Studies on the biodegradation of picloram (4-amino-3,5,6-trichloropicolinic acid) : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Agricultural Science in the University of Canterbury [Lincoln College]

Abstract

Man’s success in increasing agricultural production has resulted from his ability to adopt the environment to his ends. But such manipulation also favours pests which could wipe out hoped for increases unless further steps are taken to keep the ecological balance in favour of crops and livestock. The urgency of this pest problem is underlined by the rapid increase in the earth's population; Bloodworth (1966) estimates that it will double by the end of this century and an ever-increasing effort is being put into control measures. Farmers in the United States of America, for example, are spending more than three billion dollars each year in an effort to reduce the losses caused by pests (Shaw, 1966). Jensen (1967) suggested that the effect of technical advances on farm production had been shown in two ways – first, what has been termed the "offensive" effect, i.e. efforts to improve productivity by the development of higher yielding varieties, labour-saving machinery, more efficient fertilisers and, secondly, contributions of a "defensive" nature concerned with maintaining existing levels of productivity against the natural causes tending towards reduction, e.g. spraying for insect control, inter-row cultivation to stop competition from weeds. While the distinction is useful for analysis, and this thesis is concerned with the “defensive” category, it is appreciated that maximum yields can only be obtained by a blending of the genetic potential, correct nutrition and pest control.