Currently Tropical Storm Isaac is forecast to track to the west then to the north of Tennessee over the next 5-7 days. If chances of rain continue to decline we could get back to making defoliation applications by Friday. Calls this week focus on defoliation in different crop conditions. Many of our defoliant products are sold as generics now and we can create ‘Cadillac’ mixtures with a ‘Chevy’ budget. I strongly believe we should base most tank-mixes on a thidazuron product and minimize herbicidal products to promote ‘green leaf’ drop. Histroically, a Folex (phosphate) based defoliation program has been used in Tennessee. If you have cotton that you are proud of, you will be disappointed if you do not include thidazuron this year. Below are combinations that are working well.

Situation #1, Drought striken cotton with low yield potential (defoliation on the cheap):

Folex 4-6 oz/ac plus
Ethephon (rate depends on need for boll opening, see comment on ethephon below)

Situation #2, I want to make only one application:

Freefall (thidazuron) 1.6-2.0 oz/ac plus
Finish 6 Pro 8.0 oz/ac plus
Ethephon (rate depends on need for boll opening, see comment on ethephon below)
Folex can be added at 4 oz/ac if cotton is tall/rank

Situation #3, I would like to make one application, but I will make a second if needed:

Freefall (thidazuron) 1.6-2.0 oz/ac plus
Finish 6 Pro 8.0 oz/ac plus
Ethephon (rate depends on need for boll opening, see comment on ethephon below)

Situation #4, I am planning on making two applications:

First application:
Freefall (thidazuron) 2.0 oz/ac plus
Finish 6 Pro 8.0 oz/ac plus

Second Application: (applies to second application in Situation #3 above)

Folex 6-8 oz/ac or Aim 0.75 oz/ac, or ET 1.5 oz/ac plus
Ethephon (rate depends on need for boll opening, see comment on ethephon below)

Comments on Ethephon:

One of the most asked questions I receive each year is about the rate of ethephon needed in different situations.

• This year with a mature crop and high percent of open bolls, we do not need much ethephon to complete the boll opening process.
• Comparisons (see below) of ethephon and Finish 6 Pro (ethephon + cycanalide) are often debated. Finish 6 Pro is a great syngernist when making a one shot application, or the first shot of a two pass approach. The addition of 8 ounces of Finish 6 Pro speeds up defoliation and under certain conditions hastens boll opening. If you require more than 8 ounces of ‘boll opener’ switch to a ethephon product. At 12 ounces or greater the advantage of Finish 6 Pro is reduced.
• The maximum labeled season use rate of ethephon is 42.5 ounces per year. So, how much ethephon do I need to open bolls? Generally, 16 oz/ac (1 pint/ac) is sufficient when temperatures are above 70 F. Many times we are tempted to apply 24-32 oz/ac which is not necessary unless temperatures have cooled off and we are wasting money using the higher rates.  Currently 8-16 oz of ethephon per acre is adequate to open bolls.

Surfactants:

Very few defoliants require the addition of surfactants. Aim and Display requires 0.25% v/v Non-Ionic Surfactant and ET requires 1% v/v Crop Oil Concentrate for the best activity. Addition of surfactants or other ‘enhancement’ products is NOT recommended for defoliation products other than Aim, Display and ET. Use of surfactants and ‘enhancement’ products can increase the chances of leaf desiccation and ‘stuck leaves’.