Screening lentil germplasm for stemphylium blight resistance

Abstract

Stemphylium blight is an important fungal disease of lentil caused by Stemphylium botryosum. It occurs in all major lentil growing regions of the world, including Bangladesh, India, Nepal, Syria, USA and Canada. As lentil production in Australia is increasing, stemphylium blight is considered a potential threat to the industry. However, information on this pathogen and resistance levels in Australian lentil germplasm is limited. Five fungicides were tested for efficacy against seven isolates of Stemphylium botryosum. Mancozeb and thiram were the most effective in inhibiting the growth of the pathogen under in-vitro conditions. To prevent a disease outbreak, it is prudent to screen germplasm to eliminate stemphylium blight susceptible lines from the breeding program prior to release. Therefore, a screening method for evaluating stemphylium blight resistance in lentil was developed for use under controlled environment conditions. Using this method, stemphylium blight disease ratings were provided on all current Australian lentil varieties. In addition, screening of advanced breeding lines showed variation in resistance/susceptibility for this disease and allowed selection of resistant lines for stemphylium blight resistance breeding. Seven International lentil varieties were tested against Australian isolates of S. botryosum and showed varying levels of resistance. Three hundred lentil accessions obtained from the International Centre for Agricultural Research in the Dry Areas (ICARDA) were evaluated and six accessions were identified with higher resistance than the resistant check ILL6002 that could be used in lentil breeding for stemphylium blight resistance.