Diseases of cucumbers: an overview of the most common
Diseases of cucumbers are unpredictable and dangerous, first of all, because they occur at the slightest violation of the conditions for growing a crop. Despite the fact that cucumber varieties resistant to certain diseases have already been bred, most are still vulnerable to pests of all stripes. As you know, it is better to know the enemy by sight. Diseases of cucumbers and their treatment is the topic of this article.
The leader in terms of the frequency of damage to cucumber leaves is powdery mildew. It manifests itself as a mealy whitish bloom over the entire area of leaves and stems. If ignored, the disease spreads to the entire plant, leading to yellowing of cucumber shoots, and then their complete drying out. The disease is caused by fungal microflora. It often leads to the death of the plant.
The “harvest” season for powdery mildew begins in cloudy, cool periods, when the air temperature does not exceed 18-19 ° С. It survives the winter well, so it can survive on plants not harvested from the garden in order to move to neighboring bushes in the new season.
Bushes with an excess of nitrogen are most susceptible to the invasion of powdery mildew, especially if they are watered irregularly. Thus, arranging "drying" of the soil, the day before feeding the cucumbers with a large dose of fertilizers containing nitrogen, you expose the bushes to the risk of getting sick with powdery mildew.
Disease prevention is about playing ahead. Try not to plant cucumbers in the same place for two years in a row, move them around the garden so that they return to the previous planting site no less than 3-4 years later. At the end of the fruiting period, completely remove the plants from the beds. The processing of greenhouses, areas in the open field should take place immediately after picking cucumbers from the beds. The air temperature (especially in greenhouses) should not drop below plus 24-26 ° C, so as not to create a favorable environment for the growth of the fungus. Use warm water for irrigation, so that there is no sharp drop in soil temperature. Regular treatment of plantings with fungicides will not leave powdery mildew a single chance.
At the first symptoms of the disease, plants should be treated with antifungal drugs, for example, Topsin-M or Topaz. Dissolve 2-3 milliliters of the selected preparation in 10 liters of warm water, start spraying the bushes. The procedure is best done on calm, dry days.
To combat powdery mildew, use the well-proven copper oxychloride. For 10 liters of warm water, take 40 grams of copper oxychloride, and then start spraying.
During flowering or fruiting periods, the use of chemicals is extremely undesirable, therefore, you can use:
- mullein tincture (1 kilogram of raw materials for 3 days is soaked in 3 liters of water, then diluted with another 3 liters of water before use);
- milk whey (1 liter of sour milk is mixed with 1 liter of water, filtered);
- soda-soap solution (mix 50 grams of soda with 50 grams of household soap, dilute in 10 liters of water).
Remember to remove the infected areas of the plant before spraying.
Downy mildew
The disease manifests itself as light, slightly yellowish or white spots over the entire surface of the leaves. After a while, the affected areas begin to acquire a brownish tint, after which they dry out. The main danger of downy mildew is that it can appear at any stage in the life of a culture.
Downy mildew is a fungal disease that develops in high humidity conditions. This is facilitated by both excessive soil moisture and excessive thickening of the plantings.
As a prevention of the appearance of downy mildew, you need to regularly thin out the density of cucumber shoots, tie and pinch them. Of course, you should not plant cucumbers in one place for two years in a row. At the end of the season, you need to completely remove the plants from the ground. Forget watering with cold water. Excessive watering is, in principle, unacceptable. Also, spray regularly with fungicides or whey.
If a disease is detected, watering should be stopped, fertilization should be avoided, and pinching should be carried out. As a first aid, treat the plantings with polycarbicine solution, bordeaux solution or copper oxychloride. You can use drugs "Ordan", "Ridomil". During the treatment, a stable temperature in the greenhouse, about 25 ° C, is required. When growing cucumbers outdoors, hide them under plastic wrap.
Brown spot
Diseases of cucumbers usually manifest themselves primarily on the leaves and stems of plants, brown spotting is no exception. The disease is characterized by the appearance of green sores with a brown tint on the stems of plants. After a while, the spots increase, while the leaf itself darkens.
The problem is that the whole plant is affected by the brown spot. The disease actively develops and spreads in cool weather, when the air humidity rises, for example, during heavy rains. It is often caused by sudden changes in air temperature, for example, during unexpected night frosts. The spread is facilitated by rain, wind, contaminated soil. Brown spot overwinters on plant debris and in soil. The spores of the fungus are frost-resistant.
To prevent cladosporiosis, transplant cucumbers to a new place every year; be sure to decontaminate the soil before planting. Ventilate the greenhouse, and also maintain a stable temperature in it, cover the beds with foil in an open area if frost is coming. At the end of fruiting, after harvesting, be sure to remove the aboveground and underground parts of the plants.
If you find brown spots on your plants, stop watering for at least 5 days. Try to stabilize the air temperature at 20-24 ° C to create unfavorable conditions for the fungus spores to live. Plants should be treated with fungicides, Bordeaux liquid, copper oxychloride or Oxyhom. Be sure to remove bushes from the beds that are actively affected by the disease so that they do not spread it to your neighbors.
White rot
Fungal diseases are a real scourge of cucumbers. One of them, white rot, tends to appear over the entire area of \ u200b \ u200bthe plants. Its symptoms: whitish spots appear, after a while they darken to blackness, the bush becomes covered with a thick whitish bloom, becomes slimy, soft, and subsequently decays.
The root of the problem is the activity of the sclerotia fungus, which survives the winter well and develops very quickly and, most sadly, spreads in moist soil, with high humidity.
As in the case of previous diseases, you can avoid the invasion of white rot by regularly thinning the planting density, replanting cucumbers to a new place every year. It is very important not to overmoisten the ground, ventilate the greenhouse every day, thinning the leaves, and create fresh air in the beds. After harvesting, it is imperative to remove plants from the soil, treat it with antiseptics and fungicides.
It is necessary to treat the disease by removing the infected parts, treating the sections with ash or lime. In the event of an extensive lesion, you will have to completely remove the bush from the garden, because without this you will not be able to cure the plantings. Treat the bushes with any fungicide, and then apply medicinal fertilizing with mineral fertilizers (dilute 10 grams of urea, 1 gram of zinc and 1 gram of copper sulfate in 10 liters of water).
Gray rot
Gray rot is characterized by brown spots, powdered with gray bloom. It affects the whole plant, so you need to act decisively and without delay. As with all fungal diseases, gray rot actively reproduces in too humid soil, as well as when the air temperature drops.
For all fungal pests, prevention is the same: do not thicken the beds, remove plants from the ground at the end of the season, change the location of cucumbers every year. And, of course, the fight against them will not be complete without regular treatment of plants with fungicides or milk whey.
Fungal diseases of cucumbers and their treatment are largely identical. Affected bushes must be treated with a fungicide with active substances against gray rot, "Rovral" and "Bayleton" are suitable. Reduce or completely stop watering the plants during the antifungal treatment. All infected hives must be removed.
Root rot
Root rot is visible to the naked eye by the dryness of the leaves. The plant dries up, if you examine the roots, they are red and crumble. Unlike previous diseases, root rot actively develops at high temperatures, insufficient moisture in the earth, or with excessive watering with water at a low temperature.
The fight against root rot is carried out under the motto "down with thickening plantings." You can prevent the harmful activity of the disease: try not to water the bushes with very cold water, especially in hot periods, and also treat the plants with fungicides every 2-3 weeks.
In the case of root rot, it is necessary to stimulate the development of the root system of cucumbers. Add fresh fertile soil to the beds, cut off the lower leaves, and dig the stem itself in fresh soil. Irrigate the soil around the plants with warm water for the next 10 days. Use a yeast solution. Dried bushes will have to be removed from the soil, treated with antiseptics (for example, iodine solution) and fungicides.
Copperhead
Brown mosaic on cucumbers, due to which the plant begins to dry out, and the fruits become covered with moist ulcers, is a sign of the defeat of the copperhead culture. Copperhead often progresses and develops on infected seeds that have not been calcined or processed before planting. Also, the fungus hibernates calmly in the upper layers of the soil. Copperhead is activated when the air temperature drops or plentiful watering with cold water.
Pest control is carried out at several levels. Transplant the cucumbers every year first, or take care of the soil renewal. Once fully harvested, remove the plant from the ground. Do not use seeds taken from infected plants, be sure to process them before planting. Pests take advantage of your carelessness to cope with them, you must always be on the lookout.
For treatment, take a 1% solution of Bordeaux, with which you spray the bushes every week. You should also remove the infected segments of the bush, cover the sections with copper sulfate or lime. Copper sulfate can be cultivated after harvest to kill fungus.
Video "Methods to combat diseases of cucumbers"
This video will tell you a few simple and effective techniques that will help you effectively cope with various diseases of cucumbers in your garden plot.