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Weekly Field Crops Pest Report 2008

June 5, 2008                 Volume 7 Number 8

1. View from the Field

2. Weather Outlook 6.05.08

3. White Mold in Alfalfa

4. Soybean aphids 08 – looking ahead?

5. Alfalfa Weevil Biological Control, Continued

6. Potato leafhopper identification and potential damage

7. Soybean Rust Update, NYS

8. Growing Degree Days in NYS

9. Clipboard Checklist

10. Upcoming Meetings

11. Contact Information

View from the Field

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Eastern NYS

Ken Wise

This week at the SUNY Cobleskill farm all the alfalfa fields were harvested. I did find potato leafhoppers and 2nd and 3rd instar alfalfa weevil larvae in the boarders of the fields. I also found alfalfa weevil larvae in the harvested fields. While there was no alfalfa re-growth there is the potential for damage.  Remember, the action threshold for alfalfa weevil on 2nd cutting is 50 percent tip feeding with small larvae present. There were low numbers of potato leafhoppers along the edge of the fields. Potato leafhoppers infestations can increase quickly with warm weather. Having two stresses on alfalfa re-growth could have the potential to cause yield and forage quality losses. In fields like these you should monitor them closely. For management information check our on-line IPM guides: IPM for Potato Leafhopper in Alfalfa and IPM for Alfalfa Weevil in Alfalfa. I scouted 3 corn fields at the SUNY Cobleskill farm this week. There was a fair amount of yellow nutsedge starting to show-up in the fields. I saw some early signs of common ragweed also emerging in the fields.

Yellow Nutsedge in Corn Field

Many of the corn rows had large missing areas of plants. I went looking for the normal signs of pests like seed corn maggot, wireworm, seed rots and blights, and birds. There were no signs of pests causing the issue. Some seeds were just starting to germinate and some seedlings were distorted from soil crusting. See pictures.

Corn at different stages of development

Distorted corn because of soil crusting

Jeff Miller and Mike Hunter both report problems with geese digging up corn plants then eating the seed. In some cases growers are going to replant fields.

Western NY

Mike Stanyard reports that he has observed cereal leaf beetle eggs and larvae in oat and wheat fields.  Wheat is likely past the stage where control would be warranted, but oats should continue to be carefully monitored.  Mike also saw aphids on wheat heads.  The numbers he was seeing were up to 10 to 20 aphids per head.  Information from the University of Kentucky indicates that there is little chance of risk to grain unless there are more than 50 aphids per head.  Two armyworm larvae were spotted in wheat, also.  Mike says that the armyworms were about 1-inch in length.  Another pest situation Mike reported on was slug damage in a no-till corn field planted into standing rye.  In a relatively dry year, slugs are most likely to occur where moisture is conserved at the soil surface, and where there are places for the slugs to take cover.

Weather Outlook 6.05.08

Drew Montreuil
NOAA Northeast Regional Climate Center, Cornell

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Over the past week, most areas remained slightly cooler than average, with the exception being the Hudson Valley and Long Island. These locations saw temperatures run up to 3 degrees above normal levels. The coldest areas were Western New York, parts of the Southern Tier and Eastern Finger Lakes, and Northern New York. Temperatures there were between 3 and 6 degrees colder than average. Much of the state was mainly dry, with most locations picking up under a half an inch of new precipitation. Areas in and around the Buffalo metro area received up to 2", while far Northern New York saw as much as 3" of rain.

From May 28 to June 3rd, much of the state accumulated between 50 and 75 Base 50 Growing Degree Days. Southwestern New York, the Adirondack Mountains, and the Catskills saw less, with 25 to 50 Growing Degree Days. Conversely, the Hudson Valley and areas near Lake Ontario got up to 100 growing degrees day while Long Island received between 100 and 125. This puts most areas between 200 and 400 Growing Degree Days on the season, with the Adirondacks and Catskills remaining below 200 total. Most areas are 3 to 7 days behind last year, with the exception being along Lake Ontario, which is only 1 to 3 days behind last year.


A frontal system that has been stalled to our south much of the past few days will lift north through the state on Friday, allowing for the hottest weather of the year to move in. Highs Friday and Saturday will be in the 90's across most of the state, with western New York staying in the upper 80's Saturday. Low temperatures will be near 70. The frontal boundary will sag southward again by Sunday, bringing highs back into the 80's for all but the Hudson Valley, which will remain in the 90's. Low temperatures will back off some as well, with most areas seeing lows in the mid to upper 60's. The return of the front will also bring the threat of scattered showers and thunderstorms. The front will once again stall out over Southern New York, keeping a chance for thunderstorms throughout next week. Total Precipitation will be highest over Central New York, where over 1.5" may fall, while areas near New York City will see less than 1/2".  Temperatures look to remain in the low 80's, but mid 80's will not be far away over Pennsylvania, so even a small shift could bring heat back into New York. For the long range, temperatures will be near or just above normal, with slightly below normal precipitation.

White Mold in Alfalfa

Julie Dennis

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Janice Degni, Central NY Field Crop Team, saw a disease that she suspected was white mold in alfalfa in Cortland County over the past several weeks.  With the assistance of Gary Bergstrom, Cornell’s Field Crop Extension Plant Pathologist, Janice was able to confirm the presence of white mold, or Sclerotinia crown and stem rot, in 2 fields of established alfalfa. 

Wilty plants were first seen during the second week of May. (See photo)

Three weeks later, diseased plants were under the canopy and dead, with slimy, rotting stems and fluffy white mold (see photo)

Sclerotinia crown and stem rot is most commonly observed during cool and moist periods of the growing season, generally in early spring and late summer.  First symptoms observed are yellowing leaves and stems; then patches of dead or dying plants are seen.  The typical white fluffy mold grows on the stems of the dying plants.  The fungus forms hard black structures called sclerotia on or in the stem or crown of the dead plants.  These sclerotia survive the winter and are the source of the tiny mushroom infective stage that occurs when conditions are again ideal for disease proliferation in the future.

Janice noticed these disease symptoms during her observations of four fields that she is watching closely to document the impact of an aggressive cutting schedule on hay quality and alfalfa stand loss.  The fields where white mold was confirmed looked great from the road, but both probably had at least 3% loss to white mold.  Fortunately, further disease development will probably be halted by warm weather, but Janice’s observations are a wake-up call that white mold may be more commonly causing losses in alfalfa fields than we thought.  This is a timely reminder of the value of getting out into fields and scouting for insect, weed, and disease pests. 

Sclerotinia crown and stem rot can be reduced by avoiding fall seeding, especially under minimum tillage. Where the disease develops, deep plowing of infected crop residues and long rotations between legume crops are necessary.

Soybean aphids 08 – looking ahead?

Keith Waldron

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Soybean planting is underway in many areas of the state with some fields just beginning to emerge. Soybean aphid (SBA) questions are also just starting to come in. You may recall that it was about at this time last year that soybean aphids were found on very early vegetative growth stage soybeans in Ontario and NY. These infestations were scattered geographically and eventually caused economic damage in some areas of our region.

No soybean aphid populations have yet been reported in Ontario, NY and surrounding states so far this season.  Michigan State University entomologist Christina DiFonzo, however, reports SBA’s were observed in soybean seedlings May 30th. The affected field had winged aphids that were likely deposited the first few days of June when a storm front moved across central Michigan.

Will 2008 be a repeat for soybean aphid problems in NY? No one knows for certain and to be sure one should monitor soybean fields. During the early season you would want to check soybean fields for stand emergence, weed, disease and other issues anyway. So while looking over the field, check soybean seedlings for presence of the soybean aphid. Fields adjacent to windrows containing buckthorn should be targeted for inspection.

The bulk of weekly scouting for SBA should begin when soybean plants are in the late vegetative (pre-reproductive) to early reproductive (i.e. flowering) growth stages. Current research data suggests that treatment during vegetative soybean growth stage is not likely to result in an economic return.  In most cases, weekly scouting will be necessary for 8-10 weeks.

We will keep close tabs on potential soybean pest problems and share any pertinent updates in future weekly pest reports. A national perspective on soybean aphid and soybean rust information can be found at the USDA Public PIPE website.

Alfalfa Weevil Biological Control, Continued

Julie Dennis

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As Ken mentioned in the View from the Field above, alfalfa weevil larvae are still plentiful in localized areas in alfalfa re-growth, but most alfalfa weevil larvae have not even reached the 4th instar (the most damaging stage).  Since many fields are being harvested, early re-growth of the 2nd cutting may be left vulnerable to injury from alfalfa weevil larvae.  So we will take all the help we can get from biological control agents for protecting alfalfa.

In addition to the parasitoids mentioned two weeks ago in this pest report, another biological control friend in alfalfa is an entomophagous fungus.  Yes, it’s an insect-feeding fungus.  Its only choice for breakfast, lunch, and dinner is the alfalfa weevil.  The fungal pathogen, Zoophthora phytonomi, is always present in low levels in and around alfalfa fields. Under cool, wet conditions, an epizootic, or outbreak, of the fungal pathogen can occur. Infected larvae lose their normal light green color, and the pale yellow infected larvae become less active and usually die within a few days.  The fungus can cause up to 90% larval mortality under the right environmental conditions.  Zoopthora phytonomi first appeared in Ontario, Canada in 1973, and now commonly occurs throughout the weevil’s range in the Midwest and northeast.  Although there are several theories about where the fungus might have come from, its origin remains a mystery.

Unfortunately, the weather forecast is calling for unusually high temperatures over the next week, which may slow development of this fungal pathogen.

Here is a link to a photo showing what you may expect to see if you find infected alfalfa weevil larvae.

Potato leafhopper identification and potential damage

Ken Wise

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Potato leafhopper is a lime-green insect about 1/8 inch long and rides the storms that come from the south, looking for alfalfa and other host plants. The adult females are strong flyers and move from plant to plant laying 2-3 eggs per day. Bright yellow-green nymphs (looking much like adults, but smaller and wingless) hatch from the eggs to feed on plant juices. Nymphs and adults alike use their needle-like mouthparts to suck juices, replacing them with toxic saliva. Once you see V-shaped yellowing on the tips of the leaves it's too late. Potato leafhopper has likely reduced plant protein by 5% and yield by about .10 - .25 ton per acre pre cutting. New seedings are at higher risk to potato leafhopper damage. Crop stress from this insect can impact production this season as well as affect production potential for subsequent years. The key is to scout fields before the damage has already occurred. For more information on potato leafhopper checkout our online publication, Potato Leafhopper on Alfalfa Management Guide.

Potato Leafhopper Adult

Soybean Rust Update, NYS

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United States Soybean Rust Commentary (updated: 06/03/08)
Rust was reported on Jicama (Yam Bean) from the state of Chiapas in Mapastepec municipality (county) on June 3rd. Since the beginning of 2008, soybean rust has been reported on kudzu in one county in Alabama; nine counties in Florida (two of these counties had reports on coral bean and snap bean); three counties in Louisiana; one county in Mississippi, and three counties in Texas. Reported infected kudzu sites in most states have been destroyed. Rust was also reported in three states (5 municipalities)in Mexico on yam bean and soybean. These too have been destroyed or no longer active, except for the recent find in Chiapas. Soybean sentinel plots have been established throughout the Gulf Coast region, and in many parts of the lower Midwest. Additional rains throughout most of the soybean growing region could favor rust development especially in locations in the south near sources of infected plants.

NYS Soybean Rust Website

USDA Soybean Rust Website

Growing Degree Days in NYS

Ken Wise

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March 1 -  June 03, 2008

Base 48 F
Base 50 F
Clifton Springs
*Missing data 
Source: Network for Environment & Weather Awareness

Alfalfa Weevil Degree Day Development Map

Growing degree Days for peak (50%) Occurrence of Alfalfa Weevil growth stage:

Stage or Event
Accumulated growing degree days (48F base temperature)
Eggs hatch
Instar 1
Instar 2
Instar 3
Instar 4
Adult Emergence

Clipboard Checklist

Keith Waldron

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Clipboard checklist
* Emergency contact information ("911", local hospital, Chem. Spill emergency contact, other?) posted in central posting area
* Maintain crop records by field, including variety, planting date, pesticides used, nutrient inputs including manure, etc.
* Watch for winter annual and other early season weeds, any patches of herbicide resistant weeds?
* Storage areas cleaned and ready to accept hay harvest?

* Determine plant populations, make notes on emergence problems, growth stage
* Gaps in row? Check for seed corn maggot, wireworm, cutworm, armyworm, seedling blights, birds, seed placement issues
* Check no-till fields/fields with high residue or weeds for slug damage
* Monitor for weeds, note presence of "who", "how many" and "where"
* Adjust post emergence weed control actions

Small Grains:
* Monitor winter grains for crop stage (flag leaf?), insect problems (cereal leaf beetle, armyworm) and foliar / head diseases
* Evaluate crop for adequate stand and plant vigor

Alfalfa & Hay:
* Monitor alfalfa seedings for weeds, insects & diseases.
* Check regrowth of established alfalfa stands for alfalfa weevil, potato leafhopper, weed and disease problems.
* Check windrows of recently harvested alfalfa for signs of alfalfa weevil feeding damage and weevil life stage (instar cocoon).
* Storage areas cleaned and ready to accept upcoming harvest?

* Evaluate stand emergence - seedling blights, seed corn maggot, weed assessment, soybean aphid

Dairy Livestock Barn Fly Management:
* 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)

* Check storage areas (bunk silos, etc.) for readiness to accept first cutting
* Keep areas around storage bins and silos clean and mowed

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

Emergency responder information on pesticide spills and accidents CHEMTREC:  800-424-9300

For pesticide information:
National Pesticide Information Center: 800-858-7378

To Report Oil and Hazardous Material Spills in New York State_NYS Department of Environmental Conservation Spill Response:_800-457-7362 (in NYS)_518-457-7362 (outside NYS)

Poison Control Centers: Poison Control Centers nationwide: 800-222-1222

If you are unable to reach a Poison Control Center or obtain the information your doctor needs, the office of the NYS Pesticide Coordinator at Cornell University, 607-255-1866, may be able to assist you in obtaining such information.

Upcoming Meetings

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Corn and Alfalfa Field Day
*June 18 at 12:30pm – 3:30pm
At the SUNY Cobleskill Farm
Warnerville Cutoff Road
, between Rt 7 and Rt 10 just West of Cobleskill, NY

Seed Growers Field Day
*Tuesday July 8
NYSIP Foundation Seed Barn
Cornell University, Ithaca, NY

Weed Science Field Days
*Wednesday, July 9, 2008
Valatie Research Farm
9:30 am - Noon
Valatie, NY ( State Farm Road off Route 9 just north of Valatie)

*Wednesday, July 16, 2008
Robert B. Musgrave Research Farm
1:30 pm - 5 pm
Aurora, NY ( Poplar Ridge Road, connects 90 and 34B)

Aurora Field Day
Wednesday, July 23, 2008
Robert B. Musgrave Research Farm
Aurora, NY ( Poplar Ridge Road, Connects 90 and 34B)

Contact Information

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Julie Dennis: IPM Area Educator, Livestock and Field Crops, Western NY
Phone: (315) 252-5440

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

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