Annual report 2002 LBI organic fruit growing research

Summary

Overview of projects, project results, funding bodies and partners in 2002 and plans for 2003
Including:
SOIL MANAGEMENT
* Evaluation of leaf analysis in organic fruit growing as a tool for measuring the uptake of nutrients:
Consultants and researchers exchanged practical experiences and the LBI hopes to work with target values.
* Impact of sulphur stress:
The fruit quality seemed to be better in the reduced sulphur treatment (27 kg /ha instead of 60 kg /ha after flowering).
* Fertilisation:
In a late summer fertilisation trial with Elstar, trees fertilised late summer/autumn have a higher nitrogen content in the bud the following spring. And fertilising just before winter leads to increased growth of weeds in the next season.
* Ground cover:
The key to white clover undergrowth is to ‘do it properly or not at all’. It is difficult for an organic grower to restore undergrowth which has been invaded by grasses to bare earth. Undergrowth is definitely not the answer for fruit growers who have any difficulty with mechanical weeding. The management of ground cover requires at least as much mechanisation as the bare tree strip.
REGULATING GROWTH AND CROP
* Steps to counter biennialism in Elstar:
A trial was set up at three orchards combining various measures: thinning or not thinning with two or three applications of lime sulphur, adapted pruning, 3 levels of fruit bearing (30, 40, 50 tonne/ha) and early or late manual thinning. This trial should demonstrate the relative significance of the various measures. Flowering will be evaluated in the spring of 2003.
* Fruiting spur pruning in Elstar:
To obtain better insight into the effect of different pruning methods three pruning treatments were used:
standard pruning, removal of an extra large amount of fruiting spurs, and removal of extra fruiting spurs but sparing smooth one-year-old shoots.
The production of the trees has been estimated and the blossom will be evaluated in the spring of 2003.
* Effect of thinning times, fertilisation and bearing on regularity of production and fruit quality in Elstar:
Ripening was delayed by the high nitrogen dose and associated higher acid content. Despite the late ripening
the firmness was still lower, the calcium content lower and the nitrogen content higher. All three factors pro-
duce a clear deterioration in quality. On the other hand, the sugar and acidity were higher in this case, but
both these values fall within the target band. The trial will continue in 2003
CANKER
* Administering calcium hydroxide against Cancer through the sprinkler irrigation system:
Despite its effectiveness, sprinkling with calcium hydroxide cannot as yet be generally recommended for practical
application. All the difficulties stem from the fact that the agent does not really dissolve, and the suspension formed very rapidly settles out.
FRUIT QUALITY
* Optimum picking time for Santana:
Santana is a relatively new variety, and further investigation is required into optimising cultivation and storage. The apples only developed their full flavour when picked some time after the point of physiological ripeness.
* Sprinkling to combat sunscald:
By sprinkling under specific conditions an average of 1.38 fruits per tree was protected from sunscald.
Per hectare sprinkling on these three days yielded around € 621 per ha. (Assuming: 3000 trees/ha, 6
fruits/kg, price € 1.10 or € 0.20 for industrial use).
* Rot resistance test:
The Louis Bolk Instituut is attempting to develop a test for the evaluation of the natural resistance of the fruit. This demonstrates, for example that apples with a high nitrogen content have more and larger areas of rot than apples with a lower nitrogen content.
* Prospects offered by calcium chloride (CaCl2 ) before or after harvest: A pilot experiment was carried out on a farm to look into the prospects of spraying with CaCl2 before the harvest or rinsing with CaCl2 after harvest to reduce fruit rot. Neither treatment led to a reduction in fruit rot, but rather to an increase.
* International association for ‘Organic Food, Quality and Health’ (FQH):
The purpose of the group of researchers and traders brought together under the FQH banner is to develop a
new concept of quality based on life processes and to select and further develop relevant methods of measurement.