What is the reason why apples turn yellow and don't change color after picking bags?

In recent years, the situation that apples are yellow and not colored after picking bags has occurred from time to time, and some apples are colored but not completely red, which seriously affects the quality and commodity rate of apples and reduces economic benefits. There are several main reasons for this:

1, excessive use of borax or excessive spraying of foliar fertilizer with high boron content will lead to yellow fruit without coloring.

When borax is applied in spring, it should not exceed 150g per plant, but about 100g is appropriate. If it is applied excessively, it will cause the apple to turn yellow without coloring, and once it turns yellow, it will last for three years.

At present, there are many foliar fertilizers containing boron, and some fruit farmers spray a single dose of boron fertilizer many times during the apple growth period, which leads to excessive boron absorption by fruit trees and yellow and colorless fruits.

2. Excessive girdling will cause the fruit to turn yellow without coloring.

If the girdling is too heavy, the nutrients absorbed by the underground roots cannot rise, and the nutrients absorbed by the leaves on the trees cannot flow back, which will easily lead to the decline of apple trees and the yellowing of fruits due to malnutrition.

3. Continuous high temperature affects fruit coloring.

After "beginning of autumn", the high temperature of about 35 degrees appeared continuously for more than 10 days, and the temperature in the bag could reach more than 50 degrees, which affected the formation of anthocyanin, a coloring promoting substance, and the fruit turned yellow without coloring.

4. Picking the bag too late will also lead to the fruit turning yellow and not coloring.

Medium-ripe varieties, such as Gala and Yamashita, will not be colored if they are picked at the same time as red Fuji apples. Gala apples should be picked in early August. If they pick it after 6-7 days, the fruit will be yellow and colorless. It is more appropriate to pick bags from the end of September to the beginning of 10. If the delay exceeds 10 days, the fruit will turn yellow and not be colored until the middle of 10. In the case of frost, there is no coloring phenomenon.

5. During the fruit harvesting period, the temperature difference between day and night is small and the climate is dry, which will also lead to the fruit turning yellow and not coloring.

The temperature difference between day and night is small, which is not conducive to fruit coloring. After picking the bags, the weather was dry, and many orchards were not watered in time, resulting in the apples not being colored.

6. Bagged apples with excessive nitrogen application are not colored.

Especially in July and August, if too much nitrogen fertilizer is applied, the fruit will be green without coloring after picking bags.

7. Rotten roots can also cause the fruit to turn yellow without coloring.

In recent years, due to the extensive application of inorganic fertilizers, soil acidification is serious, roots are poisoned, and nutrients are difficult to absorb. At the same time, due to the poor application technology of chemical fertilizer, root burning and other fertilizer damage will lead to the fruit turning yellow and not coloring.

8. Excessive application of potassium fertilizer and phosphorus fertilizer will also lead to yellow fruit without coloring.

In recent years, many experts have pointed out that the phenomenon of potassium deficiency in orchards is serious. Fruit farmers apply a large amount of potassium fertilizer, and if they apply potassium fertilizer excessively for years, their fruits will turn yellow and not be colored.

9. Irrigation after picking the bag will also aggravate the yellowing of the fruit without coloring.

We advocate watering before picking bags, not after picking bags. If it is too dry, we can water it with a small amount of water. In addition, according to the investigation, it was found that too much "bacteria remover" was sprayed before and after bagging, and penicillin was sprayed before bagging with plastic film. It will also lead to bagging apples turning yellow and not coloring. Therefore, it is hoped that the majority of fruit farmers will manage orchards scientifically to avoid fruit yellowing.