There is white mold on the back of bitter gourd leaves, what is the disease?

The disease usually begins on the dorsal part of the lower lobe. The initial water-soaked pale yellow periphery is inconspicuous lesion, followed by brown polygonal lesions. When the disease is humid or dewy, white downy mildew grows, so it is called downy mildew.

When the environmental conditions are suitable, the lesions increase rapidly, and the leaves die. The seed collection plant is damaged, the fat is bent into a dragon head shape, and the disease grows white downy mildew. High humidity, large temperature difference between day and night, and long condensation time are beneficial to the onset of the disease.

Continuous rainy weather. Or do not let the wind out after watering. Cultivating too closely or applying nitrogen fertilizer too much will aggravate the disease.

At first, the leaves are scattered with nearly circular white mold, ranging in size from sesame seeds to mung bean grains, and the edges are unclear, and then the mold spots develop into white pink spots, and then fuse with each other, and the leaves are covered with white powder, causing the leaves to turn yellow and eventually dry up. Control methods: Choose disease-resistant varieties. Such as Hunan bitter gourd, Xiangfeng No. 11 bitter gourd, emerald, Suixin No. 1, Xiafeng No. 2 bitter gourd, etc.

In the early stage of the disease, the following agents can be used for prevention and control: 2000 times of mycloconazole emulsifiable concentrate, or 5000 10000 times of fluoromystrobin, or 750 1200 times of 10% difenoconazole water dispersible granules. Characteristics of the leaf are large, round to oval or irregularly shaped, grayish-brown to yellowish-brown, with whorl stripes, on which small black spots are produced.

The lesions of stems and vines are mostly long and irregular, light gray-brown, with small black spots on them, which mostly cause longitudinal cracks of stems and vines, which are easy to break, and form flowing gum when the air is humid, and sometimes stem nodules are formed on the stems and vines of diseased plants. At first, the melon strips were water-soaked small dots, and then turned into irregular and slightly concave yellow-brown spots, and later produced small black spots, and the tissues of the diseased melon strips became worse, easy to crack and rot. Control methods Implement 2 to 3 years of rotation with non-melon crops, and completely eliminate the litter and leaves and residues of melon crops after pulling seedlings; Choose disease-free seeds, or soak seeds in boiling water for 5 10 minutes; Apply fully decomposed manure, appropriately increase phosphorus and potassium fertilizer, strengthen management during the growth period, pay attention to wind, and avoid stuffy sheds after watering.

Seed treatment: Soak the seeds in 55 warm water for 15 minutes, and the seeds can be mixed with 50% of the seed weight of Fumei double wettable powder. In the early stage of the disease, the following agents can be used for prevention and treatment

1500 times of 25% azoxystrobin suspension, or 6000 times of 40% flusilazole emulsifiable concentrate, 1500 2000 times of 40% phenylether pyoxystrobin suspension. Characteristics of damage Yellowish and yellowish round spots appear in the early stage, and gradually expand into nearly round or irregular types, gray-brown to brown lesions with a diameter of about 1 4 hm, and the edges are more obvious. The middle of the lesion is grayish-white, polygonal or irregular, with sparse light black mold on it, which is easily visible when wet.

It is often easy to cause perforation of lesions. <>

This is most likely a symptom of watermelon powdery mildew. The main symptoms of watermelon powdery mildew: this disease mainly harms the leaves, followed by the petioles and stems, and generally does not harm the fruits.

When the environmental conditions are suitable, the pink spots expand rapidly, connect into patches, and become a large powdery area with no obvious edge, which is covered with white powdery mold (i.e., the mycelium, conidia and conidia of the pathogen), and the whole leaf surface is covered with white powdery powder in severe cases. There is less white powder on the petioles and stems. The disease gradually spreads from old leaves to new leaves.

In the later stage of the disease, the white mold layer turns gray due to the aging of the mycelium, and the diseased leaves are yellow and curled, and generally do not fall off. When environmental conditions are not conducive to the reproduction of pathogens or the senescence of the host, piles of small, yellowish-brown dots appear on the lesions, which later turn black (i.e., the closed shell of the pathogen). <

The disease is caused by algal fungi of the oomycetes, and the mycelium or spores and spores of the thick wall overwinter or summer in the soil with the diseased residues, and the spores are transmitted by wind, rain and irrigation water. It is more likely to occur in wet weather, low-lying terrain, poor drainage, or when the temperature reaches 25 28. The blight mainly occurs on the leaves and stems of green beans, which are dark green water-soaked irregular lesions at first, and then turn brown.

In high temperature and humidity weather, a white mold layer grows on the surface of the diseased part. The prevention and control of the disease should pay attention to the implementation of preventive drugs, you can choose copper oxychloride 800 times, mancozeb 1000 times, good life 1000 times spray, spray 1 time at the seedling stage, spray 2 3 times at the flowering and poding stage. In the early stage of the disease, ** agents can be used, such as 1000 times of Redomir, 1000 times of Golden Redomir, 1000 times of alum, and 1000 times of Anker liquid spray.

In addition, diseased plants should be uprooted in time. <>

Hello, this reason is likely to be bitter gourd vine blight, vine blight occurs in the production of bitter gourd in sheds, mainly to damage leaves, stems, and fruits. The leaves are infected with brown round lesions at first, grayish-brown in the middle. The stem vine is infected, the initial lesion is oval or fusiform, and after enlargement, it is irregular, gray-brown, and the edge is brown, when the disease is severe, the crack part of the vine bursts, and the crack opening at the base of the main vine will also flow gray and red gelatinous liquid, commonly known as "bursting blood vessels"; When the lateral vines split, they produce a white oily substance.

In severe cases, the whole plant dies, and the vines turn russet after drying. The fruit is infected with small water-soaked dots at the beginning, and gradually turns into yellow-brown depression spots, and the diseased melons are easy to break in the later stage, and the diseased parts also produce small black spots, and the flesh of the lower part of the diseased spots is mostly "black rot".

Momordica charantia. Onset conditions:

The disease can occur at the seedling stage of the seed with fungus, and if the nitrogen fertilizer is applied in the management process, the disease will be more severe in the shed, and the disease will be more serious when the humidity in the shed is very high.

Prevention and control methods: 1. Grafting control: use loofah as rootstock and bitter gourd as scion.

First sterilize the seeds of the loofah and bitter gourd, sow them in the seedling bowl respectively, and when the loofah grows 3 true leaves, the bitter gourd seedlings or tender shoots that have been cut off the roots are made into ears, and the loofah vines are grafted onto the loofah by tongue grafting, and then cut off the loofah vines after healing. Wait for the bitter gourd to grow 4 true leaves before planting.

2. Crop rotation with non-melon crops: It can be rotated with nightshade vegetables for 3 to 4 years to destroy the living environment of pathogenic bacteria and reduce the number of pathogenic bacteria.

3. Seed disinfection: (1) Soak seeds in 56 degrees warm water until natural cooling, then continue to soak for 24 hours, then germinate at 30 32 degrees, and sow seeds after germination. (2) Soak the seeds with 50% hydrogen peroxide for 3 hours, and then rinse them with water before sowing.

4. Strengthen management: strengthen fertilizer and water management, advocate the use of seaweed fertilizer or active organic fertilizer, increase phosphorus and potassium fertilizer, and recommend water-soluble and fast-acting water-soluble fertilizer, such as water-soluble fertilizer for fertile leaves, which has a good effect of fast absorption. Avoid partial nitrogen fertilization and be careful not to overwater to maximize soil permeability.

For example, the temperature of the shed should be raised to more than 30 degrees for 2 hours, and then the air outlet can play a dual role in ventilation and humidity.

5. Pharmaceutical prevention and control: In the early stage of the disease, it can be sprayed with 800 times of 50% sulfur suspension, 1500 times of copper master wettable powder, and 600 times of 80% spray wettable powder, once every 7 days, 3 times in a row.

Therefore, although bitter gourd is easier to grow, if you want to eat bitter gourd, you must not be sloppy, and you also need to carefully manage bitter gourd seedlings.

The upper leaves are wilting, which is caused by a lack of potassium fertilizer, so you should spray some leaf bread or something.

Lack of fertilizer. Due to the various original brother Chai Huin, the phenomenon of yellowing of bitter gourd leaves often occurs when planting bitter gourd. So, what is the reason for the yellowing of bitter gourd leaves? What should I do if the leaves of the bitter gourd are yellow?

What is the cause of the yellowing of bitter gourd leaves.

1. First of all, the bitter gourd leaves are yellow due to lack of fertilizer. When bitter gourd is deficient in nitrogen, the leaves are smaller, and the upper leaves are smaller. It gradually turns yellow from bottom to top, the internodes near the growth point are significantly shortened, the leaf veins are yellowed, the leaf veins are prominent, and then expand to the whole leaf, with less fruit set, slow expansion, and deformed fruits.

In this regard, it should be topdressed in a timely and appropriate amount, in accordance with the principle of light before, medium and heavy, and after supplementation.

Before flowering and fruiting, the growth of plants is small, and the top dressing should be less; After flowering and fruit setting, gradually increase the amount of fertilizer and water, and in the peak fruiting period, plant growth and melon setting are carried out at the same time, and top dressing should be reapplied. In the later stage of fruiting, the plant begins to senescing, and it should be properly topdressed to prevent and control the premature aging of the plant and affect the growth of the fruit.

2. The second is the yellowing of leaves caused by stagnant water. The root system of bitter gourd is relatively developed, mainly secondary lateral roots, and the regeneration ability is weak, so bitter gourd likes moisture and is not tolerant to waterlogging. The growth period needs about 85% of the relative humidity of the air and the relative humidity of the soil, and it is not suitable to accumulate water, which is easy to make the root system necrosis, rooting, and leaf wilting.

In this regard, after each watering, the field should be prevented from accumulating water for a long time, that is, irrigation and drainage, especially after the rain, it is necessary to pay attention to timely clearing and ditching drainage to prevent water accumulation in the field.

Summary. When bitter gourd grows, if there is a lack of nitrogen, it will lead to fewer leaves, and gradually begin to turn yellow from the lower part of the leaf to the top, and there are obvious shortening symptoms of internodes at the growth node position, the leaf veins are prominent and yellowing, and finally the whole leaf is yellowed. When fruiting, there are few fruit-setting trees, the expansion is slow, and the fruit is easy to deform.

Prevention and control methods: to master the fertilization technology, timely and appropriate fertilization, especially to pay attention to the application of nitrogen fertilizer, fertilization should also pay attention to the amount of fertilization. Before flowering and fruiting, the plant needs less nutrients to grow, so it is advisable to fertilize at this time; After flowering and fruit setting, the amount of fertilizer should be appropriately increased to ensure the success of fruit setting; During the fruiting period, plants need a lot of nutrients for growth and fruiting, so they should be reapplied; As a result, the plant begins to senescent in the later stage of fruiting, and proper fertilization should be applied to prevent premature senescence and poor fruit growth.

When bitter gourd grows, if there is a lack of nitrogen, it will lead to fewer leaves, and gradually begin to turn yellow from the lower part of the leaf to the top, and there are obvious shortening symptoms of internodes at the growth node position, the leaf veins are prominent and yellowing, and finally the whole leaf is yellowed. When fruiting, there are few fruit-setting trees, the expansion is slow, and the fruit is easy to deform. Prevention and control methods:

It is necessary to master the fertilization technology, timely and appropriate fertilization, especially the application of nitrogen fertilizer, and the amount of fertilization. Before flowering and fruiting, the plant needs less nutrients to grow, so it is advisable to fertilize at this time; After flowering and fruit setting, the amount of fertilizer should be appropriately increased to ensure the success of fruit setting. In the fruiting period, it takes a lot of nutrients to plant and grow and bear fruit of cherry trees, so it should be reapplied; As a result, the plant begins to senescent in the later stage of fruiting, and proper fertilization should be applied to prevent premature senescence and poor fruit growth.

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If the shadow is cautious and grows, the parietal leaf is the first to develop, and there are many insect infection rates, it may be a yellow chain fibrillation virus, and the poisonous leaves are cleared.

The yellowing of the leaves of bitter gourd is a symptom of downy mildew.

Downy mildew is an air-borne and epidemic disease, and it is necessary to do the following when preventing and controlling

1) Breeding disease-resistant varieties;

2) Strengthen cultivation management, apply enough organic fertilizer, increase phosphorus and potassium Huai Bureau back lead starvation fertilizer, and imitate dense planting to prevent water accumulation, so as to improve the disease resistance of plants;

3) Timely spraying to control the disease, the agent can be sprayed alternately with manganese zinc, copper and Kairun.