In Okayama Prefecture, natural spread of grapevine leafroll disease was suspected in a field where a woody indicator, grapevine cv. Cabernet Franc (CF) was used to index for this disease. After leafroll- and Grapevine leafroll-associated virus 3 (GLRaV-3)-free nursery vines of grape cvs. CF and Cabernet Sauvignon had been transplanted to the field in July 1999, the incidence of leafroll disease reached 82% and 20%, respectively, in autumn 2001. GLRaV-3 was detected from all symptomatic vines by ELISA. These results suggest that leafroll disease and GLRaV-3 naturally spread in the field.
A multiplex RT-PCR procedure was developed for the simultaneous detection of Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV) and Papaya ringspot virus (PRSV) from Cucurbitaceae crops. Using oligo dT primer, cDNA was synthesized from virus RNA and amplified with a mixture of three primer sets specific to WMV, ZYMV and PRSV. Three potyviruses were accurately detected from cucumber plants singly, doubly or triply infected with these viruses as well as mixtures of virus RNA. With this method, three potyviruses could be detected from various kinds of naturally infected Cucurbitaceae crops more accurately than with indirect ELISA and more easily than with uniplex RT-PCR.
A sclerotinia disease of endive, Cichorium endivia L., was found in Okayama Prefecture in November 2003. The symptoms were water-soaked, blight and soft rot of leaves and stems. The fungus consistently isolated from symptomatic leaves was identified as Sclerotinia sclerotiorum on the basis of morphological characteristics. Healthy seedlings were inoculated with the isolated fungus, symptoms of the disease were reproduced, and the fungus was reisolated from the lesions.