What diseases can crops develop after heavy rain?

Editor's note:

This article is information provided by the Central Region Agricultural Research and Extension Station of the Council of Agriculture on crop recovery after heavy rain. NewsMarket supports environmentally friendly cultivation methods and also hopes to provide various non-pesticide agricultural information. Although the information provided in this article is not necessarily organic or pesticide-free, it still offers much valuable reference information on the problems that crops may face after heavy rain, and it is published here to share with fellow farmers.

─────────────────────────────────────────────

Crop Recovery and Disaster Mitigation Measures After Heavy Rain Disasters

Under the combined impact of the southwest airflow and the plum rain front, several crops in the central region have already been affected by heavy rain. The Taichung District Agricultural Research and Extension Station of the Council of Agriculture, Executive Yuan, calls on farmers to promptly carry out management measures for cultivated crops to avoid continued expansion of damage; it also provides the following disaster mitigation and recovery measures for the main crops currently under cultivation:

Rice crops: In the central region, rice is in the grain-filling stage or is already close to harvest. Field ponding should be drained, and vertical and horizontal ditches should be cleared or deepened to avoid lodging and germination caused by standing water. For rice that has reached harvest stage, harvesting should be actively carried out after heavy rain to avoid germination. Because rice is currently close to harvest, no further pesticide application should be done after heavy rain, to avoid pesticide residues.

Vegetable crops: In some low-lying areas of the central region, vegetable gardens have experienced flooding. Field ponding should be drained, and vertical and horizontal ditches should be cleared or deepened. Water pumps may also be used to pump water so that standing water can be removed quickly. After the heavy rain disaster, field sanitation should also be carried out, removing fallen leaves and withered or diseased foliage to avoid the spread of disease, and according to the methods recorded in the Plant Protection Manual, control of downy mildew, Phytophthora blight, soft rot and other diseases should be strengthened. After spraying, attention should be paid to the pre-harvest interval to avoid excessive pesticide residues. If supports or trellises used for climbing vegetables have been knocked down by rainwater, they should be set upright again so that the vegetables can continue to grow. Replanting should also be carried out promptly to restore production.

Fruit tree crops: Drain orchard ponding as quickly as possible. If plants wilt due to standing water, they should be pruned appropriately. In the central region, for pears and grapes nearing maturity, split fruits should be cut off to prevent the spread of pathogenic bacteria. Refer to the Plant Protection Manual to strengthen control of grape downy mildew, fruit tree anthracnose and other diseases. After spraying, attention should be paid to the pre-harvest interval to avoid excessive pesticide residues. For other fruits that have not yet entered the mature stage, pesticides should be applied as soon as possible after the weather clears to control pests and diseases, and a small amount of low-concentration quick-acting topdressing and nutrient agents should be applied to promote recovery of tree vigor.

Flower crops: After heavy rain, strengthen drainage to maintain continued normal growth of crops. Strong winds can blow down branches and leaves, making pest and disease problems more likely, so these should be cleaned up quickly and plants pruned appropriately. Although some flowers have flower netting, if plants have fallen over, they should be set upright as soon as possible to maintain normal growth and ensure quality. For flowers such as gladiolus that do not have supports, bamboo stakes should be used to help keep them upright and fixed. If leaves or flowers in the field are damaged by rain, the wounds are prone to pest and disease problems, so once the weather clears, pest and disease management should be strengthened. Cut flowers harvested during the heavy rain period have a lot of moisture in their leaves, so they may be moderately dried with an electric fan at the packing house to reduce the occurrence of diseases such as Phytophthora blight and soft rot.