Disease characteristics and hazards
The tumor rust is a kind of rust, and the pathogen is cyanobacteria, belonging to Basidiomycotina, Cytobacteria, and Pyricularia. This disease has occurred in Shandong, Jiangsu, Zhejiang, Anhui, Jiangxi, Sichuan, Henan and other places. The long-term continuous planting of the national nursery base has been particularly serious. The disease is mainly responsible for the destruction of green plants such as S. obtusa, S. chinensis, and C. sinensis.
This disease mainly occurs on trunks, and leaves and petioles can also be affected. In the early stage of disease, the trunk enlarges into a spindle-shaped tumor, but the bark does not crack, so it is not easy to identify. In the middle stage of the disease, the fusiform tumor further expanded, and the bark cracked. In the open bark of the bark, brown, irregular, piles or strips and semi-adhesive powders were exposed, namely the pathogenic teliospores heap. At this time, the branches and leaves of Sangha are still developing normally. In the late stage of disease, the bark of the diseased tumor is dry, brown, blocky and fall off to expose the xylem. If this symptom develops further and one circle around the trunk, the trunk and canopy above the diseased tumor will all die. On the contrary, some canopies dry up and die.
Petiole and leaf surface with yellow spotted lesions or yellow-brown powder, pathogenic sporozoites and rust spores. Usually on the trunk of the disease, there are also branches of the same disease, a few only on the branches of the disease, resulting in spindle-shaped disease. However, the tumors of the trunk showed a more regular spindle shape than the branches.
The site of the disease is generally several parts of the trunk, near the base of the trunk, more than 40-150 cm. A spindle-shaped disease tumor is generally formed on the diseased trunk, and 2-3 tumors are individually formed.
The symptoms of S. sinensis rust on young seedlings (about 4 years) are slightly different from those on large seedlings (5 to 13 years). The spindles on the seedlings do not surround the trunk for a week. Epidermal dehiscence revealed a powdery teliospore heap with dry epidermis. The disease began to be affected in early March and the onset was severe from July to August.
Prevention and treatment measures
1. For plants with severely non-cultivated value, if the diseased site is more than 1.5 meters, they can be cut off in the healthy part under the diseased part, and then grafted into the claws or golden twigs of the dragon during the growing season; if the diseased part is closer to the ground , can be flattened and then allowed to re-germinate the plants.
2. For lighter-onset plants, first use a knife to scrape the epidermis, then use a knife to cross the disease to cross several divisions deep to the xylem, and then use 50 times the amount of Ascome or 30 times the gold toxin. The active ingredient is 23% copper rosinate). Apply it once every 15-20 days, 2 to 3 times.
3. Strengthen the management of farmland, carry out reasonable close planting, increase ventilation and light transmission, increase phosphorus and potassium fertilizers, and increase tree vigor. In daily management, timely observations were made and the diseased branches were found to be cut off in time and brought out of the nursery.
4. After the end of autumn and early winter and before the budding of early spring, after pruning the clear garden, spray the whole garden plant with 5 Baume's lime sulfur, requiring that the crown, trunk and surface be sprayed thoroughly, which will not only effectively kill the wintering pathogen. It also kills eggs and functions as a multi-drug treatment.
5. For the nursery where the disease occurred in previous years, after the trees have sprouted, use 50% thiophanate-methyl WP 500 times solution or 20% triadimefon 500 times solution and spray once every 10-15 days for good results.
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