Annual report 2003 LBI organic fruit growing research: including plans for 2004

Summary

Our objectives in soil management research combine a number of issues: soil fertility, production, fruit quality, growth regulation, prevention of night frost damage, leaf decomposition (scab) and practical feasibility. This will result in different regimes of weed control, fertilisation, foliar feeding and watering for each plot. The evaluation criteria remain particularly difficult to assess. The proposed revised edition of the soil book (LF39) is combined with the final publication of the regulation project which appeared in de winter of 2003 as a hand-book “Biologische Appels en Peren – teeltmaatregelen voor kwaliteitsfruit-” (Organic apples and pears – cultivation
measures for quality fruit) (LF75, ed. Joke Bloksma).
Time after time our research shows that good crop regulation is the basis for a quality crop. This applies to all varieties, but Elstar requires special attention because of its susceptibility to biennialism. This last year lime sulphur was available for controlling scab. This enabled us to benefit from the side effects of blossom thinning.
Trials are still being run internationally on new thinning agents for organic growing. To date however there is no prospect of a more efficacious agent than lime sulphur without the undesirable side effects. This begs the question of how much more energy should be spent on this research. We take the view that there are other areas to be developed which are essential to good crop regulation. There is scope for further development of an adapted pruning method which very specifically anticipates the prospects for the coming year. Pruning also seems to be important for the new variety Topaz, while we still need to ensure that we get sufficient fruit on the tree.
Many trials in which we monitor flowering and bearing rates show time and again that Elstar trees with slightly excessive growth levels have much poorer flowering rates in the following year, even where there is no excessive vigour. Thus much attention still needs to be paid to growth regulation.
LaMi is running a project in Utrecht province in which demonstration trials are being carried out to encourage the use of calcium hydroxide in conventional fruit growing. As advisor the LBI contributed its experience from the projects in previous years.
Infection of a fruit by fungi or disease depends among other things on the resistance of the fruit. The resistance of a product to fungi, pests and diseases is a parameter for the quality of the product. The Louis Bolk Institute is attempting to develop a test for the evaluation of the natural resistance of the fruit, in which the apple can demonstrate how well or poorly a fruit rot fungus (Botrytis c.) can spread in the flesh of the fruit.
The LBI has previous experience with self-disintegration tests. The problems here were the replicability and the unknown sources of infection.
Fruit quality is an increasingly important aspect of fruit production. The supermarkets in particular continually raise the standards required for (external) product quality. Using organic growing methods it may not always be possible to meet the high standards for external quality. This means that the internal quality will become increasingly important. LBI is currently running 2 projects on apple quality: “Classy Apples in the Chain” (2001-2004) which involves monitoring and working with partners in the chain to reduce the quality gap between supply and demand and also reduce the distance between the start and end of the chain. The second project, “Parameters for Fruit Quality” (2001-2003) addresses more fundamental issues about suitable quality parameters for organic production. (See also 2002 report).