How to promptly prevent and control common flower diseases in autumn

Powdery mildew causes the most severe damage to flowers such as cineraria (Pericallis × hybrida), Chinese rose (Rosa chinensis), dahlia, goji (Lycium chinense), garden balsam (Impatiens balsamina), zinnia, large-leaf plants, and boxwood. The affected parts first show scattered small

white spots that gradually spread and expand, and the development is very rapid. Under suitable conditions, in 7~10 days the lesions can cover the entire leaf, and the leaf surface is covered with a layer of white powdery substance, as if frosted. In severe cases, the leaves wither and drop early. The plant loses photosynthesis, resulting in fewer, smaller and paler flowers, and some even fail to bloom. This disease develops quickly and causes severe damage under conditions of overly dense stems and leaves, hot and stuffy weather, poor ventilation and light penetration, and moist soil. Control methods: 1. Improve ventilation and light penetration conditions; apply more phosphorus and potassium fertilizer, avoid excessive nitrogen fertilizer, do not overwater, and certainly do not let the pot soil become waterlogged, but also do not let it lack water; and promptly remove diseased leaves and diseased buds, pull out diseased plants, and burn them in a centralized manner. 2. Chemical control. At the early stage of the disease, some flowers can be sprayed with 1:1:140 equal-strength Bordeaux mixture, or 25% triadimefon 1500-fold solution, 70% thiophanate-methyl 1200-fold solution, 50% tuijunte 1500-fold solution. Alternating use of the above agents can improve control efficacy. In severe cases, spray again after 7 days, for 2~3 consecutive sprays. Brown spot disease also mainly damages leaves. At the early stage of the disease, brown spots appear on the leaf surface, and later the lesions gradually expand and merge into large spots. Because the lesions are restricted by leaf veins, they are mostly irregular in shape. There is a faded halo on the outer edge, the margin is reddish brown, and the center is grayish white. In the later stage, black small dots (pycnidia) form in the middle of the lesions. The leaves of affected plants tend to drop, and in severe cases not a single leaf remains, and the diseased plant gradually dies entirely from bottom to top. Flowers such as rhododendron, narcissus, jasmine, lilac, osmanthus, Chaenomeles speciosa, photinia, and lotus are more severely damaged. Control methods: 1. Promptly prune diseased branches and leaves and burn them in a centralized manner to reduce the source of reinfection. 2. Chemical control. After the disease occurs, promptly spray 80% captafol 500-fold solution, 65% zineb 800-fold solution, 12.5% diniconazole wettable powder 1000-fold solution, 70% thiophanate-methyl 1200-fold solution, etc. once every 7~10 days, for 2-3 consecutive sprays. Flower rot mainly damages flowers, flower buds, and fruit, and can also damage leaves. After the leaves are damaged, small reddish-brown lesions appear, and later gradually expand, causing the diseased parts to produce a large amount of grayish-white mold. As soon as flower buds appear, they can become infected and rot, and diseased flowers wither in yellowish brown. This disease is likely to occur under conditions of abundant autumn rain, high humidity, and frequent fog. This disease causes relatively severe damage to dahlia, cockscomb (Celosia argentea), Chinese rose, crape myrtle, zinnia, garden balsam, and fruit-bearing flowers such as fruiting pomegranate. Control methods: 1. During continuous rainy weather, take rainproof measures, and by no means allow flower buds and flowers to be attacked by rainwater. Usually strengthen cultivation management, apply more phosphorus and potassium fertilizer, prune reasonably, and enhance ventilation and light penetration. 2. Chemical control. Before the disease occurs, spray 3~5 degrees Baumé lime-sulfur mixture, which can provide protection and prevention. At the early stage of the disease, spray 5% tian'an aqueous solution 500-fold solution, 50% tuijunte wettable powder 1500-fold solution, 75% chlorothalonil 1000-fold solution. In severe cases, spray once every 7-10 days, for 2~3 consecutive control applications.