NYS IPM Weekly Field Crops Pest Report

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View from the Field

Black Cutworm

McClelland’s Agronomics report black cutworm damage over the economic threshold of 5% of plants cut in a cornfield in southern Jefferson County. This field will be treated with an insecticide. There have been other large pheromone trap captures, and these moths will potentially lay eggs in cornfields. Therefore, its’ is a good time to start scouting for black cutworm!

This is a photo of black cutworm damage to emerging corn.

Photo by: McClelland’s Agronomics

True Armyworm

There were very large pheromone trap captures of true armyworm across the state this past week. Again, while this week’s capture will not results in larvae for a while, we have had other flights of moths earlier in May, which may have already laid eggs. Make sure to start looking for armyworm larvae while they are small

Seed Corn Maggot

Mike Hunter (CCE Northern NY Team) reports a corn stand failure because of seedcorn maggot.  The seed planted in this field was not treated with an insecticidal seed treatment.  Instead, the grower used an in-furrow insecticide.  This infestation level was very high and the grower will be replanting the entire field. A nearby field was also moderately infested but didn’t require a full replant.  There are other reports of low to moderate levels of infestation of seed corn maggot in two cornfields in central and eastern NY.  Be sure to inspect skips in planted rows by V2 growth stage to find evidence of seedcorn maggot damage, and keep in mind that we may experience damage from the second generation of seedcorn maggots in newly planted corn or soy fields


Seed corn maggot

Seed Corn Maggot

Photo by Mike Hunter

Cereal Leaf Beetle

Mike Stanyard (CCE Northwest Dairy and Field Crops Team) reports finding cereal leaf beetle eggs and adults in an oat field. These are at low levels currently.

Cereal Leaf Beetle Eggs

Cereal Leaf Beetle Eggs

Photo by Ken Wise (NYS IPM)

Powdery mildew and barley yellow dwarf

Christian Malsatzki (CCE Ulster County) reports finding low levels of powdery mildew and barley yellow dwarf disease in small grains in Ulster County. For more information on this see, last week’s pest report.

photo of barley yellow dwarf on wheat

Barley Yellow Dwarf

Photo by Ken Wise (NYS IPM)

photo of powdery mildew on wheat

Powdery Mildew on Wheat

Photo by Ken Wise (NYS IPM)

White Grub

Ken Wise (NYS IPM) reports finding low levels of white grubs in an emerging cornfield in Dutchess County. Generally, white grubs do not cause much damage unless it is a first year field after sod.

photo of a white grub

White Grub

Photo by Ken Wise (NYS IPM)

Alfalfa Weevil

Aaron Gabriel (CCE Capital District) and Ken Wise (NYS IPM) report finding low levels of 1st and 2nd instar larvae of alfalfa weevil in alfalfa. Because of the cold spring, alfalfa weevil will most likely not be a big issue in the first cutting of alfalfa. HOWEVER, watch the forage regrowth because alfalfa weevil could be an issue for second cutting.

alfalfa weevil larvae

Alfalfa Weevil Larva

Photo by Ken Wise (NYS IPM)


When Can I Expect Certain Weeds to Emerge?

Bryan Brown, NYSIPM


With a warm week of weather across the state, we’re starting to see new flushes of weeds. I even saw some early waterhemp popping up! It’s good to know when your problematic species emerge so you can be one step ahead of them with a residual herbicide program or be ready to hit them early with post-emergence applications or cultivation. Some of our newly problematic weeds, like waterhemp, need to be controlled before they reach 4-inches tall! (See our 2019 results in corn and soybeans.)

Cornell is working on a model to help predict when various weeds will emergence, but in the meantime check out this graph from the University of Nebraska (adapted from Werle et al 2014) that gives a rough estimate of when you can expect to see certain weeds.

graph of degree day for early season weeds


Note that the months are shortened based on how many heat units, or Growing Degree Days, they receive. To determine how many Growing Degree Days you’ve accumulated at your farm, check out http://newa.cornell.edu/ , click on a weather station near you, select Growing Degree Days (Base 50F), and look under the “since Jan 1” column.

Black Cutworm Moths Caught

black cutworm caught may 22-28

True Armyworm Moths Caught

True armyworm moth catches My 22-28

Alfalfa Weevil, Seed Corn Maggot and Base 50 F Degree Days

Degree days for alfalfa weevil and seed corn maggot

Table of degree days for alfalfa weevil, seed corn maggot and base 50 F.


Alfalfa Degree Days Life Stages

(Base Temperature 48F)

Egg Hatch                   280

Instar 1                        315

Instar 2                        395

Instar 3                        470

Instar 4                        550

Cocooning                  600

Pupa                            725

Adult Emergence       815

Seed Corn Maggot Flight Degree-Day Model for Egg Laying

Base Temp = 390 F Peak 1st Generation Seed corn maggot fly free degree days Peak 2nd Generation Seed Corn maggot fly free degree days Peak 3rd Generation Seed Corn Maggot fly Free degree days
degree days 360 810 1,080 1530 1800 2250

Source: Insect IPM for Organic Field Crops: Seed Corn Maggot by Katelin Holm and Eileen Cullen

Black Cutworm and True Armyworm Degree Days

Degree days for Black Cutworm and True Armyworm by Location of Trap

This is a table of degree days for black cutworm and true armyworm at different locations

Black Cutworm Degree Days (Base 500 F) Lifecycle Growth Stages

Degree Days               Stage                           Feeding Activity

0                                  Moth Capture              Egg Laying

90                                Eggs Hatch

91-311                         1st to 3rd Instar           Leaf Feeding

312-364                       4th Instar                     Cutting Begins

365-430                       5th Instar                     Cutting Begins

431-640                       6th Instar                     Cutting Slows

641-989                       Pupa                            No feeding

Source: University of Minnesota Insect Pest of Corn-Stand Reducers Black Cutworm

 True Armyworm Degree Days (Base 500 F) Lifecycle Growth Stages

Degree Days               Stage                           Feeding Activity

0                                  Moth Capture              Egg Laying

113                              Eggs Hatch

612                              Larval stages               Leaf Feeding

909                              Pupa                            No feeding

Source: Scouting for True Armyworms Is Highly Recommended in Small Grains and Early Corn-University of Kentucky


Clipboard Checklist

Keith Waldron, NYS IPM


*Walk fields to check tile flow, check and clear drainage outlets. Look for line breaks
*Note and record location of wet areas on field maps or aerial photo for future tiling considerations and crop decisions, check for areas of soil erosion
*Pre-plant weed evaluation, timing cultivation and/or pre-plant weed management
*Watch for early season weeds: winter annuals, chickweed, henbit, field penny cress, shepherd’s purse, giant and common ragweed, purple deadnettle, lambsquarters, redroot pigweed, velvet leaf, Pennsylvania smartweed, common sunflower, quackgrass, foxtail

*Evaluate established legume stands for winter damage (thinning stand, frost heave, Brown root rot), determine average alfalfa stand count adjust crop plans if necessary
*Monitor for alfalfa weevil, crown or foliar diseases
*Monitor new seedings for Pythium blight and Phytopthora Root Rot.
*Monitor for Alfalfa Snout Beetle (In Oswego, Jefferson, Cayuga, Wayne, Lewis, St. Lawrence, Clinton, Essex, and Franklin counties)

Small Grains:
*Monitor winter grain fields for over wintering survival (snow mold and other cold injury issues), weed issues (such, as winter annuals, corn chamomile and chickweed), growth stage, number of tillers, foliar diseases (powdery mildew, rusts)
*Check stands for soilborne virus diseases, Wheat spindle streak mosaic and Soilborne wheat mosaic, check for signs of powdery mildew or other maladies, cereal leaf beetle, weed escapes, goose damage

*Prepare land and plant corn as conditions allow
*Pre-plant weed evaluation, timing cultivation and/or pre-plant weed management

*Emergence: assess stand, population count

*Prepare land and plant soybeans as conditions allow
*Pre-plant weed evaluation, timing cultivation and/or pre-plant weed management

Check and mend fences as needed.
*Check crop growth
*Monitor fields for invasive species, plants harmful to livestock
*Review/Plan rotation system

*Remove / clean soil and crop debris from equipment
Arrange for custom weed control or check your own application or cultivator equipment for repairs.
*Carry appropriate / necessary NYS DEC and EPA required documents: (pesticide applicators license, pesticide labels, MSDS sheets, etc.) with application equipment

-planting equipment – maintain records on planting rate per field

-manure spreaders – maintain records on amount spread per field

-pesticide application equipment – Check nozzles, pumps, etc., recalibrate pesticide application equipment before use.

* Check stored grain bins for temperature, moisture and signs of mold and insects. Aerate, core, transfer grain or treat as necessary
Check forage allocation and anticipate feed program adjustments as forages from previous year are used up
*Plan where forages should be stored for optimum allocation next feeding season




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