PROCESS AND TECHNIQUE OF STRAWBERRY CULTIVATION

2. Requirements for external conditions:

– The appropriate temperature is 24-32⁰C. When the temperature is above 40⁰C, some parts of the mulberry tree die, at a temperature of 0⁰ C the mulberry tree stops growing, the air temperature increases above 12⁰C then the mulberry tree begins to germinate.

– Light: As a light-loving plant, yield and leaf quality are closely related to lighting conditions. The number of lighting hours 10-12 hours/day is best. Without enough light, mulberry leaves are thin, the stems are weak, and the quality of mulberry leaves is poor. Mulberry trees can absorb light with a length of 400-800µ.

– Land: Can adapt well to many types of soil, however to have good yield and leaf quality and prolong the business cycle, it is necessary to choose land with a thickness of arable layer >1m, pH from 6, 5-7.0. However, mulberry trees are able to adapt to pH levels from 4.5 to 9.0. Mulberry trees have poor salt tolerance, in places with low salinity < 0.2% of trees grow well. Salinity ≥1% plants will die.

– Water and air humidity: This plant is relatively drought-resistant, but if it lacks water, the plant stops growing. On average, every 100cm² leaves in one hour release 1.8 grams of water. This proves that mulberry trees have a huge need for water. The appropriate humidity for strawberry plants to grow is 70-80%.

– Mulberry leaves are the only food for silkworms. On the other hand, over 60% of the cost to produce silk is spent on planting, managing, harvesting, and preserving mulberry leaves.

III. CULTIVATION AND CARE TECHNIQUES:

1. Like:

– Some popular strawberry varieties currently grown are black gourd variety, S7-CB variety, VH15 variety, VA-201 variety, TBL-03 hybrid combination, VA-186 variety, Sa Nhi Luan strawberry variety,…

– Mulberry trees can be grown from seeds (sexual propagation) or grown from cuttings (asexual propagation).

A. Asexual propagation:

– Caring for the original seed garden: Fertilizer regime of 15 tons of manure/ha, 300kg N-180kg P₂O₅-240kg K₂O (according to the ratio N:P:K=5:3:4)

– Number of batches of leaves picked per year: Collect 6-8 batches/year, the last batches are not picked to avoid branching, which reduces the germination rate of cuttings.

– Cutting time: Depending on the variety, the cutting time to get branches is different. VA-201 variety is cut from late September to mid-November; S7-CB variety has few branches, good disease resistance, and the appropriate cutting season is February – April every year.

– Shape the number of stems on the tree: about 6-7 stems/tree.

– Based on the rules of development of pests and diseases to take appropriate prevention measures. The best time to prevent disease is from July to October every year. Bud aphids (soft aphids) use bassa 0.2%, Bi58 0.4% sprayed periodically every 20-25 days.

– Cutting technique:

+ Cutting standards: Standard cuttings must have 2 eyes on the cuttings, diameter ≥ 0.5cm, cutting age ≥ 8 months. The appropriate density in the nursery is about 67 cuttings/m² (10x15cm). The breeding season from May to July and November to December has a garden production rate above the requirements.

+ Fertilizer uses 5 tons of microbial fertilizer/ha/year, 45-60 kg N/ha/crop and N:P:K ratio is 2:1:1.

+ Disease prevention in the nursery: Check and monitor the prevention of some main pests such as brass disease, rust disease, root rot disease, and bud pests.

B. Sexual propagation:

– Sexual propagation is growing strawberries with seeds, which are formed through pollination between male and female flowers. Strawberry trees grown from seeds have a developed root system, so they are highly resistant to drought, have a long lifespan, and have a high propagation coefficient.

– However, the propagation work is complicated, mulberry trees are often not pure, have thin leaves with many toothpicks, and many fruits. This form of breeding is still new and not yet popular.

2. Strawberry growing techniques:

– The best planting time in Lam Dong is the beginning of the rainy season from March to April of the solar calendar or the end of the rainy season from late October to early November. If planting with seedlings propagated in the nursery, the best time is March. April or May to avoid having to waste watering.

– Planting density: Depending on the type of land, farming method and investment conditions for intensive farming, determine the appropriate planting density, usually the planting density is 1.2-1.5m between rows, 0 plants between trees. ,2-0.3m, about 42,000 trees/ha.

3. Prepare the soil:

– Strawberry garden design: Choose flat land, hilly areas with slopes less than 15⁰. Land slope below 6⁰, local slope 8⁰ designed in straight lines parallel to the main contour line. Land sloping above 6⁰ design mulberry rows along the contour line, create a ledge, and in the process of gradually taking care, narrow steps will be formed to limit erosion.

– The soil is plowed 35-40cm deep 25-30 days before planting strawberries. Newly reclaimed areas need to be cleared of tree roots and weeds. After plowing the land and designing the plot, dig trenches and make rows, 0.3-0.5m wide; 0.35-0.4m deep and 1m distance between rows. In hilly and mountainous areas, pay attention to incisions along contour lines, and in riverside areas, incisions should be made following the flow of water. If planting bush strawberries, it is best to dig a hole 40x40x40cm in size, take the topsoil aside and later put it in the planting hole.

– Fertilize before planting: Depending on whether the soil is good or bad, decide the amount of fertilizer. Infertile lands need to combine soil improvement before planting by applying lime, phosphorus, and organic fertilizer. For nutrient-poor soils, the amount of fertilizer should be 15-20 tons of organic fertilizer, 700kg of fused phosphate fertilizer, and 1 ton of lime.

– How to fertilize: Immediately after digging the trench, add organic fertilizer, phosphate, lime and a part of soil into the trench, mix well, then cover with a layer of soil about 5cm on top and plant. In case the fertilizer has not decomposed, it will take 10-15 days after mixing the fertilizer before planting.

– Prepare cuttings: Tree age in the nursery is 60-70 days or more, tree height is 30cm or more, seedling trunk diameter: 0.02cm or more, mulberry tree is free from pests and diseases, no mixed varieties.

Note: Do not fertilize with nitrogen for 15 days before pulling the tree to harden the tree.

Criteria for strawberry cuttings: Strawberry cuttings must be at least 8 months old, have a diameter of 0.6-1cm, and have no sources of fungal diseases. No mixed breeds.

Choose cuttings from good mulberry fields with a branch age of 8 months to 1 year, no pests, and a branch diameter of 0.6-1cm is best, cut off the top. If planting strawberries vertically, cut them 20-30cm long. The cuttings must have 3 or more eyes, beveled at both ends 2cm from the sprouts, do not crush them, and bundle them on one side. After cuttings are cut, they should be planted immediately and must be carefully preserved to avoid wilting. The best preservation method is to dig a hole about 40cm deep, long and wide depending on the number of cuttings. The cuttings are arranged with the tops facing up, covered with grass and watered regularly to preserve for 25 days. Do not plant cuttings that have germinated.

4. Growing strawberries:

– Planting strawberries with cuttings: Inserting cuttings obliquely applies to soil with a high clay rate and moist soil, inserting cuttings obliquely 45⁰ deep ¾ of the length of the cuttings into the soil – ¼ of the cuttings above the ground. Vertical planting applies to hilly soil with low humidity. Insert the cuttings vertically in the soil. The length of the cuttings is buried in the soil, leaving only 1 eye above the ground.

– Growing strawberries with seedlings: The time in the nursery is usually 50-60 days. When the plants in the nursery reach a height of 40-50cm and a stem diameter of 0.3cm or more, they are uprooted and planted.

– Technique for growing mulberry trees with seedlings: When placing the mulberry tree, do not let the roots come into direct contact with the fertilizer layer in the trench, keep the mulberry tree roots straight, not curled up, cover the root collar with soil, and compact it tightly. soil around the root.

Note: When filling the trench with soil, only fill 2/3 of the depth of the trench. After placing the mulberry tree in the trench, keep the tree straight, then fill in the remaining soil. Make sure the strawberry bed is 10-15cm higher than the trench so that when it rains, water does not stagnate at the base.

– Caring for newly planted strawberries: 10-15 days after planting, the cuttings begin to germinate, water and weed regularly to avoid colliding with the plants when weeding . After 2-3 months of planting, replanting should be done to ensure density. You can replant with cuttings or seedlings, preferably with seedlings. One month after planting, apply the first round of 150kg of urea/ha, then periodically apply once every 1-1.5 months with a total amount for the first year of: 400kg of urea, 600kg of phosphate, 150 kg of potassium/ha.

– Shaping the tree when picking leaves: After 4-6 months of planting, the leaves can be gradually harvested, but should not be harvested. Prune to have 2 -3 main stems at each root, and regularly prune secondary branches.

– Plant protection: Pay attention to eliminating pests from mulberry trees, especially hoppers that damage mulberry buds.

5. Annual strawberry care management:

– Weeding: Depending on the conditions of each location, you can weed the base 6 times, weed the middle of the row 2 times combined with the use of herbicides such as: Gramoxone, Roundup,… should be sprayed when the grass is growing, when it is sunny and Dig the roots 1-2 times/year.

– Fertilization:

+ Organic fertilizer: Annual fertilizer dosage is about 15-20 tons. Organic fertilizers are mainly applied 15 days before or after harvest.

+ Inorganic fertilizer: Amount of pure fertilizer 400kg N-160kg P₂O₅-160kg K₂O Fertilizer for strawberries needs to be divided into many times to increase fertilizer use efficiency. After fertilizing, if possible, water 1-2 times so that the plant can easily absorb it.

Amount of inorganic fertilizer applied to mulberry trees (kg/ha)

6. Cutting down  strawberries:

– Is a technical measure to control mulberry leaves as desired.

– Cutting and shaping strawberry clusters: 12 months after planting, cut down the main stem 15-20cm above the ground, prune first-level branches, keep each cluster with 5-6 first-level branches.

– 12 months after the first cutting, cut level 1 branches 6-6cm away from the main trunk, each level 1 branch has 3-4 strong nodes.

– From the 3rd year onwards, cut level 2 branches 5-6cm away from the old cut. After 8 – 10 years, when the primary and secondary branches and production branches are old and have weak germination, they need to be cut down again.

– Low cutting every year: Applies to mulberry trees. Every year when the mulberry stops growing, cut it close to the ground or dig up the roots and cut them 6-6cm below the ground. When the mulberry germinates, cultivate the roots again.

– Cutting down (cutting back to a young age): Strawberries 5-10 years after planting often age their stems and branches. In order for the strawberry to grow well for high productivity, it is necessary to cut back to the base and then shape it to look like a newly planted strawberry.

– Felling and slow cutting: Applicable when strawberry grows slowly. When cutting, pay attention that if the strawberry takes cuttings for new planting, only cut the tip 20cm. If the strawberry does not take cuttings, it can be cut to a height of 1-1.5m.

– After this cutting, harvest the branches and cut them lower again.

– Cutting season: In Lam Dong from December to April of the following year.

– Cutting technique: Choose a cool day to cut, the best cutting tool is to use a chainsaw, avoid crushing the cut. If cutting to shape or cutting high, pay attention to pruning all small branches (toothpicks) and removing sprouted strawberry sprouts before cutting so that the strawberries grow evenly. The first cutting is 10-15cm above the ground, pruning level 1 branches, keeping 4-6 branches in each clump. Subsequent cuttings are cut 2-3cm away from the old cut. After 25-35 days of cutting, pruning is carried out to determine the sprouts. Strawberries are creating level 1 branches, level 2 pruning away weak and diseased sprouts, keeping the number of shoots to create a canopy for the tree. For low-cut strawberries, only prune away weak sprouts, keeping all the sprouts capable of yielding.

– Strawberries often age after 10-15 years of planting. In order for the strawberry to grow well and yield high yields, it is necessary to cut it back to the base, then shape it to look like a newly planted strawberry.

– When strawberries grow slowly, they can be cut down and cut slowly (note that if strawberries are planted from cuttings, only cut down the top 20cm). If the strawberry does not take cuttings, it can be cut to a height of 1-1.5m. After this cutting, harvest the strawberry branches and cut them low again.

IV. PEST AND DISEASE PREVENTION:

1.Disease: Strawberries often suffer from blight, leaf spots, leaf blight, rust, and leaf curl. It is necessary to pick leaves promptly and clean the fields.

2. Pests: Stem borers, rice beetles, leaf rollers, caterpillars, caterpillars and aphids transmit leaf and flower curl virus. Use Dipterex or Bi 58 at a rate of 10-15%, spray after 15 days before picking leaves to feed the silkworms.

– Mulberry trees are damaged by many pests and diseases, reducing productivity and leaf quality. If severe, it can cause the tree to die, and mulberry leaves cannot be used for silkworm farming.

– To effectively prevent the emergence and spread of pests and diseases that damage mulberry trees, ensuring increased productivity and safety for silkworm farming, it is necessary to master the rules of emergence and development of each type of pest. , diseases that apply effective measures for timely prevention and treatment.

V. HARVESTING AND PRESERVING STRAWBERRY LEAVES:

1. Harvest:

– Leaf picking method: Select leaves according to the silkworm’s requirements, with little impact on plant growth, reducing pest rates and labor costs. Harvesting a batch of strawberries needs to last about 7-10 days and should not be prolonged to affect the process of caring for the strawberry garden. It is best to pick mulberries for silkworms to eat at 8-10 am, do not pick them too early or at noon.

– Harvesting method by cutting branches: Less labor-intensive, fresher, easier to preserve, longer interval between batches and more time to care. The cutting method should only be applied to good lands and households with highly intensive farming conditions.

2. Preserving mulberry leaves:

– Mulberry leaves for raising silkworms should be arranged in layers and covered with absorbent cloth. Large mulberry leaves for silkworms should be stacked in a pile with a thickness of no more than 20cm. Keep moist by covering with absorbent cloth (not covered with plastic), every 2-4 Turn once now. The room where mulberry leaves are stored must be cool and have ventilation doors to reduce the room temperature.