Incidência e severidade de cancro cítrico em laranja 'Pêra Rio' sob condições de controle químico e proteção com quebra-vento

Abstract

The objective of this work was to study citrus canker incidence and severity under natural conditions in an orchard of 'Pera Rio' sweet orange planted in Ourizona county, northwest of Parana State, Brazil. Chemical control, by using copper sprays, and windbreak protection were evaluated to reduce citrus canker incidence and severity on leaves. Levels of disease incidence were determined monthly by rating diseased leaves. Severity was evaluated monthly by using specific diagrammatic scales. Levels of severity were calculated considering just the diseased leaves assessed. Data were plotted on temporal progress curves and analyzed regarding the standardized area under disease progress curve (AUDPC*). The coefficient of determination (R2) between incidence and severity levels was also determined. Whereas copper sprays significantly reduced citrus canker on leaves, windbreak did not contribute significantly to disease control. After 29 assessments, plants submitted to frequent copper sprays showed AUDPC* values for citrus canker incidence 43.5% lower than those observed on plants not protected with chemical sprays. The same result was observed for citrus canker severity. After 18 assessments, plants sprayed with copper showed AUDPC* values for severity 37.1% lower than for check plants. In both years, the values of R2 between incidence and severity levels were higher than 0.80 (p<0.01).