Asparagus has developed rapidly in Hubei Province, especially in the rural areas surrounding Wuhan, and has become a new pillar industry from production to processing.

Asparagus stem blight is a devastating disease. Once it gets stem blight disease, the production is cut, and the crop is destroyed. It causes great losses to the bamboo shoot farmers. According to statistics, asparagus production is reduced by about 40% in these two years.

Asparagus stem blight pathogenic bacteria infect the stems of plants at the beginning of the disease, forming a spindle-shaped dark brown lesions, spot-shaped fusiform or short-line, surrounded by hydrophilic edges, showing edema. Subsequently, the lesions spread irregularly and gradually expanded. The center was sunken and auburn. The spots finally turned gray and white, and many small black spots were spotted on them, namely the conidia of pathogens. One week after the diseased spot passes around the stem, the infected stems and branches will die and die.

Pathogens of Asparagus stem blight are Aspergillus. The pathogenic bacteria lived on the diseased plants or in the soil as conidiospores. In the following year, spores fly out of the spores through rainwater, tillage tools, and other means of transmission. After the initial infringement of the tender, the spores released from the mature conidia are flushed out by the rain, and are splashed with rain and rain. A secondary infection of the base of asparagus stems. The pathogen is most likely to invade when the stem is young, and the infection rate is generally highest within 10 days after the stem is grown. Asparagus can undergo more than 10 repeated infections during the entire growing season of asparagus.

The disease can be divided into two stages in a year: First, the disease expansion period, which is 30-40 days after the onset of disease. The disease rate in this period is still low, the condition is developing slowly, and the second is a serious disease period, that is, 40 days after onset. The disease rate in the field reached more than 40%. This period started from about the end of July or August. At this time, the bamboo shoots gradually became denser. Together with the onset of the rainy season, it created very favorable conditions for the occurrence of diseases, thus depressing the disease in the early stage. Control of late onset has a great effect.

The main causes of asparagus stem blight are:

1. A large area of ​​poorly planted F2 hybrids. According to the survey, more than 80% of the asparagus planted at present is a poor-quality seed of the F2 generation. Asparagus cultivation of the main varieties are UC157F2, UC800F2, UG72F2 and so on. The disease resistance of these varieties is very poor. Once the environment is suitable, it is easy to have a large area of ​​disease.

2. Clear Garden is not thorough. At present, most rural households clean their gardens in a timely manner, but there are still some farmers who are not completely clean or are not completely timely. According to the investigation, ashes were scavenged and cleared out of the ground and burned, and the garden was completely cleared. The incidence of the disease only accounted for only 5% in the second year. Unclear gardens, the incidence rate of 58%.

3. Suitable climatic conditions. The suitable temperature range for the growth of pathogenic bacteria is 23-26°C above 35°C or below 10°C. Conidia do not germinate. The temperature in the spring is closely related to the onset of the disease sooner or later. In July, August and September, high temperature and high humidity are the vegetative growth stages of asparagus, which is also the peak period of pathogenic infection. The rate of diseased plants basically increases with the increase in the number of rains. Ten days after each rain, the incidence peaks in the field.

4. The timing of the mother's stem is not appropriate. One of the main conditions for the occurrence and prevalence of asparagus disease is rain, and if the stem is kept in the rainy season, the chance of pathogen infection is greatly increased.

5. Management is not timely, fertilization is unreasonable. In the rainy season, the asparagus field should pay attention to drainage in time to reduce the water table and the humidity in the field. Excessive use of nitrogen fertilizer, nutrient growth is too strong, most bamboo farmers in pursuit of immediate interests, reapply N fertilizer or only N fertilizer, so that shoots grow densely, stem cell wall is tender and thin, the bacteria easily into the leaching, according to the survey Apply N, P, K three-element compound fertilizer, the incidence of strains only accounted for 10%, only urea, the incidence of disease strains accounted for 58%.

6. Over-reliance on pesticides and unreasonable application. Since stem blight can be repeatedly infested, the control of the pesticide must be early, and the pathogen base must be strictly controlled. At present, most of the rural households are treated lightly and recklessly. When they see the disease, they are ruled and disease-free. As a result, many drugs are used for prevention and control, which increases the cost, and the effect is not very satisfactory.

There are two main problems in the use of pesticides: First, a single drug, so that the disease resistance. The problem of drug resistance caused by a single application of a single agent for a long period of time has become increasingly serious, resulting in a significant reduction in the control effect, or even completely ineffective. Second, the use of drugs is not timely, although the number of drugs used a lot, the control effect is poor. As soon as the test rain stopped, it was immediately sprayed. The field was basically disease free. After the rain, it was not sprayed in time. The resulting diseased plant accounted for 37%.

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