By freeze-drying, the infectivity of crude extracts of plants infected with tomato spotted wilt virus was reduced to 4% of the original infectivity, whereas the preparations containing 1% cysteine maintained 81% of their original infectivity. Freeze-dried preparations of crude extracts or plant tissues lost their infectivity after preservation for 4 months at 4C, while the preparations containing 1% cysteine remained infectious for 24 months.
Rice ragged stunt virus (RRSV) was inoculated to 9 species of Gramineae by viruliferous brown planthoppers, Nilaparvata lugens (Stål). Five species, such as maize, wheat, barley, rye and common millet were infected and developed symptoms, similar to those on rice, e.g. twisted leaf, ragged leaf and stunting. Only 1 out of 10 inoculated oat plants and 2 out of 15 japanese millet plants developed slight ragged leaves about one month after inoculation, but no virus was recovered by back inoculation to rice and by electron microscopic detection. No infection occurred on sorghum and Coix lachryma-jobi var. ƒrumentacea.