Here we are, at the end of one of the more challenging seasons we’ve experienced in the past 10 years. Although some have reported disappointing yields, many have been pleasantly surprised and I believe our best crop may just now be beginning to be harvested. Still, margins remain thin. Based on our current temperatures, we have an opportunity to shave a few cents off the budget in our last few defoliation applications. In this blog, I cover some last-minute thoughts on defoliation timing and product selection.
Late planted cotton which has not yet received an application- now is the time
Timing- Boll sutures will continue to develop under clear skies even when temperatures are cool or cold (night temps into the 40s). However, we should expect very little progression of fiber and seed development, especially given the forecast of night temps into the upper 30s next week. We now must take advantage of our remaining heat units to open up our latest planted acres.
Thidiazuron? Don’t waste your money at these temps. I’ve fielded a large number of calls in the past few days asking about thidiazuron use and rate. The single ai-products like Dropp, Daze, etc. are no longer in my mix. Thidiazuron requires warmer temperatures to generate activity. I regularly test thidiazuron in my defoliation trial work in similar temperature ranges to find no activity of the product! Activity begins to slow as temperatures dip below 65F at night. We can generate some activity with the product to temperature ranges in the upper 50s if we include higher rates of Folex OR add a small amount of diuron, but we are well-below this range of temperatures. At these temperatures, expect no activity from thidiazuron. All defoliation activity from such tank mixes will be provided almost exclusively from the other products in the tank. Ginstar, Adios, and Cutout fall within this category. You have probably seen or may have been recommended to increase rates of these products as temperatures dip into the low 50s, but again- the defoliation activity you will see from thidiazuron plus diuron products at our current temperature range will be provided by the diuron which is included in the premix, not from the thidiazuron. This is wasted money.
Apply a hot rate of Folex and tribufos instead. Our best mix on acres which have not yet received an application will be 8-12 oz Folex plus 16-32 oz of ethephon. Folex is not particularly good on juvenile growth at rates below 6 oz, but as we get above 8 oz, the activity on juvenile growth increases. One other note on Folex- for those that may balk at a shot of 8-12 ounces, I would encourage you to either read the Folex label or ask those who first used the product many years ago about use rates. You’ll likely be surprised to hear that, historically, the product was regularly applied at 12-16 oz per acre in temperature ranges far warmer than this and rarely stuck leaves. If running Folex and Prep or Folex Finish and Prep, don’t waste money on a surfactant. It isn’t needed in these applications.
Don’t waste money over-saturating the plant with ethephon. I’ve been generally impressed by boll maturity, and I would strongly encourage you to not be tempted to run over 24 oz of ethephon within a single application. This 24 oz would include both Prep and Finish products. I have consistently observed, over the past several years, that if 24 oz of ethephon in a single application does not open a given boll, neither will 32 oz or 42 oz of ethephon. By far, the most effective way to open a stubborn boll is to apply a second application. The second application often requires as little as 16 oz of ethephon to open tough bolls, with no need to exceed 24 oz.
Second shot concoctions and timing
Aim or ETX plus surfactant plus ethephon will likely be the most economical second shot. Ginstar, Adios or Cutout are products I tend to lean-on in a second application if temperatures are moderate and regrowth control is needed. Now, though, temperatures are cold and regrowth control is not needed. The cheapest application will likely be either Aim or ETX with a surfactant and ethephon. Your other option here would be a shot of Folex and ethephon, but Aim or ETX will likely be cheaper and will be better on juvenile leaves.
In a second shot with these temperatures, I would consider an Aim application of 0.75 oz plus 0.5% COC plus 24 oz Ethephon (adjust this rate of ethephon down as needed, and blend in Finish, as desired). The other option would be ETX at 0.9 oz plus 0.5% COC with the same rates of ethephon. Please note that there is a new (to us) formulation of ET (ETX) that is currently being sold in the area and use rate is different than the old ET formulation.
