What are the main points of tomato cultivation techniques in open field in spring?
First, variety selection
In spring, tomato cultivation in the open field is low in the early stage and high in the later stage. Therefore, varieties with high yield, high temperature and humidity resistance, high virus resistance, hirsutism resistance and root-knot nematode resistance should be selected, and early maturity varieties should be selected as middle-early maturity or self-capping varieties.
Second, cultivate strong seedlings.
Cultivating strong seedlings is the key to high yield. Generally, 40-50g seeds are used per mu and 6-7g seeds are sown per square meter. If cold bed is used to raise seedlings, it will take 70~80 days for early-maturing varieties and 80~90 days for middle-late-maturing varieties. However, it takes 60~70 days to raise seedlings in hotbeds or greenhouses; It takes 45~50 days to raise seedlings in small arch shed in South China. Seedling raising method refers to the cultivation of tomatoes in solar greenhouse in spring.
Third, soil preparation, soil preparation and film mulching
The planting area is a plot with fertile and loose soil and convenient irrigation and drainage. Solanaceae crops have not been planted in recent 2-3 years. Before winter comes, this land should be deeply ploughed by 25-30 cm. Combined with ploughing and applying base fertilizer, 5000-6000 kg of organic fertilizer and 0/5-20 kg of diammonium phosphate/kloc are applied per mu. Fine harrow after deep ploughing. Then create the boundary. When making a border, make a border with a width of 50~60 cm and a height of 10~ 15 cm, and the direction should extend from north to south.
Generally, 80 cm wide plastic film is used for film covering. When covering with plastic film, the ridge surface should be flat to ensure that the plastic film can be close to the surface, so as to improve the ground temperature, inhibit weeds and preserve water and fertilizer.
Fourth, colonization.
It should be planted after the local final frost period and when the ground temperature at the depth of 10 cm is stable above 10℃. Pay attention to overcoming the low temperature in spring and ensure that there will be no unstable weather such as frost and cold current for half a month after planting. When planting, all localities should choose the appropriate sowing date and sowing date according to local weather conditions and their own planting conditions.
The sowing date depends on the final frost period in each place, and it is usually sown after the final frost. The sowing date is 70~ 100 days before sowing date.
Generally, North China is mostly around Grain Rain (mid-late April), Northeast China and Northwest China are mostly in the period from long summer to short summer (May), and all parts of the Yangtze River Basin can be planted at the earliest end of March, and South China (Guangzhou) can be planted at the earliest from beginning of spring to rainy season (February).
In order to ensure safe production and obtain high yield, we can use protected facilities to raise seedlings in advance, plant them in the open field as soon as possible after the end of the final frost period, and strive for early maturity, early harvest and early listing, thus obtaining higher economic benefits.
The planting density is generally 2 rows per border, with small row spacing of 50-60 cm, large row spacing of 60-70 cm, and plant spacing of 35-40 cm. Dig a hole first, the hole depth is 8~ 10 cm, generally 3500~5000 plants per mu.
When planting, choose sunny and windless weather. When planting seedlings, some areas are watered before planting seedlings, and some areas are watered after planting seedlings. There is not much difference between the two. When transplanting, the depth should be moderate, and the suitable planting depth is that the clods are flat or slightly deeper than the surface.
V post-colonial management
1, factory supervision
When planting tomatoes in the open field, intertillage should be done in time after watering the planting water, so as to raise the ground temperature and conserve water, which is beneficial to slow down the seedlings. Scaffolding shall be carried out in time. In open field cultivation, single stem pruning is generally adopted. When pruning, only the main stem grows, and all the lateral branches are removed when they are 5~7 cm long. Because the lateral branches at the same node as the ear grow particularly vigorously, topping operation should be carried out. When topping, 2~3 leaves (5~6 layers of fruit) are usually left on the inflorescence 50~60 days before seedling drawing to remove the terminal buds, which is beneficial to supply the limited nutrients for the growth of flowers and fruits.
2. Water and fertilizer management
After planting tomatoes, you should squat down properly. At present, the management work is mainly based on intertillage and soil conservation. If it is not dry, there is no need to water it. When the first ear of fruit grows to the size of walnut, the plant enters the fruiting stage at this time, and the water demand gradually increases, so it is necessary to water more. Generally, it can be watered once every 5 to 7 days. When the temperature of sandy soil is high, it should be watered more, otherwise it should be watered less to improve the fruit quality.
Topdressing tomato should be based on soil fertility and growth. At the beginning of fruiting, topdressing can be combined with watering. Topdressing is mainly quick-acting chemical fertilizer, topdressing is 2 ~ 3 times, and the application rate per mu is 10 ~ 15 kg. Leave more than 4 ears of fruit on the top of the head, and appropriately increase the number of topdressing.
Step 3 keep flowers and fruits thin
In low temperature or high temperature season, tomatoes will have poor pollination, flower dropping and other phenomena, so proper flower protection should be carried out. Generally, when there are 2~3 flowers per ear, control can be carried out by spraying control solution, the spraying concentration is 25~30 mg/L, and each sequence of flowers can be treated 1 time. Generally, large and medium-sized fresh fruit varieties leave 3-4 fruits per ear, and small varieties leave 5-6 fruits. If there are too many fruits, the fruits should be thinned as early as possible to ensure that the fruits are neat and improve the quality.
4, pest control
At present, there are many kinds of common diseases and insect pests in tomato production. The occurrence and control of some major pests and diseases are briefly described as follows.
(1) gray mold
Tomato gray mold is a common disease in tomato production, which is very harmful. It widely occurs in vegetable production areas all over the country. When tomato gray mold occurs, it mainly harms stems, leaves, flowers and fruits.
① obvious symptoms
Generally speaking, the diseases of green fruits are more serious. The infected parts are mostly residual petals and other parts, and then the disease gradually spreads to petiole and fruit, resulting in the color of tomato peel turning gray, soft rot and the growth of gray-green mold layer. Finally, the fruit hardens due to excessive water loss.
Most leaf diseases occur at the top of leaves first, and with the aggravation of the disease, disease spots gradually appear. v？ The shape extends to the inside of the leaves, and the color is light brown at the time of onset, showing a waterlogged shape with irregular edges and alternating deep and shallow rings. Then the dry leaves produce a mold layer, and finally the leaves wither and die.
When the stems of plants are infected, water stains first appear, and then expand into long or oval lesions. Under the condition of high relative humidity of air, gray-brown mold layer appeared in the lesion.
② Preventive and control measures
The prevention and control of tomato gray mold is mainly to do a good job in early prevention and manage several key periods such as seedling stage, initial flowering stage and fruit expansion stage. In terms of control, the seeds can be disinfected by soaking in ozone water for about 45 minutes before seedling raising, and the seedlings can be sprayed with 800 times solution of 65% metalaxyl wettable powder and 50% prochloraz wettable powder 1200 times solution before sowing.
(2) Tomato early blight
Tomato early blight can occur in seedling stage and adult stage, which mainly harms tomato fruits, leaves, stems and flowers.
① obvious symptoms
When leaves are infected, small black spots will appear at the beginning of the disease, and then gradually expand into wheel spots.
Fruit diseases usually occur on green fruits. At first, the symptoms appeared near the calyx, and the initial shape was black amorphous or oval patches (brown). In the late stage of the disease, the epidermis of tomato fruit cracked, which reduced the quality of the fruit, and the diseased part was hard, producing a dense layer of moldy substances (black).
Stem diseases often appear in the branches (brown), which are oval and irregular round, producing a layer of gray mildew-like substances. Oval lesions (annular, black or dark brown) appear when early blight occurs on petiole, and finally the lesions cover the stem with the expansion of the disease.
② Preventive and control measures
The control agents of tomato early blight can choose difenoconazole and boscalid for spray control. In the early stage of the disease, diseased leaves, diseased branches, diseased fruits, etc. The site should be cleared and cleaned in time, and chemical agents should be sprayed for control. When the weather is fine, apply the pesticide, and control it every 1 week 1 time for 3 consecutive times.
(3) whitefly
① Characteristics of diseases
Adults and nymphs of whitefly gather on the back of tomato leaves, which leads to yellowing and withering of the leaves. When the pest is serious, tomato plants will wither and die. Whitefly has a strong reproductive ability, and honeydew secreted by whitefly will cause serious pollution to tomato fruits and leaves, leading to the occurrence of sooty blotch.
② Preventive and control measures
Adult whiteflies turn yellow easily. Therefore, the tomato garden can be hung with a layer of sticky yellow board with a hanging density of 30~50 pieces/mu. If the occurrence of whitefly in the field is light, the natural enemy Aphid wasp can be released in the tomato garden, and it can be released 1 time every two weeks or so, and it can be released three times continuously; If the field diseases are serious, Heng Lv 20% acetamiprid 1000 times solution can be selected for spray control.
(4) Aphids
Aphids mainly harm the tender stems and leaves of tomato plants and hinder the normal growth and development of plants.
Prevention and control measures: when a large number of aphids appear in the field, 800 times of 5% acetaminophen emulsion and 3000 times of 50% pirimicarb wettable powder can be used for prevention and control, and sprayed every 1 week, twice in a row; You can also boil pepper and water at the ratio of 1: 8 for 30 minutes, or mix washing powder with water at the ratio of 1: 25, and spray it on plants, and spray it every 1 week 1 time for three times continuously. Aphids have many natural enemies, which can protect parasitic bees, ladybugs and other natural enemies, and play the role of pest control.
As an important form of tomato cultivation, open-field tomato cultivation in spring can meet people's demand for eating tomatoes in summer, is the main crop to provide cheap products for the market, and is also an important link of annual production and balanced supply in four seasons.