Grape leaf roll disease is a viral infection.
Symptoms Symptoms in the spring are less pronounced. The diseased plants are shorter and shorter than the healthy plants and germinate later. In the non-irrigated vineyards, the symptoms of the leaves were first seen in early June, and the irrigation area was delayed until August. The red variety first appeared pale red spots between the veins of the base leaves, and the summer spots expanded and healed, causing the veins to turn reddish. By autumn, the diseased leaves in the base turned dark red and only the veins remained green. The leaves of the white variety did not turn red, except that there was a slight chlorosis between the veins. In addition to discoloration of the diseased leaves, the leaves became thicker, became brittle, and the leaf margins rolled down.
The color of the ear of the diseased plant is shallow. For example, the color of panicles of the red variety is not normal, or even yellow-white. Calcium and potassium accumulated in the petiole, while the contents in the leaves decreased and the starch accumulated. Symptoms vary from species to species, and few species, such as Thompson, have very mild symptoms. Necrosis only occurs in summer leaves. Necrosis is located between the veins and the leaf margins. Most rootstock varieties are cryptotoxic.
Control methods
1. Virus-free seedlings are selected, and serum-enzyme-linked cassettes are available in foreign countries for rapid detection. European soil, France, and the United States of America are all sold. It has a variety of serotypes. China is now studying trial production. Seedlings are safe to use after they have been tested with a certified plant or serum to prove they are non-toxic.
The woody indicator plants for the detection of leafroll virus: Cabernet Franc, Jiamei, Pinot Noir, Meiluo Juice, Babila, Cabernet Sauvignon, Rice Shoots, and LN-33. Greenhouse grafting can be done in a greenhouse at 22°C. Four to six weeks after grafting, the leaves turned red. Field grafting takes 6 to 8 months to 2 years to show symptoms.
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2, to take the following measures to obtain virus-free plants: heat treatment of the whole grape, at 38 °C for 3 months, and then cut the tip of the new tip placed in misty environment rooting, or stem tip tissue culture; bottle heat treatment; micro type Grafting and meristem cultivation.
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