Common Pests and Diseases of Camellias and Their Control Methods
Which pests and diseases of camellias need to be controlled? The pests of camellias include aphids, scale insects, red spider mites, rust mites, and leaf-rolling moths. Except for rust mites, they can be controlled with ordinary insecticides. The most serious are rust mites and mite pests, which are powdery white, very small, and hard to spot, attacking specifically the young leaves and tender shoots of camellias, causing the undersides of the leaves to turn yellow as if rusted, twisting the leaves, and preventing new shoots from growing...
Which pests and diseases of camellias need to be controlled?
The pests of camellias include aphids, scale insects, red spider mites, rust mites, and leaf-rolling moths. Except for rust mites, they can be controlled with ordinary insecticides. The most serious are rust mites and mite pests, which are powdery white, very small, and hard to spot, attacking specifically the young leaves and tender shoots of camellias, causing the undersides of the leaves to turn yellow as if rusted, twisting the leaves, and preventing new shoots from growing. To control rust mites, through my pesticide control trials with various chemicals, I believe dicofol and chlorothalonil are the most effective. Rust mites reproduce fastest under high-temperature and dry climate conditions, so it is important to cool the nursery site with water sprays, and leaves already damaged by rust mites should be pruned off promptly. For leaves or branches already infested with scale insects, manual removal can be used, rubbing off the insect spots with a cotton swab dipped in alcohol.
Potting camellias. Clay pots (unglazed pots, earthenware pots) are preferable. First place 3-4 pieces of tile over the drainage hole at the bottom of the pot, then add a portion of coarse soil, plant the seedling in the pot, fill the roots with a portion of fine soil, then slowly fill the coarse soil around the pot, gently tap the sides of the pot, press the soil down with your hand, then add another portion of soil and pat it level. (The potting soil should be 2-4 cm below the rim of the pot to allow for watering. After potting the seedling, water thoroughly the first time, pouring slowly until water drains from the bottom of the pot. Pouring water quickly will cause the soil surface to cake. Newly potted seedlings should be misted frequently on the leaves to keep them moist; avoid waterlogging in the pot and avoid applying fertilizer. Watering should depend on the climate and the condition of the potting soil, with the principle of keeping the soil moist. Fertilizer should be applied sparingly or not at all; if applied, it must be very dilute. For mail-order camellias being potted, for 1-2 year old seedlings, it is best to first gently wash off the root mud or clumps with clean water before potting, because when seedlings are boxed, some root soil is usually kept to ensure survival; this soil gets packed tightly during transport, or is tied tightly when boxed to prevent the seedlings from shifting and damaging the roots, so the roots should be washed and loosened. Potting after this treatment allows faster rooting and a higher survival rate. Medium and large seedlings of three years or more need to be potted with a soil ball, otherwise the survival rate will be reduced. If the soil ball has already been compressed, first dip the soil ball in clean water and lift it out immediately, then use a bamboo stick to gently loosen the surface soil of the ball before potting. Potting time: November in winter or February-March in early spring; in northern regions it is best from late March to early April, and with heat-preservation conditions, winter potting is also possible.
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