NY Weekly Field Crop Pest Report, 2005

View From the Field

Western NYS

Julie Stavisky

Eastern NYS

Ken Wise

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Some insect problems of note arose this week, including a serious infestation of seedcorn maggot in soybean in Genesee County, as reported by Mike Stanyard (NWNY Team). Third and fourth instar alfalfa weevil larvae are still easy to find, but I did not scout any fields with more than 20% of stems showing feeding damage. While no potato leafhopper nymphs have shown up in sweep samples yet, adults are numerous, though well below threshold numbers. I continue to see soybean aphid in all the soybean fields I visit. Numbers of aphids remain low, and numbers of lady beetles seem to be increasing. Septoria brown spot has shown up in soybean fields in Ontario County. This leaf disease is prevalent in the areas that were very dry in early June then received several inches of rain over the last week. See article and photograph below for more information on Septoria. In Roundup Ready soybeans that have not been treated yet for weeds, there continues to be plenty of new annual grass and broadleaf weed emergence.

This week I found glume blotch disease in the heads of triticale in Tom Kilcer’s (Rensselaer County) research plots at the Valatie Cornel Farm. Blotch glume disease lesions begin as either grayish or brownish spots on the chaff, usually on the upper third of the glume. As lesions enlarge, they become dark brown and the centers turn grayish-white in color as tiny brown or black dots (pycnidia) develop within them.

I also discover ants on soybean plants at the Valatie Cornel Farm. Ants protect soybean aphids, so with a closer look I found aphids on new emerging trifoliate leaves.

At the SUNY Cobleskill farm I found many adult and pupating alfalfa weevils. This means that their life cycle is almost complete for this season. Potato leafhoppers in alfalfa were at very low numbers this week. I also saw much velvetleaf and yellow nutsedge in the corn fields.

Soybean Disease Update

Julie Stavisky, NYS IPM

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Soybean Rust has still not been reported outside of Florida and southern Georgia. Sentinel plots across the soybean growing areas of the US are being watched vigilantly, especially following Tropical Storm Arlene a couple of weeks ago. Regular checks to the New York soybean rust site are a must.

National updates are available on the USDA soybean rust site.

The potential for soybean rust in New York provides an opportunity to review and become more familiar with common foliar fungal diseases of soybean that are generally non-economic. Here are a few of the key diseases to watch for with tips on how to distinguish each:

Brown spot (Septoria leaf spot)

• Symptoms appear first on lower leaves

• Early signs are small irregular brown spots on upper and lower leaf surfaces

• Later Symptoms are large brown-black necrotic blotches throughout the soybean canopy

Downy mildew

• Early symptoms are yellowish spots on the upper surface of the youngest leaves

• Spots turn to grayish brown with a yellow margin as infected leaves age

Powdery mildew

• Powdery mildew has a distinctive powdery white appearance at all stages of infection, making it easy to distinguish from soybean rust

Soybean Rust

• Early Symptoms: Small gray lesions on the underside of lower leaves; lesions increase in size and become tan or reddish brown.

• Later Symptoms: Leaves of the whole plant turn yellow, and small brown or reddish raised pustules appear; the resulting necrosis causes leaves to drop.

For more information on how each of these diseases differs in symptoms from soybean rust, check out the USDA identification guide.

Velvetleaf In Corn Fields!

Ken Wise, NYS IPM

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While monitoring corn fields this week I saw an abundance of velvetleaf. Research from Purdue University suggests that just 1 velvetleaf plant per row foot, if not controlled in the first 4 to 6 weeks after planting, can reduce yields by 25 percent. Twelve plants per row foot can reduce yields by 57 percent. This means the earlier you can control them the better the yield. Research by our own Janice Degni (South Central NY Dairy Team) and Russ Hahn (Cornell Crop & Soil Sciences Department) has shown that velvetleaf yield impacts on corn were also highly affected by soil moisture. The more droughty the soil conditions were, the more significant the impact. Research continues to look for better weather prediction data to help us with developing this threshold. For management information check our on-line IPM guides: Weeds in Corn Management Guide

IPM for Stored Grain

Ken Wise, NYS IPM

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Sanitation is the key to keeping insect pests out of your stored grains. Wheat harvest is not as far off as you may think so knowing what you need to do is important. The following is a step by step method for IPM in stored grain:

1. Clean grain handing equipment (augers, combines, wagons, scoops, and trucks).

2. Clean inside the grain bin (remember to clean under the false floor). Mice, moths, weevils and much more can survive under the false floor.

3. Clean around the outside of the grain bin. Remove all weeds, spilled grain and debris 6 to 10 feet from around the grain bin. This will remove all habitats that can support a grain bin pest problem.

4. Seal all cracks and crevices. Cracks are prime locations for insects to enter grain bins.

5. Cover fans when they are not being used. Insects can enter the grain bin this way also.

6. Use a registered sanitizing insecticide spray in and around the structure after cleaning.

7. Never store new grain with old grain.

8. Dry the grain bin before adding new grain. Insect pests need moisture to survive.

9. Level the surface after filling the grain bin. Moisture accumulates in a grain peak. Microbial activity in the wet area will heat up and attract secondary insect pests.

10. Do not fill grain bin all the way to the top. Leave a few feet for aeration.

11. Aerate the grain to at least the ambient temperature. The hotter the grain gets the faster insect pests can develop. Stored grain insect pests development slows when the temperature falls below 50⁰ F.

12. Monitor grain for insect pests every 20 days from spring till fall and every 30 days in the winter.

13. If you discover an infestation of insect pests you may consider an insecticide application. Select a NYS registered product for your stored grain. READ THE LABEL.

14. Keep areas around grain bins mowed to limit rodent hiding places.

The following are common insect pests of stored grains: Common Insect Pest of Stored Grain, Granary weevil , Saw tooth grain beetle, Red flower beetle, Larger cabinet beetle , Lesser grain borer, Rice weevil, Indian-meal moth, Flat grain beetle, Angoumois grain moth, Confused flower beetle

Unusual Injury in Alfalfa

Julie Stavisky, NYS IPM

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Have you seen any unusual injury on alfalfa? It might be caused by the four-lined plant bug. This week, Bruce Tillapaugh (Wyoming County) and I saw many of these bugs and a surprising amount of the damage they cause.

The adult four-lined plant bugs are 3/8” long, and are a bright lime green color with four black stripes running down the back (see photo). Nymphs are bright red to orange (I didn’t see any to photograph). They are commonly found on many plants, including potatoes, alfalfa, and cucurbits.

Four-lined plant bug adult in alfalfa

Since four-lined plant bugs are a true bug and have piercing-sucking mouthparts, we wouldn’t expect the injury to look like defoliation, usually typical of insects with chewing mouthparts. The four-lined plant bug causes the damage by removing the plant’s chlorophyll in small, relatively uniform patches on the leaves (see photos below). The result is a translucent spot, or “window” where the upper and lower epidermis are still intact. In our observations of the feeding damage in alfalfa this week, where severe damage had occurred on several leaves of new growth, the top sections of plants were pale colored and wilted.

Damage caused by the four-lined plant bug is eye-catching, especially if there are many plants showing feeding injury within a small area. However, feeding by this bug is not generally of economic importance in alfalfa.

Four-lined plant bug injury in alfalfa

Green lacewings in Alfalfa!

Ken Wise, NYS IPM

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I have observed a few green lacewing adults in my sweep net this season in alfalfa fields and by the porch light at night. Adults feed during the evening on nectar, pollen, and aphid honeydew. Larvae are very active predators of aphids and other small insects in many agricultural crops. Adults are light green with long, slender antennae, golden eyes and large lace-like wings that are 1/2 to 1/3 inches long. Larvae are called aphid lions, and look like little green-gray or brownish alligators. Aphid lions have sickle-shaped jaws, that penetrate the prey and injects a paralyzing venom, then suck out the victim’s body fluids. The larvae will reach about a1/2" long before they pupate.

Clipboard Checklist

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General:

• Maintain crop production activity records by field, including harvest date, pesticides used, nutrient inputs including manure, etc.

Established Alfalfa and Hay:

• Monitor for Potato leafhopper

• Monitor for anthracnose, look for shepherd’s crook symptoms

• Monitor fields for weeds and diseases: record information on type and location for future cropping decisions.

Corn:

• Evaluate weeds and adjust post-emergence treatments

• - Cultivate or treat if necessary

• Monitor insects (cutworm, rootworm, wireworm, etc.), slugs, and foliar diseases (anthracnose leaf blight, eye spot, gray leaf spot, etc.)

• Pre-Nitrogen Sidedress Soil Test and apply sidedress as needed

Soybeans:

• Evaluate stand for emergence issues, plant population

• Begin to monitor for soybean aphids, soybean rust

• Watch fields for spider mites, Septoria brown spot, and downy mildew

Small Grains:

• Check condition of flag leaf for cereal leafbeetle and foliar (and head) diseases

• Continue watching for wheat head diseases including glume blotch, scab, smut and take all.

• Spring grains have headed out. Continue scouting for powdery mildew and cereal leaf beetle

Livestock:

• Insecticidal ear tags for heifers on pasture

• Manure management and initiate release of biological control agents (parasitic wasps) for house fly and stable fly control in confinement facilities.

• Check condition of pastures and animals on pastures

  - Adjust pasture rotation as necessary

  - Evaluate need for face fly and stable fly control measures

Equipment:

• Prepare small grain combining equipment or arrange for custom combining

• Check grain handling and storage equipment, augers, bins, fans.

Growing Degree Days in NYS

Julie Stavisky, NYS IPM

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March 1 - June 21, 2005

Location	Base 48 F	Base 50 F
Batavia	713.6	607.6
Chazy	565.3	476.0
Clifton Park	940.9	803.7
Geneva	746.6	633.1
Ithaca	661.4	558.2
Mexico	527.3*	444.9*
Prattsburg	615.3	520.3

* Missing data

Upcoming Meetings

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July 6 - Wednesday - NY Weed Science Field Day, Valatie Research Farm. Valatie, NY

July 7 - Thursday - Seed Growers' Field Day, NYSIP Foundation Seed Barn, Ithaca, NY (791 Dryden Road, Route 366)

July 13 - Wednesday - NY Weed Science Field Day, Robert B. Musgrave Research Farm, Aurora, NY (Poplar Ridge Road, connects 90 and 34B)

July 14 - Thursday - NY Weed Science Field Day, H. C. Thompson Research Farm, Freeville, NY (10 miles Northeast of Ithaca, Fall Creek Road, Rt. 366 extension)

July 15 - Friday - Aurora Field Day, Robert B. Musgrave Research Farm, Aurora, NY

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