Although very little, if any, cotton has been planted in the Delta, it is not too early to start thinking about managing tarnished plant bugs. The tarnished plant bug is the most yield limiting insect and the most expensive to manage in the Delta areas of Mississippi every year. There is no reason to think 2014 will be any different, so having a plan now can help save money down the road.
The first step to successful plant bug management is to get the cotton planted as early as possible. With the recent rains that we have had and those that are expected over the next couple of days, timely planting is going to be difficult. We recently had a graduate student, Mr. Brian Adams, that looked at the impact of cotton planting date on plant bug management. His research showed that cotton planted by the first week of May required up to 3 fewer applications than cotton planted on or after May 15. So it will be important to get cotton planted as soon as field conditions allow it.
Nitrogen fertilization is also a key factor that can impact plant bug management in cotton. Mr. Chase Samples, another recent graduate student, showed that cotton yields were maximized at 80 lbs of N per acre and 1-2 fewer insecticide applications were needed compared to higher rates. The higher rates of N delayed maturity compared to 80 lbs or less and made late season plant bug management more difficult. A lower N rate can provide significant benefits, especially in a year like 2014 where it looks like we are going to have a late crop.
The main thing is to remember is that promoting earliness in the crop is the most important thing to consider to aid tarnished plant bug management later in the year. There are several things that can be done during the early season to minimize delays in maturity. They include proper early season insect, disease, and weed management.
Early Season Insect Management
Use a good insecticide seed treatment. Recently, we have seen less than adequate control from seed treatments against thrips. The most important thing to remember about thrips, is that early season injury will usually delay cotton maturity. As a result, foliar sprays may be needed behind seed treatments to promote earliness.
Early Season Disease Management
Seedling disease is another factor that can delay maturity. Use a seed treatment with a good fungicide package and ensure proper drainage of recently planted fields.
Early Season Weed Management
Weed management can impact cotton maturity in two ways. If weeds are allowed to remain in the field, they will compete with the crop. Also, many of the residual herbicides that are recommended can injure cotton and delay maturity. It is important to maximize weed control with the appropriate herbicides at the appropriate rates and minimize injury from the herbicides.
There are a lot of things growers can do now to minimize the impact of plant bugs in cotton. The most important thing to remember is to do what we can now to promote an early crop. Despite all of our best efforts now, insecticide sprays are going to be the most effective tool for managing plant bugs. We will have more detailed posts later, but some things to start considering now include:
1. Plant bugs are going to cause the greatest yield losses from late squaring through the fourth week of flowering. Plan to focus on management during that time period and use the most effective insecticides at the most effective rates.
2. Plan to use Diamond during the late squaring/early flowering time period when large numbers of adults are migrating into fields.
3. Use Transform during the early flowering period.
4. Use tank mixes of OP’s and Pyrethroids.
5. Shorten spray intervals during times of intense pressure.
We will have more about plant bug management later, but start making a plan now and do what you can to prevent delayed maturity in your fields.