Development of arbitrary scale and host range studies of leaf crinkle disease in five different leguminous crops

Leaf crinkle disease (LCD) is a serious threat to the urdbean cultivation. The disease was first reported in 1968 from Delhi and surrounding areas and has become a serious threat to urdbean production in different states of India. Disease is prevalent in India and Pakistan and causes crop losses ranging from 62-100%. Based on field observation, apart from urdbean, ULCD has been reported from other pulse crops but experimental evidence for host range study in controlled condition is not available. In present study, an attempt was made to study the host range on five different leguminous crops (urdbean, mungbean, cowpea, groundnut and soybean) by mechanical inoculation under controlled conditions. The results confirmed that urdbean is highly susceptible to leaf crinkle disease with 98% disease incidence and higher severity than other leguminous crops tested in the present study. Plant disease assessment is important in predicting yield loss, judging host resistance and for studying fundamental biological host–pathogen interaction. In present study, an arbitrary disease severity rating scale (DSRS) was established based on symptom severity, consisting of five levels: 0:healthy, 1:initiation, 2:low, 3:moderate, 4:high. This study will help in screening of germplasm of urdbean and other pulse crops for resistance against LCD.