What are the prevention methods for common flower diseases in autumn

In autumn, the temperature and humidity are moderate and the light is good, which creates favorable conditions for the breeding, reproduction and infection of certain pathogens, often causing serious harm to some flowering plants. The symptoms and control methods of several major diseases are introduced below, so that flower growers can prevent and treat them in time.

I. Anthracnose

1. Symptoms:

This disease mainly occurs on the leaves, but can also infect leaf stalks, young shoots, stems and flower buds and petals.

After the leaves are affected, small round pale water-soaked spots appear at first, then gradually enlarge, turn grayish brown, with a brown edge and slight raising. Finally the center of the lesion fades to grayish white or white; this diseased part is extremely thin, semi-transparent, and easily perforated. In some cases the disease starts at the leaf tip and then spreads inward. The lesion can often reach 1/3-1/2 of the entire leaf surface, and finally the leaf withers and dies. Some leaves keep dropping; severely affected plants often lose every leaf on the whole plant.

When the leaf stalk is affected, the diseased part turns brown and slightly sunken, spreading to the leaf blade and extending to the main vein, branch veins and even the whole leaf, which turns brown; the lesion continues to spread downward, from the small leaf stalk to the total leaf stalk, the small branch, and even the stem, which turns brown and dies.

Under humid conditions, a pale red sticky substance, which is the spore bed produced by the pathogen, often appears on the lesions. Affected plants, in mild cases, have their normal growth and development affected and lose their ornamental value; in severe cases, the whole plant dies.

Flowers such as camellia, Chinese rose, Aglaia odorata, Michelia alba, lily, southern magnolia, nandina, Japanese evergreen, clivia, cactus, plum blossom and orchid are prone to this disease.

2. Control methods:

Strengthen cultivation management, appropriately increase the application of phosphorus and potassium fertilizers, avoid applying too much nitrogen fertilizer, do not water too much, and do not let the potting soil become too wet; at the same time, improve ventilation and light transmission and reduce humidity. Diseased leaves and diseased leaf stalks should be cut off and burned immediately, and dead plants should be removed in time.

When the disease occurs, spray 50% carbendazim-thiram wettable powder at 500 times dilution, or 70% thiophanate-methyl at 1000 times dilution, or 75% chlorothalonil at 800 times dilution, once every 10-15 days, for 2-3 consecutive sprays; alternating the chemicals can improve the control effect.

II. Powdery mildew

1. Symptoms:

It mainly harms the leaves, and can also infect leaf stalks, young shoots, flower stalks, flower buds, petals and other parts. The affected parts first show scattered white powdery spots, which then gradually spread and expand, and develop very quickly; under suitable conditions, they can cover the entire leaf in 7-10 days, and the leaf surface is covered with a layer of white powdery substance, just like frost. In affected leaves, because the cell tissue is damaged, the leaves and young shoots are often distorted, wilted and stiffened, seriously affecting the plant's growth and development as well as photosynthesis. Some cannot bloom normally, and some even die entirely.

Flowers such as chrysanthemum, garden balsam, Euonymus japonicus, cineraria, dahlia, goji, crape myrtle, honeysuckle, zinnia and Chinese rose are easily harmed by it.

2. Control methods:

Strengthen cultivation management; poor ventilation and muggy heat are [problems]. Powdery mildew occurs severely in high temperature and high humidity environments. Therefore, place the flower pots in a place with better ventilation and light conditions. Pay attention to increasing the application of phosphorus and potassium fertilizers, avoid applying too much nitrogen fertilizer, and do not water excessively. Also promptly remove diseased leaves and cut off diseased branches and diseased buds. Pull out diseased plants and burn them together to reduce the source of reinfection.

At the early stage of the disease, spray 1:1:140 equal-strength Bordeaux mixture; after the disease occurs, spray 25% triadimefon wettable powder at 1000 times dilution, or 70% thiophanate-methyl wettable powder at 1000 times dilution. In severe cases, spray once every 10 days or so, for 2-3 consecutive times.