*Department of Agricultural Meteorology, Punjab Agricultural University, Ludhiana-141004
Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana-141004
National Symposium on “Plant Pathology in the Changing Global Scenario” held at National Bureau of Plant Genetic Resources, New Delhi on February 27–28, 2009
Mungbean [Vigna radiata (L.) Wilczek] is an important pulse crop grown in diverse agro climatic conditions and thus is subjected to various metrological factors which have direct impact on the most potential disease, mungbean yellow mosaic virus (MYMV) caused by a begomovirus and transmitted by white fly. Practically there is no variety of mungbean which is completely resistant to MYMV, neither there is consistency of resistant reaction. Large variation in disease intensity observed during the last 24 years of screening under natural epidemic of disease encouraged to establish an empirical relationship between the weather variables and MYMV to work out disease predictive model. For this there is a need to consider year to year fluctuation in disease intensity and climatic variables governing this effect if any. The crop in all the years was sown in the third week of July following the prescribed package and practices for cultivation. The data on disease intensity on mungbean lines recorded from 1985 to 2008 were categorized into resistant group and Plant disease index (PDI) calculated. The data on climatic variables during the period under consideration was obtained from Department of Agrometrology. The meteorological observatory situated in Research Farm (30°-45’N, 75° 48/E and 247m above sea level) during July to September each year, corresponding with the growing period of the crop. The metrological factors were average monthly mean maximum and minimum temperature, RH, total rain and rainy days. It was observed that high rain fall during the month of July and very less or no rain in the month of August was crucial for the disease. The highest MYMV PDI was observed when maximum temperature was 34–35°C and minimum temperature 26–27°C, total rain fall 55mm which did not exceed 100mm during the month of August. The RH should be 87–89%. In years of heavy and wide spread rain during August there was low PDI. Mungbean lines with least fluctuation in disease rating that remained with in resistant category can be true sources of resistance to MYMV. These were MLnos1194, 1229, 1294, 1352, 1354, 1361, 1392, 1451, 1464 and 1465. In the years of no rain in the month of August control measures to combat white fly, the vector of MYMV should be considered.
