The influence of nutrition on foliage growth and tip necrosis on container-grown Chamaecyparis lawsoniana 'Ellwood's Gold'

Abstract

The Chamaecyparis lawsoniana "Ellwood's Gold" is a commonly grown ornamental golden conifer. A nutritional trial was set up to investigate the problem of tip burn or necrosis which had been noted on a South Island nursery. Large growth responses to added N, with a range of small conifers grown in outdoor beds, were reported by Benzian. In a trial carried out with a range of soilless media using Chamaecyparis lawsoniana "Ellwoodii", the largest plants were observed at the highest level offertilisation equivalent to 675 g N/m3 of 5-6 month slow-release fertiliser. However, Istas et al reported little affect on growth when comparing several fertilisers at 3 or 4 kg m,3 on C. lawsoniana "Columnaris". A similar trial was used by Anon to look at the response ofthe latter species to different fertilisers, but growth was relatively poor in response to various mixtures of slow-release fertilisers. Hawkins reported thatrooted cuttings ofthe yellow cypress exposed to very low levels of nutrients were less tolerant of low N than low P or K, although plants survived very low additions if given balanced nutrient levels. Nutrients provided in excess resulted in luxury consumption and eventually resulted in plant death. However, there were clonal response differences. Field work conducted on C. lawsoniana "Alumii" resulted in a recommendation of 1.7% to 1.9% foliar N content for good plant growth and quality. Winter injury, as evidenced by browning, was more serious in the plants with higher N contents. Container research conducted by Thomas resulted in the conclusion that the xCupressocyparis leylandii (Leyland cypress) requires medium to high N fertiliser levels but prefers an acid mix with a pH of about 4. High liming coupled with low N rates was particularly unfavourable for growth. This contrasts with other work when researchers found that this species preferred a pH of 6.5, while superior results occurred at pH 5.5 for Juniperus xmedia and Taxus baccata, and pH 4.5 for Thuja plicata. An experiment was carried out to evaluate the influence of N, P, and lime on the foliage growth of C. lawsoniana 'Ellwood's Gold' so as to provide a fertiliser recommendation for future production.