NYS IPM Weekly Field Crops Pest Report, August 28, 2019

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Volume 18  Number 17

View from the Field

Jeff Miller (CCE Oneida County) reports finding western bean cutworm larvae in the corn ears in field corn. He also is finding Japanese beetle and grasshopper damage in soybeans. Note that even 20% defoliation by Japanese beetles in the reproductive stages of soybeans will not affect yield.   Jeff reports that potato leafhopper are at low to moderate levels in alfalfa but is still seeing some V-shaped yellowing of the leaflets.

Jodi Putman (CCE Northwest New York Dairy, Livestock & Field Crops) reporting that her pheromone traps are still getting high western bean cutworm moth captures.

Mike Hunter (CCE Northern New York Dairy, Livestock & Field Crops) reported very dry conditions in areas of Jefferson and Lewis Counties. He states that western bean cutworm peak flight is over in Northern NY, and that moth counts have been dropping. He is finding western bean cutworm egg masses and larvae.

Mike Stanyard (CCE Northwest New York Dairy, Livestock & Field Crops) reports extremely dry conditions in some areas of Northwest New York. He also reports a LOT of herbicide-resistant marestail that was not managed and is now flowering and will spread seed. Mike states that the crop consultants in NW NY are finding low levels of gray leaf spot and northern corn leaf blight.

Aaron Gabriel (CCE Capital Region) reports low levels of soybean aphid on soybeans, and is also finding low levels of gray leaf spot on field corn.

Janice Degni (CCE South-Central Dairy & Field Crops Team) reports finding low levels of white mold on soybeans. She also states that western bean cutworm moth counts have dropped to very low levels.

Ron Kuck (CCE Cayuga County) is reporting white mold in soybeans. He also found a significate amount of glume blotch in wheat that reduced yields and straw quality.

Jaime Cummings (NYS IPM) reports finding white mold, low levels of soybean aphids and septoria brown spot in soybeans. She also identified two soybean fields with severe northern stem canker epidemics, along with moderate frogeye leaf spot infection in Tompkins County.  Jaime also states finding very low levels of northern corn leaf blight. She is also finding some northern corn rootworm adult beetles feeding on pollen and silks on field corn.

Ken Wise (NYS IPM) reports finding a moderate amount of gray leaf spot in Dutchess County. He also reports finding Cercospora leaf blight and downy mildew in soybeans.

Weather Outlook – August 22, 2019

Samantha Borisoff

NOAA Northeast Regional Climate Center, Cornell University

A pretty tranquil week is in store for New York.  Temperatures will be very close to normal and there will be little if any rainfall through late Tuesday at the earliest.  Daytime high temperatures will be mainly in the 70s to low 80s at best through Tuesday and a bit warmer on Wednesday (low- mid 80s). Nights will be clear and crisp with lows from the low 50s to about 60 across the state.  By Wednesday lows will be in 60s everywhere.  Over the weekend upstate locations will see lows in the 40s especially in the North Country and Southern Tier, which is normal for late August.  Expect less than an inch of rain for the week. The week 2 period which will take us into early September appears to be near normal temperature-wise, maybe a tad on the warm side.  There will be a weak trough to our west which will give us a few chances of rain in this period, but I would not expect any big rain producers with such a pattern.

Maps of 8-14 day outlooks:

http://www.cpc.ncep.noaa.gov/products/predictions/814day/index.php

National Weather Service watch/warnings map:

http://www.weather.gov/erh/

US Drought Monitor:

http://droughtmonitor.unl.edu/Home.aspx

CLIMOD2 (NRCC data interface):

http://climodtest.nrcc.cornell.edu

 

Unfamiliar Foliar Lesions on Your Corn???  It Could Be Southern Corn Leaf Blight.

Jaime Cummings (NYS IPM), Joe Lawrence (PRO-Dairy), and Josh Putman (CCE)           

Southern corn leaf blight lesions on corn leaf.  (Photo by C. Grau, and image courtesy of Crop Protection Network)

Reports of Southern Corn Leaf Blight, have been confirmed by our neighbors near Erie, PA this past week.  This is on our radar, because that area shares latitude with some of our corn acreage in our southern tier and Hudson Valley region.  Therefore, you may want to keep an eye out for atypical corn foliar disease symptoms as the season progresses.

Most corn growers are unfortunately familiar with many of our common foliar diseases, including northern corn leaf blight, gray leaf spot, and eyespot.  Sure, at first they all look alike as all young lesions start out as small chlorotic spots.  But, as the disease progresses, and as the lesions mature, each disease has fairly distinctive lesion types that a trained eye could possibly identify even from the window of the truck on a drive-by scouting effort.  But, throw an unfamiliar leaf spot into the mix, and it might get a little more confusing.

Southern Corn Leaf Blight (SCLB), though not common in NY, was confirmed in 2018 on Long Island, and may be appearing again in 2019.  Suspicious samples have been submitted for ID.  SCLB lesions may not be as distinctive or easy to identify, because they are somewhere intermediate in size and shape between gray leaf spot and northern corn leaf blight, and they also resemble lesions of the northern corn leaf spot disease.  With so much overlap in symptoms, it’s best to get an accurate diagnosis before making any management decisions.

SCLB typically appears on corn leaves between VT and R4 growth stages as irregular tan lesions with vaguely reddish margins.  Lesion shape and size may vary among hybrids.  There are different races of this pathogen (races T, O, and C), but race O is most common in North America and is restricted to leaf infections.  However, race T also exists in the US, and can infect leaves, stalks, and ears.  As with most of our corn diseases, the fungus overwinters on corn debris, and can be further disseminated by wind or rain within and among fields in subsequent seasons (Fig. 1).  There can be multiple cycles of this disease in one season if conditions are favorable (warm and wet).  However, this hasn’t been a major disease of concern since the 1970’s, and we don’t anticipate it to be a chief concern here in NY compared as compared to our regional issues with northern corn leaf blight and gray leaf spot.

Figure 1.  Typical disease life cycle of a corn foliar pathogen such as southern corn leaf blight. (Image courtesy of Pioneer)

As with all corn foliar diseases, the incidence and severity of the lesions and the level of epidemic in the field will determine its impact on yield, because all foliar diseases affect photosynthesis and may leave plants more susceptible to stalk rots.  The first and best option for managing SCLB is through genetic resistance.  However, since this is such an uncommon disease in NY or other northern production areas, resistance ratings specifically for this disease may not be widely available in seed catalogs when making hybrid selections.  And, as for many of our common foliar diseases, an integrated management approach will work best.  Reducing primary inoculum through residue management and crop rotations, in combination with genetic resistance and use of fungicides only when necessary will successfully minimize losses from southern corn leaf blight.  Please remember, research has shown that fungicides are most cost-effective with a single application at VT/R1 when disease pressure is >5% throughout the field, and when the disease reaches at least the ear leaf by tasseling on susceptible hybrids when the weather is expected to be conducive for the disease to spread (Fig. 2).

     

Figure 2.  Corn fungicide timing and disease severity trials summary of hundreds of trials in 2013 by Dr. Kiersten Wise of University of Kentucky show that a single fungicide application at VT/R1 with disease severity >5% resulted in the best yield response.

 

A corn field in Chautauqua County with suspected southern corn leaf blight infection.  Samples submitted and awaiting diagnosis. (Photo by J. Putman)

 

 

Western Bean Cutworm (WBC) Update 8.28.19

The 2019 peak flight of the Western Bean Cutworm moths occurred the second week in August. This is later than most years. Normally, peak flight is the last week in July or the first week in August. This late flight was due to the cool, delayed spring. The average moths per trap in field corn was 515 moth/trap (this average will go up as we get all of last week’s data added). Last year (2018), the average per trap was 450 moths. Many Northern NY traps that caught between 1000 to almost 3000 moths affected the overall average.  Much Central and Eastern NY moth captures were down from the previous year, with exception of Washington County.

Western Bean Cutworm Peak Flight 2010-2019

Western Bean Cutworm Peak Flight 2010-2019

Weekly Moth Capture by County and Trap Location

 

Clipboard Checklist

Keith Waldron, NYS IPM

 General

*Walk fields to check general field condition, weed, vertebrate and other issues

*Watch for crop maturity, stand assessments, weed escapes, nutrient deficiencies, lodging issues

*Update crop records and field history

 

 Alfalfa:

*Evaluate established legume stands for approximate days until harvest
*Monitor potato leafhopper, foliar, systemic and crown rot diseases
*Monitor new seedings for potato leafhopper, Pythium blight, Phytophthora root rot

Small Grains:
*Monitor grain fields for growth stage, disease and lodging issues, grain maturity, harvest timing
*Record diseases present, location and types of weed escapes

* Prepare for planting winter small grains after the Hessian Fly Free Date

 

Corn:

*Monitor for mid-season corn pests including European corn borer, corn rootworm, western bean cutworm, slugs, foliar diseases such as northern corn leaf blight and gray leaf spot, weed issues, nutrient deficiencies, vertebrate damage

 

 Soybeans:

*Monitor for growth stage, soybean aphid, defoliators, foliar diseases, white mold, stem canker, Fusarium wilt, brown stem rot, weed issues, vertebrate damage

 

 Pastures:

*Check water sources, mend fences as needed
*Check crop growth, clip pastures between grazing as needed
*Monitor for invasive species, plants harmful to livestock
*Review/Plan rotations

 

Storage:

* Check stored grain bins for temperature, moisture and signs of mold and insects. Aerate, core, transfer grain or treat as necessary

* Clean and disinfect empty storage bins in preparation for grain harvest
*
Check forage allocation and anticipate feed program adjustments as forages from previous year are used up
*Mow around storage bins and facility to minimize pest hiding places

 

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

 

Dairy 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 per animal side, 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 exercise yard
*Check pasture for forage quality / quantity, rotate as appropriate
*Check pasture for vegetation poisonous to livestock
*Consider use of pasture fly traps to help reduce deer, horse and stable fly populations