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NY Weekly Field Crop Pest Report, 2005

July 8, 2005 Volume 4 Number 12

1. View from the Field

2. Soybeans at Risk From Spider Mites

3. Start Thinking Corn Rootworm-What fields are at Risk?

4. Do you have Wirestem Muhly?

5. European Corn Borer Opens the Door for Anthracnose Stalk Rot

6. Clipboard Checklist

7. Growing Degree Days in NYS

8. Contact Information

View From the Field

Field Days!

Eastern NYS

Ken Wise

Keith Waldron, NYS IPM

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

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

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

Potato leafhoppers on alfalfa at the SUNY Cobleskill farm remain at low infestation levels. Both established stands and new seedings had lower levels of potato leafhopper. One reason that potato leafhopper are remaining at lower levels is the heavy rains help control the insect.

While scouting field corn I saw several plants with European corn borer damage. There were very few weeds in both the no-till and conventional tilled corn fields.

Soybean aphid populations in most of our production areas appear to be stable and still well below the 250+ SBA’s per plant action threshold. Opportunities for SBA Treat / No Treat insecticide comparisons are being sought.

Soybeans at risk from Spider Mites

Julie Stavisky, NYS IPM

While some areas of NY have received substantial rain over the past week, other places remain very dry. Compound the dry weather with the recent high temperatures, and we have the ideal conditions for spider mite invasions into soybean fields.

Two-spotted spider mites are tiny, oval, 8-legged, pale-bodied arachnids. The feeding of spider mites causes a stippling of leaves. Severe feeding by many mites causes a bronzing of the leaf. The injury from spider mite feeding can resemble a foliar fungal disease infection. Another identifying factor of spider mites is the silk-like webbing they produce. The webbing can be seen on leaflets and petioles in a heavily infested field. The mites are able to use the silk to transport by wind to uninfested areas of a field. When scouting, to help to confirm the presence of spider mites, hold a white piece of paper under a plant. Tap on the plant, and some of the mites should fall to the paper. They appear as yellow or yellow brown moving specs.

Spider mite injury to soybean leaf

Spider mite populations can increase extremely rapidly - they can develop from egg to adult in 5 days with high temperatures. Cool, damp weather often leads to steep declines in spider mite populations by encouraging fungal pathogens to take control.

Spider mites are regular residents of weedy areas at field edges. During dry weather, if these weed hosts become stressed, spider mites may begin to move into the nearby crop. Thus, an infestation usually begins at field edges and radiates into the field. While a spot-treatment with an insecticide may be helpful to combat the start of a severe infestation, it is critical to scout the whole field. Low numbers of spider mites can be present before the injury can be seen from a distance. When chemical control is chosen for spider mite management, it is critical to bear in mind the risks of "flare-ups" from use of pyrethroid insecticides.

Start Thinking CORN ROOTWORM: What Fields are at risk?

Ken Wise, NYS IPM

Corn rootworm populations build in a cornfield from year to year. Fields that are not rotated and remain in corn for several years are most at risk from corn rootworm damage. A two to three year rotation reduces the risk that a corn field will reach an action threshold for this pest. This spurs the question, “Do you scout a 1st year cornfield after sod for corn rootworm?” Yes, because any pollinating cornfield can attract corn rootworm. Even worse, late pollinating corn can attract many hungry corn rootworm beetles from fields where they did not get enough pollen. After the beetles eat their fill on late season pollen they will lay eggs in the soil. So yes, you have to scout all cornfields for corn rootworm that are going to be planted to corn next year. You do not need to scout fields that will be rotated out of corn next year. For more information on corn rootworm checkout our online publication: Corn Rootworm Management Guide 972 pdf file

Do you have Wirestem Muhly?

Ken Wise, NYS IPM

Wirestem Muhly is a warm season perennial grass. Itis native to the North America and has become problematic in field corn in certain areas of NYS. The grass spreads by short and scaly rhizomes. The stems are 2 to 3 feet in length, smooth below joints, very tough, leafy, branch freely, and often root at the lower nodes. Leaves are flat, rough, pale green, scattered along the stem, and dense near the tip, giving the plant a brushy appearance. The panicle barely protrudes from the leaf sheath. This weed normally starts as scattered clumps in a field and will spread over time. The problem with wirestem muhly is that only glyphosate products can control this weed. This limits your choices to using glyphosate resistant corn plus glyphosate or rotate the field to a different crop. One thing you need to think about is not transferring the weed around your farm. If you have wirestem muhly make sure to clean tillage equipment before working a field that is free from the weed. The rhizomes can be transferred on tillage equipment from field to field. For pictures of the weed view this website: Wirestem Muhly

European Corn Borer Opens the Door for Anthracnose Stalk Rot

Ken Wise, NYS IPM

While scouting, I observed signs of European corn borer (ECB) in field corn. There were broken leaf midribs, frass in the whorls, and holes in the stalks. European corn borer damage, can on occasion cause localized problems for field corn producers. However, while it's damage may be conspicuous, it more typically does not cause significant economic losses in NYS. If a field has had a history of ECB problems producers might consider crop rotation or the use of an ECB resistant (Bt) hybrid. In addition to direct feeding damage the holes bored by ECB larvae can provide a means for the anthracnose fungus to enter the plant. Conditions that favor anthracnose stalk rot are continuous corn, surface corn residue (minimum & no tillage) and wet, humid, warm weather. Anthracnose stalk rot symptoms may appear after tasselling. Look for vertical, tan to reddish brown, water-soaked lesions (streaks) in the rind. Lesions become large, dark brown to shiny black. The best management practices to minimize or avoid anthracnose require action before or at the time of planting, i.e. the use of diseases resistant hybrids and hybrids with a good standability rating. Crop rotation with non-grass crops and plow under infected residue are also recommended. Fields with high amounts of anthracnose leaf blight should be checked for indications of anthracnose stalk rot. If stalk rot is found you may wish to target that field for early harvest to avoid losses associated with premature lodging. For more information on corn diseases checkout our online publication: Diseases of Corn Management Guide 234k pdf file

Soybean Rust Update

Keith Waldron

Septoria brown spot and bacterial blight have been observed in NY, but fortunately still no reports of SBR.

From the NYS soybean rust website: 2005 Asian Soybean Rust Status

Soybean rust on soybeans has been reported in Florida and some adjacent counties in Alabama and Georgia. Recent Alabama and Florida finds were in sentinel soybean plots, the Georgia find was on volunteer soybeans. Scouting and spore trapping continues throughout the soybean production areas of the U.S. Scouting of sentinel plots in NYS continues this week and to date no soybean rust has been found. Septoria brown spot is the most prevalent foliar disease in all 10 of the research protocol sentinel plots in NYS over the past two weeks. Bacterial blight has also been observed. Growth stages in NYS sentinel plots range from V3 to R1 stages and several will come into flowering soon. Scientists are monitoring two current tropical storms for their potential to move soybean rust spores to wider areas of the U.S. (Last updated 7/6/05). For more see New York State Soybean Rust Information Center.

Soybean Rust in US ­ 7.6..05 USDA Public Soybean Rust Website

National Map Commentary (updated: 07/01/05)

Intensive scouting is continuing throughout eastern North America from the Gulf coast to southern Ontario wherever soybean is grown with no new finds. Although many areas in the southeast U.S. has been wet this past month, which encourages disease spread, air temperatures are now climbing to levels that are less favorable for spore production. However, if the winds and rain associated with tropical storm Arlene were involved in transporting soybean rust spores from known U.S. sources, and potentially other unknown sources in the U.S. and the Caribbean basin, new soybean rust infections could soon be observed.

Clipboard Checklist

Keith Waldron

General:

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

Alfalfa & Hay:

• Continue monitoring for potato leafhopper- harvest early or spray on basis of need.

• Monitor for diseases, particularly Verticillium wilt, record information on type and location for future cropping decisions.

• Prepare for summer seedings of alfalfa. Test soils. Lime as needed.

Small Grains:

• Prepare for grain harvest: combine ready?, check and disinfect inside, under and around grain bins.

• Watch wheat grain moisture. Be ready to combine at 18 percent.

Corn:

• Monitor for foliar and stalk diseases, nitrogen and other nutrient deficiencies, European corn borer, weeds.

• Monitor corn rootworm adults at silking.

Soybeans:

• Monitor for soybean aphid, soybean rust, foliar diseases.

Livestock:

• Continue livestock facility sanitation management (manure, feed bunks and storage areas, waterers, etc.). Cleaner, less fly production

• Initiate integration of biological control agents into house fly and stable fly management program.

• Mow around facilities to minimize rodent habitat.

• Monitor young stock for cattle lice and mange mites

• Check condition of pastures and animals on pastures

- Evaluate need for face fly and stable fly control measures

- Check and clean pasture water supplies.

Growing Degree Days in NYS

Keith Waldron

NYS IPM

March 1 - July 5, 2005

Location

Base 50 F

Batavia

936.05

Chazy

753.65

Clifton Park

1053.5* * Missing data

Geneva

952.65

Ithaca

855.1

Prattsburg

811.0

Source: http://newa.nysaes.cornell.edu/

Contact Information

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