Cucumber leaves with big spots? What should I do if cucumber leaves have yellow spots?

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.

Prevention and control methods: pay attention to timely spraying protection and prevention.

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.

Prevention and control methods: 1. Low temperature and high humidity, poor ventilation and light transmission, humidity above 97%, humidity of about 22-27 degrees, the most prevalent disease, open-field cucumber is easy to mix with bacterial diseases;

2. Choose sandy loam soil with good drainage for planting, and avoid low-lying and poorly drained plots.

This is cucumber bacterial horn spot disease, the main symptom of the lesion does not extend more than the leaf vein, which is the biggest difference compared with downy mildew. If you can't distinguish it, you will be mistaken for downy mildew, so this point is very much worth paying attention to.

Cucumber bacterial horn spot disease should be controlled with agricultural streptomycin to kill bacteria and obtain better control results.

Downy mildew, spraying well-gangmycin, or other fungicides.

It is necessary to strengthen cultivation management, ventilate more, irrigate with small water, avoid flood irrigation, reduce the humidity in the shed, and control the temperature in the shed at 25 -28 during the day, preferably not more than 30. In addition, it is necessary to choose the road agent for timely prevention and control.

Try to avoid pruning and pruning, fruit picking and other agricultural operations in the early morning when the leaves are humid and there is more dew, so as to prevent the spread of pathogenic bacteria with operators or operating tools.

In addition, cucumbers require more water, but they are afraid of stains. Pay attention to watering and drainage in management. After planting, it is necessary to water 1-2 times, properly control the water before setting the melon, increase the amount of watering after fruiting, and the spring open-field cucumber growth is in the rainy season, and the ditching and drainage work should be strengthened.

Prevention and control of yellow spot disease of cucumber leaves:

Because the disease spreads quickly, it is necessary to pay attention to prevention in advance. For prevention, spray Antaisheng 25 grams of bucket water + Jiayuan Yiwei 20 grams of bucket water, once every 7 days, and spray 3-4 times continuously for effective prevention. When the lesions are found, the foliar spray of Haolik 5ml bucket water + Jiayuan Yiwei 30g bucket water + Qibajie effect 5ml bucket water, once every 5 days or so, spraying 3 times in a row can effectively prevent it.

Is there a **? There may be a disease, try the antiseptic medicine.

It may be good to apply potassium dihydrogen dihydrogen to a dot of coate.

1. Reason: cucumber downy mildew, commonly known as "running horse" and "dry leaves", can be damaged by adult plants at the seedling stage, and the main damage is to carry leaves and stems, and the tendrils and flower stalks are less damaged. Downy mildew occurs mainly on leaves.

At the seedling stage, the cotyledons initially appear greenish spots, gradually appear yellow irregular spots, and the back of the cotyledons produces gray-black mold layer when wet, and with the development of the disease, the leaves quickly turn yellow and dry up.

Second, prevention and control measures:

1. Properly control watering in the early stage of the disease, pay attention to enhancing ventilation and reducing air humidity in protected land cultivation.

2. Cultivate disease-free and strong seedlings, increase the application of basal fertilizer, and pay attention to the reasonable combination of nitrogen, phosphorus and potassium fertilizer.

3. Completely remove the fallen leaves of diseased plants after harvesting.

In short, to prevent and control cucumber downy mildew, we must conscientiously implement the plant protection policy of "prevention first, comprehensive prevention and control", and focus on ecological defense and chemical prevention and control on the basis of comprehensively doing a good job in the comprehensive prevention and control of pollution-free and pollution-free pests and diseases in energy-saving greenhouse vegetable cultivation.

Cucumber is a common vegetable that is loved by the general public. However, what to do if yellow spots appear on cucumber leaves? Let me show you how to solve this problem.

First of all, the cause of yellow spots on cucumber leaves is most likely due to a bacterial infection. Therefore, we should take timely measures to control the growth and spread of germs.

Secondly, when choosing seeds and soil, you should pay attention to quality and avoid using inferior seeds and soil, which can reduce the growth and spread of pathogens.

Thirdly, for cucumbers that have already developed yellow spots, we should treat them in a timely manner. Infected leaves can be cut off in time and then incinerated or buried to prevent the germs from continuing to spread, Bili Zhengru said.

In addition, chemicals can be used to control the growth and spread of germs. However, when using chemicals, it is important to pay attention to safety and correct use methods to avoid damage to the human body and the environment.

Finally, in order to ensure the health and quality of cucumbers, we should strengthen the daily management of cucumbers, including regular watering, fertilization, insect control and other measures to ensure the healthy growth and high yield and quality of cucumbers.

In conclusion, the appearance of yellow spots will not only affect the growth of cucumbers, but may also affect the quality and nutritional value of cucumbers. Therefore, we should take timely measures to control the growth and spread of pathogens and strengthen daily management to ensure the healthy growth and high yield and quality of cucumbers.

1. Infected with downy mildew.

When cucumbers are infected with mildew, there will be gray-brown mold on the front and back of the leaves, and gradually start to turn green, and the leaves will slowly turn yellow. The back of the leaf will have a black mold layer. This disease is mostly caused by improper management.

At the beginning of the disease, it is necessary to spray the medicine in time to treat it, and guess that the diseased part will be removed to avoid further infection. In addition, it is necessary to change the maintenance environment, usually ventilate more often, and provide a suitable environment for growth, so that it is possible to recover slowly and avoid further disease.

Second, it is caused by direct blowing of cold wind.

Cucumbers like to grow in relatively warm places, and are not resistant to wind, especially cold winds, otherwise the leaves are easy to lose green after a long time, and yellow spots and white spots will slowly form. Pay attention to the wind when giving it from small to large, not in a hurry, to avoid direct blowing of cold wind. As long as the management is strengthened in the later stage, the plants can still recover slowly.

3. Hypothermia frostbite.

Cucumbers have limited cold tolerance and prefer warm environments. If the temperature provided for a long time during the maintenance period is below 0 degrees, it is easy to frostbite the plant. There are yellowish-white spots on the leaves, and they will even die slowly, and the growth rate will become very slow, and the plant will not be able to continue to take root and grow.

It is necessary to find the cause of low temperature as soon as possible, and take warm measures in time. It is best to maintain the temperature between 25 and 30 degrees Celsius during the day and above 10 degrees Celsius at night so that it can grow vigorously.

The appearance of macula on the leaf surface of cucumber is divided into two types: agricultural control and chemical control.

Agricultural control: give priority to disease-resistant varieties; Reasonable fertilization, drip irrigation and dark irrigation technology under film are used in protected areas; After 9 o'clock, the indoor temperature rises and accelerates, and the vent is closed at this time, so that the indoor temperature in the shed is quickly raised to 34, and the indoor temperature is maintained at 33-34, so as to reduce the indoor air humidity at high temperature and inhibit the occurrence of the disease; After harvesting, the remains of diseased plants are completely removed and taken out of the field for deep burial.

Chemical control: 25% pyrazoxystrobin emulsifiable concentrate 2500 times, 50% enoylmorpholine wettable powder 1500 times, Pulik water 800 times or 72% frosturea manganese-zinc wettable powder 800 times spray control at the initial stage of the disease, once every 5-7 days, 3 times in a row. When applying pesticides, please wear protective clothing, and the application method should refer to the dosage, application time and safety interval indicated on the product label.

Precautions for cucumber planting

Choose fertile, loose, well-drained soil for planting. Cucumbers prefer soil pH in the range. Choose cucumber seeds that are of good quality and resistant to pests and diseases.

Before sowing, the seeds can be soaked in warm water for about 6 to 8 hours to promote germination. Cucumbers are generally sown in the spring when temperatures are stable and frost-free. Make sure the soil temperature reaches 15-30 degrees Celsius, which is conducive to seed germination and growth.

Cucumbers can be grown by direct seeding or seedling planting. According to the requirements of planting density, arrange the row spacing and plant spacing reasonably to ensure that there is enough space between the plants. Keep the soil moist but avoid overwatering.

Irrigation frequency and water use should be adjusted according to weather and soil moisture. Try to avoid drenching water on cucumber leaves to reduce the occurrence of diseases. Soil tests are carried out before sowing, and an appropriate amount of organic or mineral fertilizer is applied according to the test results.