Risco climático para ocorrência da requeima da batata no Brasil

Abstract

The Blitecast model uses temperature and relative humidity data to indicate daily severity values (VSC) for the occurrence of potato late blight (Phytophthora infestans (Mont.) De Bary), assisting in its phytosanitary management. Therefore, the objective of this work was to evaluate the climatic risk for the occurrence of potato late blight throughout the year in the main states producing this vegetable in Brazil based on the Blitecast model. Relative air humidity (RH) and average air temperature (T) data from 265 National Institute of Meteorology automatic weather stations distributed across the states of Minas Gerais (65), São Paulo (38), Paraná (25), Rio Grande do Sul (43), Bahia (46), Goiás (25) and Santa Catarina (23). From the raw data, collected since its foundation until the year 2022, the number of hours with RH≥ 90% and T in this period were obtained to calculate the VSC. Consequently, monthly and annual averages of hours with RH≥ 90%, T and VSC were calculated for each meteorological station and Boxplot graphs were created to verify the uniformity of the data and the Pearson correlation test to evaluate which of the factors had the greatest influence on the accumulation of VSC. The average monthly VSC data were subjected to the Scott-Knott test, with a significance level of 5%, to verify the significance of the difference between the months of the year. Quarterly maps were created in the QGIS software to verify the spatial distribution of VSC, T and hours with RH≥ 90% for each state. The RH was the most important meteorological event in the oscillation of VSC throughout the year in relation to temperature, except when the temperature was below 12.4 °C, or the reduction in temperature was associated with a reduction in the moistening period. The greater volume and uniform distribution of precipitation in the South Region caused it to have the highest VSC throughout the year, which justifies the greater distribution of climate risk in this region. The state of Santa Catarina presented the highest VSC, with average monthly values above 1 VSC in several months of the year and minimum values that exceeded the maximum values found in Goiás in its months of greatest climate risk. In states with seasonal precipitation, the greatest climate risk was concentrated in the rainy seasons, despite having lower average VSC values than states in the Southern Region.