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Weekly Field Crops Pest Report 2007

May 1, 2008 Volume 7 Number 3

1. View from the field

2. Weather Outlook May 1, 2008

3. Will early-planted corn be vulnerable to Seed Decay and Seedling Diseases?

4. Alfalfa Weevil and Growing Degree Days in NYS

5. Using NEWA to Determine Growing Degree Days

6. Alfalfa Snout Beetles Begin Spring Emergence

7. Soybean Rust Update

8. Clipboard Checklist

9. UP-Coming Events

10. Contact Information

View from the field

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Eastern NYS-Ken Wise

You know you live in the Northeast when you have to wear a hat so your balding head does not sunburn one week and the next to cover it from the falling snow! Even though it was cold and snowing at SUNY Cobleskill this week I found alfalfa weevil adults in Julie Hansen’s alfalfa trials. There were not many weevils but the fact it was so cold might mean there were more in the lower canopy. I did not find alfalfa weevil eggs in alfalfa stems but the fact it was cold, blowing and snowing I did not look too closely. (More on alfalfa weevil see the article below.) The alfalfa was 10 to 12 inches tall and looked very good. I did not even see signs of a disease called “spring black stem” as I normally do each year.

Other CCE educators in Eastern NY report that the cool, wet weather slowed field operations. Jeff Miller, Oneida County, reported that alfalfa and grass (including pastures) doubled in height since last week. Wheat is up to 17 inches tall! Mike Hunter, Jefferson County, reported that winter wheat, rye, and triticale all look great - conditions were good for establishment last fall, they overwintered well, and are growing well. Joe Lawrence, Lewis County, reports that homeowners continue to call asking “What’s this bug?” as alfalfa snout beetles continue to emerge. See Keith’s article below for more details. In response to a question about glyphosate effectiveness for killing sod, Russ Hahn reminded us that glyphosate works better the more actively growing the plants are. Therefore, following below-freezing temperatures overnight, sprays should be delayed a day or two.

Western NYS and the Finger Lakes

Keith Waldron reported that clover root curculio and alfalfa weevil adults are present in alfalfa in the Geneva area. He also saw parasitized pea aphids already! Gary Bergstrom, Plant Pathology, has observed that wheat diseases in Genesee, Livingston, Seneca, and Cayuga Counties are still pretty well suppressed this spring.

Weather Outlook May 1, 2008

Art DeGaetano
Director, NOAA Northeast Regional Climate Center, Cornell University NYS

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New York saw another warm week, as mainly high pressure dominated the weather with the exception of two weather systems that crossed the state on Saturday and Monday. Saturday's system brought 1-2 inches of rain to central NY from mainly Elmira to Watertown. The precipitation on Monday was more widespread. Combined, most parts of NY saw 1-2 inches of rain, with the exception of western NY were precipitation was < 0.5. For the week, temperatures averaged 3-6 degrees above normal, despite noticeably colder temperatures Tuesday and Wednesday nights with below freezing temperatures common across upstate. It was the warmest April on record at many upstate weather stations.

High pressure will move off the east coast on Thursday (today) and a slow moving warm front will essentially stall though northern Pennsylvania through the weekend. This will give keep the state cool and wet for much of the coming week. Expect 1-2 inches of rain through Monday with the higher amount in southwestern NY. The showery weather should end by Tuesday, but temperatures will remain slightly below normal (highs in the low 60s and lows in the 40s).

Beyond this period there are discrepancies in the different forecast models, however it is unlikely that temperatures will return to above normal levels.

Growing degree day accumulation (base 50 F) since 3/15 has been between 100-150 across upstate.

Will early-planted corn be vulnerable to Seed Decay and Seedling Diseases?

Julie Dennis
NYS IPM

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There was a lot of discussion last week as to whether farmers were jumping the gun by getting corn planted on a time frame that seemed extra early. The ground was dry and air temperatures were well above average, so soils were warming. Weather conditions were conducive for early corn planting in many areas of the state at least for a portion of a farm's corn acreage.

One major risk is that early planted corn seed will likely sit in cold soils for awhile before seeds germinate, giving them extra time to be vulnerable to seed decay and seedling rots, in spite of improved seed genetics and traits.

Seed Decay
Seed decay is caused by a number of soil-inhabiting fungi such as Pythium, Fusarium, Diplodia, Rhizoctonia and Penicillium. These fungi can infect seed before it germinates, causing mortality. Seeds infected with decay fungi are discolored and soft. Many times fungal material may grow on the seed. If you are digging around in the soil in a few weeks to investigate those gaps in the row, a seed that has rotted may be completely decomposed and therefore cannot be found. This can make tracking down the culprit a little difficult!

Seedling Blight
Sometimes the seed may germinate and grow but then die as the plant emerges from the soil. Seeding blights are caused by many of the same fungi that cause seed decay. Seedling blight symptoms include discolored seedling coleoptiles and roots. Seedlings may have a wet, rotted appearance before they reach the soil surface. Above ground symptoms of blight may include seedlings that turn yellow, wilt and die.

Factors that contribute to both seed decay and seedling blights may include cold (<65^oF), wet soils. These unfavorable conditions can lead to slow emergence and slow growth of seedlings. Plant or seed injury from fertilizer burn, incorrect herbicide application, or soil crusting can add to plant stress at the vulnerable seedling stage.

Fortunately, planting high quality corn seed is common practice, and fungicide seed treatments are a normal part of the spring routine for many producers. These practices help prevent many outbreaks of seed decay and seedling blight.

Alfalfa Weevil and Growing Degree Days in NYS

Ken Wise
NYS IPM

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Adult alfalfa weevils are now moving back into established alfalfa fields. Remember alfalfa weevil populations can build up over the life of the alfalfa stand. The longer an alfalfa field is in production the higher the risk of alfalfa weevil damage. Adult weevils that enter fields in the spring are light brown and 3/16" long. They have a band of darker brown down the center of their back and a long snout.

If you keep track of growing degree days you can predict when certain stages of alfalfa weevil development occur. Remember that alfalfa weevil’s base temperature for determining its growth stages by growing degree days is 48 degrees F. You should start scouting and sampling fields at about 350 growing degree days. For more information on alfalfa weevil, view the Alfalfa weevil management guide.

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

Stage or Event Accumulated growing degree days*

Eggs hatch 280

Instar 1 315

Instar 2 395

Instar 3 470

Instar 4 550

Cocooning 600

Pupa 725

Adult Emergence 815

* 48F base temperature

CURRENT Accumulated Growing degree days (48F Base)

March 1 - April 28^th , 2008

48F 50F

Batavia: 218 184
Chazy: 185 158

Clifton Park:                    338               299
Geneva:                             207             173
Ithaca:                              132              110*

Prattsburg: 167 141

*Missing Data

Using NEWA to Determine Growing Degree Days

Julie Dennis
NYS IPM

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Our insect pests of field crops depend on accumulations of heat units, or degree days, for their growth and development, given their “cold-blooded” nature. Researchers have extensively studied the biology of some of our key pests in relation to heat accumulation from the environment, and thus we are able to monitor and predict the timing of development of damaging stages. One example of such a pest is the alfalfa weevil.

In past years, we have provided growing degree day accumulation tables for a few locations around New York State in this weekly report. This year, we encourage our readers to use the NEWA website, where many more locations than we are able to summarize in our brief GDD section can be accessed.

NEWA is NYS IPM’s network for environment and weather awareness. It is a network of electronic weather instruments associated pest forecast models, and radar weather forecasts. Weather and pest data is relevant for farmers across commodities, from field crops to fruit to vegetables. Data available include hourly rainfall, temperature, leaf wetness, relative humidity, and soil temperature readings. All of this information, as well as degree day accumulations are available from almost 50 on-farm locations around NYS, primarily in western NY, the Finger Lakes region, and the Hudson Valley. Additional information is available from many regional airports.

Access to the NEWA home page

growing degree day site

predictions for alfalfa weevil

Be sure to bookmark this location and check back as often as you need.

Alfalfa Snout Beetles Begin Spring Emergence

Keith Waldron
NYS IPM

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Alfalfa Snout Beetle emergence time....

One indication that spring is here is the sighting of newly emerged alfalfa snout beetle populations. Elson Shields (Cornell Entomology) and Joe Lawrence ( Lewis County) both reported alfalfa snout beetle (ASB) spring emergence in NY's north country last week (Jefferson and Lewis counties). Warmer temperatures should continue to enhance ASB viewing opportunities as adults of this unique species emerge and begin moving to new alfalfa fields.

Alfalfa snout beetles (ASB) are root-feeding weevils found only in nine northern New York counties (Cayuga, Clinton, Essex, Franklin, Jefferson, Lewis, Oswego, St. Lawrence and Wayne). ASB was also discovered on a number of the thousand islands in the early 1960s. and in Prescott Ontario, Canada in 1986. The native home of snout beetle is Europe where it can be found from Italy to England and Poland.

ASB adults are mottled gray, humpbacked, 1/2 inch long, do not fly, and are all females. Adult alfalfa snout beetles leave fields void of alfalfa this time of year en mass (by the tens of thousands) in search of new alfalfa fields to lay their eggs. Once they find a suitable location, ASB adults feed on alfalfa foliage and lay eggs that hatch into root feeding larvae. While adult feeding can trim the tops of alfalfa and other hosts, the vast majority of plant death comes from direct root loss caused by ASB larvae feeding.

Alfalfa snout beetle larvae are legless, white, and 1/2 inch long. ASB larvae are found shallow in the soil when very small but move deep in the soil during mid July to late August (18-24 inches). In September the large larvae move back up to the top 8 " and do most of the tap root severing in September and October. After development is completed, they then move deep in the soil to overwinter. Larvae move deep in the soil in the fall after feeding (18-24") and remain there for the next 18 months. Midway through the summer they pupate but remain deep in the soil until the following spring.

ASB damage in the spring looks similar to winter killed alfalfa with plants failing to "green up".Areas of dead alfalfa may also indicate presence of brown rot rot. (See last week's WPR for more information on this disease).

Alfalfa Snout Beetles in your neighborhood? In addition to alfalfa, other host plants for ASB include: red clover, dock, wild carrot, quackgrass, and white clover. ASB control is best achieved with a three year rotation of alfalfa with a row crop. Non hosts, i.e. good crops to have in rotation to minimize ASB losses include: corn, wheat, oats, soybeans, and potatoes. Insecticides are not recommended to control ASB.

More information about ASB, including highlights on two on-going Cornell ASB management research efforts can be found at: http://www.nnyagdev.org/ipm.htm

Soybean Rust Update

Gary Bergstrom
Department of Plant Pathology, Cornell University

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Rust continues to be found in the southern U.S. On April 19th, rust was detected on kudzu in a kudzu sentinel plot in Polk County, Texas. This is the second detection at this site since January. Active disease is still being reported on kudzu in six counties in Florida. Efforts continue in the Gulf Coast Region to establish soybean rust sentinel plots.

Coordination of soybean rust sentinel plots in New York State is currently underway. Many of last year’s cooperators will be volunteering their time again to establish and scout these plots. Please visit us again for future updates.(Updated April 23, 2008 )

NYS Soybean Rust Information Center

http://www.plantpath.cornell.edu/soybeanrustny

National Soybean Rust Website

http://www.sbrusa.net/

Clipboard Checklist

Keith Waldron
NYS IPM

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Clipboard Checklist
Keith Waldron-NYS IPM

General:
*Emergency contact information ("911", local hospital, Chem. Spill emergency contact, other?) posted in central posting area
*Review EPA Worker Protection Standard training and posting compliance needs
*Walk fields to check tile flow, check and clear drainage outlets.
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

Corn:
*Finish corn planting by May 15, if soil conditions allow
*Use corn insecticide seed treatment in the planter box, if available, or plant insecticide pre-treated seed
*Monitor for weeds, note presence of "who", "how many" and "where"
*Adjust post emergence weed control actions
*Determine corn plant populations, make notes on germination problems

Small Grains:
*Monitor winter grains for crop stage, insect and disease problems
*Assess crop for adequate stand and plant vigor
Alfalfa & Hay:
*Monitor alfalfa seedings for weeds, insects & diseases.
*Check established alfalfa stands for over wintering injury, frost heaving, alfalfa weevil, weed and disease problems.
*North country counties: Monitor alfalfa for Alfalfa Snout Beetle (In Oswego, Jefferson, Cayuga, Wayne, Lewis, St. Lawrence, Clinton, Essex, and Franklin counties)
*Timothy stands: check fields for symptoms of cereal rust mite

Pastures:
*Check and mend fences as needed.
*Check crop growth
*Review/Plan rotation system

Storage:
*Check forage allocation and anticipate feed program adjustments as forages are used up from previous year
*Plan where forages should be stored for optimum allocation for feeding
*Keep areas around storage bins and silos clean and mowed

Equipment:
*Note any repairs needed for corn planter, seeding equipment, alfalfa harvesting equipment, and tillage implements as they are cleaned and lubricated.
*Service corn planter as needed.
Calibrate manure spreaders - maintain records on amount spread per field

PESTICIDE EMERGENCY NUMBERS
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.