Identification and Control measures of Flower Diseases

I. physiological diseases

The main causes of physiological diseases are: inappropriate temperature, unsuitable light, water imbalance, unsuitable nutritional conditions, excessive soil salinity, harmful gases and substances, unsuitable soil acidity and alkalinity will affect the normal growth and development of flowers, leading to the occurrence of diseases, therefore, this kind of disease is also called non-infectious disease. It can not be effectively prevented by spraying. It is common in the field, there is no disease center, the time and location of the disease are consistent, and it is not contagious. Physiological diseases have something in common: that is, they are often first shown on tender leaves and new branches, such as yellowing, withering, withering of leaves, rotting of roots, soft and easy breaking of stems and leaves, lodging and so on.

II. Bacterial diseases

Flower diseases caused by bacteria: if the control is not timely, it will often cause devastating disasters. The main types of bacterial diseases are stripes, spots, blotches, wilting and decay. Bacterial leaf spot is generally characterized by acute necrotic spot, waterlogged, and there is a yellow halo around the spot, such as chrysanthemum and begonia. Bacterial rot has a fishy smell, and the decaying tissue has yellow bacterial pus, such as lily soft rot, calla lily rot, soft rot. Bacterial wilt often causes bacterial wilt (and fungal wilt is often accompanied by yellowing), such as bacterial wilt of chrysanthemum and Dahlia, bacterial wilt of carnation, bacterial wilt of chrysanthemum, bacterial wilt of primrose.

III. Fungal diseases

Most of the diseases of flowers are caused by fungi, such as chrysanthemum downy mildew, geranium gray mildew, rubber tree anthracnose, sweet-scented osmanthus anthracnose, calla black spot, rose downy mildew, cockscomb brown spot, tulip blight and all kinds of flower seedlings. The mycelium of fungi is vegetative, asexual and sexual spores are vegetative forms, which can be transmitted by wind, rain, insects or seedlings and weeds, and can also be subcultured by soil. through the stomata, water pores, lenticels and other natural pores and various wounds in the epidermis of flowers and plants. Fungal diseases often cause plant decay, wilting, discoloration and other symptoms, especially obvious. Pathogens or their abnormal forms can be observed with the naked eye, such as white powder, gray mold, black mold, frost poison I |, j, black spots, sclerotia and other symptoms. Fungal necrosis is one of the most important symptoms of fungal diseases.

IV. Viral diseases

It is mainly caused by viruses: most of the virus diseases of flowers are chronic diseases of the whole plant, and the external symptoms are often flowers or leaves fading edge, ring spot, blistering, yellowing, withering spot, cluster spot, or leaf thinning, wrinkling and deformity of branches, leaves, flowers and fruits, etc. Viral diseases have only symptoms and no symptoms, which is different from fungal and bacterial diseases. The symptoms of some viral diseases are easy to be confused with non-infectious diseases. The difference is that the occurrence of viral diseases has obvious I spreading from point to surface, and the symptoms on diseased plants often start from the top. Then it extends to other parts of the plant. Such as Compositae flower virus disease, Phnom Penh Daphne virus disease, carnation virus disease and so on. Virus diseases are mainly caused by pests such as aphids, leafhoppers, planthoppers, planthoppers. The transmission of thrips can also be transmitted through nematodes and fungi, seedlings and pollen in the soil; at the same time, in the process of grafting and management of seedlings, contact between diseased plants and healthy plants, asexual spikes, tubers, bulbs, bulbs, etc. may be the opportunity for the spread of virus disease, and even when pruning and cutting flowers, human hands and tools are the conditions for transmission.

5. Nematode diseases

Root-knot nematode disease can harm a variety of flowers, such as all kinds of ornamental tomato, ornamental pepper root-knot nematode disease, cockscomb flower and Compositae flowers root-knot nematode disease and so on. The disease only affects the roots of the plant, and the lateral roots suffer more severely, forming many root knots on the lateral roots, which are connected to each other into beads, root knots are often spherical or conical, of different sizes, and there are many fibrous roots on the surface, forming clumps of fibrous roots and cutting open the root knot. Many pear-shaped nematodes the size of translucent white needles can be seen. The root knot is light in initial color, smooth and solid on the surface, and gradually becomes light brown, brown and dark brown rot. When the nematode sucked sap in the tumor, the susceptible plants showed malnutrition, dwarfing, small and wrinkled leaves, clumps, and then gradually withered, root necrosis, resulting in leaf withering, flowers and other consequences.

VI. Prevention and control measures

In order to control flower diseases, the following key measures should be taken:

1. Strictly implement the relevant national quarantine laws and regulations: diseases belonging to quarantine objects should be strictly prevented, and species and seedlings should not be introduced from the areas where such diseases occur. Seeds and seedlings should be carefully checked when purchasing seeds and seedlings. If found that there are quarantine objects should be resolutely refused to accept, refuse to enter, and for destruction and disposal, such as burning, deep burial, and so on.

2. Select disease-resistant varieties: for example, the same Compositae varieties should also be introduced in a small area, and some should be identified by inoculation and natural induction to screen out varieties with strong disease resistance.

3. Strengthen the disinfection of soil and seedlings: in particular, many precious flowers, whether locally planted or potted, should disinfect the soil, such as spraying potassium permanganate mixed with quicklime powder. If possible, carbendazim and pentachloronitrobenzene are also used for disinfection and sterilization. the former can be mixed with 1.5g per square meter, or the medicinal soil can be sprinkled on the seedbed according to 1:20, while the latter is mixed with 4g of pentachloronitrobenzene and 5g of Dyson zinc per square meter. mix well with 12kg fine soil. The cover under the cushion during sowing has a special effect on anthracnose, blight, sudden collapse and sclerotiorum. When sowing, the seedlings can soak the seeds with 0.3% to 0.5% potassium permanganate solution for 0.5 to t hours. Haoke electricity is not sure to soak the seeds in copper sulfate solution for 1 to 2 hours, rinse and drain the seeds before sowing.

4. Strengthen cultivation management:

First, the greenhouse flowers should pay attention to ventilation and light, even in the cold winter, it is necessary to uncover the side film or open the window at noon every day to reduce the humidity in the greenhouse, otherwise it will induce the occurrence of gray mold, leaf spot, frost mildew and powdery mildew. The light intensity should be controlled at the degree suitable for plant growth and development.

Second, reasonable irrigation, drip irrigation, furrow irrigation or soil surface water supply, prevent irrigation water splash, bring pathogenic spores or bacteria to healthy plants, can effectively control the occurrence of diseases. Do not allow water to remain on the petals or leaves to provide conditions for germs to germinate and invade plants. If the soil moisture is too high, all kinds of root rot pathogens will do harm to the roots.

Third, try not to cause wounds when transplanting, pruning and heart-picking, so as to provide a point of invasion for bacteria. It is best to operate on a sunny day to facilitate wound healing and prevent the invasion of pathogenic bacteria. When cutting, it should be disinfected to avoid spreading germs through fingers and tools as far as possible.

Fourth, rational fertilization. No partial application of nitrogen fertilizer, appropriate application of phosphorus and potassium fertilizer, too much fertilizer will cause fertilizer damage to the plant and even cause plant yellowing and poor growth.

Fifth, pay attention to field hygiene. Removing diseased plants, diseased leaves and weeds and destroying them from the cultivation site can reduce or even completely remove the density of pathogens in the field and reduce the incidence, especially for the prevention and control of systemic diseases such as bacterial diseases, viral diseases or Fusarium wilt.

5. Timely and moderate chemical control. The type and severity of visible diseases are treated with protective agents, eradication agents, therapeutic agents, etc. Fungal diseases can generally be controlled by 72.5% Pulicol water agent, 15% vermicellin wettable powder, 50% Sukeling powder, 64% poison alum wettable powder, 50% carbendazim wettable powder and so on. Generally speaking, 72% agricultural streptomycin wettable powder, 77% killing wettable powder and 25% complex ammonia copper water agent can be used for the prevention of bacterial diseases. Viral diseases can generally be controlled with 1.5% Zhiyangling emulsion, 20% virus A wettable powder, 83 resistance enhancers and other agents. To control root-knot nematode disease, we can choose Kexianling emulsion, or irrigate the flower rhizosphere soil with 1000 times of dichlorvos to kill the nematode. Physiological diseases are not contagious. By improving the environmental conditions that cause diseases and implementing symptomatic treatment, plants are generally easier to recover.