What is the disease of cucumber leaves that are wine like and yellow?

Cucumber has this symptom due to several reasons, not one.

Cucumbers often find that there are many problems in the process of planting, among which cucumber yellowing is one, so what is the reason for cucumber yellowing? How can we prevent it? Let's take a look!

1. External environment.

Cucumbers are sensitive to changes in the external environment, and during the planting process, sudden changes in temperature, humidity and light will cause cucumbers to be unable to adapt in time. If it is not in the appropriate range of cucumbers, the photosynthesis of cucumber leaves is insufficient, resulting in a decrease in nutrient accumulation and yellow leaves.

Solution: Control the surrounding environment when planting, and control the temperature at about 28 degrees during the day and about 16 degrees at night. The humidity should also be kept at about 80%, not too high or too low, to meet the light needs of cucumbers and improve the photosynthesis of cucumbers.

2. Overwatering.

Cucumbers prefer water, but many friends do not control the amount of watering when watering, and water blindly. It leads to excessive water in the field, which causes the roots of cucumbers to be rooted, resulting in yellowing of leaves, especially the yellowing of the top leaves, the growth rate is slow, and in severe cases, wilting and death.

Solution: When planting, it is necessary to control the watering, keep the soil moisture content at about 88%, although cucumbers like moisture, but too much humidity will cause various pests and diseases. Therefore, when we water, we should water more and a small amount as the principle to prevent too much water from affecting the growth of cucumbers.

3. Excessive fertilization.

Although cucumbers like fertilizer, they also have a limit to fertilizer, and excessive fertilization will easily cause cucumbers to grow. The permeability of the field decreased, which affected the photosynthesis of the internal leaves, resulting in the yellowing of the leaves due to insufficient nutrition. And it can also cause fertilizer damage, causing harm to cucumber plants.

Solution: We need to strictly control the frequency and amount of fertilizer used, and adjust it according to the different growth stages of cucumbers. For example, potassium fertilizer is the main fertilizer in the middle and late stages, and the nutrient ratio of fertilizer is balanced, and it is applied every half a month or so.

Apply about twice at the seedling stage, try to use water-soluble fertilizer with fertile leaves, and then apply plantar fertilizer before planting, and do not apply a single fertilizer.

4. Lack of nutrients. The nutritional requirements of cucumbers are relatively comprehensive, and many growers do not pay attention to the use of trace elements, such as iron, zinc and boron, when fertilizing. Trace elements are very important for the growth of cucumbers, if they are missing, they will affect the growth of cucumbers, reduce the quality of cucumbers, and cause yellow leaf phenomenon.

Solution: When fertilizing, do not apply basic fertilizers such as nitrogen, phosphorus and potassium, and spray foliar fertilizers according to the specific growth of cucumbers. Provide complete nutrients for cucumbers, meet the various nutrients required for cucumber growth, improve cucumber quality, and enhance disease resistance.

Reduces yellow leaf phenomenon.

The causes of cucumber yellow leaves are also the harm of pests and diseases, which will harm the leaves of cucumbers, resulting in the growth and development of leaves being hindered, and there is no sufficient nutrients to cause the phenomenon of yellow leaves.

Yellowing leaf curl virus, spraying biological pesticide 30% suspension, three times is almost the same, it should almost stop growing!

Spray fungicides, such as amicida, mancozeb, etc.

The cucumber trees are weak and the leaves are yellow, what's going on?

First, it is mainly downy mildew, the resistance is different in various places, it is recommended to choose one or two mixtures of enoylmorpholine, manganese zinc frost urea, downy mildew hydrochloride, manganese zinc methyl frost, manganese zinc sulfaline, flumorpholine manganese zinc, cyanofrostazole, fluoroether amide and other ingredients to choose one or two mixtures (in severe cases), alternately.

If it is a protected greenhouse, pay attention to controlling the humidity, and on rainy days, it is recommended to use chlorothalonil fogging agent to control the condition. ）

Prevention first, comprehensive prevention and control (prevention of diseases, dosage reduction). Use pesticide ingredients alternately, and do not use the same pesticide ingredients consecutively. This is the principle of crop protection.

Second, it is recommended to mix bacterial pesticides such as streptomycin or mesomycin or thiamethone or chunleimycin or thiazolezinc and so on to prevent and control bacterial diseases.

Because the situation in the field is complex, you can't just look at the symptoms of a few leaves. It's important to take precautions.

Cucumbers are missing elements, and it's better to put a little fertilizer and mix fertilizer.

No nonsense, you're too hard under the fertilizer.

1. Climatic factors.

There are many rainy days in spring, and the light is insufficient, and the air damage in the shed can cause cucumber yellow leaves. Prevention and control measures: timely curtain ventilation, light and elimination of harmful gases, and foliar spraying chitin mixed with full nutrient leaf fertilizer to maintain leaves.

2. Lack of nutrients. The low temperature in spring, the poor vitality of the root system, the nutrients absorbed by the root system are not enough to meet the needs of cucumber plant and fruit growth, or it may be that the trace elements of the nutrient solution prepared by themselves are insufficient, thus causing cucumber yellow leaves. Element-deficient yellow leaves are divided into two situations: middle and lower old leaf yellow and middle and upper young leaves first yellow

1) The middle and lower leaves are yellow, and most of the missing elements are the elements that are easy to be reused in the plant, such as nitrogen, magnesium, potassium, zinc, etc.

The growth of the whole plant is resisted, and the whole leaf lacks green first, which is nitrogen deficiency. The control countermeasure is foliar spraying of urea solution2-3

There was no obvious inhibition of plant growth, and the leaf margin was green necrosis, and sometimes there were green necrosis spots on the leaves, and potassium deficiency. The control countermeasure is to spray potassium dihydrogen phosphate solution 2-3 times.

There is no obvious resistance to plant growth, and the whole leaf has green to necrotic spots or streaks, which is zinc deficiency. The control measure is foliar zinc sulfate spray.

2) The middle and upper young leaves are yellow, and most of the missing elements are the elements that are not reused in the body, such as calcium, sulfur, iron, etc.

3. Infectious diseases.

1) Downy mildew: Downy mildew is a common and serious disease during the growth period of cucumbers. At the seedling stage, the leaves turn green and yellow, and finally die.

At the adult stage, the leaves are diseased, and they begin to appear water-stained yellow round spots on the back of the leaves, especially in the morning, and gradually develop into yellow-brown polygonal lesions with yellow-green edges. Under high temperature conditions, a gray-brown mold layer grows on the back of the lesions, and in severe cases, the lesions become patches, the whole leaves are yellow-brown, and the leaf margins are curled and wilted. Prevention and control measures:

Foliar spray with 500 times of Ruixinhua, manganese zinc 58% WP or 75% chlorothalonil WP and 50% lysobacterim WP600 times, once every 7 days, generally 3-4 times can be sprayed.

2) Fusarium wilt yellow leaves: the leaf color gradually changes yellow-green to yellow-brown, and gradually expands to the whole plant from bottom to top. The main vine near the ground is brown and water-stained and rotten, thinning or longitudinally cracked, gradually drying up, and the whole plant is dead.

Amber gelatinous flows out of the diseased part of the rhizome, and when the temperature is high, white or pink mold is produced on the surface, and when the stem or taproot is broken, the inside can be seen to turn brown. Irrigate the roots with 50% carbendazim WP500 times, or 50% WP500 times solution of methyl tobujin, not less than 250ml of each plant, once in 5-6 days, and 2-3 times in a row.

Like fertilizer, is it raw manure used?

This is an obvious deficiency of nutrients, the reason for the lack of trace elements, should be used in a timely manner in micro fertilizer seedlings to produce wealth trace element water-soluble fertilizer, supplement cucumber calcium, zinc, boron, molybdenum, copper and other trace elements, promote the healthy growth of cucumber roots, stems, leaves, regulate their own nutrient absorption balance, prevent and control due to insufficient nutrient supply, nutrient imbalance caused by the occurrence of local yellowing and serious dry death of leaves.

1. Cucumber care skills.

1.Temperature. Likes warmth and is not tolerant of cold. The fertility temperature is 10 32. Generally, 25 32 during the day and 15 18 at night grow best; The most suitable ground temperature is 20 25, and the lowest is about 15.

The optimal temperature difference between day and night is 10 15. Cucumber high temperature 35 poor photosynthesis, 45 high temperature obstacles, low temperature -2 0 freeze to death, if low temperature refining seedlings can withstand 3 low temperature.

2.Illumination. South China varieties are more sensitive to short days, while North China varieties are less strict about the length of sunshine and have become sunshine neutral plants. Most varieties grow well in 8-11 hours of short daylight.

3.Moisture content. Cucumbers have a high yield and a large water requirement. The suitable soil moisture is 60 90%, the water at the seedling stage should not be too much, the soil moisture is 60 70%, and sufficient water must be supplied at the fruiting stage, and the soil moisture is 80 90%. The suitable air relative humidity of cucumber is 60 90%, and excessive air relative humidity is easy to get sick and cause yield reduction.

4.Soil. Cucumbers like moisture but not waterlogging, fertilizer but not fertilizer, and it is advisable to choose fertile soil rich in organic matter. Generally prefer soil between pH, but pH is the best.

Second, the value of cucumbers.

1.Ornamentation: Plant a cucumber on the balcony, not only as a green plant for ornamentation, but also to see small yellow flowers, and then see small cucumbers.

2.Edible: Cucumbers are ripe in summer, picked, eaten raw, and served cold, which are one of the ways to escape the heat and fight the summer heat to the end.

3.**: Cut the cucumber into thin slices and apply it to the face to experience coolness and achieve the effect of skin care.

At present, there are two kinds of common leaf spots on cucumber leaves, one is polygonal, and a lot of black mold can be seen on the back of the leaves, which is called downy mildew. There is also a disease spot that is nearly round and tends to break when there is a lot of rain, and this is anthrax.

Cucumber downy mildew - causes yellow spots on the leaves.

It can occur at both seedling and adult stages. It is mainly harmful to leaves. The cotyledons are yellowish at first, and then turn yellowish brown after enlargement.

True leaf infection, leaf edge or leaf back of the appearance of water-soaked lesions, especially in the morning, the lesions gradually expand, limited by the leaf veins, polygonal light brown or yellow-brown patches, when the humidity is high, the back of the leaf or the leaf surface grows gray-black mold layer, that is, the pathogen sporangia and sporangia. In the later stage, the lesions are cracked or connected, causing the leaf margins to shrink and wither, and the serious fields are yellow. The symptoms of the disease are related to the disease resistance of the variety, and the susceptible varieties such as dense thorns show typical symptoms, with large lesions, easy to connect into large macules and then dry up quickly; Disease-resistant varieties such as Jinyan and Jinhezi have dark green series of leaf color, small lesions, long duration of green spots, formation of round or polygonal yellow-brown spots on the leaf surface, slow expansion rate, sparse or very little mold on the back of the lesions, generally 7-12 days later than the former.

Cucumber anthracnose - causes the leaves to have yellow spots.

Cucumber anthracnose can be diseased from seedlings to adult plants, and seedlings are diseased, mostly on the edge of cotyledons, semi-oval light brown lesions, with orange-yellow dotted gum; Adult leaves are infected, the lesions are nearly round, 4---18 mm in diameter, grayish-brown to reddish-brown, and in severe cases, the leaves are dry; The stems and petioles are infected, the lesions are oval or oblong, yellowish-brown, slightly concave, and in severe cases, the lesions are connected, around the stem, and the plant dies; The melon strips are infected, the lesions are nearly round, pale green at first, and then yellowish-brown, the lesions are slightly concave, there is pink sticky material on the surface, and the later stage is cracked.

Pest and disease control.

There are many cucumber diseases and insects. The blight, downy mildew, wilt, anthracnose, powdery mildew, etc., which have a greater impact on yield and quality, and the insect pests mainly include cucumber, aphid, American banshi fly, etc. Cucumber blight is a devastating disease.

In southern China, cucumber occurs seriously in spring, and low-lying land and high-temperature, rainy and humid weather are the most prone to disease and cause serious epidemics. The internodes of the main stem of the susceptible plant reappear with water-stained lesions, and then the wet rot and shrinkage around the stem, the vines and leaves above the diseased part wilt, and the melons and fruits rot, resulting in the death of the whole plant.

Cucumber gray mold.

Downy mildew is mainly transmitted by air currents, with frequent infestation, short incubation period and strong parade nature. It mainly harms the leaves, forming yellow or light brown polygonal disease classes, and there is a purple gray mold layer on the back of the leaves. This disease is more common in low-lying, poorly ventilated, and overwatered places, and the yield of cucumbers cultivated in facilities is often lost.

Fusarium wilt mostly occurs in the flowering and fruiting stage, and the diseased plants grow slowly, and the lower leaves turn yellow, and gradually develop upward. The disease is not significant at the beginning, wilts at noon, recovers in the morning and evening, and then withers and dies after several days. The occurrence of this disease is serious, and the prevention and control effect of pesticides is poor, which often affects the yield in the later stage.

Anthrax is severe in the hot and wet season. The onset temperature is 10 -38, and 22 -27 is the most suitable, and cucumber bacterial horn spot is the most suitable.

The disease can occur from seedling stage to adult plant stage, mainly with mycelium or sclerotia overwintering in the field on seeds or diseased plants. In early spring, the temperature in the facility shed is low and the temperature is high, and the leaves often have water droplets, which is most likely to be epidemic at this time, and the disease is more serious in the open field from May to June. In addition, continuous cropping, excessive nitrogen fertilizer, flood irrigation, poor ventilation, and plant weakness are prone to serious diseases.

Powdery mildew mostly occurs in the middle and late stages of growth, and the earlier the onset of the disease, the greater the loss. It mainly harms leaves, and the field temperature is large, and it is very easy to epidemic when the temperature is 16 -24. The disease is more serious.

Comprehensive control should be adopted for cucumber diseases. The first is to select disease-resistant varieties, our province uses Zaoqing No. 2 and No. 3 in spring, and Xia Qing No. 4 and No. 5 and other new varieties with specific resistance in summer and autumn, which can reduce the number of spraying times and increase yield; The second is a reasonable rotation, taboo.