A brief history of the beginnings of the use of rockwool in horticulture in overseas countries, an outline of uses overseas of the current forms of water absorbent and water repellent horticultural rockwool, a summary of manufacturers of the product, a consideration of some of its advantages and disadvantages, and a listing of the crops grown in horticultural rockwool are given in this paper. An outline of the overseas experiences in both the disposal of and the sustainable reuse of horticultural rockwool is also given. A history of use in New Zealand of horticultural rockwool and the crops grown on the product are outlined. Options, which are both within and outside horticulture, for the sustainable reuse of the relatively small volume (c. 300 m 3 /year) which becomes available for reuse in New Zealand at present are described and discussed. Many of these options may be applicable in other countries where the volume of horticultural rockwool used is relatively small.

No abstract

In New Zealand, copper (Cu) applied to soils in fertilisers, urban and animal wastes, or pesticides may increase Cu concentrations from an average of 30 mg kg -1 to more than 10 times this value and may restrict the development of treated areas for residential use. Guidelines for assessing such possible hazards have been proposed by planning authorities. The behaviour of Cu in soils, plants, and animals is reviewed to test the validity of these guidelines. It is concluded that the potential risks associated with Cu in horticultural soils are very much less than those implied by current New Zealand guidelines.

In seven replicated cultivar assessment trials of asparagus (Asparagus ofjicinalis L.) carried out at Levin, Lincoln, and Hastings, and harvested for 4 -6 years, accumulated saleable yield from the first two seasons was highly correlated with accumulated saleable yield for the remainder of each trial. Yield ranking of cultivars after two years and at the end of each trial was nearly the same. Yield correlation coefficients and Spearman rank correlation coefficients were high in all trials, and significant when a large number of cultivars were tested. Two years of harvesting is considered to give a reliable evaluation of yield performance of new cultivars in New Zealand conditions.

A feathery mottle pattern, typical of dasheen mosaic virus infection, was observed on the leaves of one Japanese and two traditional New Zealand cultivars of taro (Colocasia esculenta Schott) grown in the Auckland area of New Zealand. Electron microscopy and serological testing confirmed the presence of dasheen mosaic virus.