A limited supply of thidiazuron has many Georgia cotton farmers concerned about cotton defoliation efforts in 2018.
In a useful Extension white paper, Dr. Jared Whitaker, University of Georgia Extension cotton agronomist, and Mark Freeman, UGA Extension agronomist in east Georgia, provide recommendations on how cotton growers should proceed with defoliation this year.
Thidiazuron is a key component of many cotton defoliation tank-mixes and is excellent at preventing regrowth after defoliation. The entire UGA Extension paper can be read here.
In general, Whitaker and Freeman provide to growers these suggestions:
- Use the TDZ you have wisely, if regrowth potential is low then consider rates between 1.5 to 2.0 oz/A, if regrowth is expected and there is a lot of juvenile tissue is present consider higher rates between 3.0 to 4.0 oz/A
- If no TDZ is available, mixtures of ethephon + Ginstar (TDZ + diuron) can be very effective at removing juvenile tissue and preventing regrowth. An 8 oz/A rate of the Ginstar products has 2.0 oz of TDZ (a 4 lb ai/A TDZ product) and 1.0 oz of diuron (4 lb ai/A diuron product)
- If TDZ isn’t available and Ginstar products are not used, be aware that regrowth can be more troublesome and harvest as timely as possible.
- If no TDZ is available and regrowth potential is lower, then the mixture of ethephon + tribufos (Folex) can be very effective.
- Mixtures of ethephon + PPO herbicides (ET, Aim, Display, etc.) can also be effective. However, these mixtures are sometimes less consistent than mixtures of ethephon + tribufos (Folex) and in general are more consistent later in the defoliation window.