What causes gray mold in garlic chives? Introduction to prevention and control methods
Garlic chives are a very vigorous vegetable that can grow well even in harsh environments, which is why they are also called the lazy person's vegetable. During the cultivation of garlic chives, they are easily attacked by gray mold. Below is a detailed look at the causes of the disease in garlic chives and an introduction to prevention and control measures.
I. Causes of gray mold in garlic chives
1. Improper variety selection. Some garlic chive varieties are relatively susceptible to gray mold, so before planting, it is necessary to understand this knowledge in advance and select seeds well.
2. Abundant pathogen sources. Long-term cultivation of garlic chives, a single variety, and farmers' weak awareness of crop rotation lead to a large amount of gray mold pathogens remaining in the soil and rapid pathogen reproduction. This is one of the causes of the disease.
3. Improper fertilization. Insufficient nitrogen, phosphorus, and potassium fertilizer, especially insufficient phosphorus and potassium fertilizer, reduces the disease resistance of garlic chives.
4. Improper cultivation management. The occurrence of gray mold is closely related to the level of field management. Fields with low-lying terrain, shallow ditching, and poor drainage have more severe disease; poor or compacted soil lacking oxygen, with weak plant growth, is conducive to the occurrence of the disease; excessively dense planting causes vigorous leaf growth, and excessive nitrogen fertilizer application causes excessive vegetative growth, which is conducive to the disease; continuous cropping fields, especially those continuously cropped with legumes, have severe disease; if drought occurs and flood irrigation is then used, causing excessive soil moisture, the disease is likely to occur; if temperatures drop, the occurrence of the disease can be aggravated.
5. Contaminated softening materials. Due to the long cultivation period, farmers use softening materials for producing yellow chives many times, and if they are reused without disinfection and sterilization, they directly carry pathogens and cause infection, leading to the disease.
II. Occurrence pattern of gray mold in garlic chives
This disease is caused by infection by the fungus Botrytis squamosa, a member of the Deuteromycotina. It mainly harms garlic chives, onions, Welsh onions, and other allium vegetables. The pathogen overwinters in the soil with diseased residues in the form of mycelium or sclerotia, and conidia can also overwinter on the surface of bulbs. However, in warm climate regions, it mostly overwinters on diseased residues as conidia. In the following spring, when conditions are suitable, conidia are produced. Conidia are spread by airflow or rainwater splashing, and the pathogen invades leaves through stomata or wounds, causing primary infection. Conidia produced on diseased parts spread with airflow, rainwater, and farming operations, causing secondary infection. Sclerotia buried 15 cm deep in soil still had a survival rate of 79% after 21 months.
The pathogen prefers cool, high-humidity environments. The most suitable climatic conditions for disease occurrence are a temperature of 15-21°C and relative humidity above 80%.
III. Prevention and control measures for gray mold in garlic chives
In spring, the weather is changeable, temperatures rise in waves, and rain accompanies it, resulting in high humidity. Garlic chives are very susceptible to gray mold, and after gray mold substances cover the stems and leaves, they rot, soften, and lodge, causing reduced yield or crop failure, and it spreads rapidly, causing the entire field to become diseased. Therefore, in spring, attention should be paid to preventing and controlling gray mold in garlic chives to protect the stems and leaves.
Usually, check the stems and leaves of garlic chives. If gray mold substances appear on the stems and leaves, and the stems and leaves soften, lodge, and rot, spray the leaves with a 1500-fold aqueous solution of 50% procymidone wettable powder or a 1000-fold aqueous solution of 40% iprodione wettable powder for control. Spray the leaves once every 7-10 days, for 2-3 consecutive sprays, evenly wetting all stems and leaves, until water droplets begin to drip down.
During consecutive rainy days, when humidity is high, seize the brief sunny period to spray the above fungicide once on the leaves for prevention, in order to protect the stems and leaves.
If 0.2%-0.3% potassium phosphite aqueous solution can be added to the fungicide solution and sprayed together, the control effect is better. It can not only strengthen the sterilization and disease treatment efficacy and improve the control effect, but also enhance disease resistance, accelerate the recovery of diseased stems and leaves to normal growth, and also supplement nutrients from the leaves, promote strong stems and leaves, increase yield, and improve quality.