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4 rules to consider for late-season peanut defoliation

Virginia type peanuts have characteristically exhibited more of a tendency for pod loss due to over maturity than runner varieties.

Farmers know timing matters when it comes to digging peanuts and strive each season to promptly invert peanuts to preserve the best yield and quality.

In an Oct. 5 post, Ian Small, University of Florida plant pathologist, provides timely tips on late-season peanut digging and says two things decrease yields: over maturity and disease.

http://nwdistrict.ifas.ufl.edu/phag/author/ismall/

“Though slightly different, both have the potential to weaken pegs and increase pod loss, and both can be influenced by late season rains and delayed field access. In the past, Virginia type peanuts have characteristically exhibited more of a tendency for pod loss due to over maturity than runner varieties.  The same appears to be the case when looking at losses due to late or early leaf spot diseases. While late and early leaf spot have some differences, they both cause lesions and can defoliate canopies,” Small says.

Researchers at the University of Florida teamed up with scientists across the southeast and in the Virginia-Carolina regions to pool together data and conditions from many years to look at two common questions:

  1. How much loss occurs with different amounts of leaf spot infection?
  2. Is there a disease threshold where we might consider digging a field early?

Based on their research, he says, the team was able to develop some rough rules of thumb:

  1. Mature runner type losses became significant after approximately 30% of the canopy was defoliated due to disease, whereas mature Virginia type losses became significant when 25% or more of the canopy was shed.
  2. If a field is not yet at optimal maturity, it appears that when Virginia types pass 40% defoliation, they generally tend to increase losses (due to defoliation) faster than maturity is improving or yield is increasing in an otherwise healthy field.
  3. While it doesn’t look pretty, runner types appear to be able to sustain up to 50% defoliation while waiting on optimal maturity before losses increase more than the yield gains from additional maturity.
  4. In other words, if the crop is not mature there is a critical threshold (40% for Virginia types and 50% for runner types) where yield losses due to defoliation will outweigh any further improvement in maturity.

Read more about this research and recommendations.

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