Pest and Disease Control Methods and Key Technical Points for the Chinese Medicinal Herb Asarum

Asarum prefers a cool, moist environment and cannot tolerate strong light or drought. The ideal soil is loose, fertile and rich in organic matter.

Seeds sown in early July typically crack open in early August, reveal the radicle in mid-August, reach 4 cm by early September and can exceed 6 cm by October. They do not sprout in the same year; after dormancy is broken by low temperatures below 4 degrees C, the young shoots emerge the following spring when the soil temperature rises to around 6 degrees C. The peak emergence period occurs at 8-12 degrees C. Asarum grows and develops extremely slowly: in the second year after sowing it produces only two cotyledons; in the third spring it grows just one true leaf; in the fourth year it still has five true leaves, or a few plants have 2 true leaves, and only a very few flower; not until the fifth and sixth years do most plants have 2 true leaves and flower and set seed abundantly. The seedlings emerge in spring, and the above-ground part basically takes shape in May, after which no new branches or leaves grow. Even if the stems and leaves are lost to pests, disease or mechanical injury, no new growth occurs that year. The rhizome lies dormant underground, forms a small bud in autumn, and after overwintering sends out smaller leaves the following year. Therefore, protecting the healthy growth of the above-ground part is extremely important.

Pest and Disease Control

1. Disease control. Asarum has relatively few diseases; the most serious one at present is sclerotinia blight, which occurs from early spring to summer each year and damages the whole plant. Control methods: strengthen field management, keep the beds free of standing water and compaction, ensure good ventilation, and adjust light to 50%-60% transmittance. Harvest at the proper time or rotate to a different plot. For chemical control, spray the leaves or drench the roots with a 500-1000 times dilution of 50% carbendazim. Diseased plants should be thoroughly removed, and the diseased planting holes should be treated with lime or disinfected with 5% formalin.

2. Pest control. The main pests are cutworms, black hairy caterpillars, locusts and asarum swallowtail butterflies. Black hairy caterpillars, locusts and asarum swallowtail butterflies chew the leaves, and in severe cases most of the leaves are eaten. Cutworms cause the most serious damage, biting the young shoots and cutting through the leaf stalks and rhizomes. Cutworms can be trapped and killed with poisoned bait made from trichlorfon mixed with fried fragrant soybean cake or wheat bran, or killed with poisoned soil. Other pests can be controlled by spraying the leaf surface with a 1000 times dilution of trichlorfon.