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Detailed Guide to Controlling Leaf Spot Disease in Rhododendrons

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Symptoms: It mainly infects the leaves. In the early stage of the disease, small reddish-brown spots appear on the leaves and gradually expand into lesions or irregular polygonal lesions that are dark brown. In the later stage, the tissue in the center of the lesions turns grayish-white. When the disease is severe, the lesions connect with one another, causing the leaves to turn yellow, wither, and drop early. Control methods: 1. In autumn, clear away and dispose of fallen leaves, and during the growing season promptly remove diseased leaves. 2. Planting or potted flower placement density should be appropriate to ensure ventilation and light penetration for the plants and reduce leaf surface humidity. In summer, place potted flowers in an outdoor shade shed to reduce sunscald and mechanical

Symptoms: It mainly infects the leaves. In the early stage of the disease, small reddish-brown spots appear on the leaves and gradually expand into lesions or irregular polygonal lesions that are dark brown. In the later stage, the tissue in the center of the lesions turns grayish-white. When the disease is severe, the lesions connect with one another, causing the leaves to turn yellow, wither, and drop early.

Control methods: 1. In autumn, clear away and dispose of fallen leaves, and during the growing season promptly remove diseased leaves. 2. Planting or potted flower placement density should be appropriate to ensure ventilation and light penetration for the plants and reduce leaf surface humidity. In summer, place potted flowers in an outdoor shade shed to reduce wounds caused by sunscald, mechanical injury, and the like. 3. Immediately after flowering, spray 65% zineb wettable powder at 500-600 times dilution, or 50% carbendazim wettable powder at 500-800 times dilution. Spray once every 10-14 days, for 2-3 consecutive sprays.

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