Effect of Trichothecium roseum, lime sulphur and phosphites to control blossom blight and brown rot on peach

Abstract

This study assessed the efficacy of phosphites, Trichothecium roseum (TR) and a combination of phosphites and TR compared with lime sulphur (LS) to control brown rot, caused by Monilinia fructicola, in an organic orchard with high inoculum pressure under subtropical conditions in Brazil. The treatments were applied from blossom to harvest on two peach cultivars (‘Granada’ and ‘Chimarrita’) during 2005 and 2006. Disease incidence was assessed from full bloom to post-harvest. Two other experiments were performed under post-harvest conditions using mature fruit harvested from organic and conventional orchards and inoculated with 106 conidia mL−1 of TR followed by M. fructicola. The incidence of blossom blight ranged from 25% to 64% on flowers collected from untreated controls, whereas all treatments reduced blight over both cultivars and years. For ‘Chimarrita’, disease incidence reached 8% in mature fruit on the tree and 43% on fruit post-harvest. In both years, TR treatment reduced fruit infection by 50% and 63% during the growing season and post-harvest, respectively, when compared with untreated trees. ‘Granada’ did not set enough fruit to be assessed. The TR applied as a post-harvest treatment to fruit also significantly reduced final disease incidence. Applications of TR combined with phosphites or lime-sulphur were not better than TR applied alone, and TR was equivalent to LS, indicating that both treatments have the potential to reduce brown rot in organic peach production.