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Title: INTEGRATED MANAGEMENT OF PHYTOPHTHORA ON STRAWBERRY WITHOUT METHYL BROMIDE

Author
item Browne, Greg
item Becherer, Harold
item MCLAUGHLIN, S - UC DAVIS PLANT PATH
item FENNIMORE, S - UC DAVIS PLANT PATH
item DUNIWAY, J - UC DAVIS PLANT PATH
item MARTIN, F - UC DAVIS PLANT PATH
item AJWA, H - UC DAVIS PLANT PATH
item WINTERBOTTOM, C - UC DAVIS PLANT PATH
item GUERRERO, L - UC DAVIS PLANT PATH

Submitted to: Proceedings of Methyl Bromide Alternatives Conference
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2003
Publication Date: 7/1/2003
Citation: Browne, G.T., Becherer, H.E., Mclaughlin, S., Fennimore, S., Duniway, J., Martin, F., Ajwa, H., Winterbottom, C., Guerrero, L. 2003. Integrated management of phytophthora on strawberry without methyl bromide. Proceedings of Methyl Bromide Alternatives Conference.

Interpretive Summary: Phytophthora cactorum causes crown and root rot and plant collapse on strawberries in California and in most other areas where strawberries are grown commercially. Pre-plant soil fumigation with methyl bromide-chloropicrin (MB:Pic) mixtures helps prevent disease caused by P. cactorum and other soilborne pathogens by reducing pre-plant inoculum densities. We determined potential contributions of genetic resistance, systemic fungicides, and alternative fumigants for managing Phytophthora crown rot on strawberries without methyl bromide. Among cultivars tested for resistance to P. cactorum, selections ranged from resistant (Camino Real, Pacific, Parker, Cal Giant [CG] 2, CG 3, and CG4) to highly susceptible (Catalina, Diamante, Gaviota, Pajaro, and Ventana. Aromas and Camarosa were intermediate in susceptibility. Apparently, there is potential to select cultivars that combine general horticultural acceptability with moderate to high resistance to P. cactorum. Both Aliette WDG (applied as labeled as a plant dip plus 5 monthly foliar sprays) and Ridomil Gold (applied as a soil drench to mimic chemigation at planting and at two additional intervals during the fruiting season) prevented most of the yield loss caused by P. cactorum on cultivars Aromas and Diamante. Fumigants iodomethane and propargyl bromide were simiar and superior, respectively, in efficacy compared to methyl bromide for reducing survival of P. cactorum inoculum in soil. Fumigants chloropicrin, and Telone C35 were occasionally less effective than methyl bromide for this purpose.

Technical Abstract: Phytophthora cactorum causes crown and root rot and plant collapse on strawberries in California and in most other areas where strawberries are grown commercially. Pre-plant soil fumigation with methyl bromide-chloropicrin (MB:Pic) mixtures helps prevent disease caused by P. cactorum and other soilborne pathogens by reducing pre-plant inoculum densities. We determined potential contributions of genetic resistance, systemic fungicides, and alternative fumigants for managing Phytophthora crown rot on strawberries without methyl bromide. Among cultivars tested for resistance to P. cactorum, selections ranged from resistant (Camino Real, Pacific, Parker, Cal Giant [CG] 2, CG 3, and CG4) to highly susceptible (Catalina, Diamante, Gaviota, Pajaro, and Ventana. Aromas and Camarosa were intermediate in susceptibility. Apparently, there is potential to select cultivars that combine general horticultural acceptability with moderate to high resistance to P. cactorum. Both Aliette WDG (applied as labeled as a plant dip plus 5 monthly foliar sprays) and Ridomil Gold (applied as a soil drench to mimic chemigation at planting and at two additional intervals during the fruiting season) prevented most of the yield loss caused by P. cactorum on cultivars Aromas and Diamante. Fumigants iodomethane and propargyl bromide were simiar and superior, respectively, in efficacy compared to methyl bromide for reducing survival of P. cactorum inoculum in soil. Fumigants chloropicrin, and Telone C35 were occasionally less effective than methyl bromide for this purpose.