Tobacco ringspot virus disease of carnation

(TobaccoringspotvirusdiseaseofCarnation)

[Symptoms] Mottle, light mosaic and plant degeneration appeared on the affected leaves.

Tobacco ring spot virus (TRSV). It belongs to the genus Nematovirus of Cowpea Mosaic Virus Family. The virus particles are spherical and about 28nm in diameter. There are three kinds of virus particles: empty shell without RNA (T), non-infectious nucleoprotein (M), infectious nucleoprotein (B) and a similar satellite (SL). The sedimentation coefficients are 535 (T), 915 (M), 1265 (B) and 1225 (5L) respectively. The satellite size is 359nt. The genome consists of RNA1 and RNA2 with molecular weights of 2.73×106 and 1.34×106 respectively. The RNA1 genome is 7514nt. Sedimentation coefficients were 32S for RNA1 and 24S for RNA2. Diluted with distilled water 1:5, lethal temperature 65℃, dilution end-point 0.001~0.0001, survival time in vitro 6~10 days at room temperature, 3 weeks at 18℃, lost infectivity after several months at 2℃, frozen liquid at low temperature still has activity after 10 years of storage under sealed conditions, leaves dried with calcium chloride still have infectivity after more than 1 year at-10℃. TRSV has good immunogenicity, and antiserum with titer of 1:2000 or more can be obtained easily. TRSV has no serological relationship with other viruses of the same genus, such as tomato ring spot virus and mustard mosaic virus.

[Pathogenesis] The virus is transmitted by juice and seeds, and there are many hosts for seed transmission, such as melon, globeflower, lettuce, cowpea, dandelion, tobacco and European senecio. In addition, potato, zinnia, geranium, etc. are transmitted by seeds. The vectors were mainly adults and third-instar larvae of Xiphinema americana in soil. Monocephalous nematodes can also transmit viruses. Nematode was infected within 24h. Infected nematodes can transmit virus after 49 weeks storage at 10℃. In addition, thrips nymph, mites, leafhoppers, tobacco leaf beetle and peach aphid can also transmit virus.

[Prevention]

1. Strengthen quarantine and prohibit the import of diseased seeds, scale bulbs and seedlings from infected areas.

Application of nematicide treatment to eliminate nematodes in soil; spraying thrips, locusts, leaf beetles and aphids with insecticides. For nematodes in the soil, D-D mixture can be used for soil application or Kexanphos can be used for soil treatment. To thrips, locust, leaf beetle, aphid usable insecticide sprays kill. Commonly used pesticides are 50% malathion emulsifiable concentrate 1000 times, 40% dimethoate emulsifiable concentrate 1000~1500 times, compound fruit emulsifiable concentrate (dichlorvos 40%, omethoate 10%) 2000~3000 times, 20% methomyl emulsifiable concentrate 3000 times, 50% fenitrothion 1000 times, 25% carbaryl 400 times, etc.

crop rotation and weeding. Rotation with non-infective soil for 1~2 years can eliminate or reduce nematodes in soil, and weed removal can eliminate vectors and infection sources.