Occurrence of rust rust

Rust can infect a variety of cold season lawns and is a serious fungal disease. It mainly harmed Kentucky bluegrass, perennial ryegrass, Bermuda grass root, tall fescue, Taiwan grass (leaved knotweed, velvet grass), horseshoe golden, etc. Among them, bluegrass was seriously affected. After turfgrass is damaged by rust, it will grow poorly, leaves and stems will become abnormal colors, growth is short, photosynthesis will decline, and serious turf will cause death. Under appropriate environmental conditions, a large area will occur within a few days, resulting in yellow leaves and even dead plants. The lawn will become sparse and seriously affect the lawn landscape.
First, the rust of the lawn rust symptoms according to parasitic species, symptoms, pathogenic bacteria in different forms, can be divided into leaf rust, strip rust, stem rust, crown rust. At the early stage of disease, yellow-brown colonies were formed in the diseased areas and rust-like substances were scattered, causing the chlorophyll of the leaves to be destroyed, the photosynthesis was reduced, and the respiration was unbalanced. After a large number of water loss, the leaves turned yellow and died. Poa pratensis, ryegrass, and zoysia grass are all sensitive to rust. The disease mainly occurs in leaves and leaf sheaths, but also infects the base and panicles. At the beginning of the disease, the lawn was dotted and quickly spread to the surrounding areas. When the damage was serious, the lawn became yellow.
The spores of the pathogens were divided between the summer spores and the teliospores. The yellow powder on the leaves was uredia spores, and the dark brown powder was teliospores. The pathogens overwinter on damaged plants with mycelium or uredospores.
In the early stage of disease, light yellow spots appeared on the leaves and stems. With the development of the disease, the number of lesions increased, and the epidermis of the leaves and stems ruptured, emitting yellow, orange, brownish-yellow or pink uredia spores. Hand rub the diseased leaves, there will be a layer of rust-colored powder on the hand. As the disease progresses, the lesions gradually develop into a tan-colored urediasporidium, which breaks through the epidermis after ripening. It is pulverized and orange-yellow, making the lawn look rust-like. After the lawn is infected with rust, the leaves yellow and die, seriously affecting the ornamental.
Second, the incidence of turf disease conditions and epidemic law Suitable conditions for growth of bacteria for the temperature of 17-22 °C, relative humidity of 80%. When the temperature is 20-30 °C, it is conducive to the formation of spores, especially the moist leaves conducive to the germination and invasion of uredia spores.
Rust is the most serious turfgrass disease. High air temperature, large turf density, improper irrigation, poor drainage, surface waterlogging and partial application of ammonium fertilizer are the main causes of rust.
The rain in the south is relatively high, the air is humid, and the weather is mild. It occurs more commonly. The onset begins in late March and is heavy from April to June and late fall and early winter. Especially in the autumn of low temperature and high humidity, when the hot summer season passes, the temperature will drop, and the air will be damp and the disease will happen quickly. It has been observed that when the temperature of the 5 cm soil layer reaches 24.5°C, the germs begin to infest. As the temperature continues to fall, if there is a lot of rainfall, the disease spreads quickly. Within a few days, the lawn is obviously yellow. Turf rust in the northern region generally begins to occur from the end of July to the beginning of August. In July and August, it is the most serious period and continues to endanger until October.
The end of summer and early autumn is the most critical period for controlling turf rust. Attention should be paid to strengthening prevention and control, timely controlling the occurrence and prevalence of rust, and reducing its harm to lawns.