Peronosporosis and powdery mildew on cucumbers - folk remedies and chemistry, resistant varieties
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TWO DISEASES THAT CAN LEFT WITHOUT CUCUMBERS
Of all pumpkin crops, cucumber is the most susceptible plant to diseases. The most common and dangerous are peronosporosis and powdery mildew.
PERONOSPOROSIS
This disease affects cucumbers (as well as pumpkins, squash, watermelons and melons) at any age, starting with seedlings. It is especially dangerous for plants grown in unheated film greenhouses. This is due to the fact that peronosporosis develops most actively at high humidity and an air temperature of more than +16 degrees.
How it manifests itself. In wet weather, light yellow rounded or angular oily spots appear on the underside of the leaves. In the future, they apply to the entire sheet. On the underside, the spots look weeping, droplets of liquid often appear on them, which, when dry, turn into a film that looks like a white bloom. If you do not fight the disease, the leaves turn yellow and dry up, the plants stop growing and bearing fruit. Peronosporosis is most dangerous at the beginning and middle of fruiting (mid-July - early August).
HOW TO FIGHT.
Any disease is easier to prevent than to cure it later. Therefore, so that cucumbers do not get sick with peronosporosis, grow plants of the most resistant varieties to this disease (Verasen, Zarnitsa, Svitanok, Slavyansky, Belarusian Gherkin F1, Vyaselka F1, Coral Reef F1, Malysh, Janus F1).
Perform two preventive treatments. In mid-July, spray the plants with 1% Bordeaux liquid, and after 7-10 days - with the drug diluted according to the instructions (Previkur Energy, Reed il Gold, Sandofan).
In addition, starting from the third week after germination, process cucumbers in the open field with Fitosporin-M every 14 days.
If, despite all efforts, the plants still get sick, cut off all the affected leaves and spray the cucumbers liberally with any copper-containing preparation. Next, alternate treatments with biologicals and copper-containing fungicides.
TIP: Spraying with Fitosporin can be alternated with treatment with a copper-containing preparation Abiga-Peak or a solution of azophos (50 g per 10 l of water - for open ground; 25-30 g per 10 l of water - for greenhouses), which will also help protect cucumbers from anthracnose and bacteriosis ...
See also: Combating the peronosporosis of cucumbers - a memo to the summer resident
Mealy dew on cucumbers
Weeds (plantain, sow thistle, etc.) are the source of infection. The disease is aggravated by high humidity, abundant dew, sudden temperature fluctuations, watering with cold water over the leaves, and also due to drafts in greenhouses.
How it manifests itself. The first signs of powdery mildew are pale yellow spots on the petioles and leaves. Then a white coating appears on them, which spreads quickly. As a result, the leaves turn white (as if dusted with flour), then they dry up and the plants die.
See also: Powdery mildew on cucumbers - how to deal with folk remedies and chemistry
HOW TO FIGHT.
The main condition in the fight against this disease is to create favorable conditions for cucumbers: weed the beds in time, water it exclusively under the root with water heated in the sun, loosen the soil, feed not only macro- but also microelements.
In addition, spray cucumbers and other pumpkin seeds with infusion of rotten hay or hay dust once every 7-9 days until symptoms appear. Prepare it like this: pour 1 kg of dust or rotten hay with 3 liters of water. Insist for three days, strain. Dilute 1: 3 with water. Add 5 g of copper sulfate to a bucket of composition (first dilute it in a little hot water).
If you notice leaves that are affected by white bloom, immediately cut and destroy them. Spray the plants with a fungicide (Topaz) or a biological product (Fitosporin).
The fruits of watermelon, pumpkin and melon are harvested only after the fruits are fully ripe, so they can be safely treated with potent substances, however, the timing of harvesting after spraying must be taken into account (indicated in the instructions). And cucumbers and zucchini, the harvest of which is harvested almost daily, is extremely undesirable to process with chemicals.
So use folk remedies.
Pour a third of a bucket of fresh mullein to the top with water, leave for 3 days, stir occasionally. Strain, add 1 tsp. copper sulfate. Spray the plants once a week in the evening. Prepare a fresh infusion for each treatment.
Dissolve 1 liter of milk in 10 liters of water. Spray cucumbers every 5-7 days for prophylaxis and at the first sign of illness. By the way, studies have shown that the effectiveness of treatment with milk solution is comparable to many fungicides. Whey can be used instead of milk (it leaves fewer marks on the leaves). But for the treatment of powdery mildew, it will have to be sprayed once every three to four days, and for the prevention of the disease - once every two weeks.
© Author: Alexander Gorny, Cand. of sciences
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I first encountered cucumber anthracnose last year. Brown "blots" appeared on the edges of the leaves, which eventually turned into one continuous spot. Yellowish depressed spots also became noticeable on the fruits. Treatments with a serum solution did not help, and part of the cucumber plantation died. Fortunately, friends suggested how to slow down the development of the disease. On their advice, I removed buckets of water from the greenhouse and began to ventilate the structure well. I generously sprayed the soil with 1% Bordeaux liquid, then poured the roots and the base of the stems from the watering can. For each bush used about 1 liter of solution.
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When choosing seeds for cucumbers, it is imperative to pay attention to the type of these plants.
If the planting will be in the greenhouse, then you should focus on hybrids. They tolerate heat and humidity better, and produce longer, well-branching whips, which is favorable for vertical cultivation. They also have a long fruiting period. Such modern cucumber hybrids are parthenocarpic, which do not require pollination, which is good for greenhouses, where beneficial insects practically do not fly. They successfully resist powdery mildew, downy mildew, root rot, olive spot.
In the open field, bee-pollinated varieties and hybrids of cucumbers are usually grown. These more compact plants have coarser stems and stiffer leaves. When choosing a variety, you should pay attention to the resistance to downy mildew (peronosporosis). In the open field, this disease develops almost at lightning speed and is capable of destroying all plantings of cucumbers.