The main production mode of grapes in Taiwan is twice a year, with the harvest peaks for summer fruit between June and August, and winter fruit between December and February of the following year.
During the fruiting period of the first crop of grapes, there are often continuous rainy season. It causes insufficient sunlight may lead to ineffective photosynthesis and the excess nitrogen uptake and accumulation, affecting the growth and ripening of the fruit. In the hot and humid season, increase the risk of diseases in berries, which can cause shattering, fruit cracking, and poor coloring, etc. Management should focus on reducing soil moisture, air humidity, and temperature to prevent excessive nutrients absorption then cause spindling. During the mid to late period of the second crop of grapes, low sunlight and low temperatures can cause leaf loss, which can affect the ripening of the fruit. To improve this, reducing the usage amount of nitrogen fertilizer at the early stages of growth can help prevent excessive branches and leaves growth, which can affect flowering and fruit set or excessively high yields but poor quality in grapes. |
Common physiological disorders in grapevine include the following:
Flower or bud drop
Also known as shatter. When incomplete differentiation of flower buds, the unfertilized ovaries of flowers fail to develop into berries then drop down or cause parthenocarpy fruit (development of fruit without fertilization). This can be caused by various factors, such as a previous crop or at the early growth stage with insufficient sunlight, improper management of the vine, excessive winter pruning, excessive shoot thinning, excessive use of nitrogen (N) or potassium (K) fertilizers or high nitrogen (N) organic fertilizers, over-irrigation leading to excessive nutrient uptake, and insufficient use of phosphorus (P) and boron (B), all of which can lower the C/N ratio of vines, causing excessive vegetative growth, flower bud incomplete differentiation, which will cause spindling, resulting in flower drop.
Berry cracking
This disorder is when the berries get cracks or splits before maturity. It is caused by excessive nitrogen fertilization during the late ripening stage, insufficient phosphorus (P) fertilization, thick-skinned berry with poor elasticity or toughness, early drought stress followed by heavy rain at the later stage or rain at low temperatures seems to be the reason for berry cracking.
Berry drop
Berry drop is the disorder after the berries are ripening, due to the weak pedicel grape berries drop from the pedicel. It often occurs in vineyards with excessive irrigation and nitrogen (N) and potassium (K) fertilization, and insufficient use of phosphorus (P), boron (B), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu).
Sun scald
Sun scald will cause the surfaces of grape berries occur yellow-brown spots, which gradually turn brown and with slightly shriveled, usually happens at veraison stage. This disorder often occurs when excessive use of nitrogen (N) fertilizer and irrigation, which leads to soft and dark green grapes. Directly sunlight and high temperatures can damage and kill the skin cells.
Poor skin coloration
Extreme nitrogen (N) deficiency before flowering can cause excessive weakening of the branches, while too much nitrogen (N) can cause excessive growth during the fruiting phase. Insufficient nitrogen (N) and sunlight, excessive rainfall during the fruit development phase, Additionally, insufficient calcium (Ca) before coloring and excessive nitrogen (N) after coloring and insufficient phosphorus (P) during the period from flowering to fruit enlargement stage, insufficient calcium before coloring can all lead to poor coloring of the fruit.
Cold Damage
Cold damage may occur in three period. The first occurs in the autumn and winter, before the harvest period of second crop. When a cold wave hits, the temperature drops, and the leaves turn yellow and fall off severely, some even completely bare. The second occurs during the dormant period in winter on the fruiting branches, where the front end of the branches ranging from a few centimeters to tens of centimeters turn black and die. The third occurs during the spring germination and early growth period, especially when the winter is warm, the branch buds grow early, and suddenly encountering frost, the main symptom is that the new branches and leaves are frost-damaged and die. This phenomenon occurs more easily when there is insufficient use of phosphorus (P) and potassium (K) fertilizers, excessive use of nitrogen (N) fertilizer and organic matter, high groundwater levels or excessive irrigation frequency, significant after-effects of nitrogen (N) fertilizer cause spindling in summer and autumn, leading to insufficient nutrient storage in branches and a low C/N ratio. |
【Using foliar fertilizer in grapes】
Planting stage (After the fifth leaves have grown) - strengthen the root system and promote lateral bud growth. Increase the C/N ratio and fertilizer utilization efficiency.
Root Forte 110 (Special for Rooting and Germination)
Full Energy 100 (Special for full growth period)
Young fruit stage - Promote fruit enlargement without cracking and increase yield and quality.
Go Growing 370 (Special for Growing, High in Nitrogen)
Fruit Bagging – Small molecule calcium easy for uptake, promote fast andhealthy growth, strengthen nutrient storage capacity, and reduce flower and fruit drop.
Full Energy 100 (Special for full growth period)
Go Growing 370 (Special for Growing, High in Nitrogen)
Post Enlargement stage (Before coloring) - Contains high phosphorus (P) and high potassium (K) to improve brix levels (sweet taste). Enhance the coloration include the pedicel and skin with the smooth peel. Increase the rate of photosynthesis and carotenoids synthesis.
Go Beauty 380 (Special for Color Enhancement)
Go Sweet 390 (Special for Increase the Sweetness of Melons and Fruits)
Post Enlargement stage(After turning halfway to a different color.) - Increase the rate of photosynthesis and small molecule calcium easy for uptake, reduce fruit cracking, improve crop tolerance.
Ca Strong 801(Special for Summer and Water Retention)
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