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Weekly Field Crops Pest Report 2012

June 28, 2012, Volume 11 Number 11

  1. View from the Field
  2. Weather Outlook
  3. Watch out for Two-Spotted Spider Mites in Soybeans
  4. Clipboard Checklist
  5. Mark Your Calendars
  6. Contact Information

View from the Field

Ken Wise

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Move over, true armyworm. Potato leafhopper is the insect pest of the week! There are reports that potato leafhopper (PLH) have reached economic thresholds on many fields across the state and Extension Educators report a lot of yellowing fields. This is a byproduct of not scouting for potato leafhopper earlier. Once you see the yellowing the quality and yield are dramatically reduced. When the alfalfa is 8 to 10 inches and has yellowed due to PLH damage and nymph infestation levels are high the question is what to do?

potato leafhopper damage

Potato Leaf hopper Damage on Alfalfa

Elson Shields (Cornell University Extension Field Crops Entomologist) states it is better to clip off the damaged alfalfa then to spray the crop, since if you spray the alfalfa, forage quality will remain poor. If you clip off the 8 to 10 inch PLH damaged alfalfa you get rid of the potato leafhopper nymphs and can start over managing the alfalfa for leafhopper. The regrowth would have normal high quality forage. BUT…. You have to scout and manage PLH after clipping the alfalfa to monitor infestation levels in the field. While scouting the Cornell research farm this week, I found some alfalfa research plots loaded with nymphs. They far exceeded the economic threshold and the alfalfa was yellowing. These plots were in the middle of an alfalfa field that had been harvested the week before with the exception of those plots. The re-regrowth on the alfalfa was good and infestation levels were very low. The harvesting had removed the nymphs from the field. As we get hotter and drier again this next week PLH levels will continue to rise—PLH loves hot, dry conditions and populations can explode very quickly. For information on how to scout for PLH please consult last week's article, Time to Start Scouting for Potato Leafhopper on Alfalfa.

Ultimately, you should be planting PLH resistant alfalfa. The level of resistance is very high in current varieties. In some cases they are 70% resistant. Yield and quality of the resistant alfalfa are better in years when we have PLH issues. Yield and quality are similar to susceptible alfalfa in years without PLH problems.

Kevin Ganoe reports soybean aphid on soybeans. He stated that populations were high, exceeding 250 aphids/plant. Mike Stanyard found soybean aphids at low levels on soybeans this week in western NY. SBAs are very tiny, soft-bodied insects. They are pale yellow-green and less that 1/16 of an inch long. The aphid has black cornicles, aka "tail pipes" on hind end of the insect. Most generations of SBA lack wings with the exception of early field invaders and a population readying for migration or dispersal. They are the ONLY aphids that infest soybeans in North America. The economic threshold for SBA is an average 250 aphids per plant, population is increasing, natural enemies like lady beetles are not holding the infestation down and the crop is prior to early pod fill (R4). More on soybean aphids next week!

soybean aphid

Soybean Aphids on Soybeans (Photo taken by Kevin Ganoe)

At the Cornell Research farm this week I was scouting a cornfield that had an infestation of European corn borer. About 15 percent of the plants showed corn borer feeding. I have not seen this much corn borer in several years.

black cutworm damage

Alex Wright CCA with Carolina Eastern-Vail found a large population of black cutworm in corn. The cutworm dramatically reduced corn populations.

black cutworm
Black cutworm in corn (Photo by Alex Wright)
black cutworm damage
Black Cutworm Damage in Corn (photo taken by Alex Wright)

Armyworm infestation levels have fallen off this week. There are still a few report of true armyworm damage statewide, but far less than the past few weeks. The second generation of true armyworm is not supposed to be a problem.

As it get HOT and DRY watch for 2 spotted spider mites on soybeans. The can increase in population in a field under these conditions. See article below for more information.

Western Bean Cutworm moths were caught in Clinton, Genesee, Monroe, Schuyler, Tompkins and Cayuga counties this week.
They found only 1 moth per county.

Weather Outlook

June 28, 2012
Jessica Rennells, Northeast Region Climate Center, Cornell University

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Last week we had hot weather followed by a cooling trend bringing the overall temperature departure to 0 to 6 degrees above normal. Precipitation amounts ranged from a trace to an inch for most of the state, though some areas did see over an inch. The base 50 growing degree-days ranged from 100 to 150. Hot again! We’ll see hot and humid conditions starting today and through the weekend. Today will be sunny with highs in the mid to upper 80s, some near 90. Overnight will also be warm, with temperatures in the 60s. Showers and thunderstorms are possible tonight into Friday morning, some of which could be severe producing heavy rain. Friday will be sunny with temperatures rising into the upper 80s and low 90s. Lows will be in the upper 50s to mid 60s. Saturday will again be hot and sunny with temperatures in the upper 80s and low 90s. Overnight temperatures will be in the 60s. Sunday will be mostly sunny with a chance for showers and thunderstorms and highs in the mid 80s to low 90s. Lows will be in the 60s. Monday will be mostly sunny with a chance for showers and thunderstorms. Highs will be a little cooler, throughout the 80s. Lows will be in the upper 50s to low 60s. Tuesday will be mostly sunny with highs in the upper 70s to mid 80s. Lows will be in the low to mid 60s. Wednesday’s temperatures will be throughout the 80s with a chance for showers and thunderstorms. Lows will be in the 60s.

The five-day precipitation amounts will range from a tenth to half an inch. The 8-14 day outlook is showing normal temperatures and below normal precipitation for most of the state.

National Weather Service Climate Prediction Service Maps of 8-14 day outlooks

National Weather Service Eastern Region Headquarters watch/warnings map

NRCC Drought Page which features the US Drought Monitor map (updated every Thursday)

Watch out for Two-Spotted Spider Mites in Soybeans

Ken Wise

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Two-Spotted Spider Mites (Archnida: Acari:Tetranychidae) can commonly be found in soybeans. They become a problem under certain environmental factors. Two-Spotted Spider Mites are not insects. They are more closely related to spiders. Spider mites are VERY VERY tiny… less than 0.002 inches long. They look like a speck of dust to the naked eye. To really see them well you’ll need a 30+ hand lens or a dissecting scope. Note two spots on either side of their back.

Like their spider relatives, spider mites make fine, silky webs. Heavily infested fields show webbing on leaflets and petioles (where the leaves meet the stem). The mites cannot fly—but they can float. Their silk threads can carry them far on a breezy day, which is how they move to new fields. Mites really thrive in soybean fields when the weather is hot and very dry. Many times the soybeans are under some drought stress when mites cause damage. The mites normally infest fields in July and August. You rarely see damage when it’s wet and or cool.

Spider mites increase on soybeans when it’s droughty and hot. Here’s why: When alfalfa or grass hay is cut, the weather is normally dry. This causes the mites to set afloat their silk thread and travel to a nearby soybean field. The drought stress improves the soybean food quality for spider mites. Also, naturally occurring fungus diseases that normally help control mites can’t develop when it’s dry. And mites reproduce more when it’s hot and dry.

How can such a little beast damage a soybean plant?

  1. A lot of them are on the plant at once.
  2. Mites pierce plant cells and suck out the contents.
  3. As cells die, the surface area available for photosynthesis becomes smaller.
  4. Plants continue losing water from the damaged cell.

Heavily infested leaves are stippled yellow with lots of tiny dots. Stippled leaves are an early feeding sign. Later, note bronzed leaves. Injury can look like a fungal disease. Damage normally starts along the edge of fields as mites migrate in from the hedge rows. You can find them on weeds long the edge of fields.

Early season applications of pyrethoids (tank mixed with herbicide like Roundup) often trigger spider mite outbreaks when the weather turns warm and dry. Resist the urge to “just add insecticide” to herbicides. These early applications also can trigger soybean aphid rebounds by killing off the beneficial insects—requiring a second application to prevent loss.

When scouting for spider mites, start along the egde of the field. Look for symptoms first. Pull a plant out of the ground and look on the underside of the leaves, starting with ones that have that show damage. Examine the damage and webbing and see how they progress up the plant.
Tap the plant over a piece of white paper. The mites will fall onto the white paper where you can see them. Use a 30X hand lens to confirm it is the 2 spotted spider mite. Walk a “U” pattern, checking at least 5 plants in 5 different locations in the field. Assess damage with this scale:

Here’s how to record field conditions and the possible economic threshold for spider mites.

Stippled Leaves
0 – No spider mites or injury
1 – Minor stippling on lower leaves; no premature yellowing
2 – Frequent stippling on lower leaves; yellowing on small areas or
scattered plants
3 – Heavy stippling and distinct yellowing on lower leaves; some
stippling in middle canopy. Mites present in middle canopy;
scattered colonies in upper canopy. Patches of lower leaf loss.
(Economic Threshold)

Mites on Leaves
4 – Heavy yellowing easily seen on lower leaves; some leaves drop. Frequent stippling, webbing, and mites in middle canopy. Some mites and minor stippling in upper canopy. (Economic Loss)
5 – Frequent lower leaf loss; yellowing and browning shows higher in middle canopy; frequent stippling and distortion of upper leaves. High levels of mites in middle and lower canopy.

Check fields every 4-5 days during dry weather, since damaging infestations can develop quickly.

Spider mites do economic damage to plants between R4 and R5 growth stage. Because the mites reduce photosynthisis and promote drought stress, a reduction of 10 to 15% in the leaf surface area causes damage. Pod set, seed size and number of seeds are less. Pods are more prone to shattering. These are critical times affecting the yields of soybeans. If the plants reach economic threshold at the R4 to R5, an insecticide should be used to avoid economic losses. For an insecticide please consult the Cornell Guide for Integrated Field Crop Management. Note: a single rainstorm will normally not stop a spider mite infestation. Several days of rain can stop an infestation.

Clipboard Checklist

Keith Waldron

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*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.
*Walk fields to check crop condition, growth, and emergence. Look for signs of vertebrate pests (birds, ground hogs, deer, etc.).
*Mow around farm buildings to minimize rodent and other pest habitat
*Begin grain bin and auger clean up and preparations for storage.
Alfalfa and Grass Hay:
*Monitor alfalfa for crop condition, watch re-growth for alfalfa weevil, potato leafhopper, and diseases.
*Evaluate alfalfa seedings for weeds, insects (potato leafhopper, armyworm) & diseases.
*Monitor grass hay for crop condition, watch re-growth for armyworm

Small Grains:
*Monitor winter wheat for foliar & grain head diseases, Fusarium Head Blight incidence
*Monitor winter grain fields for crop growth stage, signs and symptoms of diseases, weed pressure, insects (armyworm, cereal leaf beetle)
Field Corn:
*Post emergence: Determine corn plant populations, monitor for emergence problems, weeds, noting presence of "who", "how many" and "where"
*Early season corn pests: seedling blights, seed corn maggot, white grub, wireworm, black cutworm, armyworm, slugs, birds
*Adjust post emergence weed control actions
*Post emergence: Determine plant populations, monitor for germination and emergence problems, monitor for weeds, noting presence of "who", "how many" and "where"
*Monitor for soybean aphid
*Monitor pastures for crop condition, watch re-growth for armyworm
*Check and mend fences as needed.
*Check crop growth
*Check for presence of undesirable plant species harmful to livestock.
*Review/Plan rotation system
*Arrange for custom weed / disease management or check your own application or cultivator equipment for readiness or need for repairs.
*Check nozzles, pumps, etc., recalibrate pesticide application equipment regularly before use.
*Calibrate manure spreaders - maintain records on amount spread per field
Cattle on Pasture:
*Monitor animals for presence of face flies, horn flies and stable flies. Action guidelines: face flies (average 10 per animal face), horn flies (average 50 / dairy, 200 / beef cattle per animal side), stable flies average 10 per animal (all four legs)
*Check feed bunk / water source locations for signs of stable fly breeding (moist undisturbed organic matter – spilled feed, round bales, etc.), minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard
*Check paddocks for forage quality / quantity, rotate as appropriate
*Check paddocks for vegetation poisonous to livestock
*Consider use of fly traps to help reduce deer, horse and stable fly populations
Dairy Cattle Barn Fly Management:
*Monitor animals and barn area for house fly, stable fly and other pest management needs including presence of rodents and birds.
*Check facilities for favorable fly breeding conditions: (organic matter + moisture): leaks in watering systems, roof gutters for leaks and potential overspill, drainage,
*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
* Continue fly monitoring: install "3X5" index card fly speck monitoring cards throughout barn
*Use, replenish, replace fly management materials: sticky fly tapes/ribbons, insecticide baits, natural enemies (parasitoids), fly population monitoring (3 x 5) spot cards
*Consider purchase and release of Muscidifurax raptor and/or M. raptorellus natural enemies of house and stable fly pupae

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.

Mark Your Calendars

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Tuesday, 3 July 2012
For Seed Growers, Seed Treatment Applicators, and other Seed Professionals
Place: NYSIP Foundation Seed Barn, 791 Dryden Rd., Rt. 366, Ithaca, NY
Time: 8:30 AM-12:00 noon (registration starts at 8:30 and the program runs fro 9:00 until noon)

Freeville, NY (10 miles Northeast of Ithaca, Fall Creek Road, Rt. 366 extension)
8:00 a.m. Registration
Coffee (beverage), doughnuts, and informational trial packet
8:30 a.m.-11:30 a.m. Vegetable Crop Weed Control (Bellinder)

Aurora, NY (Poplar Ridge Road, connects 90 and 34B)
12:00 – 1:30 p.m. NYSABA Pork BBQ lunch at Musgrave Research Farm.
1:30 p.m. Registration
2:00 - 5:00 p.m. Field Crop Weed Control (Hahn)
CCA and DEC Credits have been requested for field crop and vegetable

July 18-Robert B. Musgrave Research Farm Field Day
1256 Poplar Ridge Road, Aurora, New York
WEDNESDAY, July 18, 2012, 9:00-3:00 pm

FREE and open to all!
Registration at 9:00 with Coffee and Donuts (no preregistration)

Contact Information

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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