What are the control methods for scale insects on nursery stock and flowers?

Scale insects are a major enemy of flowers, and there are many kinds of them. Common ones include the cottony cushion scale, the felt scale, the wax scale, the grass scale, the armored scale, the pear scale, the globular scale, the cactus scale, the mealybug, the brown soft scale, the transparent scale, and so on. They vary in size and form, and the flowers and trees they damage also differ. For home gardeners, there is no need to carefully distinguish and study them. However, almost all flowers and trees suffer from them, and once they appear they are very hard to eradicate. Only latex-containing flowers and trees such as the rubber tree and other Moraceae plants, as well as Euphorbiaceae plants, are not attacked.

The larval stage of scale insects is very short, and the larvae move slowly. When they crawl to the underside of leaves or the forks of branches, they stop moving, then form a shell, and later larvae line up in order and form shells, very regularly. After forming the shell, they use their piercing-sucking mouthparts to suck the sap of the flowers and trees for a long time to sustain life, and at the same time excrete honeydew that pollutes the branches and leaves. In a humid and hot environment, this quickly triggers sooty mold, making it impossible for the plant to carry out normal photosynthesis, and also hindering respiration, causing leaves to turn yellow and branches to shrivel.

To prevent scale insects, first strengthen ventilation and light penetration, and prevent stuffiness and humidity. Once they appear, they should be eliminated at the larval stage. There are many methods of chemical control. Commonly used ones include 90% crystal trichlorfon at 1500 times dilution, 50% phoxim at 1000 times dilution, 80% dichlorvos at 1500 times dilution, 50% fenitrothion at 100() times dilution, 40% omethoate at 100() times dilution, 50% monocrotophos at 1500 times dilution, 25% parathion at 800 times dilution, and so on; in winter, for deciduous flowers and trees, a 10 to 15 times dilution of rosin mixture can also be sprayed. The above chemicals have different killing abilities against different kinds of scale insects. When one chemical has a poor control effect, another chemical can be used instead.

Once scale insects form a shell, their resistance to chemicals greatly increases. If scale insects on small potted flowers grown at home have already formed shells, you can use absorbent cotton dipped in low-proof white liquor to wipe off the insect bodies, and at the same time remove the sooty mold, then spray and wash with clean water 2 times. If scale insects occur on large potted flowers such as cycads placed in a courtyard and have already formed shells, manual removal is quite labor-intensive and cannot be thorough, so only highly toxic pesticides such as 1059 or 1605 can be used. First use a knife to make a cut at the base of the stem, then use a writing brush dipped in pesticide to smear it on the cut. This pesticide is a systemic agent and can penetrate into the plant body and be transported to all organs. After the scale insects suck the sap containing the pesticide, they die immediately and fall off. The above pesticides can cause human death and must not be used in homes or public gardens.