Reasons for Citrus Re-greening During the Color-Break Period and Preventive Measures

It is currently the season when citrus ripens and hits the market, but at this time a phenomenon that gives fruit growers a headache appears——citrus re-greening. Citrus re-greening seriously affects the quality of citrus; not only is the appearance affected, but it also lowers the sweetness of the citrus, having a considerable impact on the income of fruit growers. So what causes re-greening at citrus harvest time? Let's find out together.

I. Reasons for citrus re-greening

1. Weather

Low temperatures help the accumulation of sugars and anthocyanins in the fruit, thereby promoting fruit coloration, but if abnormally warm weather occurs during the color-break period, the not-yet-fully-ripened peel will resume synthesizing chlorophyll, resulting in re-greening.

2. Poor tree vigor

For fruit trees with poor tree vigor, the nutrients synthesized through leaf photosynthesis are limited, and the minerals absorbed by the roots are also insufficient, unable to meet the needs of fruit growth, so the fruit will color prematurely and show false ripening. After nutrients are replenished later through root fertilization and foliar spraying, the fruit will show a brief period of re-greening.

3. Excessive nitrogen fertilizer

When a foliar fertilizer with too high a nitrogen content is sprayed during the citrus color-break period, the excess nitrogen reacts with the sugars in the fruit to form organic nitrogen, thereby reducing the sugar content in the fruit, causing the branches and leaves to grow excessively and compete with the fruit for nutrients, leading to a decline in citrus fruit quality; the anthocyanin content in the peel will also decrease, resulting in re-greening.

II. How to prevent citrus fruit re-greening?

1. Adjust tree vigor

Proper pruning should be used to enhance tree vigor and avoid decline in tree vigor and leaf yellowing, which cause the fruit to remain unripe. Many fruit growers spray paclobutrazol during the color-break period; this generally does not cause fruit re-greening, but if a large amount of high-concentration paclobutrazol is sprayed when tree vigor is weak, it will make the tree vigor even weaker, thereby causing re-greening.

2. Fertilization

When fertilizing during the fruit color-break period, unless the tree vigor is too poor and leaf color has faded severely, root fertilization is generally not advisable. It is recommended to start with foliar nutrient supplementation to promote fruit coloring, fruit enlargement and sweetness; you can spray Zigohong or Gaoweilu K400 foliar fertilizer, which sweetens and colors the fruit while enlarging it, and enhances the storage tolerance of the fruit.

3. Timely harvesting

To avoid overripe fruit losing sugar and re-greening, citrus fruit should be harvested promptly and at the right time. In addition, in winter with many rainy days, long-term insufficient light, excessive nutrient consumption by the tree, and large fruit loads, as well as delayed harvesting of citrus, can easily cause decline in tree vigor, and both fruit drop and re-greening may occur. Fruit grower friends had best harvest in batches in a timely manner.

  The above is an introduction to the reasons for citrus re-greening during the color-break period and preventive measures. We hope it can help you. For more related knowledge, please stay tuned to us.