How to control seedling leaf blight of Pinus tabulaeformis? These measures must be known!

Pinus tabulaeformis is a coniferous evergreen tree of Pinaceae, up to 30 meters high. Its trunk is straight and its branches are curved and colorful. From a distance, it looks like the Hulk in American movies. But Pinus tabulaeformis seedlings are easy to get leaf blight, so how to control Pinus tabulaeformis seedling leaf blight? What are the specific measures?

I. main hazards

The seedlings and needles of Pinus massoniana, Pinus tabulaeformis, Pinus elliottii and Pinus elliottii can cause the death of a large number of seedlings in bed.

Second, symptoms

Pine seedling leaf blight first infected the lower needles, gradually spread to the upper needles, the injured needles began to appear a section of brown macula from the end of the leaves, and then gradually turned dark brown to grayish brown, and the diseased leaves dried up and drooped, but did not fall off. When the disease spread to all the needles, the diseased seedlings withered and died.

Third, occurrence regularity

The pathogen overwintered with mycelium in the diseased needles and produced conidia in the following summer when the environmental conditions were suitable. The conidia spread with the wind and invaded the needles when they encountered pine seedlings. The pine trees sown in the same year began to get sick in the middle of July, the peak period was from August to October, and gradually stopped after November. On the seedlings of the second year, conidia were produced in early May.

The occurrence of disease is closely related to environmental conditions. high temperature and high humidity in summer are beneficial to the infection of pathogens, the cultivated land in nursery is too shallow, the root system of seedlings is underdeveloped, the ability of soil water and fertilizer conservation is poor, the growth of seedlings is weak, and the disease is easy to occur; in the susceptible nursery, when newly planted pine seedlings are not cleared of diseased seedlings, deep ploughing and soil disinfection treatment, the disease is often serious; the growth of seedlings is too dense, ventilation and permeability is poor, the disease is easy to spread. The disease is serious in the nursery with lack of fertilizer and poor management.

IV. Prevention and control measures

1. Eliminate the source of infection (bacterial source): remove the susceptible needles or remove the diseased seedlings and burn them centrally to prevent the seedling from forming the disease center and cause the spread of the disease.

2. Strengthen the management: fertilizing, watering, loosening the soil during the seedling growing period, and requiring ventilation and light transmission to reduce humidity. Balanced fertilization of nitrogen, phosphorus and potassium and increased application of organic fertilizer. To ensure the healthy growth of seedlings and enhance their disease resistance.

3. Chemical control: at the beginning of the disease, the needle leaves can be evenly sprayed with 500-fold liquid of Green Shield (300kg) or 800-1000-fold solution of Youlejing (240,240-300kg). When the disease is serious, you can use 1000 times liquid (water 100kg) spray, spray every 7 days or so, 2 Mel 3 times in a row. In the process of use, if combined with foliar fertilizer-greening, the effect is better.