Korean pine blister rust

Symptoms: the disease occurs in the skin of branches. At the initial stage of the disease, the susceptible skin swollen and softened slightly, and cracks began at the beginning of May, from which yellow-white blister cysts were produced, which was the sporidium of the pathogen. The sporophore matured orange in the first and middle of June. Since the middle of May, the cyst broke, scattered powdery spores, and finally left a membranous white coating, and gradually scattered and disappeared. By the end of June, most of the blister sacs had been broken, the old diseased skin was rough, and there was often a layer of coal fouling bacteria, showing black. Due to the disease year after year, the skin thickens and thickens, and turpentine flows out. At the end of August and the beginning of September, the milky white and then orange honey droplets were spilled in the disease department, with a sweet taste. When you peel off the diseased bark, you can see the sexual spore organ in the cortex, which is bloodstained and dark red after drying.

Pathogen: the pathogen is CronartiumribicolaJ.C.FischerexRab. It belongs to basidiomycetes subphylum, Dipterospora, Puccinia and Puccinia.

The regularity of the disease: the pathogen produced winter spores at the end of July, produced successively from mid-August and late August to early September, and germinated to form basidiospores and basidiospores, which spread to pine needles by airflow, invaded by stomata after germination, and some invaded by twigs. The hyphae continued to spread to the cortex of the branches, and disease spots appeared in the skin of the branches after 2-3 years. Honey droplets are produced from August to September, which is a mixture of sexual spores. In the spring of 3-4 years, the diseased part produces rust spores and conidia. If the diseased tree is not dead, it produces rust spores year after year. The spores spread to the leaves of tea sugarcane or Artemisia annua by airflow and invaded through stomata after germination. After 10-11 days, summer spores are produced and re-infected. Winter spores are produced from August to September. There are a lot of weeds around the trees, especially when there are many alternate host plants such as tea sugarcane or Artemisia annua, the trees are prone to diseases.

Prevention and treatment: ① strictly tests the condition of seedlings with disease and puts an end to the use of diseased seedlings. ② used pentachlorophenol sodium or dipotassium tetrachloro, atrazine, fenvalon, cypermethrin and other herbicides to kill tea cane and Artemisia annua within 500m around Korean pine, the dosage was 1-5g/ square meters. When the young trees are sick, when the spores are not scattered, brush the diseased part with the original solution of pine tar to kill the spores. After brushing continuously for 2-3 years, the diseased trees can recover to health. Timely pruning of ③ is an effective measure to prevent and cure the disease.