Yield and cost–benefit analyses for apple scab sanitation practices in integrated and organic apple management systems

Abstract

Societal Impact statementReduced fungicide use lowers environmental pollution and enables safer food production. The usage of fungicides in apple orchards can be reduced through the application of sanitation practices which decrease the inoculum sources of apple scab disease on fallen leaves. This study found two non‐chemical sanitation practices, namely the collection of fallen leaves (CFL) and CFL combined with straw mulch in tree rows, were beneficial. These two practices are not only biologically and environmentally valuable, as they reduce disease levels and can replace chemical fungicides, but they are also economically efficient options for integrated and organic orchards compared to non‐sanitized ones.Summary Severe fungicide use can be reduced by applications of sanitation practices in order to reduce scab incidence, yield and fruit quality losses in apple orchards. In a 5‐year study, we aimed to investigate the effect of sanitation practices on biological and cost–benefit parameters in two sustainable apple management systems, and to find significant correlations among the parameters. We investigated the effect of five sanitation treatments (lime sulphur, leaf collection, mulching, lime sulphur + leaf collection, leaf collection + mulching) on four biological (scab incidence, fruit parameters: total yield, yield class I and II) and seven cost–benefit (three cost types, three annual revenue types, income surplus/deficit) parameters in integrated and organic apple orchards. Correlation, linear regression and principal component analyses (PCA) were performed to find correlations among biological and cost–benefit parameters. Results showed that fruit scab incidence was 3.4–8.1 times higher, while total yield was 1.4–1.8 times lower in the organic management system than in the integrated one. The treatment of leaf collection and/or leaf collection + mulching showed higher total cost (180.3 and 675.2 EUR ha−1) but lower scab incidence (5.3 and 27.3%; 4.8 and 26.7%, integrated and organic, respectively) and higher yield with greater total revenues (10,235 and 10,329 EUR ha−1; 8,136 and 8,230 EUR ha−1, integrated and organic, respectively) and income surpluses (851 and 451 EUR ha−1; 897 and 496 EUR ha−1, integrated and organic, respectively) compared to non‐sanitized control treatments in most cases. Other sanitation treatments provided fewer biological and/or no financial benefits. Results from correlation and linear regression analyses indicated strong relationships among the factors of total yield vs surplus, class I vs surplus, and fruit scab vs class II) in both management systems. Further relationships were detected among almost all parameters in the PCA. Overall, our study demonstrated that two non‐chemical sanitation treatments could not only reduce scab incidence and increase fruit yield, but could show positive cost–benefit outcomes in both management systems.