July 24, 2023

NYS IPM Weekly Field Crops Pest Report-July 24, 2023

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New Online Pesticide Applicator Course for Credit: IPM for Insect Pest of Small Grains

We have a new online course for applicator credits. This course discusses integrated pest management for insect pests of small grains. It focuses on correct insect pest identification, lifecycles, and management strategies that can be employed.

https://pmepcourses.cce.cornell.edu/product?catalog=1689623724FsLF1

 

This is a photo of cereal leaf beetle. It has a red head and a black thorax. The beetle is rather shiny.

Cereal Leaf Beetle Adult

 

Potato leafhopper (Empoasca fabae)

Potato leafhopper in some parts of NYS is at high levels. Several fields were reported to be over the economic threshold. If you are within a week to ten days of the normal harvest it is best to cut the alfalfa to maintain yield and quality if over the threshold. If you are not and the alfalfa has not yet started to yellow, it is best to spray the field with an insecticide. It the alfalfa is still short and yellowing due to potato leafhopper it is best to clip the field and monitor the regrowth closely. It is time to get out and start scouting alfalfa fields.

This is a photo of Potato leafhopper damage on alfalfa

Extreme Damage From Potato Leafhopper on Alfalfa

For more information see below:

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

 

Soybean Aphid (Aphis glycines)

There were some reports of soybean aphids over thresholds in fields. Remember soybean aphids have a lot of predators and parasitoids that control them. If a field is hanging around threshold with a lot of natural enemies monitor the field for 2 to 4 days to see if the population increases. If not, the natural enemies are doing their job. It is best to get out and scout.

The following is a guide on how to estimate the number of aphids on the plant by the University of Wisconsin: chrome- https://soybeanresearchinfo.com/wp-content/uploads/2019/03/aphid_visual.pdf

This is a photo of the multi-colored lady beetle feeding on soybean aphids

Multi-colored Lady beetle in soybeans

For more information view the following website:

https://cals.cornell.edu/field-crops/soybeans/insects-soybeans/soybean-aphid

 

Western bean cutworm (Striacosta albicosta)

Western bean cutworm (Striacosta albicosta) (WBC) is starting to increase in flight numbers. It is not at peak yet but will be approaching it soon. WBC lays eggs on corn just before pollination. It is best to target these fields when scouting. The economic threshold for WBC is an accumulated 5 percent of plants having egg masses or small larvae.

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

This is a photo of western bean cutworm 1st instar larvae

Western Bean Cutworm newly hatched larvae on Corn Leaf-Photo by Mike Hunter

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

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

Slugs and Snails

Slugs and snails have been reported to be in soybean fields across the state. With the rain much of the state has received makes the conditions slugs and snails to proliferate. Generally, these do not do a lot of damage but in some cases molluscicide maybe needed.

For more information view the following webpage: https://extension.entm.purdue.edu/fieldcropsipm/insects/soybean-slugs.php

 

Gray leaf spot

Gray leaf spot has been found in some areas of the state.

“Symptoms of gray leaf spot are usually first noticed in the lower leaves. Initially, lesions of gray leaf spot begin as a small dot with a yellow halo. Lesions will elongate over time running parallel to the veins becoming pale brown to gray and rectangular in shape with blunt ends. These lesions can be described as having the appearance of a “matchstick.”  Lesions may eventually coalesce killing the leaves.  Leaves appear grayish in color due to the presence of fungal spore” Written by Dr. Gary Bergstrom (Gray Leaf Spot) Cornell University

For more information: https://cals.cornell.edu/field-crops/corn/diseases-corn/gray-leaf-spot#:~:text=Symptoms%20of%20gray%20leaf%20spot,in%20shape%20with%20blunt%20ends.

This is Gray Leaf spot on Corn. It has little match stick like lesions.

Gray Leaf spot on Corn