Time to Start Thinking About Plant Bugs

Jeff Gore, Research and Extension Entomologist
By Jeff Gore, Research and Extension Entomologist March 25, 2012 21:18

Time to Start Thinking About Plant Bugs

The time until cotton starts to square is still a few months away, but it is not too early to start thinking about managing plant bugs in cotton. With the mild winter, plant bug population densities appear to be a little higher on wild hosts than they have the past couple of years. 

We have been sweeping wild hosts all winter and have been able to find plant bug adults every week.  This past week (March11-17), we started finding significant numbers of nymphs on several hosts. We have been finding low levels of nymphs on henbit for several weeks, but have recently started finding them in other hosts. We are currently finding them on henbit, shepherd’s purse, and curly dock.  The highest numbers have been collected on flowering curly dock. Given the current conditions with warmer than usual temperatures and adequate rainfall across the Delta, a lot of plant hosts are doing well and flowering earlier than normal. Because of this, plant bugs are able to successfully reproduce and develop higher densities earlier than normal. As a result, growers and consultants need to start formulating a plan now to deal with plant bugs later. Eliminating or minimizing these hosts now through the use of mowing and/or selective herbicides is the best way to begin the fight now.  

Another thing to consider now is planting date and variety. One of our current graduate students, Mr. Brian Adams, just completed a 2 year study looking at the impact of cotton planting date and varietal maturity on plant bug management. His data showed that planting from mid-April through the first week of May required fewer insecticide applications and sustained less yield loss from plant bugs than later planting dates. Similar results were observed with an early maturing variety compared to a mid-late maturing variety.  As in years past, insecticides are going to be our primary tool used to manage plant bugs in cotton.

As of right now, we will have the same insecticides available this year that we have had the past few years.  Acephate, Bidrin, Centric, imidacloprid, and pyrethroids have been the staple for plant bug management. The other insecticide that needs to be considered is the insect growth regulator, Diamond. Be prepared now to make applications early in the season on squaring cotton. Our research has shown significant yield benefits from using this insecticide before large numbers of nymphs show up in cotton. Another possibility for the upcoming season is Transform from Dow AgroSciences.  This is a new class of insecticide that will provide an additional, much needed tool to our current list of insecticides for plant bug control in cotton. As of right now, full Section 3 registration is expected in the second quarter of 2012. If this registration is granted in the second quarter, Transform will be available for use by the end of the 2012 season. Just in case, we submitted a request for a Section 18 emergency exemption that would allow use beginning June 1, 2012 in the Delta counties. The reason we submitted a Section 18 again this year is a precaution in case the full registration is not granted and to allow use slightly earlier in the 2012 season where it is desperately needed to control early season plant bugs and aphids. The Section 18 has not been granted yet, but we will let everyone know when we hear something one way or the other. 

Regardless of what tools are available in 2012, growers and consultants need to start formulating a plan now to deal with plant bugs. Based on the last few years, the question has not been whether or not we will have a bad plant bug year. The question has been: How bad will the plant bugs be? Based on the current conditions, we may be setting up for a very bad plant bug year.  Fortunately, we still have time before cotton goes in the ground and a lot of things can change between now and June, let’s hope they do!  With a proper plan in place now, growers will be able to effectively manage plant bugs and still be able to economically make a good cotton crop.

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Jeff Gore, Research and Extension Entomologist
By Jeff Gore, Research and Extension Entomologist March 25, 2012 21:18
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