Contributed by: Christy Hicks,Regional Extension Agent
- July 13th SunBelt Expo – Moultrie, GA
- July 19th Stored Grain Workshop – Marion Junction
- July 27th – Central AL Crops Tour
Cloudy and Wet Weather Effects on Crops
Since May 1st, I’ve had 18.7” of rain at my house, and it is continuing to rain as I write this newsletter. I’ve walked in many cotton fields that are suffering from lack of adequate oxygen in the soil due to water logged soils. Pre-emergence herbicides have broken early this year because of all the rain and timely POST applications are delayed because of field conditions. Cloudy wet weather favors grass weeds over broadleaf weeds. I have heard that grasses are out competing pigweeds in some field. Here are a few thoughts that may be helpful as we hope for sunny days ahead.
POST Herbicide Leaf Burn (info from Larry Steckel, UT)
The cloudy and wet weather cotton and soybeans have been through has left the cell walls in the leaves very thin and therefore susceptible to herbicide injury. High humidity also makes the herbicide more active. Will the POST applied herbicide injury effect yield? Expect a good recovery in soybeans and no effect on yield. POST injury in cotton can cause a delay in maturity. If we have good, warm weather in September the delay in maturity will not likely effect yield. However if the fall weather is cool, a yield penalty could occur. Applying Dual separate from Liberty or Roundup will greatly reduce injury. However a number of factors must be considered before making this decision. These include: the degree of weed infestation in the field, maturity of the cotton and logistics of coming back over the field with Dual a day or so after applying Liberty or Roundup.
Cotton Fertility Information (info from William Birdsong and Christy Hicks)
June is cotton sidedress time in Central AL. Auburn University recommends applying all P and K at planting or just prior to planting. Some farmers split apply potassium. This is certainly not wrong, however much of the split applied K may not be available to the plant soon enough to receive maximum benefit. I conducted potassium trials in 5 locations last year. The plots that had all potassium applied at planting out yielded the plots that had potassium split applied. This was true for all locations. Nitrogen is a different story. Nitrogen will leach more than P or K. The general amount of N recommended for cotton is 90 lbs./acre plus or minus 30 lbs depending on soil type, previous crop and history of rank growth on certain soils. Sidedress is recommended between the 5th and 10th leaf. It is better to be early than late this year with all the rain, much of our at plant N has leached out of the root zone. Waiting till peak bloom (90 DAP) is the equivalent of not applying any N according to a study in the FL panhandle.
Regional Extension Agent
EV Smith Research Center