First report of charcoal rot on canola caused by Macrophomina phaseolina in Western Australia.

In the spring of 2006, canola (Brassica napus L.) plants suffering from wilt were observed in an experimental plot at Merredin, Western Australia. Symptoms on the affected plants were tan-brown, longitudinal streaks along the main stem and on some lateral branches. Lesions on the stem were predominantly unilateral but sometimes covered the entire stem. Some of the lateral branches were completely wilted, and if present, pods were either shriveled or contained small seed. At the base of the stem, the lesions were grayish brown streaks that caused longitudinal splitting of the stem base. Small spherical (55 to 75 μm in diameter) and elongated (75 to 120 μm long) microsclerotia were seen in the pith and vascular region. Roots appeared to be symptomless, but upon removing the epidermis, grayish streaks were also seen on the roots and small sclerotia were observed in the pith and the vascular region of roots. One hundred and four small pieces (1 to 2 cm) of stem and root from 10 symptomatic plants were surface...