Causes and control measures of yellowing of Chinese medicinal materials
During the process of planting Chinese herbal medicines, many growers reacted with the yellowing, slow growth and even stagnation of the peony plants in the field. What is the cause? How to effectively prevent and cure? Let's take a look at the following.
1. Underground pests
The cockroach is the nemesis of peony. Once the underground pests are raging, a four-year-old peony root, one cockroach can lose its value by biting the roots. Therefore, it is the key to prevent high glutinous cockroaches. When a piece of peony field shows yellowing or flaky yellowing, it is not necessary to think about it. 80% of the roots are foraging roots, and the plants are not transported with nutrients, which causes yellowing and wilting.
Control method: the root can be irrigated with the agent, the dosage of 25% thiamethoxam 100g + 2.5% beta-cypermethrin 500g or 25% thiamethoxam 100g + 40% phoxim 400g, the combination of these two formulas is highly efficient and low-toxic, The control has a long-lasting effect, and there is no residue on the rhizome of Chinese medicinal materials, which is in line with the green application standard, so it can be used with confidence.
2, root disease
Since it is a Chinese medicinal material of roots and stems, root diseases are inevitable, such as sclerotinia sclerotiorum and stem-based rot, which can cause lesions in the roots or stem bases of the peony roots, resulting in obstruction of nutrient transmission, resulting in yellowing and wilting of the plants.
Control method: need to use bactericide for treatment, the better treatment formula is (mu amount): 24% thiabendamide 40 ml + 45% methyl carbaryl 20 g or 32.5% methicillin 20 g + seaweed 30 grams of sour leaf fertilizer, 30 kg of water for spray treatment, 7 days a course of treatment, even spray twice to cure.
3. Physiological diseases
Perhaps the peony is physiologically yellow, especially the annual and biennial peony. The peony of the plant is yellowed. There is often no white root (sessile root) on the rhizome, especially in dry weather, and the soil moisture is reduced. This is especially serious.
Control method: In addition to maintaining soil moisture, this should be done with some regulators that promote root growth, such as brassinolide, sodium nitrophenolate, potassium citrate, etc., in combination with seaweed fertilizer for spray treatment.
4, the cause of freezing damage
The frozen peony plants, except for the yellowing of the leaves, also show that the leaves are slightly rolled up. Compared with normal plants, they cannot grow. In this case, the growers can water the peony or spray before the cold air arrives. Chitosan or seaweed fertilizer is used for prevention. For the freezing damage that has already been suffered, it can be evenly sprayed by means of brassinolide + chitosan or seaweed fertilizer, which can be alleviated twice.
5, herbicide phytotoxicity
Nowadays, there are many kinds of herbicides on the market. Some herbicides are not safe. If we use whole field spray to weed, the cockroaches will inevitably be harmed by phytotoxicity. Some herbicides will not see the symptoms of phytotoxicity in the same year, but in the spring of next year, the peony will appear. The yellow and leaf twisting phenomenon cannot be recovered during the entire growing season.
If you want to avoid this situation, you must use the herbicide scientifically, can direct the spray, try not to spray the whole field. For those that have caused harm, we should pay attention to the spring root fertilization to promote the growth, and at the same time, combine the leaf spray application of brassinolide + gibberellin + humic acid foliar fertilizer to adjust the growth, and re-spray once every 7 days.
The above is the reason for the yellowing of the leaves during the cultivation of the drug, and the prevention and treatment measures. No matter what the reason, as long as the disease occurs, it is very unfavorable for the growth of the drug, so the farmers must understand this control method.
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