Detailed Explanation of Key Points of Virus-Free Strawberry Cultivation Techniques
After many years of asexual propagation, strawberry virus diseases have become increasingly severe, the varietal characteristics of cultivars have begun to degenerate, and both yield and quality have declined year by year. Virus-infected plants generally show stunted individual growth, smaller leaves, and sharp, pointed serrations along the margins of the leaflets; the heart leaves are sometimes yellowed; the flowering period is earlier, the fruit is small, yield is reduced, ...
After many years of asexual propagation, strawberry virus diseases have become increasingly severe, the varietal characteristics of cultivars have begun to degenerate, and both yield and quality have declined year by year. Virus-infected plants generally show stunted individual growth, smaller leaves, and sharp, pointed serrations along the margins of the leaflets; the heart leaves are sometimes yellowed; the flowering period is earlier, the fruit is small, yield is reduced, stolons are difficult to produce, and the number of stolons emerging is reduced. A virus is a kind of non-cellular obligate parasite, the smallest living entity, containing only one kind of nucleic acid and protein, and it must be inside a cell in order to multiply. At present, there are as many as dozens of viruses infecting strawberry, among which Strawberry mottle virus, Strawberry crinkle virus, Strawberry mild yellow edge virus, and Strawberry vein banding virus are the 4 viruses that are widely distributed and seriously harmful on strawberry.
If a single virus infects the plant, yield is reduced by 20%-30%, and if two viruses infect it in combination, yield is reduced by 50%. Strawberry virus diseases are mainly transmitted through stolon seedlings, grafting, and aphids. At home and abroad there is still no effective drug for treating strawberry virus diseases, and in cultivation the use of virus-free seedlings is an effective method to reduce the degree of harm from virus diseases.?
Seedlings that do not contain the above 4 viruses are called virus-free seedlings. Virus-free strawberry seedlings grow uniformly and consistently, and yield and quality are markedly improved. Virus-free seedlings generally can increase the number of stolons by 30%-80%, increase the number of fruits by 15%-40%, increase single fruit weight by 10%-15%, and increase soluble solids content by 5%-15%. The key points of virus-free strawberry cultivation techniques are as follows:?
1. Planting: Choose flat terrain, convenient drainage and irrigation, good aeration, and soft-textured sandy loam soil, thoroughly clear weeds, control underground pests and carry out soil disinfection, avoid planting virus-free strawberry seedlings near old strawberry gardens, and pay special attention to the control of aphids. Strawberry is not suitable for repeated continuous cropping, and paddy-upland rotation can reduce pest and disease damage. Half a month before planting, deep-plow the disinfected garden plot and apply sufficient organic fertilizer, applying 3,000-4,000 kg of fully decomposed farmyard manure, 150-200 kg of cake fertilizer, and 50 kg of compound fertilizer per mu, mix thoroughly with the soil, and level it. Cultivate on ridges, with ridge width 50-60 cm, ridge height 20-30 cm, and furrow width 15-20 cm. Plant 2 rows on the ridge, with plant spacing of 20 cm. Plant from mid-September to early October; the seedlings should be required to have 5-6 unfolded leaves, a well-developed root system, root length 1-1.3 cm, plump central buds, no mechanical injury, and no quarantine pests or diseases. When planting, the root crown should be kept level with the ground surface, with the top of the stem exposed above the ground. To facilitate fruit padding and harvesting, it is required that the inflorescences of plants in the same row all face the side of the ridge. Water thoroughly immediately after planting, and water continuously 2-3 times within one week after planting, until new leaves emerge after the seedlings recover.?
2. Fertilizer and water management: Rational fertilization can make strawberry plants grow robustly, bloom and bear more fruit, and produce large fruit. During the growing season, generally topdress 3-5 times, preferably with fully decomposed human excrement and urine. Water shortage during the flowering period and fruit enlargement period will affect yield; irrigate promptly in case of drought. Strawberry is not tolerant of waterlogging, and after rain, if there is excessive soil moisture, it should be drained promptly.?
3. Plant management: Remove stolons promptly and thin out excessive flower buds to reduce nutrient consumption and improve fruit yield and quality. Stolons are the reproductive organs of strawberry, directly consume the nutrients of the mother plant, affect flower bud formation and yield, and at the same time also reduce the plant's overwintering ability, so they should be removed promptly. The inflorescence of strawberry is an indeterminate inflorescence; the flowers that open first bear good fruit, the fruit is large and matures early, while the later flowers often cannot form fruit. Therefore, when the inflorescences separate, appropriately remove the late-opening small flower buds. Virus-free seedlings have an increased number of fruits set within each inflorescence, so fruit thinning should also be done appropriately to promote fruit enlargement.?
When growth is excessively vigorous, gray mold and leaf blight are likely to occur; remove old and diseased leaves early and control pests and diseases promptly. When cultivating in protected facilities, attention should be paid to ventilation inside the greenhouse.?
During the production process, virus-free strawberry seedlings can still become reinfected. Under normal circumstances, if they still appear virus-free after 2 years of cultivation, they will become reinfected by the 3rd year. Therefore, generally every 2-3 years, new virus-free mother plants need to be used to propagate seedlings for production.