How to Manage Citrus After Flooding? A Detailed Guide to Practical Remedial Measures

The heavy rainfall brought by this year's No. 15 typhoon “Koppu” caused torrential rain in parts of Xinyi City in Maoming, Yangchun City in Yangjiang, and Luoding City in Yunfu in western Guangdong, causing widespread damage and loss to crops such as rice, and severe damage and harm to fruit trees such as citrus. After the flooding, citrus orchard management measures must keep pace to reduce economic losses. The following aspects should be done well:

1. Dig deep ditches for drainage

After the flood recedes, some low-lying areas may still have standing water. A “cross”-shaped ditch 50 cm deep and 33 cm wide can be dug in the orchard for drainage.

2. Straighten trees and wash leaves

For citrus trees that have been knocked over, straighten them and set them upright as soon as possible, and set up supports. For orchards where the topsoil has been washed away, earth should be mounded early to protect the roots, but never mound soil too thickly around the root crown, to prevent trunk rot. Try to remove debris from the citrus trees and silt from the leaf surfaces. It is best to use a sprayer to spray clean water to wash the branches and leaves, so as to ensure the normal physiological activities of the tree.

3. Loosen the soil throughout the orchard

After flooding in the orchard, the soil becomes compacted and the roots lack oxygen, so the whole orchard should be cultivated and loosened to promote root growth. For citrus trees with severe root rot due to flooding, the soil should be scraped away to air the roots during cultivation, and the already rotted roots should be removed.

4. Foliar fertilization

For flooded citrus plants, since the roots' ability to absorb fertilizer and water is weakened, foliar fertilizers such as 0.3%-0.5% urea plus 0.3% monopotassium phosphate or 10% decomposed human urine can be sprayed on the canopy 2-3 times, once every 10 days, to supplement nutrition, promote new root growth, and restore tree vigor.

5. Moderate pruning

After citrus is flooded, pruning should be carried out reasonably to reduce water evaporation from branches and leaves. Generally, heavily damaged trees should be pruned somewhat more heavily, while lightly damaged trees should be pruned lightly, cutting off dead and weak branches.

6. Pest and disease control

After flooding, flooded citrus orchards are very prone to pest and disease damage, especially canker, scab, anthracnose, and red spider mite, which can occur severely. After flooding, corresponding fungicides and insecticides should be sprayed in time to prevent the occurrence and damage of pests and diseases. For canker control, options include copper hydroxide, copper oxychloride, and agricultural streptomycin; for anthracnose and scab, options include mancozeb, tebuconazole, thiophanate-methyl, carbendazim, and Score; for red spider mite, options include fenazaquin, propargite, hexythiazox, neem oil, and abamectin. When controlling pests and diseases, attention should be paid to rotating pesticides and avoiding the single use of one pesticide.