Cultivation of strawberries
Strawberries will grow on nearly all kinds of soil. However, the crop makes strict demands on the structure of the soil. A proper soil hydrology and water management are very important. The soil should be suitable for due root penetration, whereas the subsoil water should range between 80 and 100 cm below ground level. The soil should be worked in time in order to let it settle well. On sandy soils use can be made of a furrow compactor, which allows of a far shorter period between ploughing and planting. Sometimes it is useful to loosen up the soil to a depth of 80 to 100cm. Each type of soil is different and consequently it is difficult to give some general advice. In order to prevent any mistakes and disappointments, the best thing to do is to call in an expert in advance. Besides, the soil should be free from eelworms. In case of doubt, it will be necessary to prove the necessity of disinfection by means of soil analysis.
Our range of strawberry varieties offers a wide selection for almost every commercial grower. We have varieties for late as well as early crops, for optimal flavor, optimal yield, or even both.
Our strawberry varieties have also been included in a maturity time overview, where you can easily compare times of maturity.
For a number of years now, Vissers Aardbeiplanten BV has invested time and energy in a breeding programme in an attempt to find new varieties that are interesting for the commercial grower.
The best strawberry plants will not achieve their full potential without a good cultivation system.
Strawberry plants are susceptible to threat from various pests and diseases. A number of precautionary and protective measures are required in order to achieve maximum production.
Strawberry plants are classified as follows:
- Pre-basic material (PBM) - This plant is registered at the Netherlands Inspection Service for Horticulture (NAKT) and has been tested for the absence of viruses. The propagating material obtained from candidate plants is classified as BM.
- Basic material (BM 1, 2 or 3) - These plants are propagated in an aphid-proof greenhouse. The first generation of propagating material is BM1. As long as these plants are raised in an aphid-proof greenhouse, the stock they produce will be classified as BM2. The stock produce by BM2 will be classified as BM3 ans is propagated in an aphid-proof greenhouse. If the generation of BM1 or BM2 or BM3 is raised outdoors, in these circumstances BM5-plants are produced.
- BM4 - The generation BM1 or BM2 or BM3, which are propagated in greenhouses, are suitable for propagation.
- BM5 - The generation BM1, 2, 3 or 4 suitable for propagation
- Certified material (CM) - Propagating material, obtained from BM certified mother plants.
CAC - Non-certified production plants, therefore not suitable for propagation purposes. The reasons for certification not being granted may be the foreign origin of mother plants, proximity of production fields or a too high percentage of plants with deviating traits.
The text above is derived from the guidelines set up by the NAKT in the Netherlands.Outside the Netherlands apply the same classification less stringent growth conditions.
For the next production season we can offer the following types of plants:
- Heavy and Medium waiting bed plant - It is the waiting bed plant with the largest production potentioal. This plant will come out best if it is planted in the months of April and May.
- Small waiting bed plant - This size is suitable to continue cultivating. To achieve this, the plant may not be planted too early. The best time of the year is May.
- A+ extra - Thick plants are involved here obtained from normal propagation. Experience has taught that these plants can bear somewhat fewer but thicker fruits than the medium waiting bed plants.
- A+ plant - They are particularly suitable for 2 year cultivation. In the initial year the crop is moderate, however, the fruits are excellent. The second year the crop is large.
- The small A+ plant - The plant can produce fruit in the initial year. In this way the cost of the plants are in general recovered and in the second year the normal crop will be obtained.
- The standard frigo plant - This plant should be considered only for production after the initial year.
- Heavy and MediumTrayplants -This potted plant type is generally used in glasshouse production system or covered table top system.
- Mini Tray plants- These potted plants have a smaller rootsystem in a smaller pot and are best used in table top systems outdoors. This plant type is also usable for day neutral varieties.
- Plugplants / Modules- These are produced as potted fresh plants to be used in August or stored in the frigo for use in spring.
- Fresh plants- These are lifted in July or August and either planted on waitingbed or in the production site.
- Unrooted tips - These can be used for the production of tray-plants, mini tray and plug plants.
Fertilization by means of 80 to 100 tons of old stable manure is ideal. Of course you should reckon with the national legislation as regards the application of manure. Fresh stable manure, semi-liquid manure, chicken manure and mushroom fertilizer have to be applied preferably in the autumn of the preceding year. Additional fertilization with NPK fertilizer may only be applied when the plants are growing well. Basic manuring with a prolonged acting fertilizer for planting, will see to it that the crop can regularly dispose of nutrients. Dosage depends on the fertilization condition. Fertilization should always be done on dry crop. If subsequently it should not rain, sprinkling should be carried out. Subject to the kind of soil the pH for strawberries should range between 5 and 6. Nitrogen should be applied about 4 weeks after planting. Maximum 50 kg pure nitrogen. Fertilization of some varieties may not exceed 25 kg. Much nitrogen always results in soft fruit. The optimum PW value ranges between 21 and 30. In that case a maintenance fertilization with 120 kg of phosphate will be satisfactory. The potash condition should be on an optimum level, especially during picking time. Potash provides strong fruit and a beautiful colour. The optimum P number is about 13. A maintenance fertilization of 200 kg on sandy soil and 280 kg on sea clay will do. Potash will reduce the occurrence of mildew and phytopthora.
The major cultivation measures before and after planting
- Upon receipt of the plants, put them at once in duly fertilized soil, up to the collar, with properly spread roots and firmly pressed.
- In dry weather the young plants should be kept sufficiently wet for about 14 days, so that they can strike root smoothly. Doing this, care should be taken that especially the evaporation of the plants will be compensated by sprinkling. Just keeping the soil wet is not sufficient.
- Spacing between plants in a line is 25 to 30 cm; line width is 75 to 100 cm. This subject, however, to your mechanization and system of cultivation.
- To prevent damage by mite, red spider or lice, the plantings should be inspected intensively and subjected to a control, if necessary, using the pesticide allowed for the purpose.
- Control of fruit rot with the help of fungicides allowed for the purpose.
Sketch of the proper planting method
The correct planting depth is important. In case of planting to deeply, the risk of stems rotting at the base is very great, whereas in case of planting too shallow the risk of drying out will increase.
Chemical or mechanical weed control?
In the cultivation of strawberries weed control plays an important part. Crop which has been run to weeds will always produce less than crop that is free from weeds. There has been a discussion for many years about the question whether weed control should be done by chemical or mechanical means. It is not the intention to pronounce here upon what would be the best thing to do. Anyway, this is not possible, because the circumstances may differ completely from parcel to parcel. These circumstances are also decisive for the choice to be made. Besides, the fact whether you have enough personnel at your disposal for removal of weed by hand is a decisive item to make a choice.
When can chemical weed control not be applied?
Chemical weed control is useless if the crop is in bad condition. Flooding or damage by frost can be the cause of such bad condition.A different reason why chemical weed control can not be opted for can be the weed vegetation. This weed vegetation may include kinds on which the available weed killers can not get a hold. Also the way of cultivation can be determining for the decision to weed killers or not. For example, if planting is carried out in spring, spraying crops should wait until the plants in question have duly rooted. Before using chemical weed control, always accurately read the label on the packing. Protect yourself well during spraying. You are advised to wear waterproof spraying clothing, rubber or synthetic gloves, boots and a good quality protective mask. Carry out the spraying only with the help of good quality spaying equipment.