What causes radish spot blight? How can it be prevented?

It can occur throughout the growth period, and after the radish leaves are damaged, the irregular greenish yellow spots appear at first, and then gradually expand into polygonal yellow-brown lesions, and the disease extends from the lower part of the plant to the upper part. When the humidity is high, frosty white mold appears on the back of the leaf or on both sides of the leaf, and the lesions are connected into patches when the disease occurs severely, mainly for the fleshy roots, and the leaves can also be damaged. Irregular or round, slightly concave black lesions are formed on the fleshy roots, and black mold grows on them, and in severe cases, the lesions expand to the interior and make the fleshy roots black and rotten.

The leaves are damaged and diseased, and the yellow spots are prevented.

<> pesticide seed dressing: select phosphine or dimethoate emulsifiable concentrate and other agents, dilute with water, evenly spray on the seeds, pile up for several hours, and sow seeds after the liquid is sucked dry, which can prevent needleworms, grubs, and other harmful seed buds. To prevent pests and diseases, we should first take agricultural measures, apply foot fertilizer, base fertilizer to well-rotted organic fertilizer, microbial fertilizer, balanced use of phosphorus and potassium fertilizer, for the spread of soil-borne diseases, soil disinfection can be carried out, the use of 70 thiophanate-methyl wettable powder.

Radish seedlings are mainly used to control yellow koji jumping beetles and cabbage insects, boron and calcium fertilizer should be sufficient in the growth process, especially can not lack boron fertilizer, boron deficiency is easy to lead to radish hollow, black heart, fruit bran, and poor storage tolerance. It is mainly affected by leaves, but also stems, flowers and seed pods. Water-soaked greenish spots are produced in the initial stage of the diseased leaves, and then develop into polygonal or irregularly shaped yellow-brown lesions.

When the humidity is high, a white mold layer grows on the reverse side of the leaf. When the disease is severe, the lesions are patchy, causing the leaves to turn yellow and dry up.

Use biachlorthoprid and chlorfenamide to control aphids, and use morpholinoguanidine hydrochloride and toxin fluorophos to control mosaic diseases and viral diseases. Soft rot is a bacterial disease that is controlled with agricultural streptomycin or thiazine copper. Commonly known as greasy insects, they feed on plant juice and spread viruses.

It reproduces quickly under high temperature and drought conditions, and the harm is serious. For pesticide control, choose 2000-2500 times of 5% pyrethroid emulsifiable concentrate, or 3000 times of 20% Kangfu multi-concentrated solvent.

Carrots are more susceptible to disease, and carrot spot blight is a disease that is more likely to occur in September, especially if the growth is weaker or the management is extensive. The following measures can be taken to prevent and control carrot spot blight: First, choose good seeds when planting carrots, because the disease will be spread through seeds, so comprehensive disinfection measures should be taken before planting carrots.

Second, strengthen the usual field management. Give plantar fertilizer, proper top dressing, scientific watering, and timely drainage. Third, actively use the drug **spot blight, and use the drug in time to avoid infecting more plants.

It may be that there is no regular pest control and lack of water, so we should pay attention to buying some pest control sprays for spraying, watering frequently, supplementing sunlight, fertilizing, and supplementing nutrition.

Carrot spot blight, also known as leaf spot. The pathogens are scattered on the surface and in the soil with the disease residues for overwintering, and the seeds can also carry the bacteria, which are the primary source of infection. The conidia absorb water and then gush out of the conidia, which are spread by wind, rain and irrigation water, and invade through the stomata or through the epidermis.

Strengthen the usual field management. When planting carrots, it is necessary to give foot fertilizer, and then appropriate top dressing, usually can choose phosphate fertilizer, potassium fertilizer as the main fertilizer of top dressing. Usually it is necessary to water scientifically, and after watering, it is necessary to do a good job of loosening the soil, so that the humidity in the field can be controlled.

After the rain, it is necessary to drain the excess water in time to avoid the occurrence of water and root rot.

At the initial stage of the disease, 500 times of 70% mancozeb wettable powder, 600 times of 80% Xinwansheng wettable powder, 80% 800 times of wettable particulate powder or 50 60 kg of 1 200 Bordeaux liquid can be sprayed alternately per mu, and an appropriate amount of new high-lipid film can be added to prevent pests and diseases from developing resistance and enhance the efficacy.

Use the seeds harvested from disease-free plants, treat the seeds before sowing, dress the seeds with Fumei Shuangjia new high-fat film, dispose of the diseased plants in time, and spray pesticides in time.

Carrot spot blight is very common, and the prevention and control methods of carrot spot blight:1Using seeds harvested from disease-free plants, the seeds are treated before sowing, and 50% of the seed weight is used to mix the seeds with a new high-fat film, which can repel underground pests and diseases and isolate virus infection; 2.

Strengthen management, apply enough manure, timely top dressing, and increase phosphorus and potassium fertilizers; 3.The use of pesticides for prevention and control, according to the requirements of plant protection, spray 70% mancozeb wettable powder 500 times or 1 1 160 200 Bordeaux liquid and other agents for prevention and control, and cooperate with the spraying of 800 times of the new high lipid film to improve the utilization rate of the active ingredients of the agent.

The prevention and treatment of pharmaceuticals implements the principle of "prevention first, comprehensive prevention and control", and rationally selects pharmaceuticals. After winter shearing, spray Baume 3 5 degree stone sulfur mixture solution in time to clear the garden. Drugs in the growing phase:

It can be chemically controlled with 1000 1500 times of 50% promethane wettable powder. In the early stage of the disease, 750-1000 times of 6% gangpyrin can be used for liquid spray control, and 45% prochloraz isodidione 1000-1500 times liquid spray can be used in the later stage.

Strengthen cultivation management: We can increase the application of organic fertilizers to promote the growth of plants and improve disease resistance. For low-lying or poorly drained orchards, we need to do a good job of drainage.

Increase the application of organic fertilizers and microbial fertilizers such as farm fertilizers, and use fast-acting fertilizers scientifically in proportion to promote the growth of trees and improve their disease resistance. Orchards with low-lying terrain and poor drainage should be drained in time.

In the growth period of fruit trees, generally after flowering to young fruit stage, that is, in late April to early July spray protection, the following agents can be used: 65 dycob zinc wettable powder 500-600 times liquid; 75 chlorothalonil wettable powder 800 times liquid seed treatment; The selection of seeds should be based on the local climate, soil texture, and disease occurrence to select excellent varieties with strong disease resistance and disease resistance; Before sowing seeds, soak them in warm water at 55 degrees Celsius for half an hour, remove them and dry them before sowing.

Strengthen cultivation management and non-cruciferous vegetables alternate year rotation, deep ploughing, remove disease residues, you can add an appropriate amount of quicklime to mix the chicken, the first can improve the soil, the second can kill a lot of germs. Of course, you can also buy agricultural disinfectants for dilution and disinfection, proper fertilization, this situation is probably a lack of calcium, so in order to avoid this situation, it is necessary to fertilize properly, supplement calcium in time, and use fertilizers at different stages in different growth periods to ensure that the fertilizer is sufficient for large-scale crop rotation, and the land is cleaned in time after harvest to reduce the source of bacteria in the field.

It can be controlled in this way: large-scale crop rotation, timely turning over the land after harvest, cleaning the field, and reducing the source of bacteria in the field. Seed disinfection:

Seed dressing with 50% Fumei double wettable powder, 40% sterilized Dan wettable powder, 50% sterilized urea wettable powder, and 50% iprodione wettable powder with seed amount. Pharmaceutical prevention and control: spray 20% thiohedrone 500 times, 75% chlorothalonil wettable powder 500 600 times, 50% sterilized urea wettable powder 1000 times, 58% methamalene manganese zinc wettable powder 500 times, 50% Pythium wettable powder 1500 times, 40% sterilized Dan wettable powder 600 times, 80% spray gram wettable powder 600 times, every 7 10 days for prevention and control, continuous spraying 3 4 times.

You can strengthen field management, loosen the soil, apply more fertilizer, and then clean up the plant disease and residue in time, so as to prevent the occurrence of this disease.

Choose excellent disease-resistant varieties. Reasonable crop rotation and strengthen field management. Timely loosening of soil and top dressing, delaying leaf senescence and promoting root growth; Clean up the plant disease residue in time to reduce the source of disease in the field; Reasonable irrigation, timely drainage after rain, increase air circulation between plant rows, reduce soil and leaf moisture, and reduce pathogenic transmission conditions.

Before sowing, the seeds were treated by warm soup soaking method, or 50% Fumei double wettable powder by seed weight, or 40% seed dressing double powder, or 70% mancozeb, 75% chlorothalonil, 50% prodidione wettable powder were used to dress the seeds. At the beginning of the disease, spray 2000 times of 30% etherstrobin suspension, or 600 times of 75% chlorothalonil wettable powder, or 500 times of 78% wave manganese-zinc wettable powder, 600 650 times of 80% mancozeb wettable powder, and 1000 times of 50% iprodione wettable powder, spray once every 10 days or so, and continuously control 3 4 times.

It is likely to be caused by improper water and fertilizer management, or due to excessive soil moisture, or due to improper fertilization, or due to unsuitable temperatures, or due to weather problems.

Carrot spot disease, a common disease on carrots, is more prevalent in summer and autumn during high temperatures.

The pathogen overwinters on diseased residues inside and outside seeds, in the soil, and on wild hosts, and produces conidia for dissemination and spread the following year. It can survive for more than a year, produce conidia in the next spring, spread by wind and rain, when the conidia fall on the carrot leaves, germinate in dew drops or water droplets, produce germ tubes invaded by the stomata, expand and spread between cells, after a few days of latent incubation, disease spots appear on the leaves, and a large number of disease spots are formed on the plant after repeated infection for many times. The epidemic of the disease mainly depends on the meteorological conditions, the number of overwintering bacteria and the resistance of the host, the appropriate temperature for the development of the pathogen is 25 28, the average temperature is 19 23, the incubation period is 5 8 days, the relative humidity is higher than 98% for the formation of conidia, and it is easy to get sick in case of rain, fog, heavy dew or excessive irrigation in production.

Generally, 10 to 20 days after rain, the incidence peaks. The disease spreads rapidly. Heavy cropping, large amount of fungus, heavy soil clay, and low-lying terrain are serious.

If the symptoms are not particularly severe, it is fine to cut off the black leaves with scissors. If there is already a large area of melanoma, be sure to spray targeted agents.

Select high-quality heat-tolerant radish varieties, and soak the seeds in advance with 50% Pythium wettable powder or gibberellin when sowing radish to improve the disease resistance of radish.

When planting, it is necessary to choose a place with high terrain and a place that is not easy to accumulate water. Usually water in moderation. Fertilize with fertilizers that contain high-quality fertilizers.

Symptoms: The disease mainly harms radish leaves. At the beginning of the disease, the diseased leaves appear black-brown slightly raised small round spots, gradually enlarged after the edge is pale, the middle light brown to gray-black, with or without obvious concentric wheel patterns, and the lesions are pale black mold when the humidity is high.

The diseased part is brittle and brittle, and when the disease is severe, the confluence of the diseased spots causes local death of the leaves. The leaves, stems and pods of the collected plants can be diseased, and the lesions are mostly black-brown oval or longitudinal strip-shaped patches, and black mold is also formed on them. Pathogenesis:

Bacterial diseases. The fungus overwinters in seeds, diseased plants, and soil. Germs can also be transmitted through splashes of irrigation water or rainwater, as well as insects.

The optimal temperature for the onset of the disease is 24 25 . Prevention and control: large-scale crop rotation, timely turning over the land after harvest, cleaning the field, and reducing the source of bacteria in the field.

Seed disinfection: Seed dressing with 50% Fumei double wettable powder, 40% sterilized Dan wettable powder, 50% sterilized urea wettable powder, and 50% iprodione wettable powder with seed amount. Pharmaceutical prevention and control:

At the beginning of the disease, spray 500 times of 20% thiohedone, 500 600 times of 75% chlorothalonil wettable powder, 1000 times of 50% sterilized urea wettable powder, 500 times of 58% methamalene manganese zinc wettable powder, 1500 times of 50% pythium wettable powder, 600 times of 40% sterilized dan wettable powder, 600 times of 80% spray wettable powder, 1 time every 7 10 days, and spray 3 4 times continuously.

Hello Seed Treatment. Seeds are collected from disease-free areas and disease-free plants.

Crop rotation. Crop rotation with non-cruciferous crops for more than 2 years.

Field management. timely drainage and flood prevention; high ridge cultivation; apply enough organic fertilizer, increase phosphorus and potassium fertilizer; application of micronutrient fertilizers; appropriate late sowing; Clean up the diseased plants in the field in time, bury them deeply or burn them to reduce the source of disease in the field.

Pharmaceutical prevention and control:In the early stage of the disease, azoxystrobin or pyraclostrobin 10 grams can be mixed with water for prevention and control.

May be bacterial leaf spot.

Carrot bacterial leaf spot, also known as bacterial blight, black spot. Disease diagnosis is mainly harmful to leaves, petioles, and can also be harmful to flowers. The leaves are diseased, with small yellow spots at the beginning, which become round and irregularly shaped lesions after expansion, and the middle of the lesions is dry and cracked due to water loss, and there are irregular yellow halos around it.

When the disease is severe, the leaves are covered with diseased spots, causing the leaves to dry up and die. The petiole is diseased, producing dark brown and strip-like lesions, and when it is severe, the leaves are inverted from the lesions, wilting and dying. After the onset of flowers, many of them wither and die.