Pull The Trigger... Well at least take good aim. 7-29-16 The beginning of the intense period for the insect invasion into cotton is beginning now for our region. Moth numbers are picking up from south moving toward the James River as is pretty typical, only this year, I am seeing more moths in cotton fields than I have since the last time we planted a lot of corn. Also, in a somewhat predictable fashion, the levels of stinkbug damage are increasing as the cotton begins setting a boll load. I am not seeing it consistently this week. I would say the characteristic of the fields that are hitting threshold have been early cotton with a good boll load in drier areas where corn is no longer attractive to insects. In particular, early planted early maturing varieties have more bolls at the bottom and have been easier to find threshold levels. On the other hand, later blooming cotton and areas that had good rain about 10 days ago have had lower infestations. Most likely, as the moth flight grows through the weekend, our cotton will be hitting thresholds over the next 10 days beginning this past Wednesday (7-27) on the early planted cotton close to unattractive corn. Use the highest labeled rates of a pyrethroid.
A word on worms in Bt cotton Rarely have we had any worms get through the Bt genes on modern cotton production to cause any economic concern (less than 1 field out of a hundred). And even when it has rarely happened, there still were not that many worms hitting bolls. I am not too concerned this year either although we have three situations to keep in mind that we should consider. Worm resistance to pyrethroids is increasing.
Pyrethroid resistance appears to be at least 33% of the moths and in some cases more than half, based on sampling in Holland and Franklin.
More corn this year = more worms and egg laying.
Our crop is generally later primarily from later planting dates meaning that we will have more bolls susceptible to damage during the second half of August in these later fields.
This is not as likely to be a concern for this first round of spraying, and around the middle of August, we will have a better idea of the situation. The main areas for concern will be: non-scouted cotton with heavy egg laying, good soil moisture, and late planted/late maturing Widestrike 2 cotton that is blooming right on through the second half of August. Also any field with 3% live worms in bolls is a concern along with the above conditions. Call me or send me an email if you want to dive into this conversation deeper. I think the bottom line is that we are not going to be able to spray our cotton the first week of August and be done with it.
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