The Latest Technical Methods and Tutorial for White Orchid Tree Pest and Disease Control

The white orchid tree (Michelia alba) has an upright, branching form and an elegant, graceful appearance. It is native to Java, Indonesia, and is now widely cultivated in Southeast Asia. In China, it is grown extensively in provinces and regions such as Fujian, Guangdong, Guangxi and Yunnan, while in the provinces and regions of the Yangtze River basin it is mostly grown in pots. It can also serve as a fragrance material and for medicinal use. Now let us take a look together at the pest and disease control techniques for the white orchid tree during cultivation!

Red wax scale

[Damage characteristics] The nymphs and adults of the red wax scale (Ceroplastes rubens) pierce and suck the sap of ornamental plants. Their excrement often induces sooty mold, causing a layer of black mold or a thicker black film to form on the leaves, turning the whole plant into a black tree. The plant becomes weak and rarely flowers or fails to flower at all.

[Control methods] 1. In winter and early spring, remove some of the heavily infested branches along with pruning. 2. If the affected ornamental plants are few or short, they can be scraped clean by hand in winter and spring. 3. At the peak of nymph hatching, spray 25% phosmet emulsifiable concentrate at 1000 times dilution, or 40% omethoate emulsifiable concentrate at 1500 times dilution, once every 4-6 days, for 3 consecutive sprays. 4. When introducing ornamental seedlings, carry out strict quarantine to prevent bringing in the insects.

Red spider mite

[Damage characteristics] The red spider mite pierces the leaves with its mouthparts and sucks the sap, destroying chlorophyll. The leaves show grayish-yellow spots or patches, turn orange-yellow and fall off, or even drop completely.

[Control methods] 1. Soak citrus peel in 10 times its volume of water for a day and a night, filter, and spray the plants. 2. Mix 15 g of laundry detergent, 15 ml of 20% caustic soda, and 7.5 kg of water, then spray the mixture on the plants. 3. Take 50 g of plant ash, add 2.5 kg of water, stir thoroughly, soak for two days and nights, filter, then add 3 g of laundry detergent and mix well before spraying, once a day for 3 consecutive sprays, then after 1 week spray 3 more times; this can eliminate the second generation of pests, and mixing it into the soil can control maggots. 4. Light 1 mosquito coil and place it in the pot of the affected plant, then tie a plastic bag tightly around the pot; after 1 hour of fumigation, the eggs and adults can be killed.

Cicada

[Damage characteristics] The nymphs of the cicada suck the sap from the roots of ornamental plants in the soil, while the adults pierce and suck the sap from the main leaves. The female inserts her ovipositor into the branches to lay eggs, causing the branches to die.

[Control methods] 1. Kill the mature nymphs that have just emerged from the soil in time. 2. If the infestation is severe, light a fire near the trunk on hot summer nights and shake the branches so that the cicadas fly into the fire and are killed, and also kill the cicadas that fall outside the fire. 3. Apply sticky tung oil or a sticky ball kneaded from spider webs to the tip of a bamboo pole to catch the adults. 4. From April to August, inspect in time and cut off the egg-laying branches.

Cottony cushion scale

[Damage characteristics] The cottony cushion scale (Icerya purchasi) often gathers in groups on leaf buds, tender buds and new shoots. When the infestation is severe, the leaves turn yellow, causing leaf drop and shoot dieback, and even entire branches or the whole plant may die. Even if some branches remain, their excrement causes sooty mold, leaving them grayish-black and seriously reducing their ornamental value.

[Control methods] 1. Manual control: pick off the females and egg sacs by hand or with tweezers, or cut off the heavily infested branches and leaves. 2. Biological control: introduce natural enemies such as the vedalia beetle (Rodolia cardinalis) and the Australian ladybird to prey on the cottony cushion scale. 3. Chemical control: during the dispersal period of newly hatched nymphs, spray 40% omethoate at 1000 times dilution, or 50% fenitrothion at 1000 times dilution, or ordinary laundry detergent at 400-600 times dilution, once every 2 weeks, for 3-4 consecutive sprays.

Anthracnose

[Symptoms] Dark brown round or nearly round lesions appear on the leaves, with slightly darker edges. After expansion, the center gradually turns grayish-white, 2-8 mm in size. In the later stage, small black dots form on the lesions, which are the acervuli of the pathogen. When humidity is high, orange-yellow sticky substance, the conidial mass of the fungus, oozes from the lesions. The disease is severe in rainy and humid weather.

[Control methods] In the early stage of the disease, spray Bordeaux mixture at 1:1:100, or 25% carbendazim at 500 times dilution, or 70% thiophanate-methyl at 600 times dilution.

Chlorosis

[Symptoms] It first appears as loss of green color in the young leaves on the tender shoots, then spreads from top to bottom and from the leaf margin toward the leaf base. After the leaf margin loses its green color, it gradually spreads to the mesophyll tissue, causing the tissue between the veins to lose color. As it continues to develop, the veins also lose their green color, turning the leaves milky yellow to milky white. In severe cases, the leaf margins scorch, and even the entire leaf dries up and falls off. If 1-year-old seedlings are affected, their height is shorter than normal plants. If 3-4-year-old young trees are affected, they turn completely yellow and are about 30 cm shorter than generally healthy ones. Chlorosis causes slow plant growth, shortened internodes, and symptoms such as dieback of the shoot tips.

[Control methods] 1. Bury mung bean-sized ferrous sulfate under the bark at the base of the seedling, then wrap it with plastic film to help the wound heal. 2. Dig a trench and apply ferrous sulfate, add decomposed cake fertilizer, and cover with soil. 3. Choose a clear morning before sunrise or after 4 p.m. to spray the leaves with a 0.5% ferrous sulfate aqueous solution or a 500 times dilution of a yellow-leaf rapid-greening plant antiviral compound nutrient, at intervals of about 7-10 days.