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Weekly Field Crops Pest Report 2007

July 5, 2007                Volume 6 Number 11

1. View from the Field

2. Are soybeans at risk from spider mites?

3. Thinking Corn Rootworm? Know Which Fields are at Risk

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

5. NYS Soybean Rust Update

6. Clipboard Checklist

7. Upcoming Events

8. Contact Information

View from the Field

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Eastern NYS
Ken Wise

This week soybean aphids were over threshold at the Columbia County soybean sentinel plot field. They ranged from 45 to 600 aphids/plant with an average of 260/plant. There were many lady beetles larvae and pupae in the field. The photo below shows a leaflet with 190 soybean aphids.

I also saw many aphid mummies that had been previously home to parasitoids. The following photo has several soybean aphid mummies.

I saw a few Japanese beetles in the soybeans. Watch for next week’s article on defoliating insect pests of soybeans.

Potato leafhoppers were over threshold this week at the Cornell Research Farm in Valatie this week. The 10 to 12 inch alfalfa is starting to exhibit the characteristic “V-shaped” yellow leaf tip.

Western NY and Finger Lakes
Julie Dennis

Bruce Tillipaugh, CCE of Wyoming County, reported finding spider mites on soybean fields. See the article below for more details.

have been seen on soybeans. See the article below for more details.

I’ve seen a few potato leafhoppers (PLH) in alfalfa, but most of the PLH I’ve seen are adults. This is typical of other areas of the western part of the state, according to several reports. I’ve been asked several times in the past week about PLH on soybeans. They are not a pest threat at the low numbers we typically see, that is, fewer than 4 PLH per leaf.

Soybean aphids are at or close to the 250 per plant threshold in several locations in Cayuga County. They are being watched carefully to see if populations are increasing. In most cases, ladybugs of all stages, syrphid fly larvae, and aphid mummies are all common. Sarah Woodard, scout for the Cayuga County Soybean TAg saw downy mildew in soybeans this week, too.

Low numbers of soybean aphids were seen at a soybean field during Mike Stanyard’s Livingston/Ontario County Soybean TAg team meeting this week, and numbers of soybean aphid were still low at the Ontario County sentinel plot.

Are soybeans at risk from spider mites?

Julie Dennis

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Many areas of NY are experiencing a lack of rainfall, which are often associated with outbreaks of spider mites in soybeans. We’ve also had short spells of really high temperatures. Together, hot and dry are 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 un-infested 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 mites on soybean:

Early symptoms of spider mite injury on the upper leaf surface:

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.

Thinking Corn Rootworm? Know Which Fields are at Risk

Ken Wise

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Corn rootworm populations can 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 out of corn or cucurbits such as pumpkins 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 will 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

European Corn Borer Opens the Door for Anthracnose Stalk Rot

Ken Wise

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While scouting, I observed signs of European corn borer (ECB) in corn this week at the Cornell Research Farm in Valatie. 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 its 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 plowing 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

NYS Soybean Rust Update

Gary Bergstrom
Cornell University

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New York State Soybean Rust Information Center

Weekly scouting is being done in twenty New York State sentinel plots located in the following counties: Cayuga, Chautauqua, Chemung, Chenango, Columbia, Cortland, Jefferson, Oneida, Onondaga, Ontario, Orleans, Oswego, Otsego, St. Lawrence, Seneca, Steuben, Suffolk, Wayne, and Wyoming. Plant stages in these plots reported to date range from V-2 to V-5.

Soybean rust (SBR) was confirmed on June 29th in a soybean sentinel plot in Assumption Parish, Louisiana. This makes six new positive rust finds in the month of June. Four of these are in Louisiana and two in Texas. With regular rainfall in Louisiana and surrounding states to the west and north, there is an increased chance of soybean rust being found north of Louisiana in the next few weeks. So far in 2007, soybean rust has been detected in 10 counties in Florida, five counties in each of Georgia and Alabama, five Parishes in Louisiana and three counties in Texas. (Updated July 5, 2007)

NY SBR and soybean aphid (SBA) updates can also be found at the national sbr/sba website.

Clipboard Checklist

Keith Waldron

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* Maintain crop records by field, including variety, planting date, pesticides used, nutrient inputs including manure, etc.
* Watch for early season weed escapes, any patches of herbicide resistant weeds?

* Determine plant populations, make notes on emergence, drought, and other problems
* Check for cutworm, armyworm, European corn borer, leaf blights, slugs, bird and deer damage
* Monitor for weeds, note presence of "who", "how many" and "where"
* Adjust post emergence weed control actions as appropriate

Small Grains:
* Monitor winter grains for crop growth stage, insect and disease problems
- evaluate crop for adequate stand and plant vigor
- evaluate crop for Fusarium head blight (Scab) and other grain head diseases
* Check, clean, prepare storage bins to accept upcoming harvest?
* Mow around storage bins to remove rodent habitat, remove spilled grain
* Clean grain handling equipment (conveyors, wagons, trucks, combines, elevators, etc.) for signs of leftover grain - remove potential sources of stored grain insect infestations.

Alfalfa & Hay:
* Monitor alfalfa seedings for weeds, potato leafhopper and diseases.
* Check established alfalfa stands for potato leafhopper, weed and disease problems

* Monitor for soybean aphids, and other insects, including natural enemies such as lady bird beetles.
* Check droughty fields for presence of spider mites

Dairy Livestock Barn Fly Management:
* Check confined animals and barns for house and stable fly populations
* Sanitation, sanitation, sanitation - clean animal resting areas, feed troughs, minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard
* Check waterers, drainage, roof gutters for leaks and potential overspill
* Begin fly monitoring: install "3X5" index card fly speck monitoring cards through out barn
* Order fly management materials: fly tapes, insecticide baits, natural enemies (parasitoids)

Dairy Livestock Pasture Fly Management:
* Monitor animals for face, horn, and stable fly populations
* Check feed troughs, around waterers for signs of stable fly breeding.
* Consider use of traps if horse and stable fly populations are a problem

* Note any repairs needed for recently used equipment: tractors, tillage implements, planters, etc. as they are cleaned and serviced.
* Service planters, alfalfa harvesting equipment, and tillage implements as needed.
* Calibrate manure spreaders - maintain records on amount spread per field
* Check, clean, adjust and service small grain harvesting equipment as needed.

Upcoming Events

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NYSIP Foundation Seed Barn
Thursday, July 5, 2007
Ithaca, NY (761 Dryden Road, Route 366)
Registration and Coffee at 9:00 AM
Tour Begins at 9:30 AM


Valatie Research Farm – July 6
(Stage Farm Road just off Route 9, North of Valatie)
Registration and Coffee at 9:00 AM
Tour Begins at 9:30 AM to 12 Noon
(Field Crops)

Robert B. Musgrave Research Farm- July 11
(Popular Ridge Road, connects 90 and 34B)
11:00 am to 1:00 pm-Chicken BBQ
1:00 pm Registration
1:30 pm to 5:00 pm Tour
(Field Crops)

H.C. Thompson Research Farm- July 12
Freeville, NY 10 miles north of Ithaca, Fall Creek Road Rt. 366 extension)
8:00 am Registration ($8 Informational Packet)
8:30 am to Noon-Vegetable Weed Control


Thursday July 26, 2007
Poplar Ridge Road, Aurora, NY (connects 90 and 34B)
Coffee at 9:30 AM
Tour Plots 10 AM to 3 PM

Contact Information

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Julie Dennis: Western NYS IPM Area Educator, Livestock and Field Crops
Phone: (315) 331-8415
Fax: (315) 331-8411

Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Phone: (315) 787 - 2432
Fax: (315) 787-2360

Ken Wise: Eastern NYS IPM Area Educator, Livestock and Field Crops
Phone: (518) 434-1690
Fax: (518) 426-3316