Author Archives: Kenneth Wise

August 8, 2023

NYS IPM Weekly Field Crops Pest Report August 8, 2023

Corn Diseases

There are many reports of corn disease issues in fields across the state. Most reported ones are gray leaf spot, northern corn leaf blight, eyespot, and northern corn leaf spot.  For management information please view the website for the disease of interest:

  1. Gray Leaf Spot https://cals.cornell.edu/field-crops/corn/diseases-corn/gray-leaf-spot
  2. Eyespot https://cals.cornell.edu/field-crops/corn/diseases-corn/eyespot
  3. Northern Corn Leaf Spot https://cals.cornell.edu/field-crops/corn/diseases-corn/northern-corn-leaf-spot
  4. Northern Corn Leaf Blight https://cals.cornell.edu/field-crops/corn/diseases-corn/northern-corn-leaf-blight
This is a photo of Northern corn leaf blight. It has long cigar like lesions running up and down the leaf. The range from a 1/2 inches to 5 inches long.

Northern corn leaf blight

Soybean Diseases

Soybeans are starting to show some disease issues. These are Cercospora leaf Blight, Downy Mildew and Phytophthora root and stem rot. With all the wet weather we have had, and the soybean canopy starts to close white mold may become an issue in fields.

Cercospora Leaf Spot on Soybeans

Cercospora Leaf Spot on Soybeans

Field Corn Pheromone Trapping Network

Western Bean Cutworm

This last week was most likely the peak flight of Western Bean Cutworm in much of the state. Northern NY peak flight is normally a week later. It is time to get out and scout fields to look for egg masses and small larvae.  The economic threshold is an accumulated 5% egg masses or small larvae on the corn plants. This means that you could have 3 percent one week and 2 percent the next week and reach the 5 percent economic threshold.

this is a photo of western bean cutworm feeding on an ear of corn

Western Bean Cutworm Larvae- Photo taken by Aaron Gabriel

Photo by Mike Hunter-1st instar western bean cutworm larvae

Photo by Mike Hunter-1st instar western bean cutworm larvae

This a photo of Western Bean Cutworm Eggs (Photo by Mike Hunter-CCE)

Western Bean Cutworm Eggs (Photo by Mike Hunter-CCE)

For more information view the following webpage: https://cals.cornell.edu/field-crops/corn/insects-corn/western-bean-cutworm

Potato leafhopper (Empoasca fabae)

There are still reports of alfalfa fields over threshold across the state for potato leafhopper. Remember the best way to avoid economic damage (loss of yield and quality) is to scout fields on a weekly basis. This way you know if a control is needed or not before damage can occur.

There is yellowing in a V-shape on the tip of each leaflet on the alfalfa plant. This is the damage potato leafhopper can do to alfalfa.

Potato leafhopper damage to alfalfa

See information below on how to scout.

A Video on IPM for Potato Leafhopper in Alfalfa:

https://www.youtube.com/watch?v=8BIZYTq7Zec&list=PLE19BD8A62BE7D671&index=14&t=9s

Publication on Potato Leafhopper in Alfalfa:

https://cals.cornell.edu/field-crops/forages/insects-forage-crops/potato-leafhopper