Phytophthora infestans Prediction for a Potato Crop

The present work studies the seasonal variation of Phytophthora infestans concentrations in the atmosphere of a potato crop grown in A Limia. Different models have also been tested to predict the attack of this pathogen in order to establish the necessary treatments. Sampling has been carried out during crop cycles in 2004, 2005 and 2007 by using a volumetric spore trap, located in the centre of the plot at a height of 1.5 m. The collection of meteorological data was done with an automatic gauge. The highest concentrations of Phytophthora infestans were registered during June and July, with maximum daily levels ranging from 82 to 145 spores/m(3), as a result of the maximum temperature average, around 16-23 degrees C. Three prediction models for Phytophthora infestans have been adjusted to our area of study. The Smith Periods model provides better results in years with low and medium levels of the oomycete inoculum. The NegFRY model is useful to adjust the day of first treatment application, when used together with the Negative Prognosis model. To observe the influence of meteorological parameters on Phytophthora infestans spore concentration, besides applying these models, a Spearman correlation analysis was carried out. This test allowed the establishment of a correlation between the temperature parameter and the oomycete, obtaining positive and significant correlations (p<0.01).