Detailed Explanation of Greenhouse Vegetable Management Methods and Pest and Disease Control Techniques
Greenhouse vegetables, also known as plastic tunnel vegetables, refer to vegetables grown inside tunnels covered with plastic film. This model artificially controls a series of ecological conditions such as temperature and moisture inside the tunnel, thereby adjusting the vegetable production season and producing off-season vegetables to meet market demand, thus achieving the goal of increasing farmers' income. So how should vegetables under this model be managed, and how should greenhouse vegetable pests and diseases be controlled?
First, greenhouse vegetables must be diligently managed in all aspects, including variety selection, temperature, humidity, light, and fertilizer and water, to ensure that vegetables develop as few diseases as possible or only mild ones, reducing pesticide use, which both lowers economic input and reduces labor intensity while ensuring the quality and safety of agricultural products.
I. Management Methods
1. Select disease-resistant varieties suitable for the local area and adopt grafting techniques.
2. In cultivation, adopt a high-ridge cultivation model with wide ridges and double rows or single ridges, equipped with under-film micro-drip irrigation technology. This can increase ventilation and light penetration, raise low temperatures, 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 (thoroughly but not to the point of waterlogging); after seedlings emerge, basically do not water unless there is drought. Before grafting, water the nutrient pots thoroughly; after grafted seedlings recover, control watering as much as possible, but because nutrient pots contain relatively little soil, avoid drought causing small old seedlings. After transplanting, the recovery water must be watered thoroughly; until the flowering stage, basically do not apply large amounts of water, to avoid excessive vine growth. In the early picking stage, water once every 7 days, applying water-soluble fertilizer with the water; during low-temperature periods, water once every 10—15 days, using micro-drip irrigation or hole watering as much as possible. After the Beginning of Spring, as 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 cloth. According to temperature conditions, uncover insulation covers as early as possible and cover them as late as possible. On consecutive cloudy days, supplemental lights can be used, 20 lamps per mu, but do not use them at night. Hang reflective film on the back wall; it is best to use one strip in the middle of the back wall, as the upper and lower parts of the back wall absorb light during the day and can release heat at night. After consecutive cloudy days suddenly turn sunny, do not rush to open the insulation covers; appropriately open a few cotton quilts or straw curtains, then spray water or foliar fertilizer to wet the leaves, and only then fully uncover the covers.
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 occurs at the seedling stage, spray 1—2 times with 0.1% urea and 0.2%—0.4% monopotassium phosphate or Haifa Magic Strong and other foliar fertilizers for extra-root topdressing. After transplanting and before picking, try not to use water-soluble fertilizer, to avoid excessive seedling growth. In the early picking stage, water-soluble high-potassium fertilizers (Haifa Magic Rich, potassium nitrate) can be applied, not exceeding 20 jin per mu. During the full fruit stage, water-soluble fertilizers with a balanced N, P, K formula can be applied, not exceeding 30 jin per mu. During low-temperature periods, apply water-soluble fertilizers such as amino acids and humic acids that promote rooting and nourish the plants.
7. Increase 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; at this time, supplementing carbon dioxide is extremely beneficial for increasing vegetable yields. A carbon dioxide generator can be used, or simple special carbon dioxide hanging bags can be used.
8. Prune in a timely manner. Promptly hang vines, lower vines, remove old leaves, pinch tendrils, and remove ineffective inner branches, and carry 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 ventilation openings with insect-proof nets to block the transmission routes of pests. For vegetable production, it is advisable to use nets of 14—40 mesh. On the premise of effectively preventing aphids, the smallest main pest on vegetables, the mesh number should be as small as possible to facilitate ventilation. The surroundings 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; 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 the use of colored boards, it is best to continuously raise their height as the vegetables grow, so that the colored boards are always above 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. Colored boards are best used in the early stage or initial stage of pest occurrence, when pest numbers are extremely low, for good trapping and killing results.
2. The reasonable use of ozone generators 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, not facing downward. The pipeline should be in the front-middle part of the greenhouse frame, with the top end about 50 cm from the plants. Generally, lighting electricity can be used.
(2) Reasonably determine the ozone concentration and release duration. The ozone release concentration and release duration 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 amount of ozone released is too large or the greenhouse fumigation time is too long, in mild cases it will cause greenhouse vegetable leaves 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) Starting use at the seedling stage can significantly prevent the occurrence of airborne diseases throughout the entire growth period, and use at the middle growth stage can have significant effects within one month. Note: when used at 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 later growth is vigorous and disease-free, with significant control effects on gray mold. During release, uniformity should be ensured as much as possible, and the air outlet 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; generally, the ventilation time should not be less than 30 minutes.
(4) Temperature and humidity regulation. When ozone is released, the temperature inside the greenhouse should be maintained within the range of 10°—30°, and the control effect will be better under conditions of relatively high air humidity. 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 will form strong nitric acid over time. Extra care should be taken during discharge; never let it splash on the body or 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 occur. Moreover, the more specialized the pesticide, the more easily it becomes ineffective. This is mostly because pathogens and pests have developed resistance. Research shows that after developing resistance to one chemical pesticide, agents of the same class often also fail. Therefore, it is best to alternate biological agents with chemical agents. Alternating biological agents such as veratrine, matrine, liuyangmycin, agricultural streptomycin, and xinzhiromycin with chemical agents such as Actara, Amistar, DuPont Curzate, and Kocide 3000 avoids cross-resistance of pesticides and also reduces chemical pesticide residues. Master the characteristics of pesticides, apply the right pesticide for the right disease, apply at the right time, and alternate and combine pesticides. It is strictly forbidden to use pesticides explicitly prohibited by the state. To ensure the safe use of pesticides, in addition to considering the toxicity of the pesticide, a comprehensive understanding and strict compliance with the permitted number of applications on vegetables, maximum residue limits, and pre-harvest intervals are also required.
The above are the cultivation and management methods related to greenhouse vegetables, and methods for controlling greenhouse vegetable pests and diseases are introduced from the physical level and the biochemical level. I hope this can be of some help to everyone.