Scout, Spray, Decision time. Cookie Cutter approach - NO One size Fits all approach for 2020
(The whole point of this blog is to decide what to spray on 1646 which is at the end)
The approach we like to take for the choice of insecticides as well as the decision to spray as a sort of “cookie cutter” method. (shout out to WG from Capron for the idea). This year is not a cookie cutter year; nevertheless, here are some ideas to help navigate through all the decisions.
Timing - (the plant physiology approach)
First of all the timing of the 3rd through the 6th week of bloom represents the time that the cotton plant has much of the bolls susceptible to damage without time for recovery. So damage during this stage directly correlates to yield loss. The cookie cutter approach is to spray on the front side of this period with a ”‘Clean up” spray. Then during the backside of this period, we consider a second spray (usually a couple weeks after the first spray) when the cotton continues to bloom and set a top crop, soil moisture is good, yield potential is high, and insects are still active. The Dry July weather disrupted our cookie cutter approach and caused a rapid advancement of fruit this year and there are some fields planted early that are so advanced and blooming right out the top that they are getting safe and may not need spraying if they are clean right now.
Don’t forget the insects - Of course, a proper application of insecticides is based on scouting and thresholds which creates the variability of when some folks are spraying and some folks are not. This year has remained one of the lowest insect pressure years we have had since the last dry July. Having spotty insects when it is time to spray disrupts the cookie cutter approach.
Insecticide Choices - We are primarily targeting three insects (bollworms, Stinkbugs, and plant bugs). 3 Bt gene varieties practically take care of the bollworms so we can simplify our choices for these varieties. I like a pyrethroid and/or acephate. Each one is good individually and probably adequate by themselves for this year. And together they are excellent.
PHY 333 is the only W2 variety that needs a premium worm material (Prevathon or Besiege) plus one of the above for bugs.
THAT LEAVES THE BG2 varieties that are less cookie cutter. DP 1646 is our most planted variety. The BG2 has held up for bollworm and worked though last year in Virginia, although mainly because of lower moth pressure. This year there is more corn, and moth numbers are building, but eggs have been low, but now are building. THE QUESTION IS: Do I treat it more like the 3-gene varieties and trust that it will continue to hold up, or do I treat it more like PHY333 and offer the protection of the premium worm product? By all means do what your consultant advises, talk to Dr. Taylor and use the expertise of your distributor.
JOHNNY’S RECOMMENDATION - For Me, I think I would use the plant physiology approach and let the crop tell me whether or not to use a premium worm material. Younger cotton or cotton that has been getting rain in July with more than 5 nodes above white bloom would get the premium product and cutting out cotton with blooms right in the top of the plant would be treated with just a pyrethroid/acephate approach. I am expecting worm pressure to continue to build and just in terms of numbers, I think over time, they could overcome the BG2 genes. The cutting out cotton will be safe but the greener higher potential cotton will still be susceptible.
FINAL COMMENT - The Compromise solution is also treating it with a pyrethroid, then making a second trip if things keep looking good and the moths are building.
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