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Updates From the Field

European corn borer larvae are leaving their tell-tale early sign in local fields. Pin holes in your corn leaves like those in the photo below are an indication that the young larvae have started boring into the corn. The European corn borer is a tiny pest at first, but the worms grow quickly and can have significant impact on your corn. The introduction of BT varieties has reduced the corn borer populations in NYS significantly, but there are still occasional infestations. If you observe corn borers feeding in your BT hybrids, it's likely you have found the refuge corn. Conventional corn hybrids that do not have BT protection are susceptible to damage from this pest, which can result in weakened stalks and lodging, as well as creating entry points for diseases and ear and stalk rot. One local grower is using pheromone traps to assess whether a threshold population is present, informing the decision whether to spray.

For more information about European corn borer, see the Cornell Field Crops website at

We are all hoping for more rain soon, so hopefully we won't have to worry about the impact of drought stress on corn in the V6 stage! But in case you are wondering...

Drought stress at the V6 stage has the biggest impact on the number of kernel rows. The number of kernels in each row can also be affected by drought as early as V5, and can be impacted through pollination and grain fill. Corn hybrids have a typical size and shape that is determined by genetics, but environmental factors like drought can have a significant impact on ear development resulting in potential yield losses.

Stephen D. Strachan, Ph.D., DuPont Research Scientist, has written an excellent article, Corn Grain Yield in Relation to Stress During Ear Development. Strachan summarizes the following impacts:

"In general, ear responses to environmental stress factors at specific times of the corn life cycle include:

· A reduction in the number of kernel rows around the ear if substantial stress occurs at or just before ear initiation (approximately V7).

· A reduction in the number of kernels along the length of the ear or a shorter ear if substantial environmental stress occurs from the late vegetative phase until just before pollination.

· A portion of the cob that may be barren if substantial environmental stress occurs during pollination.

· A portion of the cob that shows either very small kernels or kernel dieback if substantial environmental stress occurs during grain fill."

The good news is that rain later in the season can help compensate for early drought if it comes ahead of pollination and grain fill.

Fingers crossed for a good soaking rain ahead!

If you see these pheromone traps in fields around the Finger Lakes, they are part of a study to assess the presence of serious and invasive pests in New York soybean fields. Researchers are looking for two moths, Golden Twin Spot moth (Chrysodeixis chalcites) and the Silver Y moth (Autographa gamma), which cause significant damage to soybeans and many other crops across parts of the world. No sitings yet!

The multi-year study also includes soil analysis which has found soybean cyst nematode (SCN), a number 1 pest of soybeans, in at least 1 field in 7 counties in NY, including Tompkins and Cayuga. Fortunately, soil egg counts are still much lower than in other states. Continued monitoring and an IPM approach are the key to combating SCN. Crop rotation, resistant varieties, and nematocidal seed treatments offer effective strategies for minimizing risk. For more information, see this blog post by Jaime Cummings of the NYS IPM Program and colleagues published in the Cornell Field Crops blog, What's Cropping Up?

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