How to Grow Pollution-Free Vegetables? A Detailed Guide to Companion Planting Techniques

In recent years, the promotion of new varieties and the application of new technologies have greatly increased vegetable yields, but pests and diseases have also become more and more prevalent during the growing process. Many vegetable growers have become locked in a battle with pests and diseases, spraying pesticides as soon as problems appear, and applying preventive pesticides when there are none. Preventive spraying and repeated spraying have created considerable expenses for farmers in pest and disease control, and are not conducive to the production of pollution-free vegetables. Vegetable growers can apply the following six companion techniques for pollution-free cultivation to reduce disease incidence and cut down on pesticide use.

I. Insect-proof Net Isolation Technique

Insect-proof net isolation refers to fully covering the surroundings and top of a greenhouse with insect-proof nets, or covering the top of a greenhouse with film and shade netting while covering the surroundings with insect-proof nets, or building a flat trellis structure of several thousand square meters fully covered with insect-proof nets, also known as an insect-proof net house. The inside of the net is isolated from the outside, so that larger pests (tobacco cutworm, beet armyworm, imported cabbageworm, diamondback moth, etc.) cannot enter the net to damage vegetable crops. Through insect-proof net covered cultivation, vegetable pesticide use can be greatly reduced, solving the difficult problem of the safety interval for continuously harvested vegetables, and greatly improving the food safety of vegetables.

In summer and autumn, leafy vegetables, fruit vegetables, cucurbit vegetables and legume vegetables can all be cultivated with insect-proof net covering. For cruciferous and solanaceous vegetables, autumn seedling raising takes place during the hot, rainy season; covering seedlings with insect-proof nets can reduce pest and disease damage, protect seedlings from rainstorms, reduce soil compaction in the seedbed and loss of fertilizer, and increase the seedling survival rate.

II. Colored Board Trapping Technique

The colored board (yellow and blue boards) trapping technique uses the strong attraction of certain pest adults to yellow and blue colors to physically trap and kill pests. Its main targets are aphids, whiteflies, leafhoppers, etc. of the Homoptera order; leafminers, seed flies, etc. of the Diptera order; and thrips, etc. of the Thysanoptera order. Yellow boards are often used in protected and open-field cultivation to trap whiteflies, leafminers and aphids, etc.; blue boards are used to trap thrips, etc.

This technique is simple, and can be used in both open-field and protected cultivation, with better results in protected cultivation. Generally, 30 insect-attracting boards measuring 25 cm x 30 cm or 40 boards measuring 25 cm x 20 cm can be hung evenly per mu. According to trials, yellow boards can reduce aphid population density by 20%-40%. Insect-attracting colored boards can not only kill large numbers of adults and directly reduce pest damage, but also provide pest forecasting and early warning to determine the exact timing of control.

III. Insect Sex Pheromone Technique

Killing pests with insect sex pheromones works by slowly releasing synthetic sex pheromone compounds from a lure core into the field to attract male moths into a trap, or by using a confusion method so that male moths cannot find female moths, thereby disrupting mating and ultimately achieving control.

Using insect sex pheromones to kill pests can reduce the number of eggs in the field, effectively control the occurrence of the next generation, reduce the number of chemical control applications in the field, and lower pesticide use. At the same time, it is highly specific, has no effect on insects other than the target pest species, can better protect natural enemy populations, give fuller play to their potential for controlling pests, and improve the agricultural ecological environment. This technique can also be used for monitoring and early warning of target pests.

IV. Insect-killing Lamp Trapping Technique

By making use of pests' characteristics such as phototaxis, wave taxis, color taxis and taxis, the light wave of an insect-killing lamp is set within a specific range, using light at close range and waves at long range, combined with the sex pheromones produced by the pests themselves to lure adults to the lamp, and then paired with a specially made high-voltage electric grid to electrocute them, so that pests fall into a dedicated insect bag, achieving the purpose of killing pests. At present, the insect-killing lamp most widely promoted and applied in agricultural production is the frequency-vibration insect-killing lamp.

In vegetable production, lamps are generally installed in mid-April and removed in early November. The daily lamp-on time is generally from 9 p.m. to 4 a.m. the next day. Lamps with a light control system can switch on and off automatically according to natural light brightness, and each insect-killing lamp generally has an effective coverage range of 30-50 mu.

Promoting and applying insect-killing lamps can greatly reduce the field pest population base, reduce the use of chemical pesticides, and improve the safety of vegetable products.

V. Micro-irrigation Technique

This is a local irrigation technique in which micro-irrigation equipment is assembled into a micro-irrigation system to transport and distribute pressurized water to the field, moistening the soil near vegetable roots through emitters at a very small flow rate. In practical application, there are mainly two types: drip irrigation and micro-sprinkler irrigation. Supplying water in the form of intermittent drops is called drip irrigation, and discharging water in the form of spraying is called micro-sprinkler irrigation. Drip irrigation can be used for tomatoes, eggplants, peppers, long gourds, pumpkins, cucumbers and other vegetables planted at row and plant spacings; micro-sprinkler irrigation is suitable for vegetables with high planting density and soft, tender plants, such as bok choy, celery and Malabar spinach, and can also be used for vegetable seedling raising.

Micro-irrigation technology has the advantages of saving labor and water, reducing energy consumption, improving fertilizer use efficiency, lowering field humidity, reducing diseases and field weeds, and promoting high-quality, high-yield vegetables.

VI. "Micro-storage Micro-irrigation" Technique

This is a highly efficient water-saving irrigation technique formed by combining "micro-storage" and "micro-drip irrigation," that is, using storage ponds to collect small water sources in mountainous areas, using the natural drop of hillsides to generate water pressure, transporting water to the field through plastic pipes, and using drip irrigation pipes to deliver water evenly and precisely to the roots of plants, forming gravity-flow irrigation. This system effectively solves the problem of inconvenient electricity use in mountainous areas, enabling the drip irrigation system to be used without electricity or pumps, and is suitable for vegetable irrigation on non-flat terrain such as mountainous, semi-mountainous and hilly areas.