Pesticidi i Fitomedicina (Jan 2011)
Optimal Timing of Fungicide Applications for the Control of Podosphaera leucotricha, the Causal Agent of Peach Rusty Spot in Serbia
Abstract
Peach rusty spot has regularly occurred in Serbia in recent years, causing significanteconomic losses in the production of late maturing cultivars (Summerset, Suncrest, Fayetteand O’Henry). Concerns regarding the etiology of this disease have been solved using molecularidentification and cross-pathogenicity tests, which have proved that peach rustyspot is caused by Podosphaera leucotricha. The usual recommended strategy for its control,by multiple treatments starting from petal fall phenophase, has not proved satisfactory inagro-ecological conditions in Serbia. After testing the fungicide efficacy, a three-year studywas carried out to determine the precise treatment terms and make the control of P. leucotrichamore efficient.The investigation was conducted in the conditions of natural infection in a Summersetcultivar orchard at the locality of Bela Crkva, during the period 2006-2008. Nine differentvariants of both single and mixed treatments were tested, covering six defined peachgrowth phenophases - from green top, until the phenophase of second fruit falling. In theconditions of high levels of natural infection in the control plots, in all three investigationyears the most efficient was the variant in which kresoxim-methyl was applied three times:in green top, pink bud and full bloom phenophases (91.69 - 91.92%), followed by the variantof treatments in the phenophases of rose bud, full bloom and petal fall (86.3-87.87%)and the variant of two treatments, performed in the phenophases of pink bud and full bloom(79.3-83.09%). The other tested variants showed significantly lower efficiency. The resultsobtained could significantly contribute to better peach fruit production, without lossescaused by peach rusty spot which is commercially very important disease in Serbia.
