cardinal symptom
Under humid conditions, a dense gray mold layer appeared on the back of the leaves, that is, conidiophore and conidia of pathogenic bacteria.
morphological character
The daughter seat is densely conidiophore, knee-shaped with 0 ~ 6 septa. Conidia are nearly colorless or light brown, cylindrical or inverted rod-shaped, straight or slightly curved, with a blunt end, the size of 14 ~ 80× 3 ~ 6 (um), and the length varies greatly.
Prevention and cure method
(1) After harvesting, carry out deep ploughing and crop rotation.
(2) spray 1000 ~ 1500 times of 50% carbendazim (carbendazim plus wanjunling) wettable powder or 600 times of 75% chlorothalonil wettable powder, 500 ~ 600 times of 50% mixed sulfur suspending agent, 400 times of 30% basic copper sulfate suspending agent and 65438 times of 75.
How is the potato leaves turning yellow? Judge and take measures according to the following conditions:
1, lack of yellow, mainly concentrated in the old leaves or new leaves, no macula will be more uniform; Immediately apply quick-acting fertilizer and compound fertilizer, and if the new leaves turn yellow, apply fertilizer containing iron and manganese.
2. Waterlogging, mainly manifested as yellowing of leaves and stems, yellowing and blackening of near-ground bases, and blackening and rotting of roots after digging out; Trenching and drainage shall be carried out immediately.
3, disease, black due to bacterial infection, usually accompanied by obvious macular. Spraying fungicides, such as mancozeb or thiophanate-methyl, should be selected.
If you can't judge for yourself, you can go to the township agricultural service center or the township store that sells pesticides and knows the technology, or go to the county agricultural bureau for consultation (with yellow potato plants).
What are the rust spots on beans? Have you been away too long?
What's the matter with rust spots on radish leaves? Radish is a negative plant, and the suitable temperature in wet winter is 10-20 degrees, so the house should not be hot and dry. To ventilate and humidify, you can put the radish in a ventilated place, spray water on the leaves twice a day and water it once with 0. 1% ferrous sulfate solution. In addition, wipe the leaves with water soaked in cigarette butts once to ensure that they will dry. After buying the green radish for more than half a year, it is necessary to change the soil and fertilize it. It depends on wet and dry watering, usually twice a week.
What happened when the potato leaves were rolled? (pictured) Hello! Caused by high temperature and water shortage.
Why are there yellow spots on the bean leaves? Brown spot disease
Mainly occurs on leaves. In the early stage, the lesions were round or oval purple-brown lesions with different sizes, and in the later stage, they were black to dark black, and the boundary between the diseased part and the healthy part was obvious. In the later stage, the center of the lesion turned light gray with black spots. In severe cases, most of the diseased spots are connected together, and the diseased plants wither in turn from the lower leaves, leaving only 2-3 leaves in the upper part. Other diseased leaves are black, dry and fall off, which affects flowering. Such as chrysanthemum brown spot (also known as leaf blight), is a common leaf disease in potted and open chrysanthemum cultivation in various places. Some lesions are round or nearly round, brown or dark brown, with black particles on them, that is, conidia of pathogenic bacteria.
Occurrence law
Pathogens overwinter in dead leaves or soil with hyphae and conidia. It can be spread by wind and rain, irrigation and man-made, and it can be harmful from spring to autumn. It's rainy in autumn, and I'm seriously ill. High temperature and humidity, too dense plants and continuous cropping of soil are all conducive to the occurrence of diseases. From August to September, chrysanthemum cultivated on land suffered the most. If the soil moisture is high, the drainage is not smooth, the illumination is insufficient, and the plant growth is not robust, the disease will be more serious.
Prevention and cure method
(1) Remove diseased branches and leaves in time, burn or bury them centrally, and reduce the source of germs.
(2) Strengthening cultivation management, shaping and pruning to make the plants ventilated and transparent; Potted soil needs new soil every year.
③ At the early stage of onset, 50% carbendazim wettable powder 500 times, 65% zineb 500 times or 75% chlorothalonil 500 times were sprayed 1 time every 7-l0 days for 3-4 times.
What's the matter with rust spots on the flying grass? Diagnosis and control measures of yellow leaf disease
During the growing period of potted plants, the leaves often turn yellow. The reason is mostly due to improper cultivation management. Here are some "yellowing" phenomena.
1. Long-term waterlogging of soil in the Yellow River Basin leads to soil hypoxia, which weakens the ability of some roots to rot and absorb water and fertilizer. It is characterized by dark yellow leaves, atrophy of the top of new shoots and small yellow-green branches. In this case, we should loosen the soil, control watering and stop fertilizing. In severe cases, we can take off the pot and put it in the shade to dry the soil balls and put them in the pot.
2. The yellow leaves caused by excessive fertilization or high concentration, especially the biased application of nitrogen fertilizer, show that the new leaves are thick and shiny, but the leaves are uneven and the old leaves gradually turn yellow and fall off. At this time, fertilization should be stopped, the amount of watering should be increased appropriately, and nutrients should be diluted. Potted flowers are short of fertilizer and water, or a big pot is small, and the roots in the pot are aging or too dense, which will also make the leaves of flowers and plants thin and yellow. At this time, it is necessary to change pots and soil, usually from rainy to long summer.
3. Alkaline yellow potted flowers, such as camellia, Milan, Michelia, Rhododendron and Jasmine. Due to the alkaline reaction of soil, they often lose their green and yellow colors. It is manifested in the veins starting from the new leaves at the branches, while the veins, especially the main veins, remain green and the yellow-green phenomenon is very obvious. With the aggravation of yellowing, the veins gradually turn green, then the whole leaves turn white, the leaves are scorched, the leaves wither, and in severe cases, the branches wither and the whole plant dies. For this "yellowing" phenomenon, acid fertilizers or acidic substances can be used to improve it, and alum fertilizer can also be used frequently.
4. Flowers as dark as sunlight often turn yellow due to insufficient indoor light. At this point, pots and pans should be moved to outdoor ventilation and lighting. For semi-negative flowers, such as asparagus, leaves will turn yellow under strong light, so to avoid exposure to high temperature and strong light in summer, they should be moved indoors or stored in a light-proof shed.
5, drought and yellowing Due to long-term non-watering, or less watering, the leaves turn yellow or brown ends and brown edges appear, and the old leaves fall off from bottom to top. However, new leaves generally grow normally, so when this happens, water should be added to make the soil no longer short of water.
6. Burning yellow likes wet potted flowers, such as chlorophytum, evergreen, Hosta, etc. If exposed to strong direct sunlight, leaves also have brown ends and brown edges. If this happens, put the jar in the shade.
7, hot and humid yellowing Some potted flowers that are not resistant to high temperature and high humidity, the leaves are yellow due to poor ventilation and improper shading in midsummer, such as hanging bell begonia, this phenomenon occurs in summer. Therefore, high temperature and high humidity can easily lead to yellowing of leaves, which can be prevented by paying attention to ventilation and cooling, and the soil in the basin should not be too wet.
What's the matter with rust spots on the green radish and yellow leaves? Long rust spots may be brown spots. If the yellow leaf is an individual phenomenon, it is an old leaf, which may be normal metabolism. If they are frozen, yellow leaves will appear.
What's the matter with rust spots on poplar leaves? 1) poplar black spot.
Poplar black spot, also known as poplar brown spot, is distributed in Liaoning, Jilin, Heilongjiang, Hebei, Henan, Xinjiang, Jiangsu and other provinces (regions). The pathogen can infect many poplars, such as Populus simonii, Populus euphratica, Populus tomentosa, Populus euphratica and Populus euphratica. Seedlings, young trees and big trees are prone to diseases, which will seriously affect the normal growth of trees and cause economic losses.
Symptoms: The disease generally occurs on leaves and tender shoots, mainly damaging leaves. At the early stage of the disease, pinhead-shaped concave and shiny spots appeared on the back of the leaves, and then the lesion expanded to about 1mm, with black slightly protruding and brown spots on the front of the leaves. After 5-6 days, the center of the lesion (the front and back of the leaf) appeared milky white spots, that is, pathogen conidia piles, and then the lesion expanded into large pieces.
Symptoms of poplar black spot disease
Pathogenesis law: the bacteria overwinter in the diseased spots of fallen leaves or branches. In May and June of the following year, the conidia newly produced by the pathogen spread with the wind, landed on the leaves and invaded the leaves through stomata. Symptoms appear in 3-4 days, abscess forms in 5-6 days, and infection occurs again. From the first ten days of July to the first ten days of August, if it is hot and rainy, the terrain is low, and the planting density is too high, the disease will be the most serious, and it will stop at the end of September. The severity of the disease in 1996 is related to rainfall, with more serious and less serious .19996.999999999999996 When the temperature and rainfall are suitable, conidia piles will be produced soon, which can promote new infection.
Preventive and control measures:
1, tobacco machine control. Smoke control with a smoke machine should focus on tall trees. The medicine can be 8% chlorothalonil smoke agent or 2.5% fluorosilicone oil smoke agent, and the control time should be controlled at 5-7 am or 18-20 am in windless weather.
2, crown spray prevention and control. At the latest, before the initial infection of the disease, spray 200 times Bordeaux solution, 600 times 70% mancozeb solution, 700 times 50% carbendazim solution or 1000 times 70% thiophanate methyl solution on seedlings and young trees for 2-3 times to control the spread of the disease. When spraying medicine in rainy season, 0.3% gelatin (or bean powder juice and soybean milk) should be added to the medicine to prevent it from being washed away by water.
3. Strengthen forest management. Increase the application of organic fertilizer and soil miscellaneous fertilizer, improve ventilation and light transmission conditions, enhance tree potential and improve tree disease resistance; After the rain, the accumulated water in the forest land should be eliminated in time; Clean and treat diseased leaves and fallen leaves at any time to eliminate pathogenic bacteria.
(2) Gray leaf spot of poplar
Poplar gray leaf spot harms many kinds of poplars, from seedlings, young trees to big trees. Seedling stage and young trees are most seriously affected. The disease can cause early defoliation, top death and cadre ulcer, and the growth of poplar is obviously reduced. In severe cases, it can lead to the death of seedlings and the survival rate of transplanting is low.
Symptoms: the disease occurs on leaves and shoots, with waterlogged spots on the leaves and dark green protrusions on the later spots, that is, the sessile spots of the bacteria. The top of seedlings and young trees died and turned black after disease, and they lost their support and drooped. The occurrence of diseases is closely related to rainfall and air humidity. The hot and rainy weather in June and July is easy to cause diseases, especially in nurseries and young trees.
Poplar gray spot disease
Law of occurrence:
The pathogen overwinters on diseased leaves, diseased branches and diseased spots of cadres as agaspore and conidia. The germination rate of conidia is over 50% after overwintering, which is the primary source of infection in spring. Another infection may occur many times a year. The occurrence of diseases is closely related to rainfall and air humidity. Generally, after every obvious rainy weather, there will be a peak of leaf flying, and a peak of leaf disease will appear a week later. In rainy season, the incidence of leaf diseases increases.
Preventive and control measures:
1. Cultivation management measures: do a good job in soil preparation and drainage of nursery and afforestation land; Appropriate sparse planting, increase the ventilation and light transmission of nursery and woodland.
2. Chemical control: When the disease is serious, chemical control should be carried out from mid-May to early July, and 400 times of 50% carbendazim wettable powder, 500 times of 50% thiophanate methyl and 500 times of 75% chlorothalonil can be used.
Three, poplar leaf rust
1. Chinese white poplar rust
Symptoms: During the spring leaf spreading period of Populus tomentosa, the diseased winter buds germinate 2-3 days earlier than the healthy buds, forming yellow hydrangea-like diseased leaves. The seriously damaged diseased leaves will dry up in about 3 weeks. After the leaves of normal buds are invaded, scattered yellow powder piles are produced on the back of leaves, that is, summer spore piles of pathogens. In severe cases, the summer spore piles can be combined into large blocks, and the back of the diseased leaves is raised. The invaded leaves shed their leaves early, and when they are serious, they form large withered spots or even die.
After the buds are damaged, ulcer spots appear on them. In cold areas, brown, nearly round or polygonal blisters can be seen on diseased leaves in early spring, which are the winter spore piles of pathogens.
Symptoms of summer spore accumulation in poplar leaf rust.
Pathogenesis: Pathogenic bacteria overwinter in the ulcer spots of winter buds and branches as hyphae. The invaded winter buds can't unfold normally, forming deformed leaves covering summer spores, which become the primary source of infection. The first peak appeared in May-June, and a small peak appeared in autumn. The incubation period of the disease is closely related to temperature and leaf age.
Preventive and control measures:
(1) Breeding of disease-resistant varieties.
(2) In the early Qing Dynasty, the source of disease and diseased leaves were removed.
(3) Chemical control: 50% triadimefon 100 times solution and 50% bactericide 500- 1000 times solution inhibited the germination of summer spores.
(4) Biological control: Alternaria, Trichoderma and other fungi inhibit the germination of summer spores.
2. The pathogen of poplar leaf rust (larch-poplar rust)
Larch-poplar leaf rust is the most widely distributed disease in poplar rust, with the largest number of host species and the greatest loss. It has been reported in nearly 40 countries and regions, covering all continents except Antarctica, and its harm can be seen in almost all places where poplars are used. The disease can occur from seedlings to adult trees, but seedlings and young trees are more seriously affected, which is one of the common diseases in nurseries and young forests.
Symptoms: On larch, at first, there is a short green spot on the needles. On the upper surface of this green dot, you can see an orange pimple with dark brown spots on it with a magnifying glass, which is the sex spore organ of the pathogen. The lesion gradually turned yellow-green, accompanied by swollen blisters. There is a yellow powder pile on the lower surface of the leaf spot, and the needles die in severe cases.
There are light green spots on the back of poplar leaves, and orange blisters soon appear. After the blisters burst, yellow powder was scattered, which was a pile of summer spores. In early autumn, polygonal rust-red spots appear on the front of the leaves, and sometimes the rust spots are connected together, that is, the pathogen winter spore pile.
The disease usually starts from the lower leaves and gradually spreads upward.
Development law: In early spring, the winter spores on the fallen leaves of poplar diseases germinated in the water or moisture of the previous year, producing basidiospores, which spread to larch with the airflow. After 7- 10 days of incubation, yellow rust spores accumulated on the back of leaves. Rust spores do not infect Larix gmelinii, but germinate on poplar leaves as hosts and invade the leaves through stomata. After 7- 14 days of incubation, yellow-green spots appeared on the front of leaves, and then yellow summer spore piles formed on the back of leaves. Summer spores can repeatedly infect poplars, and rust is often rampant in July and August. After the end of August, a pile of winter spores were formed on the diseased leaves of poplar, and they wintered with the diseased leaves. After winter, the germination rate of summer spores is only 0.3%, so it has no practical effect on infection.
There are obvious differences in disease resistance of tree species: Larix gmelinii and Larix olgensis can get sick, but it is not serious; Populus euphratica, Populus euphratica and Populus euphratica are seriously ill; Mink poplar, Hezuo poplar and Beijing poplar are moderately susceptible; Plus poplars, healthy poplars and newborn poplars all have certain disease resistance; Populus davidiana, Populus Xinjiang and Populus Golgi have the strongest disease resistance. Small trees are more likely to get sick than big trees, and young leaves are more likely to get sick.
Preventive and control measures
1. Nursery management: No mixed forest of larch and poplar, at least no mixed forest of the same age.
2. Chemical control: In the nursery, spray Bordeaux solution on larch seedlings at the end of April and spray Bordeaux solution on poplar trees in summer. Commonly used spray agents are: chlorothalonil, 50% carbendazim 500 times solution, 50% tobrazine 800 times solution, 70% methyldopa phenobutylamine 1000 times solution, 50% special sterilization 500 times solution, triadimefon 1500 times solution, sulfur mixed solution with Baume 0.3 degree, 65. 2- iodobenzoyl aniline was used abroad to prevent and treat the disease, and the effect was good.
3. In order to prevent the seedlings from growing too dense or too long, the seedlings should be thinned in time. When the leaves are too dense, the basal leaves should be ventilated to reduce humidity, control nitrogen fertilizer and improve disease resistance.
4. Cultivate rust-resistant tree species.
How is there a black spot on aloe leaves? How to treat it? Pathological changes occurred, either too much water led to root rot, or there was something wrong with the soil.
Better change the soil. If you water it too much, loosen the soil to dry.