Diseases And Pests Of Squash

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

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Zucchini viral diseases

Zucchini variety Bumblebee

Affects mainly the leaf apparatus, reducing the photosynthetic activity of leaves. Cucumber mosaics and pumpkin mosaics are more common on the zucchini.

Cucumber mosaic. It appears on young leaves in the form of greenish-yellow mosaic spots. As the disease progresses, leaf curling is observed and the formation of small tubercles, bulges between the veins, giving the leaf surface a corrugated appearance. Following this, a pronounced yellow or green spot develops, accompanied by deformation and curliness of the leaves.

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Internodes are shortened, plant growth is greatly delayed. Zucchini plants, which are largely affected by the disease, are 2-3 times lagging behind healthy specimens in the habitus of the bush and practically do not give a marketable crop. The virus is transferred from diseased plants to healthy ones by various species of aphids. The pathogen overwinters in the roots of perennial weeds, which are reserves of infection. Seed infection is usually not transmitted.

Control measures: the destruction of perennial weeds and the fight against aphids.

Pumpkin mosaic. Also lightens the color of the leaves to yellow-green. Initially, the ends of the veins stand out along the edges of the leaf as a result of lagging behind the growth of the leaf blade. Then mottling, curl appear. The leaf pulp and the thinnest veins fall out, leaving only thick veins with a narrow strip of leaf pulp along them. The pumpkin mosaic virus is seed transmitted and persists for several years.

Control measures: heating the seeds for three days at a temperature of + 50 … + 60 ° С.

Fungal diseases

Powdery mildew

Powdery mildew. One of the most common diseases. First of all, it affects old leaves, gradually moving to younger ones. A white bloom appears on the leaves in the form of spots. With a strong spread of the disease, the spots merge, forming a solid white bloom not only on the leaves, but also on the stems. Affected leaves turn brown and dry.

On the mealy plaque, which is the mycelium of the causative agent of the disease, a mass of conidia develops. They spread the disease to other plants during the growing season. The period from the moment of infection until the first signs of infection appear is three to four days. The causative agents of the disease persist in the form of overwintering fruit bodies on plant debris and weeds and serve as a source of infection in the new season.

Control measures: burning affected plants, removing plant residues and weeds, deep digging of the soil.

Downy mildew, or downy mildew. It affects leaves on plants of any age, starting from seedlings. On the affected leaves, yellowish-green spots of a round or angular shape are formed on the upper side. They gradually turn brown, dry up, crumble. A gray-purple bloom appears on the spots on the underside of the leaf - sporulation of the fungus. The development of the disease intensifies with frequent fogs, abundant dew, in protected ground - with high air humidity. The main primary source of the disease is the soil, where the pathogen can persist for several years.

Control measures: observance of crop rotation, in protected ground - disinfection or soil change, frequent ventilation.

White rot

White rot. Affects stems, leaf stalks and fruits. A white flocculent coating of the fungus appears on the affected areas. Sick fruits soften and turn into a mushy mass. The disease spreads more strongly in cool weather and thickening of plants, in protected ground - when irrigated with cold water. The causative agent hibernates in the form of sclerotia in the ground.

Control measures: removal and destruction of affected parts of the plant, dusting the primary foci of the disease with lime or crushed coal; alternation of cultures; change of soil, watering with warm water and regular ventilation in protected ground.

Gray rot. It appears on young ovaries. They first become watery, then become covered with a gray coating. The disease is most harmful in film shelters; in the open field - during prolonged cool rainy or cloudy weather. The causative agent of the disease, once on the soil, remains in it for 1-2 years and is the source of the main infection.

Control measures: crop rotation in open ground, in protected ground - disinfection or soil change; treatment of the affected areas of the plant with a mixture of copper sulfate and chalk (1: 2).

Root rot. The disease is widespread in protected ground. It manifests itself in the fruiting phase by decay of the roots and root collar. The roots darken, become rotten, soften; the lower leaves turn yellow and the plant withers. The development of the disease is facilitated by frequent feeding with organic fertilizers, high soil moisture, watering with cold water.

Control measures: adherence to agrotechnics, disinfection of soils in film shelters, maintaining an optimal soil moisture regime.

Anthracnose

Anthracnose. It affects all aerial parts of the plant: leaves, stems, fruits. Yellowish-brown spots form on the leaves, which increase with the development of the disease. Infection from the leaves spreads to the stems and fruits. The affected leaves curl and dry up, weeping spots with a slimy coating appear on the stems. Impressed spots form on the fruits, they shrivel. During the growing season, the disease is spread by the conidia of the fungus. The pathogen overwinters on plant debris, the infection can be transmitted with seeds.

Control measures: removal of plant residues, dressing of seeds before sowing and processing them with a 0.2% solution of micronutrient fertilizers (boron, copper, manganese), disinfection of greenhouses and shelters with bleach, removal of diseased plants.

Olive spot. The first signs of the disease appear on fruits in the form of small watery spots, which quickly increase to 4-5 mm in diameter. The spots gradually deepen into the idea of ulcers and, with high air humidity, become covered with a velvety grayish-olive bloom.

Irregular yellow-brown spots are formed on the leaves. The leaf tissue in these places then falls out. The infection is spread by rain, wind, irrigation, particles of contaminated soil. The pathogen is preserved on plant debris, in the soil, on wooden structures.

Control measures: destruction of plant residues, crop rotation, disinfection of wooden structures with bleach, removal of affected plant parts.

Zucchini pests

Spider mite

Spider mite. It affects squash plants when cultivated under film shelters. Mites appear on plants with the onset of warm weather. They live and feed on the back of the leaf, sucking out cell sap. At first, light green dots appear on the leaf, then the leaf becomes spotty, and from the lower side it is tightened with a spider web.

With severe damage, the leaves dry out. The tick is a very small insect, its body is 0.3-0.5 mm long, elongated-oval. It reproduces very quickly, giving about 15 generations per year. Females of the tick overwinter in groups under plant debris, dry debris, in the cracks of the wooden frames of shelters.

Control measures: destruction of plant residues and debris, disinfection of wooden frames. When the pest spreads, the plants are sprayed with a decoction of dry leaves and garlic scales (150 g per 10 liters of water, insist for 1 day) or infusion of onion scales (half a bucket of scales is poured into 10 liters of hot water, infused for 1 day, filtered and diluted with water 1: 2) … For spraying, an infusion of potato tops, black henbane, and common dope is also used. For better adhesion of solutions to the underside of the sheet, 30 g of laundry soap is dissolved in them.

Melon aphid. Sucking insect. It settles in colonies on the underside of leaves, sucking juices out of them. Affected leaves wrinkle and curl. The plant lags behind in growth, and dies if severely damaged. Aphids reproduce asexually, very quickly, giving up to 20 generations during the growing season. It hibernates on weed leaves and plant debris.

Control measures: destruction of weeds and plant residues; when spreading on plants - spraying with an infusion of tobacco dust (1 weight part is poured with 10 parts of water, infused for a day, the infusion is filtered and diluted with water 1: 3) or with an infusion of yarrow (1 kg of dry plants is poured with 10 liters of hot water, insisted for two days).

Sprout fly. Fly larvae damage germinating seeds and seedlings, causing their death. The fly brings the greatest damage in the cold summer. The fly is gray, 3-5 mm long, flies out in spring, lays eggs in damp places, near poorly sealed manure. After 2-10 days the larvae appear, after 12-16 days they pupate. It gives 2-3 generations during the season. Pupae of flies overwinter in the soil.

Read the next part. Growing zucchini in film shelters →

Tatiana Piskunova,

Candidate of Agricultural Sciences,

VIR named after N. I. Vavilova