Which kinds belong to agricultural diseases, and what are the characteristics of agricultural pests

There are many types of plant diseases, which can be divided into two categories according to the types of pathogens, one is that non-infectious diseases include those caused by abiotic elements, such as lack of nutrients, insufficient or excessive water, freezing damage at low temperature and burning disease at high temperature, unreasonable use of fertilizers and pesticides, or drug damage and poison caused by waste water and waste gas; The other category is infectious diseases, including those caused by organisms, infectious, and a variety of pathogens, such as fungi, bacteria, viruses, nematodes or parasitic seed plants.

Among the infectious diseases of crops, there are mainly fungal diseases, bacterial diseases, viral diseases and nematode diseases. Among them, fungal diseases account for about 80% of the diseases. There are many types and types of fungal diseases, and the symptoms caused by the diseases are also ever-changing.

However, all fungal diseases, no matter where they occur and what the symptoms are, hyphae and spores are produced under humid conditions, which is the main basis for judging fungal diseases. The main manifestations of bacterial diseases are: necrosis and decay, wilting and deformity.

Necrosis, decay and deformity are all caused by bacterial infection and destruction of cells and cell wall tissues.

Most of the crop diseases are caused by bacterial and bacterial infections, such as soft rot, canker, bacterial wilt, etc. The bacteria that invade plants are rod-shaped bacteria, most of which have one to several flagella, which can invade through natural orifices (stomata, skin pores, water holes, etc.) and wounds, spread by running water, rainwater, insects, etc., and spend the winter in diseased residues, seeds, and soil, and are prone to disease under high temperature and high humidity conditions. The symptoms of bacterial diseases are wilting, decaying, perforation, etc., and in the later stage of the disease, in wet weather, bacterial mucus overflows at the disease site, which is the characteristic of bacterial diseases.

As we all know, there are many kinds of pests, many pests make farmers feel miserable in the process of agricultural production, and often how to control them and rack their brains, so what are the common pest species? What are their characteristics?

1. Grasshoppers. Grasshoppers, herbivorous insects with chewing mouthparts. The tentacles are short whip-shaped, have powerful hind legs, and can use bounces to avoid predators.

The body color is green and brown, which is the protective color of the living environment. There are more than 12,000 species of grasshoppers in the world, distributed in tropical and temperate grasslands and deserts around the world.

2. Red spiders.

Red spider, also known as cotton red spider, commonly known as big spider, big dragon, sand dragon, etc., scientific name leaf mites, the species of our country are mainly cinnabar leaf mites, belonging to arachnids, ticks, leaf mites. It is widely distributed and has a miscellaneous diet, which can harm more than 110 kinds of plants.

3. Bean worms. The adult insect of the bean insect is called the bean moth, which belongs to the genus Bean Moth of the subfamily of the Lepidopteran Mothaceae, and the growth cycle occurs in 1 year from 1 generation (Hebei, Shandong, Jiangsu, Anhui) to 2 generations (Wuchang, Hubei, Nanchang, Jiangxi), mainly feeding on the leaves of soybeans, acacias, black locusts and honeysuckle and other plants.

Fourth, diamondback moth.

It is mainly cruciferous plants such as cabbage, purple cabbage, broccoli, cabbage, mustard greens, cauliflower, cabbage, rape, and radish. Characteristics of the pest: the first instar larvae only feed on the mesophyll, leaving the epidermis, forming transparent spots on the leaves, "opening the skylight", 3 4 instar larvae can eat the leaves into holes and nicks, and the whole leaves are eaten into a net when it is serious.

At the seedling stage, the central leaf is often harmed, affecting the core. On the retained seeds, it harms the young stems, young pods and grains.

5. Aphids. Aphids are also one of the most destructive pests on the planet. About 250 of these are pests that are serious for the agroforestry and horticulture industries. Aphids vary in size, ranging from one to ten millimeters in length.

Sixth, thrips. Insects of this family are widely distributed all over the world, and their feeding habits are complex, mainly including herbivorous, fungivorous and predatory, of which phytophagous accounts for more than half, and is one of the important economic pests.

To sum up, some of the more common agricultural pests for farmers and friends, and some of their characteristics for everyone, of course, in addition, scale insects, psyllids, brown planthoppers, corn borers, Spodoptera litura, codling moths, etc., are also more common types of pests.

Crops are infected by pathogens that cause root necrosis or cause plant vascular bundles to be blocked and prevent the upward transport of water, so that crops lack water and cause plant wilting, which often causes plant death after several repetitions, and some symptoms can be alleviated mildly. Such as the wilt of cotton and eggplant, the wilt of corn, etc. There are three main symptoms caused by fungal diseases, so what are the types of plant diseases?

There are many types of plant diseases, which can be divided into two categories according to the types of pathogens, one is that non-infectious diseases include those caused by abiotic elements, such as lack of nutrients, insufficient or excessive water, freezing damage at low temperature and burning disease at high temperature, unreasonable use of fertilizers and pesticides, or drug damage and poison caused by waste water and waste gas; The other type is infectious diseases, including those caused by organisms, infectious, and a variety of pathogens, such as fungi, bacteria, viruses, nematodes or parasitic seed plants.

1. Fungal diseases.

Fungal diseases account for the largest proportion of diseases, and the vegetative body of fungi is mainly hyphae, which grow in the body and outside of plants. When it grows to a certain stage, it will produce spores that continue to reproduce. Fungal diseases are mostly produced in a humid environment that grows mold and powder in the tissues of the host.

Fungal diseases are manifested externally in the form of decay, discoloration, tissue necrosis, wilting deformity, ulceration and cataplexy.

2. Bacterial diseases.

The proportion of plants infected with bacterial diseases is not large, and most of them are acute necrosis. The external manifestations of bacterial diseases are that there will be spots and ulcers on the site of the disease, and there will be water-stained, oil-stained, and bacterial pus on the lesions.

3. Viral diseases.

Viral diseases are mainly caused by viral invasion and infection, and there are many kinds of flowers and plants that are harmed. Symptoms such as clumping, dwarfing, and deformity and necrosis. The virus is mainly transmitted by inhaling plants through the mouthparts of various insects.

4. Physiological diseases.

Physiological diseases are mostly caused by the unfavorable environment, such as high temperature, low temperature, or lack of nutrition, and other external causes, which are manifested in the specific manifestation of the outside of flowers: leaf loss. Fallen fruits, yellowed branches and leaves, etc.

Summary. Dear, the yellowing and withering of melon seedling leaves may be caused by the following reasons:1

Water shortage: If the melon seedlings lack water, it will cause the leaves to turn yellow and dry, and in severe cases, it will lead to the wilting and death of the leaves. Make sure to give the seedlings plenty of water and avoid over-drying or soaking.

2.Excessive fertilization: If too much fertilizer is applied to the melon seedlings, it will cause too many nutrients in the soil, resulting in excessive fertilizer absorbed by the melon seedlings, resulting in yellowing and withering of the leaves, and even deformation of melons and fruits.

Fertilizer should be applied in moderation and avoid too much fertilizer. 3.Pest and disease infestation:

Melon seedlings are often susceptible to various pests and diseases, such as cucumber downy mildew, aphids, etc. These pests and diseases can cause yellowing, withering, deformation, etc. It is necessary to take insect prevention measures in time to protect the growth and health of melon seedlings.

4.Poor soil quality: Soil quality has a great impact on the growth of melon seedlings, if the soil quality is not good, such as too high or too low acidity and alkalinity, lack of certain nutrients in the soil, etc., it may lead to yellowing and withering of melon seedling leaves.

Using good quality soil, adjusting soil pH, and adding an appropriate amount of organic fertilizer and mineral fertilizer are important measures to ensure the growth of melon seedlings.

Crop diseases refer to a class of viruses, bacteria, fungi, protozoa, nematodes and other kinds of pathogens that affect the health and yield of crops. These diseases often cause serious losses in agricultural production and need to be detected and prevented in time. Common crop diseases include rice leaf blight, wheat wild or stripe rust, corn scab, fruit tree anthracnose, etc.

Dear, I think you should not lack water, fertilizer, or over-fertilization.

Dear, the yellowing and withering of melon seedling leaves may be caused by the following reasons:1Water shortage:

If the melon seedlings lack water, it will cause the leaves to turn yellow and dry, and in severe cases, it will lead to leaf wilting and death. Make sure to give the seedlings plenty of water and avoid over-drying or soaking. 2.

Excessive fertilization: If too much fertilizer is applied to the melon seedlings, it will cause too many nutrients in the soil, resulting in excessive fertilizer absorbed by the melon seedlings, resulting in yellowing and withering of the leaves, and even deformation of melons and fruits. Fertilizer should be applied in moderation and avoid too much fertilizer.

3.Pest and disease infestation: Melon seedlings are often susceptible to pests and diseases of various species, such as cucumber downy mildew, aphids, etc.

These pests and diseases can cause yellowing, withering, deformation, etc. It is necessary to take insect prevention measures in time to protect the growth and health of melon seedlings. 4.

Poor soil quality: soil quality has a great impact on the growth of melon seedlings, if the soil quality is not good, disadvantages such as too high or too low acidity and alkalinity, lack of certain nutrients in the soil, etc., may lead to yellowing and withering of melon seedling leaves. Using good quality soil, adjusting soil pH, and adding an appropriate amount of organic fertilizer and mineral fertilizer are important measures to ensure the growth of melon seedlings.

The common pathologies of crop diseases can be grouped into five categories, namely discoloration, necrosis, wilting, rotting and deformity.

1) After the disease, the discolored crop loses its normal green color locally or in the whole plant. If chlorophyll is inhibited or destroyed, greening and yellowing will occur; Anthocyanins are overformed, and the leaves turn red or purple-red, showing red leaves; Some of the leaves are yellow and green, showing flowers and leaves.

2) The cells, tissues or organs of necrotic crops are destroyed and die. The most common type of necrosis after the onset of crops is lesions. Disease spots can occur in multiple parts of crops, such as roots, stems, and fruits.

There are brown spots, black spots, gray spots, white spots, purple spots, etc., and there are more brown spots. The shapes are round, oval, fusiformal, polygonal and irregular.

3) The tissue cells of rotten crop diseases are destroyed and dissolved, and water flows out and decays. Such as root rot, stem rot, fruit rot and ear rot.

4) All or part of the branches and leaves of wilted crops are in a state of water loss and wither and droop. It can be divided into physiological wilting and pathological wilting. Physiological wilting is due to the lack of water in the soil or excessive transpiration at high temperature, so that the plant leaves, top tender stems lose swelling pressure and show atrophy, if the water supply in time, the plant can return to normal; Pathological wilting refers to the vascular tissue of the root or stem of the plant being invaded by pathogens, and a large number of bacteria blocking the ducts or producing toxins, hindering and affecting water transport, causing leaf wilting and yellowing, resulting in verticilla wilt, wilting, or the rapid wilting of plants and the leaves are still green is called wilt, which is mostly unable to recover, and even leads to plant death.

5) Abnormal morphology caused by stunted crop disease tissue or cell growth or excessive proliferation. The common ones are: the internodes of the whole plant are shortened, the tillering increases, and the diseased plants are shorter than the healthy plants, which is called dwarfing, such as rice common dwarf disease; Crop diseased plants grow particularly slender than healthy plants, which is called longevity, such as rice seedling disease; The development of local disease histiocytes is unbalanced, which is common in uneven foliar surfaces, called shrinkage; Crop roots, stems, or leaves that form protruding growths, called warts, such as corn warts powdery mildew.

Those who only know how to treat viral diseases, bacterial diseases and fungi can buy medicines in agricultural stores.

There are 7 kinds of bacterial diseases on crops: bacterial spot disease, bacterial perforation disease, bacterial horn spot, bacterial stem base rot, bacterial streak disease, bacterial blight disease and bacterial streak disease.

When a plant is affected by pathogenic organisms or adverse environmental conditions, its metabolism and physiological functions will be disturbed and destroyed, and a series of pathological changes will occur in the internal physiological function or tissue structure, and the external morphology will show an abnormal state, or even local or whole plant death, this phenomenon is called plant disease.

Plant diseases can be divided into non-infectious diseases and infectious diseases, and there are three types of infectious diseases: fungal diseases, bacterial diseases, and viral diseases.

1) Fungal diseases are the most common and most common plant diseases. Fungal diseases generally produce powdery powder layer, black powder layer, downy mildew layer, rust spore pile, sclerotia, etc., if one of the above characteristics is seen on the diseased plant, it can be preliminarily judged to be a fungal disease.

2) Bacterial diseases are the least common plant diseases, but there are many bacterial diseases that have a serious impact on production, resulting in a large number of yield reductions or field destruction. Bacteria invade through the stomata and wounds of the plant, and the plants after the onset of the disease generally show necrosis, decay or wilting.

3) Plant viral diseases, also known as mosaic diseases, are second only to fungal diseases in the degree of occurrence. Most of the plant diseases caused by viruses are systemic diseases, that is, the whole plant shows yellowing, local or whole plant atrophy, small leaves, small fruits, dwarfing, arbust branches, fern leaf deformities and other lesions and symptoms.

4) Physiological disease is a disease that affects plants due to improper management measures. For example, the leaf color of plants caused by nitrogen deficiency is light green, and the bottom leaves gradually yellow and withered; The old leaves caused by potassium deficiency are brownish green, and there are many small brown spots along the leaf margins.