have edges, and yellow nutsedge has a three-sided stem.

For more information on Weeds in Corn check out our on-line publication.

Happy Scouting!