Sara E. Legler, and
Vittorio Rossi, Università Cattolica del Sacro Cuore, Institute of Entomology and Plant Pathology, I-29122 Via E. Parmense 84, Piacenza, Italy; and
Riccardo Bugiani, Plant Protection Service, Regione Emilia-Romagna, Bologna, Italy
In several grape-growing areas of the world, including northern Italy, powdery mildew epidemics, caused by Erysiphe necator, are mainly triggered by the ascospores produced in overwintered chasmothecia. Growers in northern Italy usually control the disease with fixed-interval fungicide applications. A warning system was developed for early-season powdery mildew control based on (i) short-term weather forecasts, (ii) a model that simulates the severity of each E. necator ascosporic infection, and (iii) a mobile phone short-message system. This warning system was evaluated in six vineyards in northern Italy from 2006 to 2008, between bud break of vines and early berry development; an unsprayed control was compared with “low-risk” and “high-risk” model-driven sprays and a calendar-based “grower” spray program. Use of the warning system reduced disease severity on leaves and bunches compared with the unsprayed control and resulted in the same level of control of powdery mildew as the grower's spray program, with reduced fungicide applications and costs. On average, 5.7 sprays were applied following the grower's spray program (with an average cost of 221 €/ha/year); use of the warning system reduced fungicide applications by 36% (low-risk program, saving of 56 €/ha/year) or 75% (high-risk program, saving of 161 €/ha/year).