There are always yellow spots on the leaves of seedlings, which look particularly unsightly, and it is likely that rust is at work! Rust is a fungal plant disease, and it is most likely to occur in the spring and summer rainy and windy seasons. In addition to affecting the landscape effect, some rust can also cause tumors, coarse skin, clumps, curved branches and other symptoms on the branches, or cause defoliation, scorched shoots, poor growth, etc., and when the plant is severe, it will quickly die due to the evaporation of water in the body.
<h1 class = "pgc-h-arrow-right" > symptoms</h1>
Rust mainly harms leaves, but also can harm green young tissues such as fruits, petioles, fruit stalks and new shoots.
1. Leaf disease
Small oily orange-red spots appear on the front of the leaf, which gradually expand to form a round orange-yellow spot with red edges. When the disease is severe, dozens of spots appear on one leaf.
2. Onset of petiole disease
The diseased part is orange-yellow, slightly raised, mostly spindle-shaped, and the initial surface produces small dot-like spore organs, and the back of the diseased spot produces a brush-like rust spore cavity in the later stage.
3. Onset of new shoots
At first, it is similar to the petiole injury, but later the disease part is dented, cracked, and easily broken. The horns of the winter spores are dark brown, undulating in the shape of a chicken crown, and in the event of rain, they absorb water and expand, taking the shape of colloidal petals.
4. Fruit
After the onset of young fruits, most of them form spots with a diameter of about 1 cm near the calyx, which are orange-yellow in the early stage and black in the later stage, and produce sexual spore organs in the middle, and hairy rust spore organs grow around them. The fruit is stagnant, the diseased part is hard, mostly deformed, and often falls off early.
<h1 class= "pgc-h-arrow-right" > second, the incidence of the law</h1>
The pathogen is a metastatic parasitic rust fungus, which forms a winter spore pile on the cypress and juniper cypress, and the bacteria have no summer spores, so they can no longer be infected, and are only infected once a year. Sexual spore and rust spore stage parasitize pears, sticky begonias, weeping begonias, papaya and other plants. The pathogen overwinters in the diseased tissues such as cypress and juniper cypress with mycelium, and overwinters the hyphae in the early spring of the following year to produce winter spore horns, and the winter spores germinate to produce basidiospores, which are spread by air to the leaves of begonias, pears and other plants, infect the hazards, 10 to 14 days of foliar surface formation spore, about 28 days of rust spore on the back of the leaf, and June is the peak of the disease. From August to September, the rust spores are propagated by air flow to cypress and juniper cypress after maturity, and overwinter after infecting needles and young branches, and the disease is severe when the early spring is warm and rainy.
<h1 class = "pgc-h-arrow-right" > third, integrated control</h1>
1. Prevention and control together
For the roadside, we can not cut off the cypress in the nursery, then we can spray the cypress and the fruit tree at the same time, so that the cypress and the fruit tree are exempt from harm at the same time, so that the unified use of drugs, group prevention and treatment.
2. Remove diseased buds in early spring.
It must be noted that spore scattering is avoided during operation, otherwise the desired effect will not be achieved.
3. Breeding strains with strong disease resistance to breed seedlings or afforestation.
It is advisable to choose varieties with strong disease resistance and varieties suitable for local cultivation, and in the same external environment, the occurrence of rust will be alleviated to a certain extent.
3. Pharmaceutical prevention and treatment
After the discovery of rust, to timely drug prevention and control, the sooner the better, there are many agents available on the market at present, using Manchi (phenyl etherthoconazole) + Zhongshengbuzin (methylthioxine) + arcadian seaweed fertilizer
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