Prevention and Treatment Methods for Grape (T-J) Disease
Today, we will introduce the related content of the grape clinic, focusing on the prevention and treatment methods for grape (T-J) disease. Detailed information will be shared next.
This disease, also known as late blight, poses a significant threat to grape production, causing extensive fruit rot and can also infect various fruit trees such as apples and pears.
Symptoms of Damage
It mainly infects grape fruits but can also affect leaves, young shoots, tendrils, fruit stems, and inflorescence axes. Initially, the disease appears as tiny brown circular spots on the fruit surface, which gradually expand and become sunken, with small black spots arranged in a ring pattern on the surface. When the weather is humid, the center of the lesion may have a reddish sticky substance.
In severe cases, the lesions can spread to the entire fruit surface. In欧美 hybrid grapes, the infected fruits often rot and fall off; in European grapes, they generally shrink into black僵果. When the fruit stem or inflorescence axis is infected, a dark brown, oblong sunken lesion with a reddish sticky substance appears, and in severe cases, the fruit cluster below the affected part dries up and falls off.
When leaves are initially infected, they show small brown circular spots that are slightly sunken. When these small spots densely cover the entire leaf and merge, the leaves often turn yellow and fall off. When young shoots are affected, they show light yellow-brown lesions, which are prone to falling off, leaving behind a reddish sticky substance.
Incidence Patterns
The pathogen mainly overwinters in the surface tissues of one-year-old branches and infected fruits, and can also overwinter in leaf scars, inflorescence stems, and nodes. In the following spring, when environmental conditions are favorable, it can produce a large number of conidia, which are spread by wind and rain, causing the initial infection. The bark of two-year-old branches and older branches do not carry the pathogen. In the Shanghai area, symptoms of damage can be seen as early as the end of May, and the condition gradually worsens thereafter.
The pathogen requires high temperatures and humidity, with the optimal temperature for infection being between 28-32°C. Therefore, in July and August, if there is abundant rainfall, the disease is more severe, and in years with less rain, the disease is reduced. The pathogen has the characteristic of latent infection, so the closer the fruit is to maturity, the faster it develops.
If there is abundant rainfall in September, the disease can still occur on the second crop of fruit. Sunburned fruit is often more susceptible to the disease; dense planting, poor ventilation and light conditions, and a closed canopy can lead to severe disease; the closer the fruit cluster is to the ground, the higher the incidence of disease; excessive application of nitrogen fertilizer, excessive growth of branches, low-lying orchards, and poor drainage conditions are favorable for disease development. Generally, varieties with thin fruit skins are more likely to be affected, with late-ripening varieties being more susceptible than early-ripening ones. Especially, Eurasian varieties are easily infected.
Grape varieties such as Queen of Vineyards, Italiania, Red Honey, Rose Scented, and Victory are most susceptible; the Xianfeng and Jùnóng 3 in the Jùfēng series are easily infected; Jinhou, Xinmeigui, and Jùfēng are next; while Shitiben, Bèilèi A, and Heihan have strong resistance.
Prevention Methods
(1) During winter pruning, carefully remove diseased and weak branches and僵 fruits, collect them for deep burial or incineration, to reduce the source of the disease.
(2) Strengthen cultivation management, promptly drain to reduce humidity; timely bind vines and remove apical buds to improve ventilation and lighting conditions for the plants; pay attention to reasonable fertilization, appropriately increase the application of phosphorus and potassium fertilizers to enhance the plant's disease resistance; when using trellis cultivation, it is advisable to raise the position of the lowest wire to at least 60 cm above the ground.
(3) In areas with severe disease, fruit bagging can be implemented when the fruit is the size of soybeans in mid-June.
(4) Before germination, spray a mixture of 5-degree Bordeaux mixture and 0.3% sodium pentachloride solution. During the growing season, spray the first application of medicine within 3-5 days after the first appearance of spores in the orchard, and then spray every 15 days, for a total of 3-5 times. Stop spraying 15 days before the grape harvest. Medicines that can be used include 50% polyrain wettable powder at a concentration of 800-1000 times, or 75% tobramycin wettable powder at a concentration of 1000 times, or 75% chlorothalonil wettable powder at a concentration of 500 times, or 80% (T-J) captan 500 times, or 80% mancozeb 500 times, or 40% polysulfide suspension at a concentration of 500 times. To improve the adhesion performance of the medicine, 0.03% of gelatin or other adhesives can be added to the medicine solution.
This article shares the complete introduction of the prevention and treatment methods for grape (T-J) disease, for everyone's learning and understanding!