How to spread and control plum necrotic ringspot virus disease.

Occurrence of damage: Valleau first reported that Prunus necrotic ringspot virus infected peach and plum trees in 1932. Since then, many researchers have reported the infection of many stone fruit trees such as sweet cherry and sour cherry. The virus can cause a variety of fruit diseases, and its harm varies with tree species and virus strains. The main manifestations are the decline of the growth of diseased plants, the color difference of fruits, the obvious decrease of yield, and some of them can lead to the decline of trees. The virus only infects 7-year-old peach tree Lettie in California, which can reduce the growth of diseased plants by 12.2% and the yield by 5.6%. In France, a comparative experiment was carried out on two varieties, Spring and Robin. It was found that only one virus infection reduced the growth of 3-year-old peach trees by 24.5% ~ 32.8% and the yield of 4-year-old peach trees by 6 1.6% ~ 77.0%. The fruit maturity of diseased trees is delayed by 3 ~ 4 days, and the fruit is small, forming cork points and cracking, which seriously affects its commodity value. PNRSV is one of the serious viruses on cherry. Grafting survival rate can be reduced by 60% when scions and rootstocks are infected in nursery. According to the experiments of Posnette and Cropley( 1965), the height, crown width and weight of 4-year-old cherry trees with MazzardF 12/ 1 as rootstock decreased by 16%, 27.3% and 49% respectively. Generally, orchards reduce production by 30% ~ 50%. The number of buds in the nursery decreased by 50% ~ 90%, and the number of scions and seedling growth decreased obviously.

Mode of transmission: it can be transmitted through breeding materials, seeds and pollen. The spreading speed of seeds and pollen varies with the kinds and varieties of fruit trees. Among them, the seed transmission rate of sour cherry is the highest, up to 70%, and that of plum is the lowest.

Mode of transmission: nematode transmission, seed transmission and pollen transmission. Juice sauce. No insect vector of the virus was found. It is reported that a kind of gall mite Vasatesfockeui and a kind of nematode Longidorusmacrosoma can spread the virus.

Media: a kind of scabies mite, Vasatesfockeui and Longidorusmacrosoma.

Seedlings: poisonous plum and pumpkin seeds (seed transmission rate is 2.7%), European sweet cherry seeds (seed transmission rate is 37%), European sour cherry seeds (seed transmission rate is 9 1%), Mahali sour cherry seeds (seed transmission rate is 70%) and nectarine seeds (seed transmission rate is 3% ~ 12).

Pollen transmission: plants infected by PNRSV can transmit virus-carrying pollen to healthy plants and their seeds. In the field, the infection rate of PNRSV increased year by year. After seven years of investigation, it was found that the infection rate of PNRSV increased from 8. 1% to 30.3%, which was largely related to the natural spread of its pollen.

Natural Host: The natural host plants of the virus are mainly Prunus fruit trees of Rosaceae, including apricot, plum, Prunus armeniaca, plum and apricot, as well as begonia and rose of the same family.

Artificial inoculation can infect plants: artificial inoculation can infect dicotyledonous plants of 2 1 family, Comprise wild sesame, snapdragon, apocynum venetum, milkweed, safflower, cassia obtusifolia, cornflower, Chenopodium album, bitter fruit, watermelon, rape, coriander, Aristolochia, Zizania latifolia, tetraploid melon, Momordica charantia, Momordica charantia, Nicotiana, Wild Tobacco, Fructus Aristolochiae. Gaopen Cherry, Cistanche deserticola, Almond, Central China Cherry, Guangdong Cherry, Mountain Peach, Xiangyang Mountain Cherry, Mountain Apricot, Mountain Apricot, Alpine Apricot, Northeast Apricot, Taiwan Province Apricot, Taiwan Province Apricot, Taiwan Province Apricot, Taiwan Province Apricot, Taiwan Province Apricot, Taiwan Province Apricot, Taiwan Province Apricot, Taiwan Province Apricot, Taiwan Apricot, Taiwan Apricot, Taiwan Apricot and Walnut.

Prevention and treatment of diseases: The most effective way to control diseases caused by this virus is to use healthy propagation materials. The mother plant used for reproduction should keep a certain distance from other orchards, and the flower buds should be removed in time to avoid spreading the virus through pollen. Heat treatment at 38℃ for 24 ~ 32 days to obtain virus-free plants.