Detailed Explanation of Key Technical Points for Pest and Disease Control in Gastrodia elata

In recent years, we have trial-planted Gastrodia elata several times at the college and achieved a bountiful harvest, but pest and disease damage has also been common, seriously affecting the yield and quality of Gastrodia elata. The causes of their occurrence and prevention methods are described below:

I. Diseases. There are mainly two categories of diseases that have a major impact on Gastrodia elata yield: one category is diseases caused by infection with harmful microorganisms, called pathogenic diseases; the other category is physiological tuber rot.

1. Soft rot of tubers

(1) Symptoms: Tubers affected by soft rot show yellowed and withered skin, with the central tissue decayed. When the stem is split open, the interior becomes a foul-smelling thin slurry; some tissues are filled with yellow-white or brown-red Armillaria mellea hyphae, and in severe cases the entire pit rots. (2) Causes: Improper selection of cultivation site, with failure caused by using alkaline soil for cultivation. Long-term exposure to high temperatures, seed tubers exposed to direct sunlight during storage and transport, or kept for too long in an environment above 27°C, or subjected to soaking, etc.; cultivation pits affected by high temperatures above 27°C or high humidity above 70%. (3) Control methods: Strictly select fungal wood and fungal beds; choose slightly acidic sandy soil for the cultivation site; strictly select seed tubers, choosing healthy arrow tubers free from pest and disease damage and not affected by high temperature and high humidity as seed; strictly manage the field, control suitable temperature and humidity, and avoid long-term water accumulation or drought in the pits.

2. Contaminant fungi

The most serious threat to Gastrodia elata and fungal wood comes from other basidiomycetes of the same group as Armillaria mellea. Their hyphae and rhizomorphs resemble those of Armillaria mellea, but the rhizomorphs are flat and round and lack luminescence. They grow saprophytically on fungal wood, compete with Armillaria mellea for nutrients, and inhibit the growth of Armillaria mellea. Control methods: When choosing a cultivation site, be sure to choose virgin wasteland with few contaminant fungi in the environment, either free of fungi or with few fungi; select excellent Armillaria mellea strains and increase the amount of inoculum to create a growth advantage for Armillaria mellea so as to inhibit the growth and reproduction of contaminant fungi; dig drainage ditches well at fungal culture and cultivation sites; sterilize in a timely manner. If contaminant fungi are found during the culture process, promptly take control measures.

II. Insect pests. The insect pests of Gastrodia elata include white grubs, springtails, mole crickets, scale insects, and termites. Control methods:

(1) White grubs and mole crickets: Within 100 sq m, use 0.15 kg of 90% trichlorfon or 50% phoxim, dilute with a small amount of water, mix with 10-15 kg of fine soil to make toxic soil, and broadcast it.

(2) Springtails: Springtails are small in size and white in color, generally surviving under relatively high humidity conditions, most active at 20-25°C, and can reproduce 6-7 generations per year. They mainly bite and feed on the fungal film inside the cortex of fungal logs and also feed on Gastrodia elata tubers, causing rotten holes in the tubers. During peak occurrence, spray or drench with 1:800-1000 dilutions of dichlorvos or 0.1% derris extract, or fumigate with 4 tablets per sq m of aluminum phosphide.

(3) Termites: In addition to damaging fungal wood, termites also bore into and feed on Gastrodia elata protocorms and tubers. During peak damage periods, termite powder can be used for poisoning.

(4) Scale insects: Mainly mealybugs damage Gastrodia elata tubers. They are generally brought into pits by trees such as fungal wood and new wood. After damage, Gastrodia elata growth weakens and quality decreases. If damage occurs, the Gastrodia elata in that pit should be dug up promptly, all processed into commercial tubers for sale, strictly prohibited from being kept for seed, and the fungal wood in that pit should be burned to prevent spread.