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Submitted to: American Phytopathology Society
Publication Type: Abstract Only Publication Acceptance Date: 5/17/2017 Publication Date: 12/1/2017 Citation: Bock, C.H., Hotchkiss, M.W. 2017. A comparison of ground-based air-blast sprayer and aircraft application of fungicides to manage scab in tall pecan trees. American Phytopathology Society. 107:S5.37. Interpretive Summary: Technical Abstract: Scab (caused by Venturia effusa) is the most destructive disease of pecan in the southeastern USA. The most widely used method to apply fungicide is air-blast (AB) sprayers. Aerially (A) applied sprays are also used, but the disease distribution and spray coverage of these two methods has not been compared. Control of scab at 5 heights was compared using AB, A, and AB+A applications using 25 m ‘Schley’ pecan in 2013 and 2014. In control trees scab on fruit was most severe at most heights, except >12.5 m, where severity in trees receiving the AB spray was most often similar. However, severity at <12.5 m was lower in the trees receiving the AB spray compared to the control. The A application often had lower severity at all sample heights compared to the non-treated control, but the difference compared to the AB treatment was not always significant at 5 to 7.5 m. The combination of AB+A treatments had uniformly low severity of scab at all heights. Spray coverage on water sensitive cards indicated a decline in coverage with height using the AB sprayer, but A applications resulted in uniformly low spray coverage at all heights. Both AB and A sprays resulted in control of scab, but AB sprays tended to fail at heights >12.5 m, and A-treated trees tended to show a slight increase in disease severity low in the canopy. The results provide a basis for understanding the relative efficacy and advantages of these methods for fungicide application in tall pecan trees. |
