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Many gardeners are faced with such a problem as zucchini diseases in the open field and the fight against them, a photo will help identify the problem.
Zucchini get sick with viral or fungal pathologies, they are affected by various pests. An accurate understanding of the problem will help determine the choice of how to deal with it, how to preserve and protect the crop.
How to deal with zucchini diseases?
The most common zucchini diseases, depending on the causative agent causing them, are fungal. The culprits of diseases can cause death of leaves, fruits or roots. The methods of struggle common to all diseases: observance of crop rotation, timely removal of garbage and weeds from the territory of the site, destruction of the affected parts of the plant.
Favorable conditions for the development of diseases are night temperature drops and an increase in humidity, for example, after rain or with excessive watering. The source of the pathogen is the affected plants and seeds. Insects contribute to the spread.
Fungal diseases of squash and their treatment are the most common problems encountered when growing crops in open field.
Zucchini anthracnose is a fungal disease caused by a fungus of the genus Colletotrichum. First of all, weak and mechanically damaged plants are affected at any stage of development. Anthracnose affects zucchini planted in soil with high acidity, with an insufficient amount of potassium and phosphorus fertilizers.
Spots of yellow or brown color with a dark brown or purple edging appear on the leaves, which quickly grow first on the entire surface of the leaf plate, and then on the stem, flowers and fruits. The lesions go deeper into the thickness of the plant's organs and impede the movement of water and nutrients.
The stems and fruits become covered with weeping, slimy spots and begin to rot over time, and the leaves begin to curl. The fruits shrivel, acquire a bitter taste. Damage to the root zone leads to the death of the plant.
At the initial stage of anthracnose development, shoots are sprayed with a 35% solution of colloidal sulfur, 1% solution of Bordeaux mixture (100 g of copper sulfate and quicklime are diluted in 10 liters of water), EM preparations.
To reduce acidity, the soil is dug up with wood ash, dolomite flour or lime before sowing, fertilizers containing phosphorus and potassium are applied.
Bacteriosis is of 2 types and manifests itself either as angular leaf spot or as apical rot of fruits.
With angular spotting, the leaves turn white at first, why and why the leaves of zucchini turn white, it is not easy to determine, since such damage develops with several diseases of the culture. If, in the future, angular brown spots appear instead of small white spots, this is bacteriosis.
The disease affects the plant even at the stage of the appearance of the cotyledons. At first, the spots turn dark green, then brown, dry out, fall through, forming holes between the veins of the leaf plate. Since the holes are limited by veins, they are angular. Brown watery sores appear on the fruits, which lead to deformation of the zucchini.
The fight is to remove the affected parts of the culture. With minor lesions, shoots are treated with 1% Bordeaux mixture, 0.4% copper oxychloride solution. As a preventive measure, the treatment of seed material with a 0.02% solution of zinc sulfate is used, in which the seeds are immersed for a day, and then dried.
Another type of disease is apical bacteriosis of fruits. In this case, the tops of the fruits first turn yellow, then brown-brown spots appear on them. At the same time, the lower part can grow further. In the future, the fruits become glassy and rot.
It is impossible to save a plant from apical bacteriosis - it will have to be destroyed.
White rot sclerotinia
The fungus can cause various putrefactive diseases of zucchini in the open field, it is much easier to identify the type of rot from a photo.
With white rot, or sclerotinia, a flocculent white coating first appears on the leaves of the squash with black dots, which eventually spreads to the fruits, antennae, cuttings and stems. They develop white colonies of the fungus - sclerotia, which soon turn black.
Sclerotia fall off and overwinter in the ground, and in spring they are a source of infection. The damaged areas of the plant become covered with mucus, soften and rot. If the base of the stem rots, the plant dies.
An excess of nitrogen in the soil contributes to the infection of plants. Treatment consists in treating the affected areas on squash with crushed activated carbon, wood ash or quicklime.
To combat the pathogen, the following measures are taken:
- Use for irrigation with warm water.
- Root top dressing with a mixture of 10 liters of water, 1 g of zinc sulfate, 2 g of copper sulfate, 10 g of urea.
- In dry and hot weather, the affected plant organs are removed. The sections are sprinkled with crushed coal or washed with a 0.5% solution of copper sulfate.
- As a top dressing, substances containing calcium are used: ground chicken egg shells, wood ash at the rate of 200 g of substance per 1 m². Phosphorus fertilizers are introduced.
- The soil is irrigated with Fitolavin solution, and compost is added to restore the microflora.
Gray rot botrytis
Another type of putrefactive mycosis is gray rot. At the same time, the greenness of the grass changes, the leaves get sick, the leaves, the ovary of the fruits suffer. Young vegetable ovaries are most often affected. The fruits become watery, like other affected tissues, get wet, soften, turn brown, and become covered with a gray bloom with black dots. Spores of the pathogen persist in the soil for up to 2 years.
The reasons aggravating the conditions and methods of infection with the disease are the same as with white rot. The methods of struggle also coincide. The affected areas of the fruit can be powdered with a mixture of copper sulfate and chalk, combined in a 1: 2 ratio.
Root rot affects the plant, like the top rot, in the phase of fruit formation and is manifested by rotting of the root system and neck. The affected tissue darkens and turns brown, becomes rotten and soft. The lower foliage turns yellow. The culture stops growing and fades, and eventually dies.
Root rot appears due to the frequent introduction of organic fertilizers. Plants can be treated with biologics Trichodermin and Glycoladin, which contain spores of fungi - antagonists of the rot pathogen.
Seeds 3 weeks before sowing can be treated with TMTD (Tiram) at the rate of 5-6 g / kg of seed. Infected plants are watered with 0.1% Previkur solution at the rate of 200-300 ml for each bush. In addition, solutions containing metalaxyl, mefenoxam are used.
Another fungal disease of zucchini is powdery mildew. Ailments in this case are manifested by the appearance on the leaves, less often on the stem and cuttings, of small rounded white spots, sprinkled with powdery pollen - fungus spores.
Over time, the spots increase, merge with each other and cover the entire plant, as a result of which it turns yellow and dries out due to the impossibility of photosynthesis. In addition, the body of the fungus sucks out nutritious juices from the culture, which leads to the impossibility of forming fruits. The mushroom hibernates on the weeds.
Affected plants are sprayed with a solution of colloidal sulfur 35%, a solution of sodium phosphate 0.5%, a solution of isophrenic 10% or powdered with ground sulfur at the rate of 300 g per 100 m².
Downy mildew downy mildew
Peronosporosis affects the leaves of squash at all stages of the growing season. First, yellow spots appear on the upper side of the leaves, which on the other side of the leaf are covered with gray-violet spores of the fungus.
The spots increase, merge with each other, which leads to browning and drying of the foliage. The disease progresses very quickly. Sometimes the outside of the leaf is covered with a white bloom. Despite a similar description, the methods of treating peronosporosis are somewhat different from the removal of powdery mildew.
During treatment, watering is completely stopped. Healthy leaves are treated with a tank mixture, a solution of copper oxychloride, Metriam, a mixture of fungicides and growth stimulants. For prophylaxis, seeds are poured with hot water (+50 ° C) for 15 minutes.
Black pumpkin mold
Pumpkin black mold can appear on the leaves and other aboveground organs of squash. Outwardly, it manifests itself in small light brown spots, which merge over time, turn into foci of necrosis, covered with a black bloom - spores of a fungus from the Aspergillus genus.
As a result of its vital activity, the green parts of the plant turn yellow and dry out, and the fruits stop developing, shrivel and rot. High humidity and large temperature fluctuations stimulate the course of the disease.
If the plant was able to get sick and not cure it, all the zucchini on the site get sick.
Diseases and pests: pests of squash most often affect the aboveground parts of plants. Fusarium is no exception. The first sign of this disease is yellowing and weakening of the upper leaves of the bush.
The stems turn brown at the bottom (root part) and are covered with pink or orange bloom. Fusarium also affects roots. As a result, the plant dries up and dies within a few days. On the cross section of the stems, you can see the browning of the veins.
In the initial stage of the lesion, you can dust the bush and the ground around it with wood ash, but this is of little effect. The fight consists in improving the soil - sowing green manure plants, applying organic and mineral fertilizers, applying crop rotation, removing weeds, introducing EM products and calcium preparations.
How to deal with zucchini pests?
The appearance and number of pests is influenced by air humidity and temperature, crop density, irrigation intensity and general care of the site and crops. The reasons for the appearance of insects are too dense planting, weed beds, high humidity.
The melon aphid at first infects weeds, and then moves on to cultivated plants. Aphids gnaw leaf plates from the underside, stems, ovary, flower petals. The affected organs curl, dry out, and the flowers fall off. The growth and development of plants slows down, and then they die. Aphids can give up to 20 generations per season. The pest overwinters on plant debris.
The method of prevention is timely weeding of seedlings, harvesting plant residues immediately after harvesting, competent crop rotation.
To destroy aphids, 10% solutions of Karbofos or Trichlormetaphos-3 are used, infusion of tobacco dust (1 part of dust is infused with 10 parts of water and diluted with clean water in a ratio of 1: 3), infusion of yarrow (1 kg of grass is infused in 10 liters of water for 2 days).
Whitefly is a small white insect covered with powdery pollen. Both adults and larvae eat leaves and young shoots, suck the juice out of them, and also infect with various diseases. The feces of adult insects eat away at the leaf plate, which leads to the appearance of black spots on it.
The defeat of zucchini is manifested by discoloration, twisting and death of the leaves, and in the future, the whole plant.
The most effective drugs against whitefly: Aktara, Actellik, Double effect, Commander, Tanrek, Oberon and others. The products are diluted according to the instructions and sprayed on the plants and the soil around them at the frequency recommended by the manufacturers. Watering zucchini with insecticide solutions is more effective.
You can spray the zucchini with onion or garlic infusion every day for a week.
The activity of a spider mite is very harmful. It affects the undersides of the leaf plates, braids them with a thin cobweb. In places of defeat, yellow dots form, then the leaves turn yellow completely, acquire a marble pattern and dry out. With a large degree of damage, zucchini die. Ticks give up to 15 generations during the season, and hibernate in groups under plant debris and garbage.
There are ways to get rid of the pest, spider mites can be destroyed by the following means:
- Spraying leaves in hot weather. Water can be replaced with infusion of onion peel or garlic. To prepare tinctures, 200 g of raw materials are poured into 10 liters of water and kept for 2 days.
- Spraying with 20% Chloroethanol solution.
- Irrigation with Isofen 10% solution.
- Spraying of ground sulfur at the rate of 300 g per 100 m².
To improve the adhesive properties of the solutions, 30 g of laundry soap is added to them.
Sprout fly larvae can be found on germinating seeds and seedlings. Gray flies have a body size of no more than 3-5 mm. Insect years begin in spring. They lay their eggs in places with high humidity, especially near manure.
Within a week, larvae emerge from the eggs, which destroy crops in 14 days. Then the larvae pupate. During the warm season, 2-3 generations of sprout flies appear. Especially often, the larvae of sprout flies on the leaves can be found in cold summers.
As a preventive measure, it is necessary to carefully embed manure into the soil, remove plant residues, and regulate watering. In the spring, before the beginning of summer, Karbofos or Fufanon is introduced into the soil. The aerial part of the plant can be pollinated with wood ash, ground black pepper, tobacco dust. For irrigation, use the following solution: 200 g of sodium chloride and 10 liters of water.
Slugs gnaw the embryos in the seeds, eat the leaves on the seedlings. Fixing on the part of the stem, the mollusk gnaws at it, which leads to the death of most of the plant. Later, the pests gnaw the fruit ovary or damage the young zucchini, eating the pulp in them and even making moves.
In addition to reducing the yield, snails leave traces of mucus and other secretions on the affected area of the stem, leaf or fruit, thereby reducing the presentation of the product. Having got into storage with the collected fruits, slugs continue to harm, destroying the crop.
The easiest way to deal with shellfish is mechanical. They are collected by hand or using special traps. Traps are made from pieces of burlap or plywood and placed around the perimeter of the site. Around the plantings, they break through protective grooves up to 30 cm wide and fill them with needles, sand, sawdust, which interfere with the advancement of pests.
They use special preparations: lay out granules of Metaldehyde (at the rate of 4 g per 1 m²), the consumption of which leads to the death of slugs, spray the soil and plants with a solution of copper or iron sulfate, spray lime.