Studies on longitudinal splitting of bark and wood disease in acidlime: etiology, screening of bioagents and fungicides and PCR-RAPD analysis of pathogen

Pathogen associated with longitudinal bark and wood splitting disease (LBWSD) of acidlime was isolated and identified as Botryodiplodia theobromae (ITCC Acc. No. 6004.05). Among ten isolates of Trichoderma, isolates TCT₁₂ and TCT₆ recorded high percent inhibition of 36.22 and 34.67%, respectively against LBWP-4 isolate. In In vitro studies among the systemic fungicides, carbendazim and tridemorph were found very effective. Among the nonsystemic fungicides, copper oxychloride was found very effective followed by captafol. Random amplified polymorphic DNA (RAPD) pattern was established for the 6 isolates of Botryodiplodia theobromae. These isolates were characterized using 10 random primers of OPM series, out of which 7 primers gave a total of 48 amplification products, showing 75% polymorphism. Genetic distance between each isolates was calculated, and cluster analysis was used to generate a dendrogram showing relationship among them. Similarity matrix thus produced indicated that maximum genetic variation observed between isolates of LBWP-6 and LBWP-2 (77.1%) closely followed by LBWP-3 and LBWP-1 (81.8%). Isolates LBWP-6 and LBWP-5 were genetically closer than any isolate with 50% similarity followed by LBWP-2 and LBWP-1 (51.7%). The gist of analysis is that the Botryodiplodia theobromae isolates formed into two genetically distinct closest having LBWP-1 and LBWP-2 in one cluster, LBWP-5, LBWP-6, LBWP-4, LBWP-3 in another cluster in which LBWP-3 and LBWP-4 did not resemble any other isolate