Temporal progress and spatial distribution of phytophthora blight of pigeonpea in Deccan plateau of India

The knowledge of weather parameters viz.temperature, relative humidity,rain fall and soil type on disease development is a prerequisite to predict the occurrence of the disease.In this context a periodical survey was conducted at ICRISAT, Patancheru to establish correlation between weather parameters and development of disease. Survey area and assessment of disease Periodical survey was conducted in last week of July, August, September, October and November during 2012 and 2013 in the pigeonpea fieldsof ICRISAT, Patancheru.A total of 39 pigeonpea fields were selected irrespective of soil type and cultivars to document and to determine correlation between weather parameters and development of disease. Correlation and multiple regressions analysis Correlation of incidence of the disease and weather parameters for kharif 2012 and 2013 indicated that cumulative rainfall, average maximum temperature and average maximum relative humidity showed positive correlation, whereas average minimum temperature and average minimum relative humidity showed negative correlation. [...]cumulative rainfall and average maximum relative humidity had significant positive correlation at both 0.01 and 0.05 probability level(Table 2, Fig. 1).A simple linear regression disease prediction model was developed depicting maximum correlation with given PDI, which can be used to predict the incidence of disease.