What Causes Grapes to Turn Yellow?
The editor will discuss the reasons why grapes turn yellow and the topic of grape yellowing causes and solutions. Let's take a look together!
Poet Tang Yanshan from the Tang Dynasty praised grapes with the words "The珠帐 night does not close, the moonlight falls into the clear shadow," referring to grapes as round and adorable, like precious pearls. Grapes are a common fruit in life, but don't underestimate them. Grapes are one of the oldest fruit tree species in the world. Grapes have a wide range of uses; they can not only be eaten directly but also processed into many other foods, such as wine, raisins, and grape juice, all of which are loved by people. It is evident that the economic benefits of planting grapes are considerable. However, grape yellowing is a common problem during cultivation, which can lead to unhealthy plant growth and reduced fruit yield, affecting the interests of grape farmers. So, what causes this, and how should we handle it? Let's find out together.
I. Grape Deficiency in Nutrients
When fertilization is unbalanced, there is a high dependency on nitrogen fertilizer, and other nutrients are ignored, it can lead to a deficiency of trace elements like iron, magnesium, potassium, and boron in grapes. This can cause antagonistic effects between elements, impacting the plant's nutrient absorption and polluting the soil, leading to yellowing leaves and an unhealthy state.
Solution: Apply fertilizers reasonably and pay attention to supplementing trace elements for the plant. Whether it's organic or inorganic fertilizer, chemical or microbial fertilizer, they should be used in a balanced combination to ensure comprehensive nutrition for the plant.
II. Improper Management
1. After harvesting, neglecting the management of water and fertilizer can lead to soil compaction, nutrient loss, or improper watering, reducing nutrient accumulation in the plant and affecting the development of new shoots, making it difficult for the plant to survive winter, and the leaves will turn yellow the following year.
2. Improper arrangement of the orchard trellises or not pruning the grapes in time can lead to insufficient light, reduced photosynthesis, and yellowing leaves.
3. Not paying attention to pest control after harvesting can lead to early defoliation along with the phenomenon of excessive growth of new shoots, insufficient nutrient accumulation in the plant, difficulty in overwintering, root withering and death, and yellowing leaves.
Solution:
1. Strengthen water and fertilizer management, apply organic fertilizer, and water moderately and appropriately. Also, frequently loosen the soil around the plant.
2. Reasonably layout the orchard trellises and prune grape branches and leaves in time.
3. Pay attention to pest control after harvesting to keep the leaves intact.
4. In spring, when most of the absorbing roots of grapes have died, it is necessary to spray foliar fertilizer on grapes. You can use 0.2%-0.3% ferrous sulfate combined with 0.3% urea or 500 times multi-effect element, applying once every 7-10 days, for a total of 3-4 times.
III. Pesticide Damage
When controlling pests or weeding, pesticides are usually sprayed. However, if used improperly, the damage to grapes from pesticides can lead to yellowing leaves, defoliation, reduced yield, and even plant death in severe cases.
Solution: After spraying pesticides on the plants, inspect the orchard. If abnormal plant conditions are found, dilute the pesticide by spraying water on the plant immediately. If it's a herbicide or other drugs sprayed on the ground, use plenty of water to remove the pesticide residue.
IV. Fertilizer Damage
Improper fertilizer application can also cause yellowing of plant leaves. Fertilizer damage usually manifests on the plant's leaf surface and sometimes on the roots and new shoots. Excessive fertilizer application, high fertilizer concentration, or incompatible fertilizer properties can harm the plant, resulting in poor growth of new shoots, yellowing of young leaves, and in severe cases, withering and death of leaves or new shoots.
Solution: Before fertilizing, confirm that different fertilizers are compatible and control the concentration and amount of fertilizers, avoiding direct contact with the roots. After fertilizer damage occurs, immediately remove excess fertilizer, water generously to dilute, and carry out tillage to loosen the soil, improving the root environment.
V. Disease
When grapes suffer from yellow leaf disease, the leaves will turn yellow.
1. Symptoms
In the early stage, young leaves appear yellow-green or yellow-white, then the leaf edges become burnt, affecting the plant's growth and development. When the fruit turns yellow, it stops growing, and some may fall off.
2. Causes of Disease
(1) Iron deficiency. Breeding in saline-alkali soil can lead to an imbalance in the plant's physiological state, preventing the absorption and transfer of iron, causing the plant to become ill.
(2) Under high temperatures, the plant requires a large amount of nutrients to support its growth. If the water temperature for irrigation is too low, the ground temperature rises slowly, and the soil is compacted, leading to reduced root respiration and nutrient absorption capacity, causing the plant to become ill.
3. Onset Pattern
It often occurs in May and can be cured within 7-10 days if treated promptly.
Solution:
1. For new grapeyards, pay attention to trench irrigation before formal planting to reduce soil salinity.
2. After grapes are harvested, apply decomposed organic fertilizer every two years, preferably at the end of autumn, before grapes prepare for winter.
3. During the growing period of grapes, apply compound fertilizer containing multiple elements.
4. In the early stage of grape disease, spray 0.5% ferrous sulfate solution on the leaves for treatment.
The above content introduces the reasons for grape yellowing and the causes and solutions for grape yellowing. I hope it can help you, and I also hope everyone comes to see more green plant and flower experience and common knowledge!