There are aphids, tetranychus urticae, red spiders, whiteflies and so on. These pests will cause the stem tips of plants to curl, the leaves wither and shrink, and the flowers become smaller. Once it happens, it should be prevented in time.
1. Chrysanthemum aphid: 1. Symptoms: Chrysanthemum is most seriously damaged by aphids, which occurs from seedling stage to flowering stage. Among them, Coriolus versicolor is the most common and widely distributed, with a body length of 65,438+0.5 ~ 65,438+0.7 mm, dark brown or grayish brown, which harms young stems and leaves, secretes mucus, binds stems and leaves, curls stem tips and shrinks leaves. Aphids occur within 1 year 10 ~ 20 generations, and the peak of reproduction is April ~ May and September ~1October every year. 2. Control: In order to control aphids, carbofuran was applied from the soil rhizosphere. The method is as follows: firstly, the topsoil around the rhizosphere of chrysanthemum plants is planed flat, then 3% carbofuran particles are evenly buried around, 20 ~ 30 cm away from the trunk, and then covered with soil and watered. After dissolving in water, the particles were absorbed by the roots of chrysanthemum and conducted to the upper part of the plant, and aphids died after sucking. Generally, the efficacy lasts for at least 2 months, which can effectively control aphids. 2. After the chrysanthemum seedlings are planted or grafted, spray a mixture of 800 times carbendazim solution and 40% omethoate solution 1 time every 20 days.
Tetranychus urticae: 1. Symptoms: Tetranychus urticae is the most harmful to chrysanthemum, which is mainly transmitted by wind or water. It is mostly parasitic on the back of leaves, with tiny body and many peripheral branches, and the back of damaged leaves is grayish brown. It usually spreads upward from the lower leaves. When the new buds grow, mites migrate upward to the new leaves and buds, causing the branches and leaves to turn yellow. When the damage is serious, the leaves of the whole plant turn yellow, the growth is slow, the flowers become smaller and the flowering period is shortened, which affects the ornamental value. 2. Control: (1) Avoid cutting with mites. (2) The affected chrysanthemum plants can be sprayed with 0.2% urea to promote the vegetative growth. (3) Regular inspection shows that mites are sprayed with chemicals in time to prevent and control them. Common pesticides are 20% dicofol EC 1000 times solution, 35% dicofol EC 2000 times solution and 80% dichlorvos EC 1000 times solution. Acaricide and organophosphorus are used alternately to avoid making mites resistant.
Third, whitefly: the body length is about 0.6 mm, and the body color is mostly light yellow or white. Breeding fast, many groups live on the back of young leaves, sucking juice, and chrysanthemums are harmed by whiteflies, causing leaves to wither and fall off. Huang Juhua was seriously affected by the disaster, which affected flowering and appreciation. 40% omethoate 1, 500 ~ 2000 times solution or 20% metronidazole 2000 times solution were used at onset.
4. Stem borer: Also known as Apriona germari, spraying 1 000 times of acaricide every month from late May to early July to prevent stem borer from harming chrysanthemum seedlings.
5. Carnivorous insects: From mid-August to late September, spray the killing liquid on the tender top 2-3 times to prevent moths from harming flower buds.
6. Leaf miner: it is mainly harmful to leaves, and can be sprayed with 40% dimethoate EC 1000 times, 40% omethoate EC 1000 ~ 2000 times, 50% dichlorvos EC 800 times, 50% Nale EC 1500 times and 40 times.
Seven, short negative locusts: 20% metronidazole emulsifiable concentrate 2000 times solution spray to kill, you can also choose dichlorvos, permethrin and so on.
Chrysanthemum disease:
The three major diseases of chrysanthemum refer to gray mold, rust and leaf blight of chrysanthemum. It is observed that these three diseases often occur at the same time in the growing season of chrysanthemum, especially after autumn, which can cause a large number of fallen leaves, affect the flowering of plants and reduce the ornamental value. Measures should be taken as soon as possible to prevent and control it.
Gray mold mainly harms the leaves, stems, flowers and other parts of chrysanthemum. When the leaf is damaged, it is a brown lesion on the edge of the leaf, and the surface is slightly wheel-like. Petiole and pedicel soften first, and then the epidermis decays. When flowers are damaged, it affects the maturity of seeds. High temperature and rainy weather, too much nitrogen fertilizer application, too dense planting and too heavy soil texture are all conducive to the occurrence of diseases.
Prevention and control methods: 1. Planting in different places. Bacteria mainly overwinter in soil, so whether it is planted in garden or potted, the soil is required to be new soil without disease; Second, the diseased leaves and plants are found to be cleaned up in time, buried or burned centrally to prevent the spread of diseases; 3. Before planting, the roots can be soaked in 65% zineb 300 times solution for 10 ~ 15 minutes; Fourth, pay attention to cultivation, improve ventilation and light transmission conditions, not only apply nitrogen fertilizer to prevent soil waterlogging; Fifth, at the initial stage of the disease, 0.3 ~ 0.5 degree lime-sulfur mixture, or zineb and carbendazim bactericide can be sprayed.
Rust mainly harms the leaves and stems of chrysanthemum, especially the leaves. At first, there were pale yellow spots on the leaves, and small brown-green spots were also produced on the back of the diseased leaves. After that, there will be a slightly convex blister. After the blister burst, a large amount of yellowish brown powder was scattered. The color gradually changes from light thirst to yellowish brown, which often causes the whole plant to die. Poor cultivation management, poor ventilation and light transmission, soil lack of fertilizer or excessive nitrogen fertilizer, soil waterlogging and excessive air humidity are all conducive to the occurrence of this disease. This disease can be prevalent from April to 10.
Prevention and control methods: 1. Rational fertilization. On the basis of combined fertilization, the application of phosphorus and potassium fertilizer should be appropriately increased to improve the antibacterial ability of plants; The second is potted chrysanthemums, and the drainage holes should be dredged frequently to prevent waterlogging in the pots; The third is ecological disease prevention. When cultivating chrysanthemum in protected field, we should pay attention to ventilation and light transmission, increase temperature and reduce humidity, and delay the dew condensation time of leaves; The fourth is chemical control. Spraying 65% zineb 500 times solution or 0.3 ~ 0.5 Baume mixed solution can effectively control the epidemic of the disease.
Leaf blight, also known as black spot, mainly harms the leaves of chrysanthemum. At first, small brown spots appeared on the lower leaves, then gradually expanded with dark brown edges, and then expanded into dark brown round or nearly round irregular spots with a size of about 5 ~ 10 mm, and there was an inconspicuous yellow halo outside. In the later stage, the edge of the lesion is dark brown, the center is slightly faded, and the small black spots are not obvious when the humidity is high. When the disease is serious, several diseased spots are connected together, which makes the leaves fall off completely, and continuous cropping is serious.
Prevention and control methods: first, reasonably change stubble planting and select disease-free plants for grafting; Second, pay attention to ditch drainage to reduce soil moisture; Third, pruning diligently, eliminating sick and disabled people and improving ventilation and light transmission conditions. Implement chemical control technology to promote plant growth and enhance disease resistance and tolerance; The fourth is chemical control. At the initial stage of the disease, 30% basic copper sulfate suspension 400 times, 80% Dijundan wettable powder 500 times, 50% thiophanate-methyl suspension 800 times or 75% benomyl 1500 times can be used for prevention and treatment.