Continuous and long-lasting use of the greenhouse with a non-frequent and limited (usually cucumber and tomato) crop combination leads to the accumulation of pests and pathogenic microorganisms in it. Pests and diseases under favorable conditions are capable of destroying the cultivated crop within a month or two. Phytophages and pathogens are easier to destroy during the liquidation period than to control them later during the crop production. This is why conducting high-quality liquidation work in the greenhouse is so important.
Liquidation work can be divided into two stages. The first stage begins even when the plants are in the greenhouse and consists of the use of preparations for the eradication of pests and diseases on the cultivated crop. During this period, stronger preparations are used, as the crop is already harvested and the plants will soon be thrown away. To save money or time, sometimes the processing of plants at the end of the turnover is missed, throwing out plants with diseases and pests. In such cases, there is a high probability that a sufficiently large number of pathogens (such as powdery mildew of cucumber, gray rot of tomato, black stem and gray rot of cucumber) and phytophagous will remain in the greenhouse or its surroundings, even after the second stage of liquidation works. Given half a chance (when changing the conditions of cultivation, opening the windows, etc.), the "enemies" of plants will fall on a new crop and begin to damage. Therefore, it should not be allowed to develop diseases and pests even at the end of turnover.
When choosing preparations for liquidation work using IPM in a greenhouse, it is necessary to take into account the duration of their residual effect. Introduction of beneficials is possible only after the expiration of the time necessary for decomposition of the active ingredient of pesticides. A number of insecticides with a long period of decomposition are not allowed to be used. The same goes to the use of fungicides that are not compatible with beneficials, which have a long half-life of the active ingredient. IPM compatible preparations remain for long in the greenhouse and depress the development of a population of beneficials.
The type of preparations to use depends on the kind of pest present on the crop in the greenhouse. For instance, when Tuta absoluta is present, it is recommended to apply Talstar (bifentrin) and Divipan (divipan). They control imago well. Talstar kills fourth instar of caterpillars when they deposit on the surface treated by this product. However, Talstar can destroy Tuta absoluta pupae. Divipan can damage tomato miner pupae. Also Steward (indoxicarb) and Mimic (tebufenozide) are applied. To destroy the population of spider mite during this period, some products based on acequinocyl and abamectine. For whitefly control, compatible with IPM products such as pyridaben (Nekster) and imidacloprid (Kohinor). Also Dicarzol is very effective product for liquidate work.
A week after the last treatment of the crop, the herbage, blocks and mats are taken away from the greenhouse. Also all tools and things used during cultivation are taken away. After that it is important to disinfect constructions, walls, floor, irrigation system and tools of the greenhouse.
Earlier formalin was used to disinfect greenhouses. However, the progress forges ahead and now Jet-5, Delakson, HPPI etc. are used. Unlike formalin, these products decompose quickly after being applied and they are not harmful for beneficials.
Jet-5 is a strong disinfectant recognized as a food sanitary with an organic status that contains peroxyacetic acids. Jet-5 is designed for use in all areas of horticulture and agriculture for the disinfection of all surfaces, including greenhouses, tools, pots, trays, benches, equipment, paths and irrigation systems. The disinfectant contains 5% peroacetic acid, which is a very strong oxidant.
Delakson has exceptional activity against a wide range of microbes, bacteria of viruses, pathogenic fungi, molds and spores. For disinfection, use a 2% aqueous solution of the product. Delakson is based on acetic and peracetic acids. It belongs to low-hazard substances of grade 4 when applied to the skin, environmentally friendly, does not require disposal. After treatment with Delakson, it is necessary to well ventilate and rinse the greenhouse to remove the residues of peruxo acid, which can oxidize the structure of the greenhouse.
Ideally, the greenhouse should be thoroughly cleaned and left empty for a week before the next harvest. This allows to remove all stages of pests and to dispose of all remaining adults.
If the liquidation work was carried out correctly, the pests and diseases will not soon appear in the new crop, and the beneficials will quickly join in the protection of the growing plants.