Wet Weather Concerns (Prostko)
Over the past few days, many locations in south Georgia have received significant rainfall (Figure 1).
A few things to think about:
1) Keep an eye on rain-free periods for postemergence (POST) herbicides. For my crops, these are listed in the UGA Pest Control Handbook (Remarks and Precautions). If I am missing one, please let me know.
2) Cool, cloudy, wet weather has a significant influence on the cuticles of plant leaves (i.e. makes them thinner). Thus, pesticides applied during this type of weather can cause more crop injury symptoms.
3) Residual weed control will likely be compromised (shorter than normal). Applications of additional residual herbicides should be strongly considered (Anthem Flex, Dual Magnum, Outlook, Warrant, Zidua).
4) It is also very likely that some growers will not be able to get back into their fields on a timely basis to make POST herbicide applications. There are no POST herbicides, in any of my crops, that can consistently control a pigweed that is bigger than about 3-4″ tall. Thus, applying herbicides to very large weeds (revenge spraying) is a waste of time and money! Hand-weeding, mechanical cultivation, non-selective applicators, and mowing are the only effective options for large weeds.
5) Since applications of POST herbicides will be delayed, experience tells me that many growers will want to apply broadleaf and grass herbicides together. Tank-mixing grass herbicides with broadleaf herbicides (Cadre + Select or 2,4-DB + Select), is labeled/legal but will often result in reduced grass control (~10-20%). Growers can increase the rate of the grass herbicide (within label) but I prefer a split application (grass herbicide first then broadleaf herbicide ~3-5 days later).