Grapes are prone to sunburn damage in high-temperature weather
Pruning courtyard grapes is usually done during the growing season, which can help regulate the relationship between current-year growth and fruiting, control new shoot growth, increase yield and quality, and noticeably improve the ornamental effect of the grapes. The following 8 measures can be taken for summer pruning: Bud removal: when the buds grow to 2 cm to 3 cm, remove weak buds, fork-mouth buds and...
Damage characteristics: when berries suffer sunscald, light brown nearly round spots appear on the fruit surface, with indistinct edges; the fruit surface first shrivels and then gradually becomes sunken, and in severe cases the cluster turns into dried fruit. Tendrils and the young tender tips of new shoots that have not yet lignified can also suffer sunscald damage, causing the shoot tips or young leaves to wilt and turn brown. Causes of the disease: infection generally occurs from mid-June to early July (the cluster coloring and ripening stage), mostly on clusters exposed to sunlight, caused by a lack of water in the tree and insufficient water supply to the fruit. When root water uptake is insufficient, leaf transpiration is high, and osmotic pressure rises, causing an imbalance in fruit moisture, sunscald occurs. When roots suffer from waterlogging or root burn, sunscald also occurs. In production, large-berry varieties are prone to sunscald. Sometimes clusters in shaded positions, due to pruning, topping, vine tying and other position changes, or when the temperature suddenly rises and the plant cannot adapt, new shoots and fruit can also suffer sunscald.
Control methods: Strengthen cultivation management: apply fertilizer appropriately deep to induce the root system to develop deeper, enhance tree vigor, and improve stress resistance; plant appropriately densely, use a trellis system, and keep the clusters in the shade; prevent waterlogging or root burn caused by excessive fertilization; irrigate timely and appropriately during the high-temperature disease period, and water promptly when transpiration is high to lower plant body temperature and avoid sunscald. Spray fertilizer to cool down: in high-temperature weather after rainy periods, spray the leaves and clusters with 0.2% potassium dihydrogen phosphate solution or 5% wood ash extract or 27% high-fat film emulsion at 80-100 times dilution 2-3 times, which has a certain preventive effect on sunscald.
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