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Weekly Field Crops Pest Report 2006

June 29, 2006 Volume 5 Number 11

1. View from the Field

2. Lodging Problems in Winter Wheat

3. Western Corn Rootworm or Striped Cucumber Beetle?

4. Soybean Disease Update: Septoria Brown Spot

5. Soybean Rust Update

6. Growing Degree Days in NYS

7. Clipboard Checklist

8. Contact Information

View From The Field

Western NY and Finger Lakes

Julie Stavisky, NYS IPM

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Eastern NYS

Ken Wise, NYS IPM

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I continued to see alfalfa weevil larvae in sweep samples this week in Wayne County.  Since most alfalfa in this area is in the range of 15 to 25 inches tall, feeding by the few remaining larvae is unlikely to pose an economic threat.  Potato leafhopper numbers are still fairly low in most fields Iíve swept (in the range of 6-12 PLH per 10 sweeps in 15+ inch alfalfa).  In a field in Ontario County, almost half of the PLH I saw were nymphs.  They are here and they are reproducing.  Continued scouting is a must, but we should be in the clear for 2nd cutting.  Nancy Glazier reports similar numbers of PLH in Yates County, where she is conducting weekly scouting for a TAg team that Mike Stanyard is leading.

Molly Smartwood, who is working with Mary McKellar and Gary Bergstrom on the assessment of soybean rust sentinel plots this summer, visited sentinel plots in Ontario and Seneca Counties with me this week.  We observed widespread Septoria brown spot in one field, while in a field within 200 yards showed few symptoms of the disease.  We also saw significant slug damage on the lowest leaves of V-3 soybeans in a minimum-tillage field.  Molly and I observed soybean aphids on V-4 soybeans in one of Seneca Countyís soybean rust sentinel plots.  Most plants had between zero and 10 aphids, but one plant was infested with 53 aphids.  Ladybug adults and larvae were numerous.  Nancy observed very low numbers of soybean aphids in 2 fields enrolled in the Genesee County soybean TAg program.

News for this week is RAIN, RAIN and more RAIN. I was at the Cornell University Research Farm in Valatie on Monday. There was very few pests to observe. Potato leafhopper populations were very low at 1 or 2 leafhoppers/sample in 12 inch alfalfa. I did find clover leaf weevil adults in the alfalfa. The adult clover leaf weevil is brown and up to 10 mm long, with a long snout. Larvae look very similar to alfalfa weevil larvae but have a brown head. Clover leaf weevil larvae chew out small holes and irregular patches from leaves.

I collected leaves from the soybean sentinel plot in Columbia County. There appears to be brown spot on the lowers leaves but we will have a confirmation on this from Mary McKellar soon.

Lodging Problems in Winter Wheat

Julie Stavisky, NYS IPM

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From several fields Iíve seen, it looks like the recent high winds and driving rainstorms have led to some lodging.  While an excess of nitrogen fertilizer is often associated with lodging, there are a couple of fungal diseases that can cause wheat plants to lodge during grain fill despite balanced fertilization.

Strawbreaker, or eyespot foot rot, causes plants to break off about an inch above the soil line. Diamond shaped lesions (like a catís eye) appear on lower stems (see photo). As the disease progresses, the lesions take on a charred appearance. If the pathogen is present, the development of the disease is favored by dense stands, high soil moisture, and high humidity. High humidity sure sounds familiar for NY lately! Aside from the possibility of causing lodging, foot rot can reduce the quality of grain by inhibiting the flow of nutrients up through the damaged portion of the stem to the filling kernels

If instead of breaking off above the soil surface the wheat plants fall over at soil level, the culprit may be another fungal disease, take-all. With take-all, a plantís roots are blackened and rotten. Lower stems are blackish in appearance. When the lowest leaf sheath is pulled back, the infected area is shiny black. If the infestation of take-all is severe, grain heads of infected plants will appear white. The presence of shriveled kernels can lead to a decrease in yields. Take-all is favored when the soil pH is high.

A good test to distinguish between eyespot foot rot and take-all is to give a tiller a gentle tug. If the plant is easily pulled out of the ground, it is likely to be take-all. If the roots are strong enough to hold the plant in the ground, the root system remains relatively healthy and eyespot foot rot is the more likely culprit.

Both of these diseases reside in the soil and are encouraged by having a continuous grass host. Rotation to a non-grass crop for 2 years is the primary means of reducing the likelihood of crop infection.

Western Corn Rootworm or the Striped Cucumber Beetle?

Ken Wise, NYS IPM

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Have you ever gotten western corn rootworm confused with the striped cucumber beetle? Do you know the difference between corn rootworm and striped cucumber beetle? Striped Cucumber Beetle and Western Corn Rootworm look similar but are two different species of insects.

Striped Cucumber Beetle, Acalymma vittatum
The Striped Cucumber Beetle adult is about 1/4 inch long and the upper body surface is about equal black and yellow, the folded wing covers forming three longitudinal black stripes. The adult beetle starts appearing on several vegetable crops starting in mid-June.

Western Corn Rootworm, Diabrotica virgifera virgifera
Female Western Corn Rootworm is 5/16 inches long with three black strips alternating with yellow. Male Western Corn Rootworm is mostly black with a small area on the poster end that is yellow-green. Adults start appearing in mid to late July.

 

Female Western Corn Rootworm

Striped Cucumber Beetle

Insect Markings

Stripes are less distinctive and do not extend to the tip of the abdomen

Both sexes have stripes, are clearly defined, and extend to the tip of the abdomen.

Insect size

5/16 inches long

1/4 inch long

Host range

 Primarily Corn
Secondary Cucurbits

Primarily Cucurbits
Secondary beans, corn, potatoes and other crops

Emerge

July

June

Life cycle

1. Over-winter as eggs in the soil in the field
2. Eggs hatch and larvae feed on the corn roots starting in late May
3. Adults emerge at time of corn pollination. Males emerge first
4. Adults lay eggs in cornfields mid to late pollination
5. Adults die, eggs overwinter

1. Over-winter as adults in woodland litter or in the soil.
2. Lay eggs at the base of the plant in mid-June through mid-July
3. Larvae develop for 2 to 4 weeks on the roots, pupate in the soil.
4. Adults appear in early to mid-August
5. Adults produced this season overwinter

Learn more about the differences between Western Corn Rootworm and Striped Cucumber Beetle: Cucumber Beetles, Corn Rootworms, and Bacterial Wilt in Cucurbits

Soybean Disease Update - Septoria Brown Spot

Julie Stavisky, NYS IPM

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Soybean Rust has still not been reported on any commercial soybean fields in the US this year.  Sentinel plots across the soybean growing areas of the US are being sampled vigilantly. The New York soybean rust site was updated this week - be sure to take a look! National updates are available on the USDA soybean rust site.

The ongoing 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.  This week, letís review Septoria Brown Spot

Brown spot (Septoria leaf spot)

  • Symptoms appear first on lower leaves

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

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

  • Infected leaves are likely to turn yellow and drop

Soybean Rust Update

Gary Bergstrom, Cornell University

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Nearly all of New York's commercial soybean acres have now been planted.  Growth stages range from just emerged to V3.  Scouting has begun on 19 sentinel plots located in Cayuga, Chautauqua, Chemung, Chenango, Genesee, Jefferson, Montgomery, Oneida, Onondaga, Ontario, Seneca, Tompkins, Wayne, and Wyoming Counties.  Low levels of Septoria brown spot were found in several of the sentinel plots. The current risk of soybean rust infection in New York is extremely low.  Future risk in New York will depend on rust build-up in the southern U.S., especially in commercial soybean fields. To date, in 2006, soybean rust has been reported on kudzu in five counties in Alabama, 12 counties in Florida, and four counties in Georgia.  Although rust was confirmed in a sentinel soybean plot in southeastern Florida, Florida officials feel that the overall spore production in the state is still very low.  Currently, there are no known reports of rust on commercially planted soybean in 2006. Many of the southern states have experiencing hotter and drier than normal conditions, reducing the likelihood of viable spore dispersal, though recent rains may change this pattern. A report regarding Mexico indicated that rust had occurred earlier in the year (winter season seed production) before any commercial soybeans were planted in Mexico or the U.S.  There is no evidence to date suggesting that airborne spores originating in Mexico have resulted in soybean rust infection in Texas or other U.S. states. Last updated (June 26, 2006)

Growing Degree Days in NYS

Ken Wise NYS IPM

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Accumulated Growing Degree Days for March 1 to June 28

Location

Base 50 F

Batavia

669*

Chazy

745

Clifton Park

1029*

Geneva

774

Ithaca

710

Mexico

751*

Prattsburg

622*

Redhook

1107

*indicates missing data

Source: NEWA

Clipboard Checklist

Keith Waldron-NYS IPM

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General:
* Update crop records by field, including pesticides used, nutrient inputs including manure, growth and development observations, other comments, etc.
- Record hay crop yields by field and quality by storage facility; take samples for forage analysis
- Inventory remaining corn silage and allocate forages for summer feeding
* Clean and prepare storage areas for small grain harvest
* Adjust pasture rotation, check fencing, water sources

* Make plans for fun Fourth of July activity

Corn:
* Monitor fields for crop growth and condition, seed corn maggot, wireworm, cutworm, seedling blights, birds, armyworm
* Evaluate weeds and adjust post emergence treatments
- note presence of triazine resistant annual broadleaf weeds
-Cultivate or treat if necessary
* Pre-Nitrogen Sidedress Soil Test and apply sidedress as needed

Small Grains:
* Monitor for crop growth and condition, insect (cereal leaf beetle, armyworm, European corn borer) and disease problems (Fusrium (scab), other head and leaf blights, and diseases that cause lodging)

Alfalfa & Hay:
* Monitor alfalfa seedings for crop growth and condition, weeds, potato leafhopper & diseases.
* Check established alfalfa stands for potato leafhopper, weed and disease problems
- Take alfalfa stand counts while regrowth is short (if not done earlier in the season)

Soybeans:
* Check stand establishment, crop growth and condition, weed control
* Evaluate stand for uniformity,seed corn maggot, wireworm, seedling blights, birds, planter problems, drainage issues
* Monitor for soybean aphid, soybean rust, presence of natural enemies

Dairy Livestock Barn Fly Management:
Barn Areas:
* 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 water sources, drainage, roof gutters for leaks and potential overspill
* Collect and evaluate "3X5" index card fly speck monitoring cards. Record results for future comparisons. Replace with new cards
* Evaluate animals for stable fly harassment (10 stable flies per animal)
* Replace fly sticky tapes as needed, check insecticide bait traps
Pasture:
* Check condition of pastures and animals on pastures
- Evaluate need for face fly and stable fly control measures
- Insecticidal ear tags for heifers (non-lactating animals) on pasture
- Adjust pasture rotation, check fencing, water sources

Equipment:
* Note any repairs needed for recently used equipment: tractors, harvest equipment and wagons, etc. as they are cleaned and serviced.
* Calibrate manure spreaders - maintain records on amount spread per field
* Prepare small grain combining equipment or arrange for custom combining

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