Improving the use of aerobiological and phenoclimatological data to forecast the risk of late blight in a potato crop

Abstract

The paper describes phenological and aerobiological monitoring conducted during 6 years on a potato crop. The progression of the phenological stages in relation with thermal time [growing degree-days (GDD) and physiological days (P-days)] was analyzed. The growing cycle for Kennebec variety required less than 120 days and mean values of 1700 GDD and 720 P-days to complete the phenological development. The presence of Phytophthora infestans in the environment was common in each crop cycle, but the maximum peaks of sporangia were detected a few days after the emergence of the plants. The growing cycles with lower maximum temperature had the highest presence of sporangia. Thus, significant negative correlations between mean temperature, maximum temperature, accumulated growing degree-days, accumulated physiological days and the concentration of P. infestans in the environment were found. Maximum temperature and accumulated growing degree-days of 5 previous days were the parameters that best estimated the P. Infestans concentration in the regression model applied, with an explained variance of the data of 33 and 34%.