A spider mite on cucumbers in a greenhouse is a dangerous polyphagous pest. Revealed at the last stages of the growing season. Active until harvest.
The common spider mite Tetranychus urticae Koch occupies one of the most important places among phytophages. In protected ground, it is capable of active reproduction, a quick change of generations. It multiplies well on melons, potatoes, radishes, celery. Tomatoes, onions, cabbage and sorrel are of no interest to him.
With a free choice of fodder substrate, he prefers cucumbers from all garden crops. A tick on cucumbers in a greenhouse as a pest is able to distinguish varietal characteristics and choose varieties that are least resistant to pests.
A favorable habitat for the tick is created in the greenhouse:
- a large amount of fodder substrate;
- optimal modes of temperature and humidity;
- protection from wind and showers;
- lack of natural enemies.
In the open field, the greatest damage is caused to farms that grow soybeans and cotton.
Ticks spread with cobwebs in air currents. Spread by humans and animals. They penetrate from other, already infected garden structures or with seedlings. Winter is well tolerated.
In the male, the body is elongated, strongly tapering towards the end, up to 0.35 mm long. The female tick has an oval body up to 0.45 mm long, with 6 transverse rows of setae. The females laying eggs are colored green.
During the period of diapause (temporary physiological rest), their body acquires a reddish-red color. The presence of diapause in the spider mite complicates the fight against it.
Females overwinter in shelters during the period of diapause: in the cracks of the inner surfaces of greenhouses, in the soil, on all vegetative parts of the weeds. With an increase in temperature and humidity, as well as with an increase in daylight hours, they get out of diapause. Intensive reproduction begins, mainly near the structures of the greenhouse and along its periphery. During planting of seedlings in the ground, active females are rapidly spreading over the entire area of the greenhouse.
The results of the tick's vital functions:
- Having settled on the inner side of the leaves, the spider mite begins to intensively feed on sap, mechanically damaging the cells. Then it moves to the outside of the leaf, to the stems and fruits. The upper tier of plants suffers most of all.
- A spider web entwines leaves and stems. Respiration and photosynthesis are suppressed.
- Necrosis develops. Single white dots appear first, then a marble pattern. The leaves turn brown and dry
- The yield is significantly reduced.
Females lay their first eggs in 3-4 days. One female produces 80-100 eggs. She is able to give up to 20 generations in a greenhouse. They reproduce most actively at a temperature of 28-30 ° C and a relative humidity of no more than 65%.
Plant protection and prevention
If a tick has settled on cucumbers in greenhouses, you need to know how to deal with it. To destroy the phytophage, pesticidal and acaricidal agents are used.
Important! After several treatments, pest resistance to drugs develops.
Chemical means of protection against ticks are also undesirable because it is not possible to obtain environmentally friendly products - pesticides do not have time to decompose.
In a private greenhouse, biological agents can be used by spraying:
Biologicals are the least aggressive.
The safest and most effective method of control is the use of natural enemies of the tick.
Environmental protection methods
In nature, there are more than 200 species of insects that feed on spider mites.
- The use of acariphage, a predatory phytoseiulus mite, is effective. 60-100 individuals are enough for 1 m². The predator eats ticks in all phases of their development: eggs, larvae, nymphs, adults. Akarifag is most active at temperatures from 20 to 30 ° C, humidity over 70%.
- Ambliseius Svirsky is another type of predatory mite, which is used when there is a large accumulation of the pest. This predator is not picky about the environment - it is active at temperatures from 8 to 35 ° C, humidity from 40 to 80%.
- Another enemy of the spider mite is the predatory mosquito of the family Cecidomyiidae.
Environmental measures allow crops to be grown without pesticides.
Before planting seedlings, it is necessary to carry out preventive work.
- To prevent the spread, you need to carefully destroy weeds (primarily quinoa, nettle, shepherd's bag), both inside the greenhouse and outside. Deep cultivation of the soil is carried out in the greenhouse. The top layer of the earth is removed, it is disinfected or replaced with a new one.
- It is necessary to disinfect all greenhouse structures with an open fire of a gas burner or blowtorch.
- Excessive thickening of the landings should not be allowed.
- It is advisable to grow varieties of cucumbers that are resistant to spider mites in greenhouses. The least vulnerable varieties are those with leaves that have the greatest thickness of the epidermis and the lower loose part of the leaf pulp - spongy parenchyma. Long, coarse hairs limit the tick's nutrition. Varieties that can accumulate nitrates (for example, the Augustine F1 hybrid) are eaten by the tick first. Phytophages do not like cucumber hybrids, in the chemical composition of which dry substances and ascorbic acid predominate.
Some vegetable farms carry out pre-sowing seed treatment:
- warming up for 24 hours at t 60 ° С;
- calibration in sodium chloride solution;
- then holding for 30 minutes in a 1% solution of potassium permanganate with immediate rinsing and drying.
Before germination, the seeds are soaked for 18-24 hours in a solution that includes:
- 0.2% boric acid;
- 0.5% zinc sulfate;
- 0.1% ammonium molybdate;
- 0.05% copper sulfate.
If a tick is found on cucumbers in a greenhouse, both fight against it and prevention should be done immediately.