Key points for winter freeze protection measures for Chinese medicinal herbs such as Fritillaria thunbergii and Corydalis yanhusuo

Early to mid-March is a period of vigorous growth for Chinese medicinal herbs such as Fritillaria thunbergii and Corydalis yanhusuo. If they suffer a severe late spring cold spell or spring snow, plants may be broken, stems may split from freezing, leaves may be killed by frost, and even the entire plant may freeze to death. If remedial measures are not taken promptly, yield will be seriously affected. Key points for prevention and post-disaster field management:

1. For Fritillaria thunbergii that has already flowered, complete flower removal before freezing to prevent the tender stems from being damaged by cold. After a late spring cold spell or spring snow, promptly clear accumulated snow from the plants to prevent freeze damage, and at the same time prune plants broken by snow. Also do a good job of clearing ditches and drainage. Where conditions permit, shallow loosening of the soil can be carried out to reduce field humidity, which helps raise soil temperature and allows plants to recover growth quickly. After the disaster, flower removal for Fritillaria thunbergii should be appropriately postponed.

2. For Fritillaria thunbergii and Corydalis yanhusuo plants that are on the tender side in growth, promptly broadcast stove ash or spray Plant Power 2003, etc., before freezing to improve the plants' resistance. After freezing, once the plants recover growth, appropriately apply quick-acting fertilizers such as N, P and K. Foliar topdressing may be carried out to supplement plant nutrition and reduce losses.

3. After the disaster, when the temperature rises above 15°C, do a good job of disease prevention. Pesticides such as thiophanate-methyl, chlorothalonil and mancozeb may be used to prevent diseases such as gray mold of Fritillaria thunbergii and downy mildew of Corydalis yanhusuo.