What are the control methods for Asarum sclerotinia disease?

Asarum is a precious authentic Chinese medicinal herb from Liaoning, widely distributed, high in yield, good in quality, and sells well both domestically and abroad. Xinbin County began developing artificially cultivated Asarum in 1986, and the area currently retained is more than 20,000 hectares, with high economic benefits; it is one of the main varieties for farmers to get rich and a major cultivated variety of Chinese herbal medicine, compiled by the Medical Education Network. Asarum is used medicinally as the whole plant; its taste is pungent and its nature is warm. It has the functions of dispelling wind and dispersing cold, and opening the orifices to stop pain. It mainly treats wind-cold headache, sinusitis, toothache, phlegm-fluid cough, and wind-dampness arthralgia; recently it has also been used to treat rhinitis, laryngitis, gastritis, and oral erosion, all with significant curative effects.

Growth habits of Asarum

Asarum is a shade-loving plant, mostly distributed in mountainous areas with deep humus layers and fertile soil under broad-leaved forests and mixed coniferous-broadleaved forests, or growing among dense shrubs, in slightly moist places at the bottom of mountain gullies, and in forest edge areas, thus forming characteristics of liking moisture, liking fertilizer, liking shade, and fearing strong light, but under too much forest canopy closure it grows extremely slowly. Practice has proved that only through “dappled shade” or sufficient scattered light and strengthened water and fertilizer management can Asarum grow quickly and produce high yields.

How to control Asarum sclerotinia disease?

What is sclerotinia disease?

Sclerotinia disease is a plant disease caused by fungi such as Sclerotinia, Monilinia, Rhizoctonia, and Sclerotium. The affected parts form sclerotia from aggregated mycelium, with varying looseness or tightness, smooth or rough surfaces, and different shapes, sizes, and colors. Those formed by mycelium mixed with host tissue are called false sclerotia. The latter are often easier to diagnose because they often still retain the shape of plant organs (such as mummified fruit). The pathogen is Sclerotinia sclerotiorum (Lib.) de Bary of the genus Sclerotinia in the Ascomycota. The surface of the sclerotia is black, the interior is white, and they are mouse-dropping shaped. The mycelium is not tolerant of drying and can grow only when the relative humidity is above 85%. It has loose temperature requirements and can grow between 0 and 30°C, with 20°C being the most suitable; it is a disease suited to low-temperature and high-humidity conditions.

Symptoms of Asarum sclerotinia disease:

This disease mostly occurs in June-July. In the early stage of the disease, brown strip-shaped lesions appear at the base of the petiole, and after expansion the aboveground part lodges and dies. At the same time, the pathogen spreads to the roots, covering the rhizome with black sclerotia, so that the entire root rots and only the root bark remains.

Control methods for Asarum sclerotinia disease:

Loosen the soil promptly in early spring to raise soil temperature, and pay attention to drainage; remove and destroy diseased plants promptly when found; spray with 0.3 degree lime sulfur mixture, 600-800 times dilution of amobam, and 600 times dilution of zineb; harvest at the proper time and rotate to another field for cultivation.