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Common Rhododendron Diseases and Detailed Symptoms

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1. Leaf gall disease. Before onset, especially when new shoots emerge and leaves unfold, spray Bordeaux mixture at 1:1:200, and promptly remove diseased leaves when found; before budding, spray 0.3-0.5 Baume degree lime sulfur mixture or Bordeaux mixture at 1:1:200 2-3 times, usually once every 7-10 days; after onset, spray 65-80% mancozeb 500x solution or 0.3-0.5 Baume degree lime sulfur mixture 3-4 times, once every 7-10 days. 2. Leaf spot disease and brown spot disease. From May to August, spray 7

1. Leaf gall disease. Before onset, especially when new shoots emerge and leaves unfold, spray Bordeaux mixture at 1:1:200, and promptly remove diseased leaves when found; before budding, spray 0.3-0.5 Baume degree lime sulfur mixture or Bordeaux mixture at 1:1:200 2-3 times, usually once every 7-10 days; after onset, spray 65-80% mancozeb 500x solution or 0.3-0.5 Baume degree lime sulfur mixture 3-4 times, once every 7-10 days.

2. Leaf spot disease and brown spot disease. From May to August, spray 70% thiophanate-methyl 1000x solution, 20% fenaminosulf 4000x solution, 50% mancozeb 500x solution, once every 10 days, for a total of 7-8 sprays, which can effectively control the development of the disease. To prevent leaf yellowing, ferrous sulfate can also be added.

3. Mite gall disease: The tips of young branches and leaves are covered with a dense white or pink mite layer, and sometimes the leaves develop mite galls, mostly caused by aphids piercing the leaves and causing infection. Control methods: while removing diseased leaves, spray a copper sulfate-containing pesticide; spraying omethoate emulsifiable concentrate or placing carbofuran directly into the pot can all control aphids and other piercing-sucking pests.

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