Spray Coverage, Scab Control and Economics of Spraying Large Pecan Trees

Authors: Bock, Clive; WELLS, LENNY - University Of Georgia; Hotchkiss, Michael - Mike

Submitted to: Georgia Pecan Growers Association
Publication Type: Other
Publication Acceptance Date: 6/3/2021
Publication Date: 6/3/2021
Citation: Bock, C.H., Wells, L., Hotchkiss, M.W. 2021. Spray Coverage, Scab Control and Economics of Spraying Large Pecan Trees. Georgia Pecan Growers Association. https://georgiapecan.org/industry/#presentations.

Interpretive Summary:

Technical Abstract: Scab (caused by Venturia effusa) is the most important yield-limiting disease of pecan in the southeastern USA. On susceptible cultivars, the disease is managed using fungicides, but spray coverage is an issue in tall trees. Spray coverage experiments showed that whereas tere was more spray coverage at higher volumes lower in the canopy, higher in the canopy there was little difference in spray coverage between volumes applied. Speed had little effect on coverage and tended to be inconsistent. Further experiments showed that lower volumes and higher speeds were as effective at reducing disease as were the higher volumes and slower speeds (sometimes more so). The scab epidemic severity affected control efficacy. Estimated cost and water savings based on faster speed and lower volume were considerable. These preliminary observations indicate no single volume or speed was consistently superior to control scab; this suggests in most seasons, low volumes (high concentration of a.i.) may be similarly efficacious as high volumes (low concentration of a.i.) for controlling scab in tall pecan trees, and offer greater resource use efficiency.