Air September 1, 2004

Thank you Jerry, and good morning everyone.

Okay, I think everyone has had enough hot dry summer now - we can go back to rain just any day now! Just a quick reminder that the state fair will be getting started a week from Friday, September 10th. This is always a fun time so make plans now to spend at least part of a day in Hutchinson at the Fair.

Welllll, the soybean aphids arrived last week. It's no surprise and probably not much of a worry. Keep in mind that Geary County was one of the first counties to have soybean aphids back in 2002. Fortunately for us, most of the time the aphids move into our area late enough in the season that we don't need to worry about them. I have been out in several soybean fields around the county this week and have managed to find a few aphids in every field I've been in. It isn't too tough to scout for soybean aphids, you just walk into a field and start turning soybean leaves over and looking on the back. There is only one aphid that will feed on soybeans in Kansas so if you see any, it's them. However, make sure you have your reading classes or a magnifying glass along because these are very small aphids. If you are used to greenbugs or any of our standard aphids, soybean aphids are tiny in comparison, probably about ¼ the size of a greenbug. What about economic thresholds or rather at what point of infestation do you need to worry about them. These aphids don't like hot weather. This week is not going to be kind to them. But the cool weather we've had earlier in the season has been ideal for them. I've been seeing evidence of aphid parasites in most fields so those will also keep the populations low. And before long they will start to produce the winged versions which signals they are getting ready to leave the fields, fly off to the timber and lay their eggs. We don't need to worry until we are averaging 250 aphids per plant. There were a few fields in Neosho county that were at this treatment level last week. Additionally, once the plants reach the R6 growth stage, that's where the pods towards the top of the plant have a green seed that fills the pod cavity, sometimes called the full seed or full pod stage, there is no evidence to indicate that spraying is justifed even with high populations. So I don't expect any spraying to be needed. Get out there, check your fields, learn what they look like, and then don't worry about them!

This is Chuck Otte, Geary County Extension Agent, with Ag Outlook 2004.

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