What are the methods for controlling diseases and pests of Gastrodia elata?

I. Diseases and their control

1. Causes of the disease. The primary pathogens of Gastrodia elata diseases are mainly other basidiomycetes among the fungi besides Armillaria mellea, which infect the fresh wood and fungal wood symbiotic with Gastrodia elata's Armillaria mellea, competing with Armillaria mellea for nutrients. In severe cases, they not only inhibit the growth of Armillaria mellea and reduce the yield of Gastrodia elata, but also directly infect the tubers of Gastrodia elata, causing soft rot of Gastrodia elata (called tuber soft rot) or rotting death (called tuber rot). This disease mostly attacks and causes damage when the environment is poor, such as high temperature and high humidity, poor aeration and other conditions unfavorable to the growth of Gastrodia elata, causing the skin of the Gastrodia elata tuber to turn yellow and wither, the central tissue to rot, the interior to become a thin slurry, and finally dying as an empty shell due to rotting and stinking.

2. Control methods. First, strictly select Gastrodia elata seeds. In production, excellent Gastrodia elata seeds that have undergone no more than 3 generations of asexual reproduction should be selected, with obvious growth points, protruding bud tumors, and free of bacteria and disease. It is best to use zero-generation or first-generation hybrid Gastrodia elata improved seeds from sexual hybridization breeding. Multi-generation Gastrodia elata seeds from asexual reproduction suffer from seed degeneration, weakened adaptability and stress resistance, leading to disease or low yield or even total crop failure after cultivation. When selecting Gastrodia elata seeds, if the seed tubers are found to be not plump, with inconspicuous growth points, or with rot spots (even a tiny bit), they should be discarded. Second, strictly select Armillaria mellea fungal wood. When cultivating fungal wood, select Armillaria mellea seed wood free of contaminating bacteria, and promptly remove seed wood and fungal wood found to be infected with contaminating bacteria. The surface characteristics for distinguishing Armillaria mellea from contaminating bacteria are: the mycelium of Armillaria mellea is pinkish-white, growing inside the bark; the rhizomorphs of Armillaria mellea have a white front end, a reddish-brown middle, and a black tail end, are round, interwoven in a network on the surface of the fungal wood, and glow (fluoresce) in the dark. Contaminating bacteria are generally a single color, such as white, green, ink-black, etc., mostly attached to the surface of the bark, distributed in bundles, sheets or fan shapes, and do not glow in the dark. Third, strictly select the cultivation environment and cultivation site. For field cultivation, choose virgin land free of or with few contaminating bacteria, and carrying no or few bacteria, and do a good job of disinfection and sterilization during cultivation; for indoor cultivation, pay attention to cleanliness and hygiene, and maintain good environmental sanitation.

II. Insect pests and their control

Common Gastrodia elata pests include mole crickets, white grubs and white ants. Mole crickets dig crisscrossing tunnels under the topsoil as adults or larvae and chew on Gastrodia elata tubers; white grubs are the larvae of scarab beetles, with omnivorous feeding habits and wide distribution, and can bite holes in Gastrodia elata tubers or destroy the developing terminal buds of Gastrodia elata; white ants, in addition to gnawing on Gastrodia elata tubers, also gnaw on the mycelium and rhizomorphs of Armillaria mellea. Control methods: First, manual capture and killing. Once raised areas are found in the soil or sand of the cultivation site, the soil or sand can be dug open for manual capture and killing. Second, light trapping and killing. Taking advantage of the phototaxis of most insects, black lights can be set up at the Gastrodia elata cultivation site to trap and kill adults. Third, bait trapping and killing. When white ant damage is found, miewyiling or fanghailing powder can be scattered at designated spots in the cultivation site; several pine boards can also be placed around the cultivation site or on the fungal wood and fresh wood to lure white ants onto the pine boards for elimination. Fourth, before cultivation, use phoxim or trichlorfon, etc., to control the aboveground and underground pests.