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Eastern New York Field Crops Pest Report, 2004

This is a seasonal scouting report giving growers in the Eastern New York area information on the presence of agricultural pests. The report is written by Ken Wise, IPM Extension Area Educator for Livestock and Field Crops.

August 3, 2004

SOYBEANS

Soybean Aphid Found in Eastern NYS

Soybean aphids (SBA) have been found in Eastern NYS. While the infestation might be low these aphids have the potential to develop quickly. The good thing is there are many naturally occurring beneficial organisms that help control SBA. One family of beneficial organisms that are found in abundance in soybeans are Lady Beetles (Coccinellidae).  Both the larval and adult stages of lady beetles feed on aphids. I have observed an abundance of 3 different species of lady beetles in soybeans this year (note: there are several other species of lady beetles that feed on soybean aphids).

Multicoloured Asian Lady Beetle (Harmonia axyridis) has been one of the most abundant in soybean fields. While Multicoloured Asian Lady Beetle has been an annoyance to home-owners by getting in their houses in the fall, they are an effective predator of SBA. An adult is capable of consuming 100 to 270 aphids per day, and each larva can consume 600 to 1,200 aphids during its development.

Seven-spotted Lady Beetle (Coccinella septempunctata), while introduced from Europe, is also an effective predator of SBA. A single larva can consume 800 to 1,000 aphids and an adult will eat from 3,000 to 4,000 aphids during its lifetime.

Pink-spotted Lady Beetle (Coleomegilla maculata) is native to North America and is very abundant in the Northeast. Adults can consume 50 aphids per day, while larvae can eat 10 to 25 per day. The pink-spotted lady beetle will consume plant pollen that may constitute up to 50% of the diet.

What other predators like SBA as lunch? See next week's report for your enlightenment!

Soybean leaf diseases coming SOON!

Field Corn

Farm Records and Corn Rootworm

It is very important that you keep records on which corn fields were over threshold or not for corn rootworm this year. Records help us remember which fields need to be rotated or the use of some other management strategy for corn rootworm the next spring. Knowing which fields were not over threshold can save you money by rotating instead of using other control measures that can cost $15 to $25/ acre. So take a few minutes and write down which fields were over and under threshold for corn rootworm. For more information on corn rootworm checkout our online publication: IPM for Corn Rootworm

Are your weeds sending you a message?

Did you ever think that weeds could be sending you a message? Yes, they can send you a message! Many times weeds can be indicators of the condition of your soil. The following are a few weeds that can indicate soil conditions in your fields:

Quackgrass

Soil compaction at the soil surface

Milkweed/thistles

Deep soil compaction, milkweed favoring moist land, thistles growing in drier conditions with low humus levels

Chickweed

Incomplete decomposition of organic matter

Ragweed

Unavailable potassium

Docks/sorrels

Waterlogged or poorly drained acidic soil

Lambsquarters, pigweed, nettles

High fertility or humus, unless weeds are pale and stunted, then low fertility

Hawkweed

Acidic soils

Reference: Field Crops Pest Management Manual Purdue University

Are Armyworms Falling in to your fields?

Since we have had several storms this summer there is the potential to get infestations of fall armyworm. Fall armyworm moths will ride the storms from the south to the northeast. Fall Armyworm larvae are green, brown, or black about 1/8 inch to 1.5 inches long and have a dark head capsule usually marked with a pale, but distinct, inverted "Y." Along each side of its body is a longitudinal, black stripe, and along the middle of its back is a wider, yellowish-gray stripe with four black dots on each segment. Larvae are active at night, but can be seen feeding on overcast days. Larvae will hide under the canopy of the grass during the day. You will need to be aware that armyworms can move from field to field every quickly. This armyworm seldom causes economic losses in corn. Fall armyworm begins eating the edge of the leaf and works its way toward the mid-rib of the leaf. Many times there will be just few leaves chewed on by armyworm. If there are sufficient numbers and damage is present, an insecticide could be justified. Treat only the affected area and a 20 to 40-foot border around the infestation. (Note: the corn maybe too tall to treat with an insecticide). Rarely does a whole field need to be treated for armyworm. Larger armyworm larvae, greater than 1.5 inches long, are much more difficult to control. These large larvae are more tolerant of insecticides, reducing the effectiveness and economic viability of this option.

Fall Armyworm Picture

Alfalfa

Potato Leafhopper

I found only a few potato leafhoppers in alfalfa fields this week at SUNY Cobleskill. I have had reports that potato leafhopper has been at low infestation levels across Eastern NYS. For management information check our on-line IPM guides: IPM for Potato Leafhopper in Alfalfa

Thanks to:  Keith Waldron and Julie Stavisky (NYS IPM) for contributing to this week's report.

Cheers

Ken Wise