Detailed Explanation of Soilless Strawberry Cultivation Techniques and Planting Management Key Points
Strawberry is a fruit deeply loved by consumers. It is a perennial evergreen herbaceous plant of the genus Fragaria in the Rosaceae family. The berry is very rich in nutrients and contains abundant vitamin C. It has the effect of aiding digestion, and regular consumption can also strengthen the gums, freshen the breath, and soothe the throat. It is currently cultivated in all parts of China. Let us now take a look at soilless strawberry cultivation techniques together!
Cultivation Facilities
There are two types of soilless strawberry cultivation troughs: sunken cultivation troughs and raised-bed cultivation troughs. For sunken cultivation troughs, leave a 70 cm wide walkway along the base of the back wall inside the greenhouse, and dig cultivation troughs in a north-south direction. The trough width is 50 cm, depth is 25-30 cm, and the trough length depends on the greenhouse span. The walkway between troughs (trough spacing) is 40 cm, and the trough walls are lined with plastic film. For raised-bed cultivation troughs, bricks are generally used to build the cultivation troughs. Leave a 70 cm wide walkway along the base of the back wall inside the greenhouse, and build cultivation troughs in a north-south direction. The trough width is 48 cm, height is 25-30 cm, and the trough length depends on the greenhouse span. The walkway between troughs (trough spacing) is 50 cm. Line the troughs with a single whole piece of plastic film; it must not be pieced together. Punch holes moderately in the plastic film at the bottom.
Cultivation Substrate
The soilless strawberry cultivation substrate is made by mixing and disinfecting sheep manure : vermiculite : perlite = 1:1:1 (volume ratio), or sheep manure : mushroom residue = 1:2 (volume ratio) mixed and disinfected. The sheep manure used should be decomposed and sieved. If conditions permit, 1-2% sesame residue can be added to the substrate. When filling the cultivation trough with substrate, the substrate should be slightly higher than the trough surface, with a turtle-back shape on the surface to prevent water accumulation.
Cultivation Varieties
In recent years, excellent Japanese strawberry varieties used for forced cultivation in northern China's protected facilities include Benihoppe, Akihime, Sweet Charlie, Kinu-gawa, Toyonoka, Tochiotome, Sachinoka, and others. These varieties are tolerant of low temperatures, have strong growth vigor, shallow dormancy, early maturity, large fruit, high yield, and good marketability. Through several years of screening, experts found that Kinu-gawa and Toyonoka can express higher productivity in high-altitude cool regions, and they are the main varieties for overwintering soilless cultivation in protected facilities.
Planting Techniques
1. Planting preparation: 2-3 days before strawberry planting, spray an insecticide once in the nursery to control mites, aphids, and other pests, so as to reduce the insect population density in the greenhouse after transplanting and better control pest outbreaks. After spraying, water thoroughly once, which helps reduce root damage when lifting seedlings. When lifting seedlings, grade them according to seedling size and plant them in separate greenhouses. Before planting, soak the cultivation substrate thoroughly with water to keep it moist at the time of strawberry planting.
2. Planting time: The planting time for soilless strawberry cultivation is determined by the degree of flower bud differentiation of the terminal bud. Generally, when 50% of plants in the nursery have undergone flower bud differentiation, it is the suitable planting period. In production practice, if the shortened stem shows an obvious arched back and ear leaves appear on the petioles at the leaf base, it can be considered that flower bud differentiation has been reached. Planting in mid-September is most suitable, with maturity and market availability in January of the following year. This not only achieves off-season sales and enriches the variety of fruits on the winter-spring fruit market, but also coincides with traditional festivals such as New Year's Day and the Spring Festival, when market demand is strong and product prices are high.
3. Planting density: Plant 2 rows per cultivation trough, with row spacing of 30-35 cm and plant spacing of 8-10 cm, planting 15,000-18,000 plants per mu.
4. Planting method: Choose cloudy days or evening for planting, which helps seedling survival and recovery. When planting, select healthy seedlings with no obvious pests or diseases, 5-6 spread leaves, dark green and thick leaves, and well-developed roots. Remove old leaves, diseased leaves, and runners, leaving only 3-4 new leaves per seedling. At the same time, trim part of the root system to reduce water evaporation and promote new root growth and development.
5. Planting depth: Strawberry planting depth is key to seedling survival. It should be neither too deep nor too shallow, meeting the basic requirement of “deep planting not burying the crown, shallow planting not exposing the roots.” If planted too deep, the crown is buried, which easily causes crown rot and seedling death. If planted too shallow, the root crown is exposed, which easily causes the seedling to dry out and die. The suitable planting depth is for the stem part of the crown (the stipule tip portion of the outer leaves) to be level with or slightly higher than the cultivation surface, and it must not be buried in the substrate, ensuring the seedling survival rate.
6. Planting management: After strawberry planting, water promptly to stabilize the roots, which helps seedling recovery. If strong sunlight occurs, cover with a silver-gray shade net for shading.
Humidity Management
2-3 days after strawberry planting, promptly check for missing seedlings and fill gaps, and mound soil around roots while keeping the crown exposed. After strawberry seedlings recover and survive, lay black plastic film. For sunken cultivation troughs, it is suitable to cover both troughs and walkways completely. When covering with film, place the black plastic film over the plants on the trough surface. Where you can feel a plant seedling underneath, tear a small hole in the film, then carefully pull out all the leaves so that the film fits closely against the substrate. Black film mulching not only increases soil temperature, maintains soil moisture, reduces air humidity, and inhibits weed growth, but also isolates strawberry fruit from contact with the substrate, keeping the fruit brightly colored, clean, and sanitary. The suitable substrate moisture for strawberry growth is 70-80%, and the air humidity is 60-70%.
Temperature Management
Strawberry has different temperature requirements at each stage of growth and development. Because strawberries grow multiple flower clusters simultaneously, and different flower clusters have different growth and development periods, with flowering and fruiting occurring continuously and overlapping, the temperature requirements cannot be clearly and strictly delineated. Based on the characteristics and traits of strawberries, and integrating the temperature needs of each growth period, the temperature range to be maintained in cultivation management is a daytime temperature of 20-25°C and a nighttime temperature of 6-8°C. Above 30°C or below 5°C is unfavorable for normal strawberry flowering and fruiting. Fruit development is greatly affected by temperature. When the temperature is low, the time from flowering to maturity is long, and the fruit is large. When the temperature is high, fruit development time is short, the fruit is small and early-maturing, and yield is low. A large day-night temperature difference leads to more accumulation of photosynthetic products and less respiratory consumption, resulting in large fruit and good quality.
Water and Fertilizer Management
Water and fertilizer management in soilless strawberry cultivation should use drip irrigation under film, which both saves water and reduces spatial humidity, alleviating disease. Throughout the entire production period, the substrate must be kept moist. The nutrients in sheep manure and sesame residue can meet the nutrient needs of strawberries. To increase yield, after harvesting the first fruit of the main flower cluster, apply an appropriate amount of decomposed chicken manure as a top dressing, at 50-60 kg per mu. Increasing potassium fertilizer application can prevent strawberry fruit from becoming acidic.
Gibberellin Treatment
Spraying gibberellin (GA3) in soilless strawberry cultivation can break plant dormancy, promote flower bud development, advance flowering and fruiting, and increase the fruit-setting rate. Application during the bud stage has a good effect. The concentration used is 7-10 mg/kg, focusing on spraying the heart leaves. Spraying should be uniform, avoiding repeated application. The spraying concentration and dosage must be strictly controlled. If the concentration is too low, it will not achieve the desired effect; if the concentration is too high, it easily causes excessive vegetative growth, delays flowering and fruiting, and reduces the fruit-setting rate. The best time for spraying is on cloudy days or in the evening on sunny days, avoiding spraying during high temperatures.
Assisted Pollination
Strawberry is a self-pollinating plant, but in protected off-season cultivation, there are no natural insect or wind pollinators available. Therefore, in production, bees are used for assisted pollination of strawberries. Cross-pollination can greatly increase the fruit-setting rate and marketability, reduce the number of deformed fruits, and significantly increase yield. Beehives should be placed in the greenhouse 1 week before strawberry flowering so that the bees can fully adapt to the environment. Bees cannot live in an environment with too much humidity, so ventilation and dehumidification should be noted during the day. Insect-proof nets should be installed at greenhouse vents to prevent bees from flying out. Bees need to be fed artificially when there are few flowers. In the absence of bees, manual assisted pollination can be carried out. After 10:00 each day, use fanning or a brush to pollinate by touch, but this is labor-intensive and time-consuming.
Plant Adjustment
Throughout the entire growth process of strawberries, the plant continuously undergoes replacement of old and new leaves and flower clusters and the production of runners. Old leaves, flower cluster stalks after fruit harvest, and runners not only consume nutrients from the mother plant but also make old leaves prone to pests and diseases. To ensure that strawberry plants always remain in the best growth and development state and to increase yield, old leaves, diseased leaves, runners, and flower cluster stalks must be regularly removed.
Pest and Disease Control
The most common diseases in soilless strawberry cultivation are powdery mildew and gray mold, and the most damaging pests are carmine spider mites and aphids. In daily management, promptly remove old leaves and diseased leaves to reduce pests and diseases. The pest and disease control techniques for pollution-free vegetable production should be strictly followed. Avoid applying pesticides during the picking period. The requirement is to pick first and then spray. Chemical pesticides are strictly prohibited within 7 days before picking, and biological pesticides should be vigorously promoted. Reflective film can be adhered (hung) on the back wall of the solar greenhouse, which has an aphid-repelling effect. Install insect-proof nets at vents to effectively reduce pest occurrence. Hang yellow boards to trap and kill pests.
Timely Harvesting
Strawberry fruit is mainly for fresh consumption and should be harvested when the fruit is 80-90% ripe. Picking should be done between 8:00-10:00 or 16:00-18:00. Do not pick dew-covered fruit or sun-heated fruit to avoid rot and deterioration. Pick gently and place gently, do not damage the calyx, and grade and package for sale.
Strawberry Planting Techniques and Cultivation Management Key Points
Strawberry is also called red berry, foreign berry, ground berry, etc. It is a red flower-fruit. Strawberry is the general term for plants of the genus Fragaria in the Rosaceae family, and it is a perennial herbaceous plant. The strawberry has a heart-shaped appearance, is fresh, red, and tender, with juicy flesh and a special rich fruity aroma. Strawberry has high nutritional value and is rich in vitamin C. It has the effect of aiding digestion. At the same time, strawberries can also strengthen the gums, freshen the breath, and soothe the throat. In spring, people's liver fire tends to be relatively strong, and eating some strawberries can help suppress it.
In addition, strawberries are best eaten after meals because they contain large amounts of pectin and cellulose, which can promote gastrointestinal motility, aid digestion, improve constipation, and prevent hemorrhoids and intestinal cancer. The nutritional ratio of strawberries is very reasonable. The vitamin C content is about 10 times that of an equal amount of watermelon, grapes, or apples. In addition, strawberries are rich in iron, fructose, glucose, citric acid, malic acid, and others. For conditions that easily appear in spring, such as lung-heat cough, sore throat, and boils, the nutrients contained in strawberries can play an auxiliary therapeutic role. Also, because they contain iron, friends with anemia can also eat them regularly. However, doctors also note that although strawberries are a very good appetite-stimulating fruit, they are cool in nature, so in early spring, do not eat too many at one time. Especially for people with deficient cold of the spleen and stomach, those prone to diarrhea, and those with excessive stomach acid, strawberry intake should be controlled even more.
Production and Cultivation Overview
At present, most countries in the world cultivate strawberries. The United States has a strawberry cultivation area of 23,000 hectares, with a output of 567,000 tons, accounting for about 28% of world total production, with an average yield of 24.6 tons/hectare. Japan has a cultivation area of 11,000 hm2, with a output of 218,000 tons, accounting for 11% of world total production, with an average yield of 19.3 tons/hectare. Europe is a major strawberry producing region, accounting for about 50% of world production. Poland, Italy, Spain, the Netherlands, Belgium, Russia, Romania, and the United Kingdom have relatively large cultivation areas, with yields generally ranging from 9.5-18.3 tons/hectare. China is the country with the richest wild strawberry resources in the world, began using wild strawberries very early, and has continued this practice to the present day. Large-fruited strawberry cultivation in China began in 1915, but it did not receive attention in the past and developed slowly. Since the 1980s, strawberry production has developed rapidly. China currently has about 70,000 hm2 of strawberry production area, ranking first in the world in area. The main producing areas are distributed in eastern coastal regions such as Anhui, Liaoning, Hebei, Shandong, Jiangsu, Shanghai, and Zhejiang. In recent years, Sichuan, Anhui, **, Beijing, and other regions have also developed rapidly. Key strawberry producing areas include Sihong in Jiangsu, Hefei in Anhui, Dandong in Liaoning, Baoding in Hebei, Yantai in Shandong, the suburbs of Shanghai, Shuangliu in Sichuan, Lianyungang in Jiangsu, and others. Among them, Changfeng County in Hefei currently has 145,000 mu of strawberry planting area, with an annual output of more than 200,000 tons of strawberries and a total output value of more than 1 billion yuan. By 2012, it will expand to more than 200,000 mu and has built the country's only national-level virus-free strawberry science and technology park. Every year, promotion meetings are held at the Great Hall of the People in Beijing and the Diaoyutai State Guesthouse in Beijing, and matchmaking meetings between distributors and strawberry growers are held at the Beijing Xinfadi Market, Tianjin Hongqi Market, and Shenyang Fruit Wholesale Market. Its production scale has already jumped from once first in Anhui Province to becoming the largest strawberry county in China. Changfeng strawberry has become a well-known trademark in China.
Growth Conditions
Strawberries are suitable for planting in soil with plenty of sunlight and good drainage. The soil depth should be about 8-10 inches. For large strawberry plants, the row spacing should be 12 inches, and the plant spacing should preferably be about 18 inches. Promptly remove the runners from the plants to favor strawberry fruiting. Strawberry yields are cyclical, so it is best to cultivate some new plants in the first few years of planting. If you do not like managing strawberries, you can plant one strawberry every 18-24 inches, so that strawberries can spread freely. Of course, it will look a bit messy, and the strawberries will not be large. If you want to avoid this situation, you can appropriately remove some runners. In autumn, spread a layer of soil over the plants to prevent frost damage. After the soil freezes, you can spread 3-4 inches of dry straw over the plants. In the spring of the following year, after new leaves grow, remove the dry straw. After the weather warms and stabilizes, remove the top layer of covering soil from the plants. But leave some dry straw between the rows to prevent weed growth and maintain soil moisture.
Planting Techniques
In world small berry production, strawberry ranks first. Strawberry is an economic crop with quick fruiting, early maturity, easy propagation, short cycle, and high benefit.
1. Preparation of Propagation Seedling Beds
1) Choose paddy fields with convenient drainage and irrigation, not easily waterlogged, and relatively high fertility, or garden soil (previous crop and soil blocks where chlorsulfuron herbicide has been used). Apply sufficient base fertilizer (cake fertilizer, farmyard manure, human excrement and urine, phosphate fertilizer), spread after decomposition. At the same time, apply 1 jin of 50% phoxim or 3 jin of 3% carbofuran per mu, mix with 25 jin of fine soil, spread, then plow the soil and make beds. Bed width 1.5-1.8 m, turtle-back shaped to prevent water accumulation, and the soil should be fine and crumbly.
2) Selection and planting of each plant. Choose plants with normally developed new leaves, symmetrical leaflets, dark green leaf color, thick petioles, large leaves, robust growth, and good productivity. Remove diseased leaves and old leaves. In our city, planting in propagation fields is generally done in April of the Gregorian calendar (daily average temperature above 12°C). Plant two rows per bed, planting 30 cm from the bed edge, with plant spacing of 60-80 cm. After planting, water immediately to settle the roots.
3) Fertilizer and water management. The principle of fertilizing seedling beds is: moderate nitrogen, heavy phosphorus and potassium. Apply 200 jin of decomposed rapeseed cake plus 7-8 jin of urea, 50 jin of phosphate fertilizer, and 10 jin of potassium fertilizer per mu. Dissolve in water and irrigate once every 20 days. Human excrement and urine can also be used as a substitute.
4) After each plant is planted and survives (one week later), spray gibberellin (920). That is, dissolve each gram of “920” in 40-50 jin of water (first dissolve the 920 in high-concentration white liquor in a clean bowl) and spray. Spray twice consecutively, with an interval of one week to 10 days. In August, strictly control nitrogen fertilizer application and allow the plants to suffer appropriate drought, but not excessively.
2. Timely Transplanting, Preparation of the Transplanting Site, and Specifications
1) Field preparation: Choose fertile fields or soil with convenient drainage and irrigation as the field site. Strawberries have a relatively large fertilizer requirement, and generally less fertilizer is applied in the later period (fruit-picking period), so the base fertilizer must be sufficient and mainly organic fertilizer. Generally, apply 1500 kg of organic fertilizer, 50 kg of cake fertilizer, 25-30 kg of compound fertilizer, 7.5 kg of urea, 40 kg of superphosphate, and 10 kg of potassium fertilizer per mu. Except for urea and compound fertilizer, mix the other fertilizers evenly and decompose them, then mix evenly with urea and compound fertilizer and spread on the soil surface. Then plow the soil and make ridges. Generally, ridge height is 25-30 cm, ridge bottom width is 90 cm, and ridge surface is 60 cm. Ridge furrow width is 30 cm. The ridge bottom plus furrow width is about 100-120 cm. The ridge surface to furrow bottom has a certain slope.
2) Planting period and method: Protected cultivation in our city is generally transplanted from late September to early October. Planting density should be treated according to seedling condition and soil fertility or leanness. Strong seedlings, dry seedlings, and fertile land are suitable for sparse planting; otherwise, dense planting is suitable. Generally, plant 7,000-9,000 plants per mu. After the ridges are made, plant 5 cm inward from the ridge edge, with plant spacing of 12-15 cm. Ridge length generally should not exceed 30 m.
When transplanting, note the following: First, directional transplanting: with the arched back facing outward, which favors later flower cluster emergence. Second, two-row triangular (pin-shaped) planting, which favors ventilation, light penetration, and root establishment. Third, grasp the depth, ensuring roots are not exposed below and the crown is not buried above, which favors tillering. Fourth, transplant with soil, which favors survival. Fifth, plant in the afternoon on sunny days, and all day on cloudy days. Sixth, strengthen water and fertilizer management. After planting, water thoroughly immediately to settle the roots. When watering, add thiophanate-methyl at 800 times dilution. Seventh, promptly check for missing seedlings and fill gaps.
3. Field Management
1) Pre-winter management: From survival after planting to mid-to-late November, pay attention to three points: First, apply thin fertilizer frequently, mainly nitrogen fertilizer, preferably dilute manure water. Second, maintain moisture. Third, weed, loosen soil, and remove old leaves and diseased leaves.
2) Management before and after flowering: Before flowering, during the young fruit stage, and during the fruit enlargement stage, promptly spray Caiguo Zhuangdiling to increase the cyclic fruit-setting rate of strawberries and promote fruit development. At the same time, use thiophanate-methyl, procymidone, dimethoate, and others to control pests and diseases.
3) Overwintering management: Before the cold winter arrives, water thoroughly to protect against cold.
4. Timely Film Covering
Film covering can multiply yield and reduce fruit loss and contamination. Films are divided into large greenhouse film and ground film. The time for covering film should be when the daily average temperature drops to about 8°C, then begin covering. Cover the large greenhouse film first, then the ground film. Before covering film, first weed, cultivate, fertilize, and control pests and diseases. (Greenhouse construction and film purchase specifications) Due to limited space, these will not be introduced here. Interested parties please contact the Agricultural Science Institute. After covering the film, the temperature inside the greenhouse at night should be maintained at 8°C, and around 20°C during the day. On sunny days at noon, the film should be lifted, and re-covered at 3 PM. If the temperature is too high, pollen dies; if the temperature is too low, pollen activity is insufficient, making pollination difficult.
5. Greenhouse Planting
Strawberries planted in greenhouses in early spring can flower and fruit.
6. Open-Field Cultivation Techniques
Open-field strawberry cultivation can adopt two methods: annual planting or multi-year planting. The former involves rotating with other crops after each year's cultivation and harvest. Under this system, strawberries have strong vitality, good fruit quality, early maturity, and fewer pests and diseases. However, the key technique is to cultivate strong seedlings with more than 3 leaves and well-developed roots, and appropriate dense planting can be used. Plant once, harvest for many years, transplant in autumn, and harvest in May of the following year. After 3 years, renew once using runner seedlings.
1) Land Preparation and Base Fertilizer Application
Strawberry roots are shallow and suitable for growing in loam or sandy loam with good permeability and rich organic matter. The previous crop should preferably be wheat, beans, melons, or vegetables. It can also be intercropped with tall-stalk crops. Deep plow the land early, apply 3000 kg of fully decomposed manure as base fertilizer per mu, and sun the soil. When preparing the land, apply 25 kg of diammonium phosphate and 10 kg of potassium chloride. Irrigate once with a small amount of water before planting.
2) Planting
Before transplanting, select seedlings with 5-6 compound leaves, robust plants, and intact root systems, and plant them in the field on cloudy days or in the evening. The planting density is (20-25) cm × (25-30) cm. Plant seedlings so that they are shallow enough not to expose roots and deep enough not to bury the crown. After planting, irrigate thoroughly once. After the water dries, promptly check the condition of the seedlings, loosen soil, mound soil, or fill gaps. When planting, make the arched back of the seedling face toward the inside of the flat bed, which facilitates management and fruit harvesting.
3) Field Management
After strawberry planting, water to settle the roots, then maintain field moisture and lower soil temperature. Irrigate timely and appropriately according to field humidity. When irrigating for overwintering, combine with applying 15-20 kg/mu of compound fertilizer to improve overwintering ability. Spring flowering and fruiting is a water-sensitive period, and the soil should be kept moist. When irrigating, combine with applying nitrogen-phosphorus compound fertilizer or foliar spraying. Do not use too much water, and promptly drain accumulated water. At the same time, before flowering, during the young fruit stage, and during the fruit enlargement stage, promptly spray Caiguo Zhuangdiling to increase the cyclic fruit-setting rate of strawberries and promote fruit development. After strawberry transplanting and survival, cultivate frequently and weed. After fruit harvest, mound soil at the appropriate time. During overwintering, appropriately use ground cover to prevent cold, preserve warmth, and help strawberries overwinter smoothly. Now, plastic film mulching is mostly done from the end of January to early February, which can promote earlier strawberry maturity and extend the harvest period.
Strawberry Care
Once strawberries begin to fruit and turn red, be careful not to let birds peck at them, because birds easily notice red things. Put a net over the strawberries, or use a wooden basket to cover the strawberries. However, if there is a greenhouse at home, you can move the strawberries into the greenhouse, which is even better. Strawberries are also more likely to fruit. After the strawberry fruiting period is over, you can move them out of the greenhouse and place them outdoors to overwinter.
In a sense, if strawberry plants experience some frost, it is more conducive to increasing yield the following year. Strawberries are very easy plants to cultivate and can be transplanted. Sometimes you may find yellow leaves on the plants, but do not worry; just remove them. In winter, you can keep the yellow leaves until new leaves grow in the following spring, then remove the dead yellow leaves, and pay attention to watering, weeding, and pest control. You can also plant strawberries in plant bags, but be sure to water evenly and prevent birds from pecking the strawberries and pest damage. The soil in plant bags easily dries out, so check frequently to ensure the soil remains moist. If planting on a small scale, try not to use pesticides. You can spray diluted dishwashing detergent; you can also place some melon rind, beer, and so on nearby to draw away snails and other mollusk pests.
Disease Control
When growing strawberries, change or control the environmental conditions for their growth and development, overcome unfavorable factors, enable them to flower and fruit normally, achieve early harvest, and supply the market off-season. Greenhouse cultivation has the characteristics of low investment, quick results, high yield, and good benefits. It produces 1500 kg per mu, more than double that of open-field cultivation; the output value is more than 10 times higher than open-field cultivation. In order to extend the strawberry supply period and meet the demand for year-round supply, four cultivation forms are currently commonly used:
(1) Forcing cultivation (maturing and coming to market from November to December in late autumn and early winter).
(2) Semi-forcing cultivation (maturing and coming to market between February and March).
(3) Ultra-forcing cultivation.
(4) Restraining cultivation.
Although greenhouse production has many advantages, it also has shortcomings. Because the greenhouse is hot and humid inside, it easily creates extremely favorable environmental conditions for the occurrence of pests and diseases. Strengthening integrated pest and disease control, “control early, control when small, control thoroughly,” is particularly important and has become a key link in achieving high and stable yields of greenhouse strawberries.
1. Leaf Spot Disease
Also called snake-eye disease, it mainly damages leaves, petioles, fruit stalks, tender stems, and seeds. Dark purple small spots form on the leaves and, after expanding, form nearly circular or elliptical lesions with purple-red-brown edges and gray-white centers, with slight fine rings, making the entire lesion look like a snake eye. No small black granules form on the lesions.
Control measures: Promptly remove diseased leaves and old leaves. In the early stage of disease, use 70% chlorothalonil wettable powder at 500-700 times dilution, and spray again after ten days. Or use 70% mancozeb wettable powder, 200 g per mu mixed with 75 kg of water for spraying.
2. Powdery Mildew
It mainly damages leaves, and also infects flowers, fruits, fruit stalks, and petioles. Leaves curl upward in a spoon shape. Buds and petals affected turn purple-red, cannot bloom or bloom incompletely, and fruits do not enlarge, becoming slender. Young fruits lose their luster and harden. Strawberries affected near maturity lose their market value.
Control measures: On the central diseased plants and around them, focus on spraying 0.3-degree Baume lime-sulfur mixture. After harvest, cut all leaves in the entire field and spray 70% thiophanate-methyl at 1000 times dilution or 50% thiram at 800 times dilution and 30% triflumizole at 5000 times dilution, etc.
3. Gray Mold
It is the main disease after flowering and can occur on flowers, petals, fruits, and leaves. On fruits during the enlargement stage, brown spots form and gradually expand, densely covered with gray mold, causing the fruit to soften and rot, seriously affecting yield.
Control measures: From the bud stage to the flowering stage, spray 25% carbendazim wettable powder at 300 times dilution, 50% captan wettable powder at 800 times dilution, 50% iprodione at 500-700 times dilution, etc.
4. Root Rot
Starting from the lower leaves, the leaf margins turn red-brown and gradually wilt upward until death. The supporting stem begins to turn dark brown in the middle and rots, and the central column of the root appears red.
Control measures: Before strawberry transplanting, use 40% asparagus green powder at 600 times dilution and pour it on the bed surface, then cover with soil, level, and transplant, so as to effectively kill pathogens in the soil, reduce the base number of inoculum in the field, and reduce infection opportunities.
5. Verticillium Wilt
This disease is a soilborne disease. The main symptoms are deformed young leaves, yellowing leaves, and an extremely rough leaf surface. Subsequently, the leaf margins turn brown and wilt inward until death.
Control measures: Strictly introduce disease-free plants for planting; shorten the renewal period; use chloropicrin 13.5 L-20 L or solar film covering with irrigation for soil disinfection; pull out and burn affected plants.
Four-Season Strawberry Planting Techniques and Cultivation Management Key Points
For open-field cultivation of four-season strawberries, planting is at the end of September, sprouting in mid-March of the following year, first flowering in late March, and flowering and fruiting successively from late March, continuing until early November. In late October, as the temperature drops, the greenhouse is covered. Combined with protected cultivation, year-round flowering and fruiting can be achieved, with basically no obvious dormancy period throughout the year. Let us now take a look at four-season strawberry planting techniques together!
Site Selection for Four-Season Strawberry Orchards
Four-season strawberries like fertilizer, water, and light, but fear waterlogging and drought. Therefore, choose sandy loam or neutral soil with sufficient sunlight, level ground, fertile and loose soil, and good drainage and irrigation conditions to establish the orchard, with a suitable pH of 5.5-6.5. For clay loam, it is best to apply more organic fertilizer or improve it with added sand before planting. Before planting, apply 3000-5000 kg of fully decomposed high-quality organic fertilizer per mu, and at the same time apply 50 kg of compound fertilizer. After fertilizing, plow about 30 cm deep, allow the fertilizer and soil to mix fully, rake level, let settle, and then make beds or ridges.
Four-Season Strawberry Planting Techniques
1. Flat bed planting: To facilitate watering management, the bed should not be too long or too wide. Generally, bed width is 1.2-1.5 m (planting 3-4 rows), length is 10-20 m, and bed ridge height is 15 cm. After the bed is prepared, rake it level and wait for planting.
2. Ridge planting: In low-lying areas, plots with poor drainage, and winter protected cultivation, ridge planting can be used. Ridge height is 15-20 cm, ridge top width is 40-50 cm (planting 2 rows), bottom width is 60-70 cm, and furrow width between ridges is 15-20 cm. After making beds and ridges, irrigate once with a small amount of water or compact appropriately so that the soil settles.
3. Planting period: Four-season strawberries are generally planted in spring or autumn. Winter planting can also be done using winter-warm greenhouses. Spring planting is generally from mid-to-late March to early April, and autumn planting is from mid-to-late August to mid-to-late October.
4. Planting density: Four-season strawberry fields should maintain good ventilation and light conditions and a relatively large soil area, so as to achieve high yield, good quality, and large fruit. Planting should not be too dense. Plant and row spacing should be maintained at 30-40 cm × 40-50 cm, using triangular planting, with 8,000-11,000 plants per mu. The planting depth should be such that “shallow planting does not expose roots, deep planting does not bury the crown.”
Post-Planting Management of Four-Season Strawberries
1. Field weeding: Weeds compete with strawberries for water, light, and nutrients, causing reduced strawberry yield and lower quality. Therefore, weed control is an important guarantee for producing high-quality large-fruited strawberries. Field weeding can use integrated measures such as manual weeding, film mulching to suppress weeds, and crop rotation. To reduce labor, herbicides can also be used for weed control.
2. Fertilizer and water management: During the growing season, four-season strawberries require multiple underground top dressings and foliar sprays. Underground top dressing is generally done 4-6 times per year, each time applying about 50 kg of compound fertilizer or multi-element compound fertilizer per mu. When applying, spread the fertilizer evenly in the strawberry beds, and water promptly after top dressing. Never spread fertilizer into the strawberry crown, to avoid burning young leaves. Foliar spraying is done about once every 20 days, mainly with nitrogen-phosphorus-potassium compound fertilizer, at a concentration of 0.2-0.3%. After each top dressing, water promptly. In dry years, water more often during the growing season to keep soil moisture content at 70-80% of field capacity. Strawberries are not tolerant of waterlogging, so pay attention to drainage during the rainy season.
3. Flower and fruit thinning: Four-season strawberries can flower and fruit about 60 days after planting. To produce high-quality large fruit with high yield and efficiency, plant strong seedlings and grow large seedlings. Especially for seedlings planted in spring, be sure to grow the seedlings large and strong before letting them fruit. In the early stage, promptly thin out flower buds and runners. Wait until the seedling crown spread grows to 30-40 cm before retaining flowers for fruiting. Alternatively, plant seedlings in spring, strengthen cultivation and management, and let them fruit in late summer and early autumn, achieving both large, high-quality fruit and high yield and efficiency. At each flowering, retain 4-5 early flowers and large flowers, and thin out small flowers and late flowers. The earlier the flower thinning, the better. After fruit set, thin out small fruits and deformed fruits, retaining 3-4 large fruits per plant each time. After the previous fruits mature, select and retain 4-5 large flowers to maintain continuous flowering and fruiting.
4. Rational pruning: To reduce nutrient consumption and ensure high yield and continuous fruiting, continuously remove runners during the growing season. Removing runners early can increase strawberry yield by about 20%. Four-season strawberries grow new leaves and differentiate new stems throughout the year. During the entire growing season, continuously remove lower old leaves to promote the growth of upper new leaves and new stems. Old leaves can generally be removed from the base of the petiole when the petiole begins to yellow and changes from upright to flat.
5. Fruit straw mulching: As fruits enlarge, the flower clusters gradually droop and touch the ground, and are easily contaminated by soil, which affects coloring and quality and easily causes fruit rot. For strawberry orchards that have not used plastic film mulching, 2-3 weeks after flowering, spread straw between the strawberry plant clusters as a cushion under the fruit, or form straw rings with straw stalks and place the fruit on the straw rings.
6. Winter management: As long as the temperature is suitable, four-season strawberries can flower and fruit year-round. Therefore, in production, open-field cultivation can be used in spring, summer, and autumn. In mid-to-late October, when the temperature drops to 5-7°C, promptly cover the greenhouse to ensure continuous flowering and fruiting. Management inside the greenhouse is the same as for general strawberries.
6. Timely renewal: Under general management conditions, growth begins to decline in the 3rd year after planting, yield decreases, quality declines, pests and diseases occur more frequently, and economic benefits decrease. To ensure that four-season strawberries both flower and fruit continuously and achieve high yield, quality, and efficiency, renewal is generally required every 2-3 years. For open-field cultivation, planting once every two years is more suitable.
Four-Season Strawberry Disease Control
Leaf Spot Disease
[Symptoms] Leaf spot disease, also called snake-eye disease, mainly damages leaves, petioles, fruit stalks, tender stems, and seeds. Dark purple small spots form on the leaves and, after expanding, form nearly circular or elliptical lesions with purple-red-brown edges and gray-white centers, with slight fine rings, making the entire lesion look like a snake eye. No small black granules form on the lesions.
[Control] Promptly remove diseased leaves and old leaves. In the early stage of disease, use 70% chlorothalonil wettable powder at 500-700 times dilution, and spray again after ten days. Or use 70% mancozeb wettable powder, 200 g per mu mixed with 75 kg of water for spraying.
2. Powdery Mildew
[Symptoms] Powdery mildew mainly damages leaves, and also infects flowers, fruits, fruit stalks, and petioles. Leaves curl upward in a spoon shape. Buds and petals affected turn purple-red, cannot bloom or bloom incompletely, and fruits do not enlarge, becoming slender. Young fruits lose their luster and harden. Strawberries affected near maturity lose their market value.
[Control] On the central diseased plants and around them, focus on spraying 0.3-degree Baume lime-sulfur mixture. After harvest, cut all leaves in the entire field and spray 70% thiophanate-methyl at 1000 times dilution or 50% thiram at 800 times dilution and 30% triflumizole at 5000 times dilution, etc.
3. Gray Mold
[Symptoms] Gray mold is the main disease after flowering and can occur on flowers, petals, fruits, and leaves. On fruits during the enlargement stage, brown spots form and gradually expand, densely covered with gray mold, causing the fruit to soften and rot, seriously affecting yield.
[Control] From the bud stage to the flowering stage, spray 25% carbendazim wettable powder at 300 times dilution, 50% captan wettable powder at 800 times dilution, 50% iprodione at 500-700 times dilution, etc.
4. Root Rot
[Symptoms] Starting from the lower leaves, the leaf margins turn red-brown and gradually wilt upward until death. The supporting stem begins to turn dark brown in the middle and rots, and the central column of the root appears red.
[Control] Before transplanting strawberries, apply a 600-fold dilution of 40% asparagus green powder to the bed surface, then cover with soil, level, and transplant, to effectively kill pathogens in the soil, reduce the base level of inoculum in the field, and decrease the chance of infection.
5. Verticillium wilt
[Symptoms] Verticillium wilt is a soilborne disease. The main symptoms are deformed young leaves, yellowing leaves, and an extremely rough leaf surface. Subsequently, the leaf margins turn brown and wilt inward until the plant dies.
[Control] Strictly introduce disease-free plants for planting, shorten the renewal period, and use 13.5 L to 20 L of chloropicrin or solar film mulching with irrigation for soil disinfection. Infected plants must be pulled up and burned.