Organic production requires a different approach to that used in conventional production, and there are a range of technical challenges that need to be overcome.
Strategies for integrated management of nutrients, pests diseases that need to be adopted. A research work has been done by HDRA, the organic organization in the UK to produce up-to-date management guidelines for organic strawberry growers, it encompasses many of the traditional techniques used in successful organic strawberry cultivation, combined with some of the latest knowledge and advice available a from current research. We summarized from this guide the following sections:

Organic principles:

Organic management methods strive to improve the fertility and the structure of the soil by stimulating and supporting the activity of its flora and fauna - the soil food web. Soil organisms play a vital role in delivering a balanced supply of plant nutrients as well as in the formation of a good soil structure.

A sound crop rotation is another key component of organic
systems, with the exception of perennial crops like top fruit. It is through the design of the rotation that problems such as pests, disease, weed build up and nutrient depletion can be avoided.

Converting to organic production:

During conversion to organic production, growing a grass/clover ley or other fertility building crop is recommended for a full two-year conversion period. However, on a highly fertile soil that already has good structure, planting in the second year of conversion could be contemplated.

Converting a conventional specialist strawberry growing unit often requires radical changes in approach due to the introduction of a crop rotation. There must be a 3-4 year break between strawberry crops and this effectively means that only about 20% of the land is producing strawberries each year.

Suitable crop rotations:

Crop rotations should be used to maintain soil fertility and to avoid trie build up of pests and diseases. A three year gap should be allowed between strawberry crops and there are many crops which can fit into a rotation. However, it is important to avoid members of the Solanaceae, e.g. tomatoes, aubergines, peppers and potatoes, as these are all susceptible to verticillium wilt. Other crops may encourage nematode problems. If a risk for nematodes is suspected, the site should be checked before planting.

Soil preparation:

If the previous crop is a grass/clover ley, this should be chopped up before ploughing using a disc harrow or by shallow rotovation, followed by shallow ploughing (ideally no more than 15cm deep) around 4-6 weeks before planting. This allows time for the grass and clover to decompose and keeps the organic matter in the surface layers of the soil, where it can be broken down more rapidly by soil micro-organisms and where the young plants can then make the best use of the nutrients released. However shallow plougning is not so suitable where the intention is to weed mechanically rather then use a mulch.

Crop nutrition

Strawberries generally require relatively high levels of potassium,but can tolerate low phosphate levels. They also have a relatively low nitrogen requirement, but are more demanding of nitrogen around 2-3 weeks after planting. The most important ingredients for success are good levels of potassium and organic matter, but not too much nitrogen. Farmyard manure is a good nutrient source but should only be applied if the nutrient budget for the rotation or soil analysis indicates that it is required.

Farmyard manure will need to be obtained for an approved source which, while not necessarily organic, must be able to provide details of livestock housing and diet. Typically 130kg of nitrogen/ha/yr might be needed, equivalent to 10-15 t/ha of farmyard manure (especially poultry manure) to strawberries.

Composted green waste can be applied, but on average it should not exceed 25t/ha/yr.

Potassium (K) supply may become a problem on light soils but can be corrected in various ways. Plants extracts such as Kali Vinasse are also permitted. However, sulphate of potash is a restricted product.

Varieties:

Suitable varieties should have:

• high resistance to pests and diseases
• good quality and flavor

•relatively high and reliable yields

• Good appearance and shape

• Ability to travel and/or be frozen

• Shelf-life (depending on circumstances)

Habitat management: Organic strawberry production should be placed within the context of the whole farm environment and sensitive habitat management can have positive benefits in two important areas: pollination, and pest and disease control.
Encouraging bees and other pollinating insects into the area by suitable management of hedgerows and wildflower verges should take a priority.

Pollination:

To produce an evenly shaped strawberry, a high percentage of the seeds (carpel) need to be fertilized. The number of carpel and their positions on the berry will vary with variety. Self and cross- pollination can occur, mainly via insects and to a lesser extent via air movement. For outdoor cropping it is not considered necessary to introduce hives as long as there are plenty of other pollinating insects around. Bumble bees. important because they work at lower temperatures and light intensities than honey bees, can be encouraged by weed strips which contain perennial and biennial wild flowers as pollen sources for as much of the year as possible.

In protected cropping, it is essential to roll back polythene covers and open tunnel and glasshouse doors so that pollinating insects are given access to crops.

Strawberry powdery mildew (Sphaerotheca macularis):

This fungus mainly over winters on old strawberry plants.
Temperatures above 23°C encourage fungal development. During dry weather, the disease is often most severe post-harvest on regrowth of mown-off strawberry plants. Leaf-curl is the first symptom of the fungus, followed by white patches of mycelium developing on the lower leaf surface which eventually from purple- red blotches.

Mycelium can also be seen on flower stalks and developing fruits which may become hard and frail to ripen. Infected ripe fruit remains soft and pulpy. Even lightly infected fruit is affected after harvest; its shelf life is shortened, as it tends to dehydrate rapidly and quality is diminished. Plants grown under protection are particularly susceptible. June-bearers can tolerate high levels of leaf mildew after harvest but fruit infection is the most damaging aspect of the disease.

Cultural prevention:

•Ensure good air flow among plants (e.g. wide spacing or a one row system rather than 2 rows per bed)

•In problem areas, use resistant varieties such as Cambridge Favorite, Emily and Florence.

•Use a manure/fertilizer regime which avoids excessive nitrogen

• It may be necessary to crop for only one year.

•Mow off and remove leaves in autumn to reduce over wintering inoculums . This should only be carried out in sheltered areas as crowns can be exposed to winter forest damage, otherwise remove crop debris in spring.

• Ever bearing crops should be grown well away from June-bearers to avoid spreading the disease.

Chemical Control:

Sulphur is permitted but there may be restrictions on its use for strawberries as it can taint fruit. If there has been a problem with powdery mildew in the crop the year before, it is advisable to treat the new plant growth in spring after any old leaves have been removed. If infection is visible apply Sulphur and repeat after one week.