A Complete Guide to Succulent Pest and Disease Prevention and Control Methods and Techniques

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Although succulents are easy to grow and care for, pests and diseases can still occur under certain conditions. For succulents that follow a refined aesthetic, even a tiny pest or disease problem can leave "a flaw in fine jade," greatly reducing their ornamental value. And for growers, pests and diseases are undoubtedly a thorn in the side that must be eliminated as quickly as possible. Pest and disease control in succulents is relatively easy to manage, but with long-term indoor cultivation, under conditions of high temperature, dryness and poor ventilation, there are also many "common pests and diseases" and "frequently occurring pests and diseases."

1. Red spider mite

It mainly harms succulents in the Apocynaceae, Euphorbiaceae, Asteraceae and Liliaceae families. It uses its mouthparts to suck the sap from young stems and leaves. Affected leaves develop yellow-brown spots or turn yellow and drop off, and these scars remain permanently. Generally, you can check whether there are spider webs on the underside of the leaves, as well as very small red/white/dark-colored insects. If there are, it is usually red spider mite.

Control methods include increasing environmental humidity to reduce and avoid spread. You can use a 40% dicofol solution diluted 1000-1500 times to kill them, or abamectin.

2. Mealybugs

They cause harm across a very wide range, often damaging succulents with tightly packed leaves such as Agave and Haworthia, sucking stem and leaf sap, causing poor plant growth and, in severe cases, withering and death. Their peak period comes earlier than that of red spider mite, and they often multiply in large numbers as early as early spring. However, there is also an aspect of their damage that is easy to control, namely that they tend to concentrate on only a few plants. Sometimes one plant is covered with mealybugs while a neighboring plant has not a single one.

Control methods: When there are few, they can be removed with a brush. In addition, you can spray with a 800-1000 times dilution of Supracide. Mixing a certain amount of carbofuran into the potting soil has a preventive effect, but the efficacy only lasts 3 months.

3. Whiteflies

The scope of damage is not large, mostly occurring on shrub-like succulents in the Euphorbiaceae family such as Euphorbia tirucalli, Euphorbia milii, Euphorbia neriifolia and Euphorbia oncoclada. They pierce and suck sap on the underside of leaves, causing leaves to turn yellow and drop off, while also inducing sooty mold, with large patches of unsightly black powder on stems and leaves, directly affecting the plant's ornamental value.

Control methods: In addition to improving environmental ventilation, in the early stages you can spray with a 40% omethoate emulsifiable concentrate diluted 1000-2000 times, or spray with malathion diluted 500 times or dimethoate mixed with dichlorvos diluted 1000 times. Two days after spraying, use a strong water stream to wash away the dead insects together with the black powder.

4. Aphids

They mostly harm succulents in the Crassulaceae and Asteraceae families, often sucking sap from the young parts of the plant, causing weakened growth, and their secretions also attract ant infestations.

Control methods: If there are few, they can be manually caught and killed, pinching each one you see. In the early stages of infestation, spray with an 80% dichlorvos emulsifiable concentrate diluted 1500 times, or consider Bayer imidacloprid.

5. Fusarium wilt

It is a bacterial disease and a major disease of succulents. It often harms succulents with tubers, invading through root wounds, causing reddish-brown lesions on the tubers, which rot and die within a few days.

Control methods: Before potting, spray with a 70% thiophanate wettable powder solution diluted 1000 times for prevention. After drying, apply sulfur powder for disinfection.

6. Anthracnose

It is an important disease harming succulents and belongs to the fungal diseases. It mostly occurs in hot and humid seasons, especially during the high-temperature, high-humidity plum rain season, and excessive application of nitrogen fertilizer may also cause it. In the early stage of the disease, small brown spots appear on the leaves, which then expand into circular or elliptical shapes. The lesions gradually dry up, and in severe cases the entire plant is affected.

Control methods: First, open windows for ventilation and reduce indoor air temperature and humidity. Then spray with a 70% thiophanate-methyl wettable powder diluted 1000 times, or spray with 70% thiophanate-methyl, 60% anthracnose Fumei, carbendazim, etc., to prevent the disease from continuing to spread.

The prevention and control of succulent pests and diseases is mainly based on prevention. First, the environment must be clean and tidy. Strict checks must be carried out on introduced succulents, and they should only be placed in the greenhouse after confirming there are no pests or diseases. Seasonal transitions are periods when pests and diseases are likely to occur. Generally, when the weather goes "from cold to warm" and "from hot to cool," these are precisely the periods when pests and diseases are most likely to suddenly break out. In addition, just after summer, succulents have just passed through a long dormant period and are gradually resuming growth, but their physiological functions have not fully recovered and their resistance is still at a very weak stage, so they are also very easily invaded by pests and diseases. The three periods of early winter, early spring and before the plum rain season are when concentrated pesticide spraying in the greenhouse achieves twice the result with half the effort. In addition, disinfecting the potting soil has a very good preventive effect.

The pesticides commonly used for succulents mainly include two categories: fungicides for preventing and treating diseases (such as carbendazim, thiophanate, chlorothalonil, zineb, etc.) and insecticides (such as omethoate, dicofol, malathion, fenvalerate, abamectin, etc.), which can be applied according to the symptoms. The concentration of the pesticide must be strictly controlled according to the instructions, especially insecticides, as slightly higher concentrations can cause phytotoxicity. Obregonia denegrii and some Euphorbiaceae succulents are especially sensitive to this.

Regarding some of the pesticides listed in this article, some are relatively early-era pesticides, and their current effectiveness and ease of purchase may not be as good or convenient as some newer pesticides. Therefore, there is no need to pay too much attention to the names of the pesticides. You only need to know exactly what pest or disease your succulent has, and you can search on some forums for pesticides that work well, or simply search for the disease on Taobao, where you can usually find a whole bunch of corresponding pesticides, and they are very convenient to buy. As for the concentration, number of sprays and intervals of the pesticide, the outer packaging of the pesticide you buy will generally indicate this, and you just need to use it according to that amount. After using the same pesticide twice, switch to another one, because long-term use of a single pesticide easily produces resistance.

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