Withania somnifera L. Dunal, is one of the important medicinal crops and extensively used in the traditional medicine systems of India. Leaf spot disease caused by Alternaria alternata is a major concern and adversely affect the commercial cultivation as well as production of crop. The disease symptoms appear around 50 days after sowing (DAS) on naturally infected plants while on artificially inoculated plants symptoms developed within 2 weeks. The associated pathogen was characterized for precise identification based on the sequencing of partial internal transcribed spacer (ITS) and actin gene considering the microscopic observations. The disease is prevailing more severe at flowering stage, 90 DAS under high temperature and low relative humidity. In the present study 328 breeding lines and 140 accessions of W. somnifera were procured under breeding program and screened against leaf spot disease under natural field conditions for three consecutive years. The results of our study revealed that only 12.85% of accession lines viz., RAS – 36, MWS-207, MWS-211, MWS-303, MWS-304, RAS -10, RAS – 49, RAS – 50, MWS-336, RAS – 130, IC – 283942, RAS – 60, RAS – 61, RAS – 143, RAS – 133, RAS – 137, MWS-139 and RAS – 41 and 7.32% of breeding lines viz., DWS-108, DSW-130, DWS-74, DWS-118, DWS-152, DWS-279, DWS-96, DWS-37, DWS-107, DWS-133, DWS-234, DWS-311,DWS-34, DWS-41, DWS-42, DWS-69, DWS-86, DWS-127, DWS-170, DWS-223, DWS-293, DWS-270, DWS-296 and DWS-309 were falling under the highly resistant class. The pathogenesis as well as disease progress mechanisms influenced by environmental factors and growth stages of crop. Maximum temperature 35 + 5 °C when coincide with low relative humidity (66 + 5% RH1) supported the aggressiveness of the pathogen.

Withania somnifera L. Dunal是重要的药用作物之一，广泛用于印度的传统医药体系。交链孢菌引起的叶斑病是一个主要问题，对商业化种植和农作物生产产生不利影响。在自然感染的植物上播种（DAS）后约50天左右会出现疾病症状，而在人工接种的植物上，症状会在2周内出现。基于部分内部转录间隔区（ITS）的测序，对相关病原体进行表征以进行精确鉴定）和肌动蛋白基因考虑到微观观察。该病在开花期，在高温和低相对湿度下为90 DAS时更为普遍。在本研究中，在育种计划下采购了328个品系和140份W. somnifera，连续三年对自然田间条件下的叶斑病进行了筛选。我们的研究结果表明加入的行，只有12.85％即，。 RAS - 36，MWS-207，MWS-211，MWS-303，MWS-304，RAS -10，RAS - 49，RAS - 50，MWS- 336，RAS – 130，IC – 283942，RAS – 60，RAS – 61，RAS – 143，RAS – 133，RAS – 137，MWS-139和RAS –占育种线的41％和7.32％，DWS-108，DSW-130，DWS-74，DWS-118，DWS-152，DWS-279，DWS-96，DWS-37，DWS-107，DWS-133，DWS-234，DWS-311，DWS- 34，DWS-41，DWS-42，DWS-69，DWS-86，DWS-127，DWS-170，DWS-223，DWS-293，DWS-270，DWS-296和DWS-309抵抗类。环境因素和农作物生长阶段影响其发病机理和疾病进展机制。当最高温度为35  +  5°C时，相对湿度较低（66 + 5％RH1），可支持病原体的侵袭性。