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Weekly Field Crops Pest Report 2012

September 4, 2012, Volume 11 Number 20

  1. View from the Field
  2. Weather Outlook
  3. Downy Mildew on Soybeans in NY
  4. Western Bean Cutworm
  5. Clipboard Checklist
  6. Coming Events
  7. Contact Information

View from the Field


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Sudden Death Syndrome in Soybeans
Mike Hunter (Jefferson County CCE) reports that a field of soybeans in St. Lawrence County has “Sudden Death Syndrome (SDS).” This is one of the more important diseases of soybeans in the Midwest. In New York State we have had only a few cases of the disease. The disease is caused by a soil fungus Fusarium virguliforme.† The symptoms of SDS first appear after flowering and during pod fill. You first notice yellowing and defoliation of the upper leaves. Generally the disease begins in a small area of the field and spreads. Early indications of the disease include mottling and mosaic symptoms on the leaf. As SDS continues there is yellowing between the veins, followed by the leaf turning brown, death and the leaf falling off the plant. Please view Why is sudden death syndrome found in early-planted soybeans? for photos of the disease.

Management of Sudden Death Syndrome

  1. Cultivar Selection: There are some varieties of soybeans with decent resistance to SDS.
  2. Planting Date: Planting early when the soil is still cool and wet can increase the chances of the disease infecting the plant. Wait until the soil is warm so the plants can grow more quickly.
  3. Crop Rotation: There is not a lot of good information on crop rotation relative to SDS. Continuous beans do cause a buildup of SDS. A 2 to 3 year rotation has shown less disease than the continuous beans
  4. Tillage: Fields that are tilled or minimally tilled had less disease than no-tillage systems.
  5. Fungicide: Soil fumigation is not economically feasible for control of SDS.
  6. Plant health: If you maintain plant health like controlling weeds, good soil fertility, monitoring insect pests for possible damage will help the plant to better tolerate the disease.

Brown Stem Rot on Soybeans
Brown stem rot (BSR), another unusual soybean disease, is suspected of causing problems in St. Lawrence County. †Brown stem rot is caused by Phialophora gregata. The fungus survives as mycelium on soybean residue. The pathogen infects roots of young soybean plants. Wet soils and air temperature 70 to 80 F favor infection of stem tissues. At the R2 stage, symptomatic plants have a brown pith from the roots up the plant. At the R4 stage leaves of infected plants exhibit interveinal yellowing with the leaves ultimately turning brown. In contrast to SDS plants, leaves of plants infected with brown stem rot shrivel-up but remain attached to the plant.

Please view the Brown Stem Rot Fact Sheet from UMN

Management of Brown Stem Rot

  1. Cultivar Selection: There are varieties of soybeans with good resistance to BSR.
  2. Crop Rotation: †Since this disease has to survive on soybean residue rotation is an important key to its management. Rotating with corn, small grains, alfalfa or forage can dramatically reduce brown stem rot disease incidence.†
  3. Tillage: No-till fields are at higher risk for brown stem rot since the fungus can build higher levels of inoculum over time in infected soybean residues. The use of tillage or minimum tillage promotes decomposition and thus is a viable management strategy to limit the disease development.
  4. Plant health: If you maintain plant health like controlling weeds, good soil fertility, monitoring insect pests for possible damage will help the plant to better tolerate the disease.

There continue to be reports statewide of soybean vein necrosis virus (SVNV) symptoms on soybeans. See last week’s report.

We are interested in learning more about the occurrence and potential impact of this disease. If you see these symptoms collect a half dozen or so leaves that show the veinal chlorosis (often in an oak-leaf pattern) and necrosis of tissues extending from leaf veins.  Information on field location (GPS or town and county) is essential; information on soybean variety, cropping practices, and other observations is helpful.  You can put these leaves in a zip-lock bag with a slightly moist paper towel and mail them to:

Jaime Cummings
Field Crops Pathology Laboratory
Department of Plant Pathology and Plant-Microbe Biology
Cornell University
334 Plant Science Building
Ithaca, NY 14853-5904

SVNV
SVNV
SVNV
Soybean Vein Necrosis Virus Symptoms

Gary Bergstrom (Cornell U. Field Crops Plant Pathologist) reports several other soybean diseases this season. These are diagnosed cases of brown root rot, charcoal rot, and pod and stem blight complex in soybean fields in Cayuga Co.  Fusarium wilt has been diagnosed on soybeans in Cortland and Madison Counties.  

Keith Waldron reports finding bean leaf beetles in a Seneca County soybean field this week. While bean leaf beetle (BLB) has not yet been documented to cause economic impacts on soybean production in New York, it is on our “watchlist of potential soybean insect pests” and is considered a serious and larger problem in the Midwest. BLBs have a range of colors and patterns. They’re smallóabout 1/4 inch. The beetle can be golden brown, reddish, or green. Most, but not all have four black spots on the elytraóthe wing coversóand all have a triangular shaped spot behind their head on the end of their thorax.

bean leaf beetles

bean leaf beetles with penny for scale
Bean Leaf Beetles (Not the V-shape behind the head)

Adult beetles over winter in woodlots, hedgerows, and field with residue. The over wintering beetles colonize fields in June. The colonizers can feed on emerging plant structures including cotyledons, stems, unifoliate leaves, and emerging trifoliolate’s.†† As the season continues, first and second generations adult beetles feed on leaves, creating small round holes. Adult female BLBs lay orange eggs on the soil next to plant stems. These eggs hatch in 10 or 11 days. Each female beetle can lay between 125 to 250 eggs.† Larvae are cylindrical with a white body and black head. They feed on the nitrogen-fixing nodes on soybean roots. While BLB larvae can damage roots, the leaf-feeding adults cause most losses. †As mentioned earlier, BLB infestations are not known to have not to date caused economic damage to soybeans in NY. Most foliar feeding damage observed in NY soybean fields is caused by Japanese beetles, Mexican bean beetles or grasshoppers. Fortunately, soybeans have an amazing ability to compensate for a lot of defoliation. BLB’s can vector bean pod mottle virus.† One of the more critical risk periods for BLB injury is when soybeans just start to emerge from the soil. There is no leaf tissue and colonizing beetles will feed on the cotyledons and growing point of the plant. This can kill or severally damage the plant.†† This can be a problem with early planted beans.

Keith Waldron reports finding a lot of “Common Smut” in corn fields recently. Common smut forms white, soft galls that can be found on most any plant part on the corn plant above the ground. It is suggested that the galls form where hail, animal damage or machinery have injured the plant. As the smut galls age they fill with dark brown to black spore masses. The good thing is that smut rarely kills the plant, and typically causes little if any yield loss.

common smut on corn
Common Smut

Spider mites continue to be found in corn and soybeans across the state in areas that have not received much rain. More on spider mites is in the following article in our past issue, June 28, 2012.

Soybean aphids continue to be found at very low levels. A winged soybean aphid was observed this past week signaling some SBA field populations are preparing to move to buckthorn their overwintering host.

Weather Outlook

August 30, 2012
Jessica Rennells, Northeast Region Climate Center, Cornell University

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Last week temperatures ranged from 0 to 6 degrees above normal for most of the state.† Rainfall amounts ranged from a trace to two inches, the highest amounts were in the Eastern Plateau. The Base 50 growing degree-days ranged from 100 to 150, lower in the Adirondack region.

High pressure will bring sunshine and dry weather through the weekend; warm front and Isaac could bring rainfall the beginning of next week. Today will sunny with temperatures ranging throughout the 80ís.† Tonightís temperatures will range from the low 50ís to the low 60ís. Friday will be mostly sunny and hot with highs in the mid 80ís to low 90ís.† Some scattered showers are possible as a weak cold front moves through.†

Lows will be in the mid 50ís to low 60ís.

Saturday will be mostly sunny with highs in the upper 70ís to mid 80ís. Lows will be in the mid 50ís to low 60ís. Sunday will be mostly sunny with temperatures in the mid 70ís to low 80ís.† Lows will be in the mid 50ís to low 60ís.†† Scattered shows will be possible overnight into Monday as a warm front moves in.† Moisture from Isaac could combine with this front and move in our direction. Monday will be in the upper 70ís to low 80ís with scattered showers and thunderstorms.† Overnight temperatures will be in the low to mid 60ís. Tuesdayís temperatures will be in the mid 70ís to low 80ís with scattered showers and thunderstorms likely.† Lows will be in the upper 50ís to low 60ís.

Wednesday temperatures will in the mid 70ís to low 80ís with scattered showers and thunderstorms.† Lows will be in the low to mid 60ís.

The five-day precipitation amounts will range from a tenth of an inch up to 1 ľ inches; the higher rainfall amounts are expected in western NY, closer to the track of Isaac. The 8-14 day (Sept 6-12) out look is showing above normal temperatures for the northeast half of the state and normal precipitation.

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)

Downy Mildew on Soybeans in New York

Ken Wise
NYS IPM

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I have found a lot of Downy mildew (Peronospora manshurica) in soybeans that last few weeks.† This is a common disease of soybeans and only occasionally can cause yield losses. This disease proliferates under high humidity and cool temperatures. The fungus can overwinter on last seasonís crop residue and can also be transmitted by contaminated seed. Fungal spores are transmitted to the plant by wind and rain. When conditions are right the disease can spread quickly through a field. If the seed was infected with downy mildew the seeding will also be infected. Soybean downy mildew is a biotrophic organism meaning the disease can only grow and reproduce in association with soybeans. †The disease can have rapid genetic changes in response to changes among soybean varieties. There are many different races of this fungus that are monitored closely when new cultivars are being bred.

The first sign of the disease are pale green or light yellow spots on the upper leaves. As the disease progresses the spots enlarge into varying shapes and sizes. Next, lesions appear on lower leaf surfaces, particularly in moist weather. The leaves turn yellow and the lower leaf surface becomes dusted with gray or purplish mycelium. Severely infected leaves may curl turn brown, and drop off prematurely.

The pods can be infected without obvious external symptoms. Infected seeds appear dull white and partly or completely covered with a pale coating of fungal spores.

downy mildew on a soybean leaf
Downy Mildew on Soybeans

Scouting and thresholds

There are no specific economic thresholds for foliar diseases of soybeans in New York. Research needs to be done to determine these thresholds. Until then the likelihood of 10% yield loss is a reasonable rule of thumb for treatment.

What preventive measures help limit soybean diseases?††††††

  1. Rotate crops with corn (or other non-hosts). This will help reduce the amount of a certain pathogen in the field.
  2. Use certified, disease-free seed. If you use seed that is not certified are saved seed from your previous harvests many contain the pathogens we discussed earlier.
  3. †Use resistant cultivars; ask your dealer how cultivars compare for disease susceptibility or resistance and productivity. Make sure the cultivar is suitable for your specific region of the state.†
  4. Use a fungicide seed treatment at planting. This will kill pathogens that might infect the seed at planting. If you are organic make sure the soil temperature is over 500F. This will allow the soybean to grow quickly and avoid pathogens in the soil.
  5. Plow infected residue under the soil surface. This will help reduce the amount of disease laying on the surface that can infect the next crop.

Foliar fungicides are seldom warranted in New York. If you need to select a fungicide please consult the Cornell Guide for Integrated Field Crop Management. You can also contact your local Cornell Cooperative Extension Educator.

Western Bean Cutworm

Keith Waldron
NYS IPM

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Western Bean Cutworm captures are winding down with most traps not catching any WBC moths this week. In fact, several locations have not reported catches in over 2 weeks, a clear signal that flight is over. So, with our 3rd trapping season coming to a close, what information have we learned regarding its pest status in New York?

The total number of WBC moths caught was 3,350, which is more than double last yearís catch. Peak WBC flight this year was the week of July 22, which is about 2 weeks earlier than that observed in 2010 and 2011 (August 2). This earlier emergence and activity is probably related to the warm temperatures in spring and early summer. It should be noted that WBC captures in many trap locations were far below 50 moths per trap. The very good condition of moths captured in most locations indicate we have locally overwintering WBC populations. Several locations in western and northwestern NY had very high captures this season. The rough condition of moths in locations with high counts (> 150) indicate many were likely migrants.

Very few egg masses were found this season (Franklin County) and none of those fields were over threshold (field corn: 5% field infestation with egg masses and/or small larvae). Over the last 2 weeks, WBC larvae have begun to be found in corn in some locations in Wyoming and Jefferson counties. No WBC damage has been detected to date in dry beans. It will be several weeks before we will know if there has been any economic impact of WBC in NY this season.

Accumulated western bean cutworm moths captured per location as of 8.26.12

County Location Total WBC County Location Total WBC

Broome

Whitney Point

0

Livingston

Cuylerville

9

Cattaraugus

Olean

16

Livingston

Lima

57

Cayuga

Auburn

59

Madison

Kirkville

34

Cayuga

Aurora

29

Monroe

Churchville

35

Cayuga

King Ferry

1

Monroe

Hamlin

49

Cayuga

Sherwood

0

Monroe

Spencerport

27

Chautauqua

Kennedy

143

Niagara

Lockport

23

Chenango

Afton

14

Oneida

Clinton

21

Chenango

Sherburne

19

Oneida

Clinton

21

Clinton

Beekmantown

50

Onondaga

Baldwinsville

20

Clinton

Chazy

24

Onondaga

Tully

16

Cortland

Marathon

2

Ontario

Farmington

2

Cortland

Preble

77

Ontario

Geneva

45

Delaware

Oneonta

19

Ontario

Hopewell

8

Delaware

Walton

34

Ontario

Stanley

29

Dutchess

Millbrook

40

Orleans

Waterport

21

Erie

Eden Z

131

Otsego

Garrattsville

13

Essex

Westport

19

Schoharie

Middleburg

22

Essex

Willsboro

13

Schuyler

Burdett

1

Franklin

Malone

140

Schuyler

Valois

9

Genesee

Alexander

17

St.Lawrence

Madrid

301

Genesee

Batavia

23

Steuben

Avoca

19

Genesee

Batavia

36

Steuben

Wayland

34

Genesee

Leroy

36

Suffolk

Riverhead

1

Genesee

Stafford

16

Tioga

Owego

1

Genesee

Stafford

91

Tioga

Owego

13

Green

 

27

Tompkins

Varna

27

Herkimer

Little Falls

47

Washington

 

7

Jefferson

Ellisburg

192

Wayne

Macedon

13

Jefferson

Plessis

42

Wayne

Williamson

24

Jefferson

Sacketts Harbor

342

Wyoming

Attica

276

Lewis

Martinsburg

323

Wyoming

Pike

0

Livingston

Avon

46

Yates

Bellona

26

Livingston

Caledonia

28

Yates

PennYan

32

 

It should also be noted that there are several counties where WBCís have not yet been captured and that WBC captures may vary significantly within a county.

In the weeks ahead be on the lookout for signs of WBC larval feeding in corn ears. WBC infested ears may contain more than one larva. Larvae may enter through the silk channel at the ear tip or can bore through the husk or ear shank.  Excessive bird activity and damage may indicate insect larvae are in the ears. Damage caused by larval feeding can open ears up to potential risk of ear molds.

More WBC monitoring information is available at:
Western Bean Cutworm identification card Ė including larval stages.

Cornell Sweet Corn Monitoring Network

Penn State Pest Watch (Includes WBC data from NY, New England and other state)

Ontario WBC Trap Network

Cornell Field Crop Extension Homepage: “field crops.org” "blog" section. 

Western Bean Cutworm - Corn scouting videos:
Ontario
Wisconsin

Clipboard Checklist

Keith Waldron
NYS IPM

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General:
* 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 any patches of herbicide resistant weeds, weed escapes

Corn:
* Monitor fields for plant vigor, growth stage, late season pest issues (European corn borer, foliar diseases, nutritional deficiencies, vertebrate damage)
* Monitor for weeds, note presence of "who", "how many" and "where"
* Monitor reproductive stage corn fields for foliar diseases, stalk standability issues, corn ear damage (insect pests and diseases)
* Prepare storage areas to accept upcoming silage harvest

Alfalfa & Hay:
* Monitor alfalfa seedings for weeds, insects & diseases.
* Check regrowth of established alfalfa stands for potato leafhopper, weed and disease problems.
* Storage areas cleaned and ready to accept incoming harvest

Soybeans:
* Evaluate stand growth, development and condition
* Monitor fields for soybean aphid, foliar diseases, white mold, natural enemies, defoliating insects, spider mites, bean leaf beetles and weed escapes

Dairy Livestock Barn Fly Management:
* Sanitation, sanitation, sanitation - clean animal resting areas, feed throughs, 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
* Continue fly monitoring: install "3X5" index card fly speck monitoring cards through out barn
* Install/refresh/replenish as needed: fly tapes, insecticide baits, natural enemies (parasitoids)

Dairy Livestock Pasture Fly Management:
* Monitor animals for presence of pasture fly pests. Treatment guidelines: Horn flies (50 per dairy animal side, 100 per side for beef cattle), face flies(10 per animal face), stable flies (10 per 4 legs). See IPM's Livestock page.
* Consider installing biting fly traps to reduce horse, deer and stable fly populations.

Storage:
* Check temperature, moisture, pest status of recent bin stored small grains
* Keep areas around storage bins and silos clean and mowed
* Check areas around storage bins and silos for vertebrate tunneling
* Check temperature of recently baled hay in hay mow

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

PESTICIDE EMERGENCY NUMBERS
Emergency responder information on pesticide spills and accidentsÖ
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.

Coming Events


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Corn Foliar Disease In-Field Workshop.
When: Wednesday, September 5, 2012, 11am
Where: Sualpaughs Farm, Livingston, NY.
What: Visit Saulpaughs Farm to view Gray Leaf Spot and results of fungicide application; learn to rate foliar disease.
RSVP to Mary McKellar (mem40@cornell.edu) if you plan to attend.

Hosted by Alex Wright, CCA, Carolina Eastern-Vail, Inc and Kukon Farm
Organized by Gary Bergstrom, Mary McKellar, Jaime Cummings

Contact Information


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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