Why is autumn bean easy to suffer from rust? What are the main prevention and control methods?

Beans, also known as long horn beans, belt beans, undaria beans, rich in nutrition, high protein content, rich in crude fiber, carbohydrates, vitamins and iron, phosphorus, calcium and other elements, and strong adaptability, a wide range of cultivation, is one of the main vegetables in summer and autumn in China. China is the center of secondary origin of beans, with a long history of cultivation, rich variety resources, nearly a thousand germplasm resources, and has made great progress in breeding. Due to the continuous promotion of excellent new varieties, as well as the wide application of seedling transplanting, plastic film mulching, greenhouse and other technologies, the quality and yield of beans have been greatly improved. When planting beans in autumn, improper management can easily lead to the occurrence of bean rust, so why are autumn beans prone to rust? What are the main prevention and control methods?

I. etiology of autumn bean rust

The growth environment of autumn planted beans has high temperature and more rainfall, and the bacterial source (summer spores) of planting beans in spring in the field is large. Therefore, autumn planted beans are prone to rust, so comprehensive control should be carried out as soon as possible.

The pathogens are basidiomycetes subphylum and unicellular rust. The source of infection is the diseased remains of spring-planted beans or the heap of summer spores left in the field. The summer spores germinate to produce germ tubes and invade the host with stomata. At 18 ℃ ~ 25 ℃, when the air humidity is high or the fog is heavy, when there is a water dripping film on the host surface, the summer spores are most likely to germinate and invade the host, and the diseased plants spread through air flow, insects, humans and animals, causing frequent re-infection, and the resulting winter spore pile becomes the primary infection source of legume crops planted in the following spring.

Symptoms of autumn bean rust

Autumn bean can be infected with pathogen during the whole growing period, but the resistance weakens and the susceptibility increases during the period from the beginning of flowering to fruiting. The disease mainly affected the leaves, and the leaves appeared faded green, yellow and white spots at the initial stage of the disease, and the spots increased gradually, until the whole leaf was densely covered. The plant is short, the English is little and small, the growth period is shortened, and finally wither and die.

3. Control methods of autumn bean rust.

The control method is based on strengthening the management of soil fertilizer and water, and the comprehensive control measures are supplemented by timely spraying.

The main results are as follows: 1. Thoroughly remove the disease and residue of the previous crop, turn the soil deeply and expose to the sun for 2-3 days, and spray disinfectant in the whole garden to effectively reduce the source of bacterial infection.

2. Selecting disease-free varieties with good disease resistance and dressing seeds with new high-fat membrane before sowing can ward off underground diseases and insects, isolate virus infection and improve seed germination rate.

3. Timely fertilization, watering, loosening soil and weeding according to the demand of bean growth. The root nodule activity was enhanced, the plant growth was sturdy and the disease resistance was enhanced by applying sufficient base fertilizer and increasing phosphorus and potassium fertilizer. Spray vegetable and fruit Zhuangtieling before flowering, young fruit and expansion stage to improve the water absorption and fertilizer absorption of beans and promote the high and high yield of beans.

4. Chemical control, timely spraying should be applied to control bean rust, and targeted chemicals should be sprayed with new high-fat film to form protective film at the initial stage of the disease, so as to greatly improve the utilization rate of effective components.