Saturday, December 3, 2022

Can Growth Regulators Boost Yield?

The answer is in knowing how and when to use PGRs effectively. 

⋅ By Barry Tillman, UF/IFAS Peanut Breeder, and Scott Monfort, UGA Extension Peanut Agronomist ⋅

Excessive peanut vine growth can be problematic in several ways. First, too much vine growth can lead to an increase in disease because the canopy can hold moisture and create its own microclimate. Additionally, fungicides may not be able to penetrate the canopy to get to the point of disease. 

Vines damaged during mid-season pesticide applications can become areas of disease and contribute to yield losses. Finally, excessive vine growth can slow harvest operations, costing time and money. 

Control Vines, Increase Yield

Appropriate use of the growth regulators Apogee or Kudos (prohexadione calcium) can help to manage vine growth and increase yield. A recent study published in Peanut Science (Studstill et al., 2020; Influence of Prohexadione Calcium Rate on Growth and Yield of Peanut) showed that the growth of peanut was reduced by growth regulator application and that the pod yield of runner-type varieties was increased in farm-scale studies in Georgia and Mississippi. 

Using the 0.75 times rate, or 5.4 ounces per acre, of Apogee plant height was reduced by about 4 inches and yield increased by about 700 pounds per acre. This translates to about an $85 per-acre net return. Although a yield increase is not guaranteed because of specific conditions in each field and season, on average, the treatment will pay for itself or makes money. 

The Apogee label specifies that peanut should be actively growing and without stress from disease or drought when the application is made. The first application should occur when 50% of the stems are touching in the row middles and a second application 14 days later.

Application Tips

Scott Monfort, University of Georgia Extension peanut specialist, offers these tips for using a growth regulator.

“Timing is very important,” Monfort says. “Apply the first time when the row middles have reached full lapping — usually around 60 to 65 days after planting.” 

He says it is better to be a little late on the first application than too early, because it might prevent lapping altogether. The second application should be about 14 days later.

“A rate of 4 to 5.4 ounces of product per acre is sufficient for most runner-type peanuts. The addition of ammonium sulfate at one pound per acre or urea ammonium nitrate at one pint per acre is important for uptake.

If applying with a fungicide, Monfort says a crop oil is not needed. 

“Add a crop oil if applying alone at one quart per acre.”

Conduct Your Own Experiment

Plant growth regulators are not recommended in situations where vine growth is not excessive, such as non-irrigated fields, fields with history of less vine growth or under stressful situations. 

Can growth regulators boost peanut yield? The best answer is “it depends.” If you have excessive vine growth, the answer is probably yes. If you don’t struggle with vine growth, or are primarily non-irrigated, the answer is probably no. Other potential benefits are reduced disease and improved harvest efficiency, which are not easily quantified. 

The best approach is to experiment on your own farm with the appropriate timing and rate. PG

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