Acessibilidade / Reportar erro

Control of initial inoculum for reducing losses by bulls' eye rot on apples

Aiming to evaluate strategies for the control of bull's eye rot (BER) based on the reduction of initial inoculum the following fungicide treatments were applied in experimental plots established in both 2006/07 and 2007/07 seasons in Vacaria location, southern Brazil, during the plant dormancy period: lime sulfur (3,0%); b) copper oxychloride (0,5%); c) copper hydroxide (0,3%); and cuprous oxide (0,3%). The check treatment consisted of non sprayed plots. Branches of one and two years and floral buds were sampled and the associated inoculum recovered with a semi-selective media to evaluate the effect of the treatments on inoculum reduction. During harvest, BER incidence on fruits was evaluated in four categories of fruits: i) fallen on the ground under the projection of the canopy; ii) in the the plants; iii) harvested (for the detection of latent infections); and iv) harvested and stored for three months in a cold chamber. A linear relationship was observed between inoculum levels of Cryptosporiopsis sp. on buds and total losses by BER (R² = 0,948; P = 0,001). Applications of lime sulfur promoted the most reduction of inoculum on buds and 50% of reduction of total losses by bull's eye rot, differing significantly from the other treatments in 2006/07 season. In fruits, inoculum levels increased linearly during the season, being relatively higher in the 2007/08 season when the eradicant treatments led to a 40% control of losses, thus demonstrating the beneficial economic return by the reduction of initial inoculum of BER.

eradicate control; latent infections; fruit rots


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