Grape leafroll Diseases
Grape leafroll disease is a common virus disease in grape production, which is widely spread. Grape leaf roll disease has semi-latent characteristics. It does not show symptoms in most growing seasons. Most Eurasian plants show symptoms only at fruit ripening stage. Leaf symptoms were most obvious from harvest to deciduous stage. Leaf margins were rolled back, veins became yellow or red, only the main veins remained green, while some varieties gradually withered and browned. The disease is harmful and can reduce grape yield by 20%-50%.
The symptoms of grape leaf roll disease vary with environmental conditions and time. The symptoms of grape leaf roll disease vary according to environmental conditions and at different times of the year.
Grape leaf roll virus is mainly transmitted through seedlings, scions and cuttings.
Cause of disease
Grape leaf roll disease is mainly transmitted by artificial cultivation activities. It can be transmitted by using cuttings or buds and rootstocks of diseased plants as asexual reproductive materials.
Most rootstocks are cryptogenic and virulent, so the risk of disease transmission through rhizomes is high. Dodder can transmit virus from diseased grapes to healthy grapes in the field. Juice inoculation can not spread from grapes to grapes, but it can be transmitted to herbal hosts through grapes. GVA can be transmitted by pink scale, but it is observed that the spread of leaf roll disease is limited in the field.
The disease can be detected by some grape varieties as indicators, such as Lizhu, Mianjian, 6–18 months and Pinot Noir for 6 months. The reaction is early red leaves.
How to control grape leaf roll？
(1) Agricultural Control
Breeding rootstocks with anti-virus diseases is the fundamental measure to prevent and control virus diseases. Quarantine and inspection should be strengthened and virus-free mother plants should be selected to propagate seedlings.
(2) Potential Detoxification
The seedlings or test-tube seedlings were placed in a heat treatment box at 38 C for 56–90 days under artificial light. The new shoots were cut about 2–5 centimeters. The virus-free rate was 86%. The virus-free seedlings had to be tested for non-toxicity before they could be used as mother plants. However, the operation requirements of this treatment method are relatively high and the cost is relatively high.
(3) Organic Prevent Solution
Applying chitosan oligosaccharide, by activating a plant’s immune system, it can maximize plant’s resistance ability to virus, fungus and bacteria. And the control effiency is about 70%-80%。