Factors affecting the establishment of Leptospermum scoparium J.R. et G. Forst. (manuka) : a thesis presented in partial fulfillment of the requirements for the degree of Master of Agricultural Science at Massey University

Abstract

L. scoparium is one of New Zealand's most important weeds of unploughable infertile hill country. The plant is an indigenous shrub, characteristic of the early stages of succession to forest in a wide range of habitats (Cockayne, 1928). In the eight years prior to 1959/60 nearly 40,000 acres of unimproved grassland reverted to scrub, fern and second growth each year. L. scoparium is one of the most important components of the scrub, fern and second growth category. By 1959/60 the total area of reverted land in New Zealand was 5.7 million acres of which 3.65 million were in the North Island. (Rigg, 1962). Control of L. scoparium on unploughable hill country has been limited to pulling, cutting, or cutting and burning, depending on stage of growth. Chemical methods and standing burns have generally proved unsuccessful. Most methods are expensive. Levy (1932, 1940, 1946) postulated that establishment of L. scoparium in pasture could be prevented by good farming techniques. Today there is a growing body of practical evidence to support this hypothesis (Suckling, 1959; New Zealand Farmer 83 (42, 43, 45)). This study was carried out to determine what intrinsic factors favour the establishment of L. scoparium, and the quantitative effect of farm management techniques on this process.