FOREWORD

The scientific sessions were notable both for the progress reported on technical aspects which are especially important to high density systems and for the results presented on world-wide trials on integrated high density systems.

The work on PP333 (Cultar) is an outstanding example of progress on a technical component of intensification of production which may reduce the problems and costs involved. One of the first papers on the use of this chemical to control tree vigour was presented at the 1980 HDP meeting in Lana: now it has become a major subject of interest to research workers and growers concerned with a range of fruit crops.

With regard to systems as a whole, a number of the papers presented to the symposium suggest that there is little case for increasing density of planting beyond that achieved in two- or three-row-systems or even in fairly closely spaced single rows. Benefits in terms of increased early yields are being, in some cases, at least, counter-balanced by the higher investment cost and difficulties in maintaining fruit quality. This clearly identifies the targets for future research in reducing the costs of planting material and ensuring, in particular, good light exposure of fruits on trees grown in high density systems.

The orchard visits, arranged by Professor Hugard and his French colleagues, were of particular interest to the many research workers who had not previously had the opportunity to see commercial production in one of the leading fruit-growing countries in the world. The symposium also provided a unique opportunity for delegates to hear about progress in French horticultural research and for this reason this volume of Acta, unusually, includes a large number of papers in French.

The success of the symposium was primarily due to the efforts of Professor Hugard and his colleagues and I also wish to acknowledge the contribution of Mrs Ann Morrissey to the production of this Acta volume which records the proceedings in permanent form.

John E. Jackson