Peach Pruning Improves San Jose Scale Control

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By Alison DeLoach

Recent research has shown that pruning peach trees can help growers reduce pests in their orchards. One pest in particular, San Jose scale, can cause difficulties for growers, including branch die back, and can ultimately lead to tree death if left untreated.

Brett Blaauw, an assistant professor and Extension specialist at the University of Georgia and Clemson University, shared research on the impact of pruning peach trees and spraying horticultural oil to suffocate San Jose scale. He discussed this subject during an insect pest update and forecast he presented at the recent Southeast Regional Fruit and Vegetable Conference. The idea is very simple, said Blaauw. More limbs are removed to allow an increase in the spray penetration of insecticides.

After pruning, researchers used horticultural oil to treat scale-infested trees. By removing excess limbs from the peach trees, researchers were able to apply greater coverage of oil to the trees, which allowed for more control over the scale. 

Blaauw discussed a study using 400, 200 and 100 gallons of oil per acre applied at 1.5 percent. The results showed that pre-pruned trees required 400 to 200 gallons of oil. However, when applying oil to the post-pruned trees, 100 gallons per acre was found to be sufficient. Given these results, Blaauw recommended applying oil to the trees after they have been pruned.

Blaauw went on to discuss a method growers can use to track the amount of immature San Jose scale on their trees. He said black electrical tape wrapped around a branch that’s roughly an inch in diameter, along with double-sided tape wrapped around the electrical tape, creates a small sticky barrier that can be used to monitor the scale crawlers.

The immature stage is the only time that scale are mobile, explained Blaauw. Therefore, by using this tape trap, growers can determine if the scale is active and track the abundance of the pest.

Hear Blaauw’s full interview with Tacy Callies, editor of VSCNews: