2018 Volume 60 Pages 23-29
In order to develop the control measure of siso mosaic disease, whose causal pathogen is perilla mosaic virus transmitted by siso rust mite (Shevtchenkella sp.), we investigated occurrence of the mites on the perilla plants through two years and the frequency of disease occurrences on each branch of the perilla.
The first occurrence of siso rust mites appeared on perilla of self-sown seedlings from April to June. After that, siso rust mites appeared on other perilla in the next field. Three months after, siso rust mites appeared on perilla planted in greenhouse about 50 meters distant from that. The number of siso rust mites peaked from July to October in each field. The disease occurred and rapidly expanded from July to September, along with the occurrence of vector mites in each field. Therefore, this implies that the mites invaded from outside field into greenhouse and transmitted the disease despite of low density of the mites.
The frequency of disease occurrences in each perilla branch rapidly increased at 40 days after the viruliferous mites were released, but decreased 69 and 96 days later. We observed that the symptoms were disappeared on one of newly grown branches from the diseased branch, and some of those restored mosaic symptoms later. Accordingly, apparently healthy branch which has been infected can transmit the disease.
Overall, it is important to remove infected perilla in and outside of the greenhouses which can be potential sources of the disease, and to control the vector mites before their massive occurrence.
