Rusty spots on cucumber leaves: causes and solutions to the problem

Why do rusty spots appear on cucumber leaves?

A common cause of such changes is a fungal infection. She is very dangerous. If measures are not taken in a timely manner, the active spread of pathogenic microorganisms will begin. Not only leaves are affected, but also fruits and stems. This leads to the death of the plant.

Not only cucumber diseases can provoke the appearance of rust. Often similar problems are observed with a deficiency of minerals.

It is worth highlighting the most common reasons for such changes:

• black rot (ascochyta);
• copperhead (anthracnose);
• downy mildew (peronosporosis);
• brown olive spot (cladosporiosis);
• mosaic;
• deficiency of magnesium, potassium;
• melon aphid;
• spider mite

Mineral deficiency

Brown spots that are accompanied by drying of the leaves may indicate a lack of nutrient minerals necessary for active growth. At the first stage, the plant requires nitrogen in large quantities: it speeds up metabolism and is responsible for the growth of the green part. Then comes the time of phosphorus, it helps the fruits to form and saturates them with vitamins. Potassium and magnesium are no less important for cucumbers.

With potassium deficiency, the appearance of the plant differs little from the usual: the problem can be noticed at the tips of the leaves: they turn brown and begin to curl. With a lack of magnesium, redness begins to spread throughout the entire leaf from the center, along the veins. As soon as you notice a deficiency of minerals, add them along with mineral supplements.

Important!

Weeds or insect pests can pull minerals from the soil and plants. Make sure you don't have any before supplementing your micronutrient deficiencies, otherwise your efforts will be wasted.

Manifestation of diseases

Depending on the disease that affected the plants, the following changes are noted:

• Black rot . The appearance of reddish dots is observed. The leaves around the edges begin to curl up and change shape. Gradually, the stains completely fill the surface. A sticky liquid is released on the damaged areas. The seedling dries out and dies.
• Anthracnose . The development of the disease is observed at elevated temperatures, humidity, due to splashes of water settling on green plants. The yellow spots have a regular round shape. If measures are not taken in a timely manner, holes will appear in their place. Rust forms on the fruits and turns into ulcers. A reddish liquid begins to emerge.
• Downy mildew . The plant is covered with small yellow spots. Over time, they increase in size and acquire a reddish tint. The leaf blades dry out. The bush dies.
• Angular spot . Initially, a greasy green coating is noted on the leaf blades. Then red patches appear and rupture, forming holes. The fruits also turn yellow in certain areas. Whitish ulcers appear on them.
• Mosaic . The leaves become covered with yellow, star-shaped spots that increase in size over time. The leaf turns completely red and dries out.
• Melon aphid . The appearance of spots of a reddish hue is noted. The leaves begin to curl and then fall off.
• Spider mite . Mite colonies accumulate on the underside of the leaves. In addition to the red spots on the leaf blades, there is a presence of white cobwebs at the junction with the stem.

Spider mite

The key sign of a pest is a white cobweb on the leaf blades of the plant. The first symptom is lightening spots on the lower surface of the leaves. By ignoring an insect colony, you can lose your entire harvest in 10 days. They feed on sap from stems and leaves, which leads to the appearance of brown spots, indicating the imminent death of the bushes.

As for the fighting tools:

• You can save plants by making a solution at home from two tablespoons of hydrogen peroxide per liter of water. To prevent the spread of spider mites, it is enough to treat the plant once a week;
• Another treatment method is to use ammonia. To do this, you need to dilute one teaspoon of liquid in one liter of water. The frequency of spraying is similar;
• You can achieve a good effect using an infusion of garlic or onion peels. You will need to mix 200 grams in 10 liters of hot water and let it brew for 24 hours. Then all that remains is to periodically spray the affected plant until the bugs are completely eliminated.

If the number of spider mites continues to increase, you can use special biological preparations.

How to treat rusty spots on cucumber leaves

Rust signals the development of serious diseases and pest infestation. Treatment must be started without delay, otherwise the condition of the plants will begin to deteriorate and the yield will decrease sharply.

The problem must be dealt with immediately after identifying the disease.

At the same time, you should remember about preventive measures to help prevent relapses:

• grow plants in a greenhouse using turf soil mixed with humus, weathered and decomposed peat;
• water with warm water (minimum +20C);
• monitor soil humidity and temperature, avoid waterlogging and overheating;
• when symptoms of root rot appear, add soil to the stems (this will stimulate the formation of additional roots);
• carry out plant rejuvenation: bend the stem to the ground for rooting, sprinkle with fresh soil, and after 2 weeks add soil again.

Special preparations and folk remedies will also help get rid of rust. The technology of their use should be considered in more detail.

Preventive actions

Prevention begins after collecting or purchasing seeds for sowing cucumbers. They need to be hardened and disinfected in a solution of potassium permanganate.

The soil for planting seedlings must be calcined in the oven, first filled with boiling water or treated with any fungicidal preparation. Before planting seeds or seedlings in open ground, it is necessary to disinfect the soil using diluted potassium permanganate.

Do not plant cucumbers after zucchini and pumpkins. These plants leave fungal spores in the soil. In the fall, after harvesting, it is necessary to dispose of leftover vegetables and weeds.

During the growing season, fungicidal or folk remedies are used to prevent fungal diseases. Treatment must be timely so that the disease does not have time to spread to neighboring plants.

Store products

If cucumbers are affected by a fungal infection, it is recommended to use the following remedies:

• Bordeaux mixture (1%) . Plants should be treated in late spring - early summer. The procedure is carried out a maximum of 4 times. If the remedy cannot be found, it is permissible to spray the cucumbers with copper oxychloride (0.4% solution); use a weak solution of copper sulfate.
• Oksikhom . 20 g of the drug is dissolved in a bucket of warm water (10 l). The resulting solution is used to treat the affected lashes.
• Arcerides . An effective remedy that can eliminate the problem after one treatment. To prepare the solution, 50 g of the product are diluted in a bucket of water.
• Fitosporin . The product has a low price. It can also help get rid of fungal infections.
• Benomyl . It is used when plants are damaged by anthracnose.
• Formalin . Used in the fight against mosaics. A five percent solution is used to treat the soil in areas where diseased plants grow (the root system is damaged).

Before starting treatment, remove the affected parts of the plants. Watering is reduced to once a week.

The following products are used in pest control: Fitoverm, Iskra, Tanrek, Inta Vir, Apollo, Akarin. The drugs are diluted strictly according to the instructions.

melon aphid

This small pest is a carrier of pathogens of viral infections. The insect is located on the lower part of the plant, after which it moves along the stem to flowers and ovaries. Eats juice. If you do not take measures to eliminate melon aphids in time, you can see them on all the bushes in a few days. Pests reproduce excessively quickly - one female can bring up to 10 thousand new individuals per month.

The insect is recognized without any problems - they are small bugs of a yellowish or greenish color. Aphids can also be black or white. Despite their size, they are easy to detect, because pests settle in hundreds and thousands of individuals on the underside of the leaf.

The best method of protection against bugs is timely prevention:

• treat the soil in the fall to prevent the development of larvae. A sulfur bomb will do;
• Always keep the area clean and prevent weeds from spreading throughout the garden. This way you can reduce the risk of aphids;
• Special attention should be paid to the cleanliness of greenhouses or greenhouses. Wooden parts of the structure should be periodically whitened, metal and plastic parts should be treated with a solution of copper sulfate. Change the top layer of soil once a year with a new one.

If the leaves are already rusting, you need to proceed directly to treatment. Frequent use of chemicals can lead to deterioration in the taste of the fruit or degradation of quality, so it is worth considering traditional methods:

• Using onion peels will help get rid of aphids and avoid the side effects of special agents. You will need to mix water and husks in a 1:1 ratio, boil and leave to infuse for 24 hours. Next, you need to strain the liquid through cheesecloth and use it to spray the plant. The melon aphid does not tolerate the pungent onion smell;
• Another method is based on laundry soap and shag and is suitable for cases when the owner has neglected the garden for a while and aphids have spread throughout the entire area. You will need 80 grams of the first component and 400 grams of the second. All this needs to be mixed in a bucket of hot water and left to infuse for two days. All that remains is to treat the plants with this solution. It is recommended to carry out several procedures to get rid of the larvae;
• Hot peppers may also help. But it must be used carefully, because in excessive quantities it burns the plant. You will need to pour 50 grams with one liter of boiling water and leave for 2 hours. Next, you need to dilute with 10 liters of water and treat the affected areas.

See also Balcony cucumbers: planting and growing technology

If in this way it was not possible to get rid of the pests, you should use chemicals, but strictly in compliance with the dosage and all precautions.

The use of folk remedies

You can also fight fungal infections in your garden using folk remedies.

The following are effective:

• Milk serum . 1 liter of product is diluted in a bucket of water. Using the resulting solution, all crops in the garden are treated. In a small area, it is allowed to use the serum in its pure form.
• Ash solution . Helps eliminate diseases and saturate plants with useful substances. Wood ash (200 g) is poured into 2 liters of boiling water and left for 2 days. Then add 10 g of laundry soap to the composition. Seedlings are treated with the prepared solution 3 times a week. In case of significant damage, the number of sprays is doubled.
• Onion solution . The product is effective in the treatment of anthracnose. To prepare it, 50 g of onion peels are poured with water (10 l). The liquid is brought to a boil and left for a week. When processing 1 bush, 1 liter of liquid is consumed.
• Manganese solution . Helps with plants affected by blackleg. Added to water when watering.

If a spider mite is found in the garden, the following means are used:

• Potato tops . 1 kg of raw materials is immersed in a bucket of water. The liquid is infused for 4 hours. The resulting infusion is generously moistened with all the foliage.
• Marigolds . 5 kg of dried flowers are poured into 10 liters of warm water. Leave for two weeks, then filter, add 40 g of laundry soap. Spray the plants in the evenings.
• Tomato tops . 4 kg of green tomatoes are poured into 10 liters of water. The liquid is boiled for about half an hour. Add 40 g of laundry soap to the decoction and dilute it with water in a 1:1 ratio. Spray the foliage generously with the prepared product.

If the plants are affected by melon aphids, the following means are used:

• Soda solution . Add 1 tbsp to 1 liter of water. l. soda, a piece of laundry soap. The solution is sprayed on diseased plants.
• Hot pepper . 1 kg of product is finely chopped and mixed with 3 liters of water. The liquid is placed on the stove, boiled for an hour, and left for 2 days. A glass of the resulting infusion is diluted in a bucket of water. Add 50 g of laundry soap to the composition. Zelents are processed.
• Celandine . 200 g of dried plant is soaked in a bucket of water. The mixture is infused for 2 days, then filtered. All plantings are sprayed with infusion.
• Dandelion . 400 g of roots and 600 g of greens are poured into a bucket of water. The mixture is infused for about 3 hours. Cucumber foliage is processed.

Tips and recommendations from experienced summer residents

Experienced gardeners know why rusty spots appear on cucumbers.

Peter, Kaluga: “I carry out prevention before planting seeds in the ground. I soak the seed in a solution of potassium permanganate and water the beds with boiling water before planting. When the cucumbers sprout, I fertilize them with ammonia (1 tbsp per bucket of water). In the future I feed every 2 weeks. I also spray it with a solution of brilliant green (10 drops per bucket of water). I never have red spots on cucumber leaves.”

Masha, Orsk: “I always have a rich harvest. To avoid stains on cucumbers, you must follow agricultural practices. I water it 3 times a week so that water does not get on the leaves. At the beginning of the season I add ammonia, then a mixture of superphosphate, wood ash and potassium salt. I prepare the beds for planting in advance, adding compost, rotted manure, and peat.”

Symptoms and signs

Rust spot has pronounced signs, it is difficult not to notice them; the entire leaf blade is covered with red spots. The spots are small and sometimes cover most of the leaf. The spots are mostly round or oval in shape. Over time, the small dots combine into one large spot, and the entire leaf turns yellow. After this, it dries out and breaks away from the stem.

If an infection occurs, the weakened plant stops growing, the fruits become deformed, become small and not tasty. The ovaries and flowers fall off. The trunk may crack and the roots at the base may turn black.

Prevention of leaves on cucumbers

The presence or absence of bacteria cannot be determined with the naked eye, so before planting, all cucumber seeds must be soaked in a manganese or zinc solution. This kills all harmful substances. If the seeds are not treated in this way, then the risk of bacteriosis increases and it is possible to get rid of it only with the help of Bordeaux mixture.

Diseased leaves and plants must be removed immediately so that the attack does not spread to healthy vines and leaves. Most diseases of cucumbers can be avoided if temperature changes, drafts, excessive humidity or dry air are avoided.

Treating cucumber seeds before planting also reduces the risk of problems and increases productivity. When choosing the variety of cucumbers that you will plant, pay attention not to the beautiful photo from the packaging, but to the instructions from the manufacturer, which usually describes the plant’s resistance to a number of diseases.

Following simple rules will help you grow a good harvest. The best way to protect leaves and cucumbers from red spots is to properly care for them. When watering, it is necessary to avoid getting water droplets on the plants. It is better to use a drip irrigation system for watering. You can also sow cucumbers or seedlings in clean compost beds.

Causes of red spots

Rusty spots on cucumber leaves appear as a result of infections, lack of microelements and sunburn. Changes in leaf color are affected by unfavorable weather conditions, frequent rains and insufficient lighting. Changes in cucumber seedlings as a result of weather conditions are not so dangerous; only partial staining of the foliage occurs; this has almost no effect on the growth and development of seedlings. But diseases lead to large losses of greens.

Nutrient deficiency

With a lack of magnesium, the leaf begins to turn yellow and brown spots appear in the form of burns. Spotting occurs on the lower tiers, the leaves turn yellow, wrinkle, the veins remain green.

With nitrogen starvation, the leaves of cucumbers turn pale, discolored, and begin to fade. The stems become thin. The lower foliage of cucumber bushes is covered with yellow dots.

If there is not enough copper in the soil, a brown pattern appears on the foliage. Without the element, the stems weaken and the leaves fall off. Without phosphorus, the leaves become small, the lower ones turn bright yellow. Brown-brown spots are visible between the veins. They grow and fill the entire leaf plate, it dies and falls off.

Burn or hypothermia

The bright sun causes burns on the foliage. Yellow and rusty spots with clear outlines that appear due to sunburn are not dangerous for cucumbers. A few leaves will be damaged, the rest will remain undamaged. It must be remembered that the bushes are watered only at the roots; if moisture gets on the leaves during the day, they will be burned.

Sharp temperature fluctuations, when after a heat of +30 °C the thermometer dropped at night to +14 °C, cucumber seedlings can react by yellowing the foliage. Stress causes plants to shed their leaves, because when overcooled, the root system does not absorb nutrients, and cucumber seedlings lack microelements.

Diseases of culture

Rust on cucumbers can be a sign of fungal or viral diseases. You need to fight them from the first signs. If you miss the moment, when planted densely, the fungi will spread to neighboring bushes. High humidity and elevated temperatures help the development of bacteria and fungi.

Common cucumber mosaic

The first symptoms of mosaic on seedlings appear 2 weeks after infection. The cause of infection is sudden temperature changes; temperatures above 30*C are dangerous. Brown spots form on the leaves and stems, and the leaves curl toward the bottom. Flowers wither, ovaries fall off, cucumbers become deformed, and the stem cracks at the base.

More often, the disease affects plants in greenhouse conditions. The virus enters the greenhouse through soil brought from the garden. Aphids also carry diseases. The infection is inactivated for two months; in winter it is stored in the rhizomes of perennial weeds.

Important!

It is necessary to use only composted and neutralized soil substrates for planting cucumbers.

Bacteriosis of cucumber

Seeds that have not undergone pre-sowing treatment become a source of infection. High humidity 80% and temperature 25-28*C help the successful development of bacteria. Infection carriers can be humans, insects, and birds. The wind carries infected dry grass and tops throughout the area. Accumulated nitrates in the soil promote the development of bacteria, as pathogens feed on nitrates. In dense plantations, the disease quickly spreads to neighboring bushes.

The cotyledon leaves become covered with yellow spots in the corners of the leaf, then they turn brown. When humidity is high, mucus flows from the back of the plate. The spots dry out, turn white, and holes appear. Only leaf veins remain. The fruits become deformed and lose their taste, the bushes stop growing. Plants may die.

Blackleg

The fungus is transmitted through soil, manure, peat and weeds. When purchasing seeds at the market, you can purchase already infected seeds. If you do not change the planting location for cucumbers, the likelihood of infection with blackleg increases significantly. The spread of the fungus is facilitated by changes in soil temperature, watering with cold water, and low air temperatures.

First, fungal spores infect young seedlings and weak specimens. The root collar becomes brown, its shape changes, the neck becomes wet and darkens. The roots become thinner and turn yellow. The cotyledon leaves turn yellow, wither and fall off.

Attention!

If perennials with a fungal infection grow nearby, seedlings cannot be planted in this place; the area must be treated.

Anthracnose

Depressed yellow spots with an elongated brown edge appear on the leaves. They spread to all parts of the plant. Later, the spots become purple with a red border. In the heat, cracks appear on the shoots and the stems rot. Ulcers also form on fruits and look like depressed pits 3 mm deep.

The disease develops at a temperature of 20-25*C with high humidity. The time of infection before the formation of new spores is 10-14 days. Young animals with strong immunity are resistant to the disease. The infection affects old plants, but it can infect seedlings.

Ascochyta blight

Ascochyta mushrooms often settle on greenhouse cucumbers. The mushroom is dangerous for bushes with weakened immune systems. The infection affects plants during the formation of vegetables. The fungus covers the upper part of the seedlings without affecting the vascular system. The growing season occurs in a weak form. Ascochyta blight moves from the bottom of the bush to the top, gradually capturing all the fruits and ovaries.

Watery gray spots appear on cucumbers. They darken and become red. The fruits become deformed, rot and die. Rot develops in weak areas of the plant. The surface of the leaf plate becomes brown.

Angular spot

Corner spot is a fungal disease. Wet spots of angular shape appear on the leaves of cucumbers. When humidity is high, milky droplets are released. After drying, a white coating forms, then the spots become brown with a yellow border. The affected part is destroyed, the foliage has a torn appearance. Wet spots form on the stem, petioles and cucumbers. The fruits change and become covered with wet rot.

Infected seeds, weeds, insects, humidity - all this contributes to the development of infection. On sandy soil, where the wind often displaces the sand, fungi quickly move to new areas. When watering, moisture falling on the leaves also helps the disease develop.

Downy mildew (peronospora)

The fungal infection is spread by air via wind and rain. Infection can be caused by dirty hands and tools. The foliage withers, turns yellow, and then falls off. The new leaves that appear are wrinkled and underdeveloped. The white coating slows down photosynthesis in cucumbers, and the white spots grow quickly; after a week, the infection infects the stems and peduncles.

Mushrooms are most active during the rainy season, at a temperature of 18-27*C. Infection can occur during pruning of shoots. If the soil has been contaminated, the seedlings will be infected. Frequent watering and stagnant water aggravate the problem.

How to fight diseases?

Many of the common diseases to which the dacha crop in question is susceptible can lead to the formation of yellow spots on leaf blades. Cucumber plantings very often suffer from powdery mildew, fusarium and other serious ailments. Let's learn about the main features of some of them.

Powdery mildew

A rather serious disease that can cause great damage to plants. Often yellow spots on cucumber leaves appear precisely because of the destructive effects of powdery mildew. The main causative agents of this dangerous disease are spores. They have the ability to survive the winter on plant debris.

If small yellow specks are visible on the leaves, which grow in size over time and cover the entire surface of the plate, then this speaks specifically about the disease in question. Pigmentation certainly begins to grow, moving from the lower half to the tops. After some time, the seedling simply dies. Powdery mildew may also be noticed when leaves develop a purple or grayish coating. At the first stages, the resulting spots have a light green tint, but then turn yellow, become darker and clearly visible.

Fusarium

Another extremely dangerous fungal disease. Fusarium most often attacks cucumber plantings that are grown in a greenhouse or greenhouse. The symptoms of this disease rarely go unnoticed by summer residents, as they manifest themselves quite clearly. First, the leaf plates of vegetables turn yellow, and then their upper parts wither. Subsequently, the root becomes brown in color and the stem begins to rot.

The disease in question is especially dangerous because it spreads literally rapidly. Cucumber bushes can die within just a few weeks if the summer resident does not take the necessary actions in a timely manner.

In the fight against this disease, the following popular drugs are highly effective:

• "Fitosporin-M";
• "Baktofit";
• "Vitaros";
• "Maxim" and others.

Mosaic

This disease is special. It can occur even if the plant has previously received the necessary and regular care. First of all, those cucumbers that grow in greenhouse conditions are susceptible to mosaic disease.

Mosaic is most often accompanied by the following symptoms:

• yellowing of marble-type sheet plates;
• When the disease occurs, the leaves curl;
• they become smaller;
• After some time, the ovaries fall off.

Downy mildew

A common disease that also often causes yellow spotting. With this disease, yellowish spots appear on the upper parts of the leaf blades. In addition, a characteristic greenish coating forms on them. The main feature of peronosporosis is its ability not only to spread over the entire surface of cucumber plantings, but also to infect all crops that are planted in the immediate vicinity.

Another name for peronosporosis is downy mildew. This disease also needs to be treated in a timely manner, without wasting time. With this disease, not only the leaves suffer from the formation of noticeable spots, but also the plant stems crack, the necessary tone of the shoots is lost, the buds fall off, and fruits stop forming.

To combat downy mildew, it is advisable to treat diseased leaf blades with special chemicals. Products such as “Abiga-Pik” or “Consento” are ideal. For the purpose of effective prevention, the crop is sprayed with biological insecticides during the growing season. We are talking about the compositions “Baxis”, “Fitosporin-M” or “Trichoderma”.

Anthracnose

If the plant has been damaged by this serious disease, then areas of a characteristic yellow-brown hue appear on its leaf blades. They are complemented by a pinkish coating, which spreads to other surfaces of the crop. Noticeable mucus forms on cucumbers. This is what leads to the appearance of small ulcers. As a result, the plant dies.

Despite the fact that the disease in question can lead to the death of the crop, it can be dealt with quite simply. To do this, it is enough to treat the cucumbers once a week with an effective Bordeaux mixture, as well as a weak solution based on copper sulfate. Some summer residents then resort to sprinkling the cucumber bushes with lime or charcoal.