Abstract
The objective of this work was to compare fungicide application timing for the control of sooty blotch and flyspeck (SBFS) of 'Fuji' apples in Rio Grande do Sul state, Brazil. The following treatments were evaluated in two growing seasons: two warning system-based (modified version of the Brown-Sutton-Hartmann system) spray of captan plus thiophanate methyl, with or without summer pruning; two calendar/rain-based spray of captan or a mixture of captan plus thiophanate methyl; fungicide spray timing based on a local integrated pest management (IPM) for the control of summer diseases; and a check without spraying. Sooty blotch and flyspeck incidence over time and their severity at harvest were evaluated. The highest number of spray was required by calendar/rain-based treatments (eight and seven sprays in the sequential years). The warning system recommended five and three sprays, in the sequential years, which led to the highest SBFS control efficacy expressed by the reduced initial inoculum and disease progress rate. Summer pruning enhanced SBFS control efficacy, especially by suppressing SBFS signs which tended to be restrained to the peduncle region of the fruit. Sooty blotch and flyspeck can be managed both with calendar and the grower-based IPM practices in Brazil, but a reduced number of sprays is required when the warning system is used.
Highlights
Sooty blotch and flyspeck (SBFS) of apples (Malus domestica Borkh.) is caused by a complex of fungal species (Díaz Arias et al, 2010) which blemishes the epicuticular wax layer of fruit (Williamson & Sutton, 2000; Batzer et al, 2005)
sooty blotch and flyspecks (SBFS) is considered a disease of minor importance for commercial production in Brazil, relatively high incidence levels were observed even in the fungicide‐protected fruit (Figure 1)
The higher values for both model parameters and area under the disease progress curve (AUDPC) data suggest that more favorable conditions for epidemics occurred in the first year (Table 2)
Summary
Sooty blotch and flyspeck (SBFS) of apples (Malus domestica Borkh.) is caused by a complex of fungal species (Díaz Arias et al, 2010) which blemishes the epicuticular wax layer of fruit (Williamson & Sutton, 2000; Batzer et al, 2005). In the United States, SBFS epidemics may lead to downgrading fruit from premium fresh‐market grade to processing use (Sutton & Sutton, 1994; Williamson & Sutton, 2000). Infection timing and spatial SBFS patterns have been investigated recently in apples, in Rio Grande do Sul state (Spolti et al, 2011b). Recent survey data in commercial orchards, from different production regions of the country, showed increasing levels of SBFS epidemics, and SBFS signs appeared most frequently in the peduncle, possibly because of deficient fungicide cover on this fruit part (Spolti et al, 2011a)
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