What medicine works well to treat bean rust?

Planting beans requires fertile soil, and they are also prone to diseases, among which rust is a common disease. So, what medicine is used to treat bean rust?

1. What medicine is used to treat bean rust?

You can choose 50% triadimefon 600-800 times, 50% sulfur suspension 500-600 times, or 70% thiophanate-methyl 800-1000 times solution for spraying. Spray once every 8-10 days, for 2-3 consecutive sprays.

2. Symptoms of bean rust

Beans can be infected by the pathogen throughout the entire growth period, but from early flowering to podding, resistance weakens and susceptibility increases. The disease mainly attacks the leaves. In the early stage of the disease, scattered chlorotic yellowish-white spots appear on the underside of the leaves, and the spots gradually increase until they densely cover the entire leaf. On the corresponding back side of the lesions, yellowish-brown slightly raised scab-like spots, namely uredinia, form. After the uredinia rupture, large numbers of urediniospores are released. On old leaves in the later growth stage, black telia sometimes form. The leaves turn yellow, wither, and fall off, the plant becomes dwarfed, the pods are few and small, the growth period is shortened, and finally the plant withers and dies.

3. Occurrence pattern of bean rust

In the north, the pathogen overwinters as teliospores on diseased residues. Upon germination, it produces basidia and basidiospores. The basidiospores invade the host and form the aecial stage. The aeciospores produced infect the common bean and form scab-like uredinia, releasing urediniospores for reinfection, allowing the disease to spread and expand. In late autumn, telia and teliospores are produced to overwinter. In the south, the pathogen mainly overwinters between seasons as urediniospores, becoming the primary infection source of this disease, and spreads and expands throughout the year. In the north, the disease mainly occurs in summer and autumn. In particular, leaf surface condensation and water droplets on the leaf surface are prerequisites for rust spore germination and invasion. The optimum temperature for urediniospore formation and invasion is 15-24°C, and germination can occur at 10-30°C, with 16-22°C being the most suitable. With a daily average temperature of 24.5°C and relative humidity of 84%, the incubation period is 9—12 days. When common beans enter the flowering and podding stage, with a temperature of about 20°C, high humidity, a large day-night temperature difference, and long duration of condensation, this disease is prone to becoming epidemic. Seedlings do not develop the disease. Autumn-sown common beans and continuous cropping fields have severe disease incidence. In some southern regions, spring planting often has more severe disease incidence than autumn planting.

For the prevention and control of bean rust, comprehensive control measures should be adopted, adhering to the principle of "prevention first, comprehensive control," and organically combining agricultural control, biological control, and physical and mechanical control.