ISHS Acta Horticulturae 591: III International Symposium on Pistachios and Almonds
EVALUATION OF PRUNING AND FUNGICIDE SPRAYS TO CONTROL BOTRYOSPHAERIA BLIGHT OF PISTACIA VERA |
| Authors: | B. Holtz, S. Sibbett, C. Kallsen, L. Hendricks, B. Beede, T. Michailides, B. Teviotdale, L. Ferguson |
| Keywords: | Botryosphaeria dothidea, Abound (Azoxystrobin), Benlate (benomyl) Elite (tebuconazole), Kocide 2000 |
| Abstract:
Botryosphaeria panicle and shoot blight (bot) is a yield devastating disease of pistachio in the San Joaquin Valley of California. The objective of this study was to evaluate fungicide sprays and inoculum removal via pruning on a large scale in order to determine which control measure showed the greatest potential to reduce Botryosphaeria Blight while also being cost effective for practical application. Four treatments were studied: Botryosphaeria (bot) pruning combined with fungicide applications, bot pruning without fungicides, fungicides without bot pruning, and a control which received neither fungicide applications or bot pruning. In the 1999 and 2000 seasons bot pruning average $488/hectare ($197.5/acre) while fungicide applications averaged $489.46/hectare ($198/acre). Total blight management average $977.49/hectare ($395.58/acre) for the two seasons. In 1999 the fungicide/pruning treatment had less disease than the no-fungicide/pruning and the fungicide/no-pruning treatments, which also had significantly less disease when compared to the no-fungicide/no-pruning control. In 2000, the two fungicide treatments had significantly less disease when compared to the pruning/no-fungicide and control treatments. But the pruning/no-fungicide treatment still had significantly less disease when compared to the control. When green fruit yields were compared in 1999 the no-fungicide/ pruning treatment had the highest yield and it was significantly greater than the control, but there were no statistical differences when compared to the fungicide/pruning and fungicide/no-pruning treatments. There were no differences in yield in 2000, but differences in nut quality were observed between treatments, and payable yield was reduced by $600 when nuts from the fungicide/pruning treatment were compared to control nuts. This study suggests that an aggressive Botryosphaeria Blight management program should include both fungicide applications and inoculum removal through pruning in order to achieve cost effective disease control. | |
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