Autumn Pest and Disease Control Techniques for Seedlings and Flowers, and Pre-Sowing Seed Preparation

In autumn, high temperatures and dry conditions make it a peak season for flower leaf spot disease and powdery mildew.

Leaf spot disease is caused by fungi and includes black spot, brown spot and red spot, which often occur on leaves and fruits. In the early stage of the disease, circular spots of varying sizes appear on leaves or fruits, turning from green to yellow, with a clearly defined outer edge. The spots often develop a moldy layer or small black grains, and the affected tissue necroses in the later stage.

Powdery mildew is also caused by powdery mildew fungi, and mostly occurs on leaves, young fruits and tender shoots. The lesions are nearly circular, covered with a thin layer of white powder, and in the later stage many yellow-brown granules the size of pinheads are scattered on the white powdery layer. When the white powdery layer is removed, yellow spots of damaged plant tissue can be seen. Chinese roses, dahlias and others are prone to this disease.

The fundamental method for preventing and controlling the above diseases is to pay attention to daily care, thoroughly remove the source of disease, and promptly clean up dead branches and fallen leaves inside and outside flower pots, on balconies and in courtyards. If a large number of flowers are grown, spray disinfection with a 500-1000 times dilution of 50% carbendazim wettable powder. Those who grow peonies, tree peonies, chrysanthemums and carnations can also spray a 120-160 times equal-strength Bordeaux mixture once every 10 days, which can prevent tree peony red spot disease, carnation leaf spot disease and chrysanthemum brown spot disease.

In addition, applying more phosphorus and potassium fertilizer to flowers and trees to enhance disease resistance is also an effective method. At the same time, pests such as aphids, spider mites and whiteflies are also likely to occur at this time, so each plant must be checked. Once found, carefully catch them by hand immediately. When there are many, spray dimethoate and omethoate to kill them.

Before late autumn flowers and trees are brought indoors, check each pot and each branch even more carefully. If there are scale insect eggs on the branches, immediately scrape them clean with a bamboo strip. Aphids are relatively large and easy to find, while red spider mites are extremely small and mostly on the underside of leaves, making them hard to notice. Therefore, check the underside of leaves plant by plant. If small white spots are found, immediately spray with a dimethoate preparation, or wash with a tobacco infusion (about 20 cigarette butts soaked in a bowl of water for 24 hours, then mixed with some soapy water or washing powder), and rinse clean with water afterward.

If fertilizer and water and everything else are normal but the plant seems to grow poorly, you should suspect whether there are pests in the soil causing harm. The simplest and most effective method is to repot and check to see whether there are cutworms, ants, grubs and the like in the soil; if there are, remove them promptly. When repotting, mix some carbofuran into the soil (for a flower pot with a diameter of 20 cm, about one small plastic spoon), or use 2 tablets of the "Baihualing" tablet sold in stores, crush them and mix them into the soil, which also has a very good disinfecting and insect-killing effect.

What needs to be specially pointed out here is that in home flower growing, pests and diseases should be checked frequently, discovered early and controlled promptly, and manual catching or water washing should be used as much as possible. When pesticides must be used, non-toxic and low-toxicity pesticides should be used as far as possible, and spraying pesticides indoors is absolutely prohibited.

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