What are the five main causes of low yields in Gastrodia elata (tianma)

Recently, the editor has often received consultation calls from people saying that the Gastrodia elata they cultivate does not yield much, with some even below 3 kg/sq m. The reporter specifically consulted Cao Debing, a Gastrodia elata expert at the Provincial Academy of Agricultural Sciences, about these issues. According to him, based on the growth principles of Gastrodia elata, there are many causes of low yields. He listed the following five causes, and farmers can check their own production conditions to see whether any of the following situations apply:

1. Armillaria mellea has been subcultured many times, becoming aged and degenerated. Armillaria mellea is the only source of nutrition for Gastrodia elata, so the quality of Armillaria mellea directly has an irreversible impact on Gastrodia elata. In general production, it is required to use detoxified, isolated pure strains, or to use such strains to cultivate fungal material before planting, so as to ensure results; however, in order to reduce costs, some farmers either use ordinary strains, or use old fungal material as "starter", mixing in some new linden wood to let it "transfer the fungus". If a pure strain was used the first time, this method can be used the next year, but it must not exceed three years. Unlimited continuous "fungus transfer" will inevitably lead to strain degeneration and reduced vigor, causing reduced Gastrodia elata yields.

2. Ordinary tianma seed stock, self-bred and self-used for many years, with reduced vigor. In Gastrodia elata production, hybrid seed stock is generally required, just as hybrid seeds are used for corn and cabbage, because hybrid vigor can help people achieve ideal production results; traditional tianma seed stock is mostly the product of "passing it down from generation to generation". In order to reduce costs, some farmers have kept insisting on self-breeding and self-use, and in the end found that the yield was "worse year after year", without knowing why.

3. The culture sand is too fine, with poor air permeability. Like other living things, Gastrodia elata also needs to breathe during growth. Therefore, medium-coarse sand is generally required in cultivation, and when directly cultivating in soil, soil with relatively high humus content should be used. If clay soil or very fine sand such as Yellow River sand is used for cultivation, the normal growth of Gastrodia elata cannot be guaranteed.

4. The cultivation site has a high groundwater level and long-term water accumulation. As is well known, Armillaria mellea can survive and expand in water, but as a plant, Gastrodia elata does not have this ability. With only 3 days of water accumulation, Gastrodia elata can be completely wiped out, either "sucked empty" by Armillaria mellea or directly rotted.

5. Damage from diseases and insect pests. There are few diseases in Gastrodia elata cultivation, mainly certain miscellaneous fungi carried on fungal material or linden wood. Together they attack Armillaria mellea and compete for nutrients, so that Armillaria mellea cannot grow normally, making it impossible for Gastrodia elata to absorb nutrients normally, resulting in low yields; insect pests are mainly underground pests such as white grubs, which bite and feed on the hyphae and Gastrodia elata.