September 22, 2018

NYS IPM Weekly Field Crops Pest Report: September 21, 2018

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View from the Field

Anthracnose Top Dieback

This week, many corn diseases have been reported. One that is not all too common is being found across the state called “Anthracnose Top Dieback”. Jaime Cummings the NYS IPM Field Crops and Livestock IPM Coordinator has written an article on the diseases. Please see below.

Anthracnose Top Dieback

 

Corn Foliar Diseases

Many are reporting finding northern corn leaf spot, gray leaf spot and northern corn leaf blight. Since the foliar diseases infected the plants this late in the season, they should not have an effect on yield.

 

Corn Earworm and Ear Rots

Mike Stanyard (CCE NW NY Dairy and Field Crops Team) reports that 100% of ears in one cornfield were infested with corn earworm. This is rather uncommon for field corn. Marion Zuefle (Vegetable IPM Specialist, NYS IPM) states that the “flight has been very bad this year. We haven’t seen a flight like this since 2011.” The problem with any worm (western bean cutworm, corn earworm, European corn borer) entering the ear is that it opens it up to different kinds of molds aka “Ear Rots”.

Weather Outlook – September 13, 2017

Jessica Spaccio

NOAA Northeast Regional Climate Center, Cornell University

Weather Outlook –September 20, 2018

NOAA Northeast Regional Climate Center, Cornell University

 

Last week temperatures were 8-12 degrees above-normal. Precipitation has ranged from less than ¼“ to over 4”. Base 50 growing degree-days ranged from 110-170.

A strong cold front will move through Friday into Friday evening, with cooler temperatures to follow.

Today temperatures will in the upper 60s and 70s with partly sunny skies. Overnight lows will be in the mid 50s to low 60s with a few light showers possible.

Friday will be in the upper 70s to 80s with showers and thunderstorms possible Friday into Friday night with a frontal passage; some storms could be severe and there is a chance for flash flooding and gusty winds. Overnight temperatures will be in the upper 40s to low 60s.

Saturday a few morning showers are possible, then a mostly dry day with temperatures in the upper 50s to near 70s. Overnight temperatures will be in the upper 40s.

Sunday highs will be in the 60s to mid 70s. Overnight temperatures will be in the mid 40s to low 50s.

Monday temperatures will be in the 60s to mid 70s with a chance of afternoon showers. Overnight temperatures will be in the 50s.

Tuesday highs will be in the 70s. Overnight temperatures will be in the 50s with overnight showers possible.

Wednesday highs will be in the 70s with showers possible. Overnight temperatures will be in the 50s.

The seven-day precipitation amounts will range from an inch to near 3 inches.

The 8-14 day outlook (Sept 26-Oct 2) slightly favors below-normal temperatures for western and northern areas and slightly favors above-normal precipitation for western, central, and northern to eastern NY.

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

Drought Impact Reporter:

https://droughtreporter.unl.edu/map/

CLIMOD2 (NRCC data interface):

http://climodtest.nrcc.cornell.edu

 

Anthracnose Top Dieback Prevalent Across NY, September 2018

Jaime Cummings, NYS IPM

Many of us are familiar with Anthracnose leaf blight and Anthracnose stalk rot, but many of us were caught off guard this year by another form of disease, anthracnose top dieback, caused by the same fungal pathogen Colletotrichum graminicola.  Reports of this disease have been received from all parts of the state in the past week.  It affects silage and grain hybrids and is readily identified by its typical symptoms of death of leaves and stalks in the upper 1/3 of the canopy (Fig. 1).  It’s important to note that top leaves my die from a number of factors, including corn borer, drought and other environmental stresses.  Therefore, accurate diagnosis is important when suspecting this disease.  Symptoms initially involve purpling or yellowing of flag leaves, and is often more randomly distributed in a field than top dieback caused by abiotic stresses.  Anthracnose top dieback is the result of the fungal stalk rot occurring on upper internodes, which restricts upward movement of water and nutrients, thus resulting in necrosis of leaves, tassels and stalks above the point of infection.  The easiest way to identify anthracnose stalk rot and top dieback is to look for signs of the fungal pathogen.  Examine stalks for the typical black anthracnose lesions on the stalks, and peel back the leaf sheath to look for the black fungal fruiting bodies, called acervuli (Fig. 2).  A hand lens is helpful in identifying these spiny fruiting bodies, which may be full of pinkish, wet spore masses under moist conditions (Fig. 3).  Split stalks will reveal rotten or disintegrated pith tissue at the point of infection (Fig. 4).

This pathogen overwinters in corn residues and spores are transmitted via wind and rain and can infect corn plant roots or stalks.  Insect feeding damage may enhance infection by this pathogen.  Since this pathogen is more prevalent in fields with high corn residues, crop rotations can significantly reduce this disease.  Hybrid resistance is available for anthracnose stalk rot, and hybrids with good foliar disease resistance often reduce stress overall, resulting in less susceptibility to stalk rots in general.  The IPM approach to managing anthracnose top dieback in your fields would involve crop rotations, planting resistant hybrids, and cultural practices to ensure minimal plant stress (balanced fertilization, adequate plant populations, and proper drainage).

Figure 1.  Anthracnose top dieback symptoms.  Photo from Agrigold.

Figure2.  Anthracnose stalk rot lesions on stalks.  Photo from Ohio State University.

Figure 3.  Colletotrichum fungal fruiting bodies called acervuli.  Photo from Cornell University, Nelson lab.

Figure 4.  Anthracnose stalk rot internal stalk symptoms.  Photo from APS Press.

 

Making Fall Alfalfa Field Decisions

Ken Wise, NYS IPM

 

Sometimes we forget that there are IPM practices for the fall in alfalfa. Conducting stand counts is one of these activities. Fall stand counts are an indication of the health of your alfalfa crop. There are a number of pests and crop management issues that can reduce a stand count in alfalfa. The following are guidelines for stand counts in NYS:

Crowns per square foot
Harvest Year Optimum Stand Adequate Stand
New Spring Seeding 25-40 12-20
1st hay year 12-20 6-10
2nd hay year 8-12 4-6
3rd and older 4-8 2-5

Note: Number of crowns not stems

The following are photos of alfalfa stand counts from the Cornell Research Farm in Valatie, NY

4 year old field-7 crowns/25 stems per square feet

4 plus years in production-5 crowns/15 stems per square feet

4 year old field-15 crowns/45 stems per square feet

New alfalfa seeding- 20 crowns/70stems per square feet

Note that you may have the recommended crowns per square foot but they may not actually be healthy. Make sure to dig a few plants up to check the roots for signs of disease.  You may also want to look at the number of stems per square foot. Here is a guideline for an adequate stand of alfalfa using stem counts.

Stems/square feet Action

Predicted Yield Potential

(assuming on winterkill)

>55 Stem density not limiting yield Same as current year
40 to 54 Some yield reduction expected If in good health same as current year. If not could be significantly less.
<39 Consider replacing stand If in good health same as current year. If not could be significantly less.

Source: University of Wisconsin: http://learningstore.uwex.edu/assets/pdfs/a3620.pdf

 

Fall scouting before the first hard frost can also reveal pest problems. Finding yellow to brown plants may be an indication of a disease problem such as: Verticillum wilt, leaf spots, Fusarium wilt, anthracnose and more. An inspection of the root system can also help diagnose disease problems. Yellow, reddish-brown to black discolored or damaged roots may indicate disease problems such as Phytopthora root rot or Verticillium wilt. In northern NY counties where alfalfa snout beetles (ASB) have been a problem, premature senescence, stunted or yellow alfalfa fields may indicate an ASB infestation. Fields should be evaluated for presence of the root feeding larval stage.

 

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, phytopthora 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, weed issues, vertebrate damage

*Record diseases present, location and types of weed escapes

 

 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