How to control papaya rust in papaya tree cultivation?
How to control papaya rust? What harm does papaya rust cause? What methods can control papaya rust? Please provide guidance. The harm of papaya rust: after the leaves are affected, shiny orange-yellow fine spots appear, gradually expanding into round spots about 5 mm in size, and producing yellow slime. The underside of the leaf is raised. And produces gray-yellow...
How to control papaya rust? What harm does papaya rust cause? What methods can control papaya rust? Please provide guidance.The harm of papaya rust:
After the leaves are affected, shiny orange-yellow fine spots appear, gradually expanding into round spots about 5 mm in size, and producing yellow slime. The underside of the leaf is raised. And produces gray-yellow hairy growths. When the leaf spots reach 5 to 7, the leaves often age prematurely and drop early, and may even drop completely throughout the whole orchard, sometimes also causing fruit drop.
Causes of papaya rust:
Papaya rust overwinters as perennial mycelium in the galls on juniper and cypress. After spring rain, basidiospores are produced and spread by wind and rain. During the stage from papaya tree budding to young fruit formation, the spores land on tender leaves, new shoots, and young fruits, directly invading through epidermal cells or stomata. After a latent period of 6 to 10 days, orange-yellow lesions appear on the leaves, and after 20 to 25 days, bristle-like structures form, from which the pathogen spores no longer infect papaya trees but instead infect the tender leaves and new shoots of the alternate host juniper and cypress, and oversummer and overwinter on juniper and cypress.
The severity of the disease is related to the number and distance of juniper and cypress. The effective spread distance of rust pathogen spores is generally 5 to 10 km, and the disease has the greatest relationship with juniper and cypress within a range of 1.5 to 3.5 km from the papaya orchard. When papaya buds and young leaves first unfold, if the weather remains rainy and the temperature is suitable for teliospore germination, the disease is favored.
Control methods for papaya rust:
Control method 1 for papaya rust: Remove the alternate host by cutting down scattered juniper and cypress trees planted within 5 km around the papaya orchard, so as to cut off the source of the pathogen.
Control method 2 for papaya rust: Spray for protection from budding to about one month after leaf unfolding, generally spraying 3 times in succession before flowering, after flowering, and during the young fruit stage. Commonly used agents include 1:2:240 Bordeaux mixture, 20% triadimefon emulsifiable concentrate at 2000 times dilution, and 14.5% duoxiaoling at 600 to 800 times dilution, which have a relatively good effect on controlling the disease.
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