The Latest Management Methods and Pest and Disease Control Techniques for Greenhouse Vegetables
Greenhouse vegetables, also known as plastic tunnel vegetables, refer to vegetables grown inside a tunnel covered with plastic film. This mode artificially controls a series of ecological conditions such as temperature and moisture inside the tunnel, thereby making it possible to adjust the vegetable production season and produce off-season vegetables to meet market demand, thus achieving the goal of increasing farmers' income. So how should vegetables under this mode be managed, and how should the pests and diseases of greenhouse vegetables be controlled?
First, greenhouse vegetables must be diligently managed in all aspects, including variety selection, temperature, humidity, light, and fertilizer and water, so as to ensure that the vegetables get sick as little as possible or only mildly, reduce the amount of pesticide used, and thereby both reduce economic input and lighten labor intensity while ensuring the quality and safety of agricultural products.
I. Management Methods
1. Select disease-resistant varieties suited to the local area and adopt grafting technology.
2. In cultivation, adopt a cultivation mode of wide ridges with double rows on high beds or single rows on high beds, equipped with under-film micro-drip irrigation technology. This can increase ventilation and light penetration, raise the low temperature, and reduce air humidity.
3. Temperature management. Suitable for cucurbit and solanaceous vegetables.
4. Humidity management. Before vegetable seedling raising, water the bottom water thoroughly once (water thoroughly but do not waterlog); after emergence, basically do not water unless there is drought. Before grafting, water the nutrient pots thoroughly; after the grafted seedlings have recovered, control watering as much as possible, but since nutrient pots contain relatively little soil, avoid drought causing stunted old seedlings. After transplanting, the recovery water must be watered thoroughly; until the flowering stage, basically do not apply heavy watering, to avoid excessive vegetative growth of the seedlings. In the early picking period, water once every 7 days, applying water-soluble fertilizer with the water; during the low-temperature period, water once every 10—15 days, using micro-drip irrigation or hole watering as much as possible. After the Start of Spring, when temperatures rise, the amount of watering can be appropriately increased.
5. Light management. Every morning, remove dust from the tunnel film, preferably with a dust-removing cloth. According to temperature conditions, uncover early and cover late with heat-preserving coverings as much as possible. On consecutive cloudy days, supplemental lights can be used, 20 lights per mu, but do not use them at night. Paste reflective film on the back wall; it is best to use one strip in the middle of the back wall, so that the upper and lower parts of the back wall absorb light during the day and can dissipate heat at night. After a sudden clear day following consecutive cloudy days, do not rush to open the heat-preserving coverings; appropriately open a few cotton quilts or straw curtains, then spray foliar fertilizer or clean water, and only then uncover all the coverings.
6. Fertilizer and water management. Suitable for cucurbit and solanaceous vegetables. For base fertilizer, it is best to use diammonium phosphate at 100 jin per mu, potassium sulfate at 80 jin per mu, and appropriately add some calcium fertilizer at 80 jin per mu. If nutrient deficiency appears at the seedling stage, spray 1—2 times with 0.1% urea and 0.2%—0.4% monopotassium phosphate or foliar fertilizers such as Haifa Magic Vigor for root-zone supplementary fertilization. After transplanting and before picking, try not to use water-soluble fertilizer, to avoid excessive vegetative growth of the seedlings. In the early picking period, a high-potassium formula fertilizer (Haifa Magic Rich, potassium nitrate) can be applied with water, not exceeding 20 jin per mu. During the full fruiting period, a balanced N, P, K formula fertilizer can be applied with water, not exceeding 30 jin per mu. During the low-temperature period, apply fertilizers such as amino acids and humic acids that promote rooting and nourish the plants.
7. Increase the application of carbon dioxide gas fertilizer: in winter, the ventilation volume in the greenhouse decreases, and the indoor carbon dioxide concentration is low, which is unfavorable for plant photosynthesis. Applying carbon dioxide has a significant yield-increasing effect, especially from late January to the end of February, when the interior is basically closed, so supplementing carbon dioxide at this time is extremely beneficial for increasing vegetable yields. A carbon dioxide generator can be used, or simple dedicated carbon dioxide hanging bags can be used.
8. Prune at the proper time. Promptly hang vines, lower vines, remove old leaves, pinch off tendrils, remove ineffective inner canopy branches, and take them out of the tunnel at any time.
II. Physical Control of Pests and Diseases
1. The comprehensive use of insect-proof nets and colored sticky boards can achieve the goal of controlling pest numbers and reducing the occurrence of pests and diseases. Before planting, seal the greenhouse vents with insect-proof nets to block the transmission routes of pests. For vegetable production, it is advisable to choose nets of 14—40 mesh. On the premise of effectively preventing the smallest major pest on vegetables—aphids—the mesh number should be as small as possible to facilitate ventilation. The surrounding edges of the insect-proof net should be compacted with soil to prevent pests from sneaking in to lay eggs. Hang yellow and blue boards inside the greenhouse. Yellow boards can trap and kill aphids, whiteflies, and leafminers, while blue boards can trap and kill thrips. Yellow and blue boards can be hung with fine string, 20—25 boards per mu, with the height preferably 5—10 cm above the growing point; during use of the colored boards, it is best to keep raising their height as the vegetables grow, so that the colored boards are always higher than the vegetable growing point, making it easier to trap pests. When the sticky insect glue on the colored boards loses its stickiness, replace them at any time. It is best to use the colored boards in the early stage or initial stage of pest occurrence, when pest numbers are extremely low, for good trapping and killing results.
2. The rational use of an ozone generator can effectively control the occurrence of pests and diseases.
(1) When installing the ozone generator, strictly adjust the generator's working time according to the product manual; the ozone outlet holes should be on both sides and not facing downward; the pipeline should be in the middle-front part of the greenhouse frame, with the top end about 50 cm from the plants. Generally, ordinary lighting electricity can be used.
(2) Reasonably determine the ozone concentration and the length of release time. The ozone release concentration and the length of release time should be appropriately adjusted according to different crops and their growth stages. Generally, crops at the mature plant stage are more adaptable to ozone than crops at the seedling stage. In production, if the ozone release amount is too large or the greenhouse fumigation time is too long, in mild cases it will cause the leaves of greenhouse vegetables to dry up, and in severe cases it will cause plant death. As the plants grow, the release amount and fumigation time can gradually increase, so as to achieve the goal of controlling pests and diseases without harming the vegetable crops.
(3) Use starting from the seedling stage can significantly prevent the occurrence of airborne diseases throughout the whole growth period, and use in the middle growth stage can have a significant effect within one month. Note: when used in the middle growth stage of cucumbers, ozone may first worsen cucumber diseases (photosynthesis is inhibited), but after 20—45 days, after the cucumber vines adapt to the ozone environment, diseases can be significantly reduced, and in the later growth stage they grow vigorously and are free of disease, with a significant control effect on gray mold. During release, uniformity should be ensured as much as possible, and the jet holes must not directly face the vegetables; they should be more than 50 cm away from the vegetables. After the fumigation time is reached, ventilation should be carried out promptly, and generally the ventilation time must not be less than 30 minutes.
(4) Temperature and humidity regulation. When ozone is released, the temperature inside the greenhouse should be kept within the range of 10°—30°, and the control effect will be better when the air humidity is relatively high. When used for a long time in winter, water easily accumulates in the ozone delivery pipe, and because ozone air contains nitrogen oxides, accumulated water over time will form strong nitric acid, so special attention should be paid during discharge, and it must never be splashed on the body or on the plants.
III. Biological agents and chemical agent control.
When using chemical pesticides to control pests and diseases, if a single agent is used alone, the problem of gradually declining efficacy will appear. Moreover, the more highly specialized the pesticide, the more easily it becomes ineffective. This is mostly because pathogens and pests have developed resistance. Research shows that after resistance has developed to one chemical pesticide, agents of the same class often also fail. Therefore, it is best to use biological agents and chemical agents alternately. Using biological agents such as veratridine, matrine, liuyangmycin, agricultural streptomycin, and new plantmycin alternately with chemical agents such as Actara, Amistar, DuPont Curzate, and Kocide 3000 both avoids cross-resistance of pesticides and reduces chemical pesticide residues. Master the characteristics of pesticides, achieve symptom-based application, timely application, and alternating and combined application. It is strictly forbidden to use pesticides explicitly prohibited by the state. In order to ensure the safety of pesticide use, in addition to considering the toxicity of the pesticide, a comprehensive understanding of and strict compliance with the permitted number of applications on vegetables, the maximum residue limit, and the pre-harvest interval are also required.
The above are the cultivation and management methods for greenhouse vegetables, and the control methods for greenhouse vegetable pests and diseases are introduced from the physical level and the biochemical level, hoping to be of some help to everyone.