<div>Background: Alternaria leaf spot caused by Alternaria alternata is one of the most important and destructive disease of soybean causing severe yield loss in all soybean growing areas of southern and eastern part of Rajasthan. Successful management of Alternaria leaf spot is mainly dependent on accurate and efficient detection of pathogen, amount of genetic and pathogenic variability present in pathogen population. The main reason for frequent &ldquo;breakdown&rdquo; of effective resistance is the variability that exists in the pathogen population, which necessitates a continual replacement of cultivars due to disease susceptibility. 
 
Methods: The twelve fungal isolates randomly were collected from six districts of major soybean growing part of Rajasthan i.e., Udaipur, Chittorgarh, Pratapgarh, Kota, Baran and Jhalawar. The culture was purified single spore techniques. These were then further compared among each other for any variations in cultural characters, colour of colonies, Growth rate, conidial morphology and pathogenic variability. 
 
Result: Twelve different isolates of A. alternata were obtained in pure culture and characterized for cultural, morphological variation and aggressiveness of this fungus varied in their cultural characters, colour of colonies, growth rate of isolates, conidial morphology and isolates also exhibited variations in incubation period, latent period, number and size of lesions were produced.</div>

Cultural, Morphological Characterization and Aggressiveness of Alternaria alternata Causing Leaf Spot of Soybean

<div>Background: Cowpea [Vigna unguiculata (L.) Walp.], is one of an important pulse grown throughout the world. The cowpea crop helps in fixation of atmospheric nitrogen; besides, it supports the natural enemies&rsquo; population. The study on diversity of pestiferous insect associated with cowpea crop help to understand the population dynamics of these pests depending on location and seasons. These diversity studies are useful to formulate management practices which are area specific. 
 
Methods: An extensive survey was conducted at different locations (Udaipur, Bhilwara, Banswara, Chittorgarh and Pratapgarh) of southern Rajasthan during summer (Zaid) and monsoon (Kharif) seasons of 2019 and 2020. The randomly selected plants were observed for pestiferous insect population to calculate different diversity indices. 
 
Result: The insect pest complex of cowpea categorized into 5 orders viz., Hemiptera, Thysanoptera, Coleoptera, Diptera and Lepidoptera comprising 14 families. The pestiferous fauna includes population of flea beetle, jassids, whiteflies, sap sucking bugs, leaf miner, thrips, aphids, spotted pod borer and lycaenid caterpillar. During the study, it was found that overall species richness was more during the monsoon season as compared to that during the summer. The relative diversity of aphids was the maximum on account of the clumped distribution and exponential growth. In 2019, the maximum diversity was recorded in Banswara (Simpson index= 6.49 and Shannon index= 2.04) during monsoon; whereas, in 2020, the maximum diversity was recorded in Bhilwara (Simpson index= 4.03 and Shannon index= 1.81) during summer.</div>

Cultural, Morphological Characterization and Aggressiveness of Alternaria alternata Causing Leaf Spot of Soybean

Diversity of Insect Fauna Associated with Summer and Monsoon Cowpea [Vigna unguiculata (L.) Walp.]