The study of plant pathology in New Zealand was begun in 1893 with the appointment of T. W. Kirk as Biologist to the newly formed Department of Agriculture. Apart from undertaking a considerable amount of work on the identification of diseases, Kirk did much to educate farmers and fruitgrowers to appreciate what diseases were and how they could best be controlled.

In 1911 when Kirk became Director of the Horticulture Division, A. H. Cockayne was placed in charge of the Biological Laboratory, which was moved from Wellington in 1915 to the Department's Central Development Farm at Weraroa, near Levin. The development of the Laboratory was restricted by the First World War.

The post-war years saw the beginning of a new era in plant pathology in this country. G. H. Cunningham, who joined the staff in 1919 as mycologist, began a systematic survey of diseases attacking fruits, field crops, vegetables, and flowers. His work on the classification of fungi was also begun about this time. In 1925 he published the first New Zealand book on plant diseases – Fungous Diseases of Fruit Trees in New Zealand.

The Biological Laboratory returned in 1920 to Wellington where it remained until 1928 when the staff was transferred to Palmerston North to form the nucleus of the Plant Research Station, an organisation administered jointly by the Departments of Agriculture and of Scientific and Industrial Research. Within the new Station, Cunningham was placed in charge of a Mycological Laboratory. The next eight years was a period of considerable development and expansion in plant pathology. Investigations which until then had been mainly concerned with fungous and bacterial diseases were widened in scope to include virus and physiological diseases, techniques of spray application, and evaluation of therapeutants used for disease control.

In 1936, following a reorganisation of agricultural research in New Zealand, the Department of Scientific and Industrial Research was made responsible for plant research and the Plant Research Station disbanded. As a result of the reorganisation, the Plant Diseases Division was established as a branch of the Department of Scientific and Industrial Research with G. H. Cunningham as Director. The Division moved in 1939 to permanent quarters at Mount Albert, Auckland, where modern laboratory and glasshouse facilities had been provided on an area of 16½ acres.

Plant Diseases Division, the centre of plant pathological work, has a permanent staff of 70 including 24 professional plant pathologists. Of the latter, 19 are stationed at Mount Albert where they are grouped in teams working in the fields of systematic mycology, economic mycology, bacteriology, virology, and therapeutant control of diseases, each group being responsible for both basic and applied research in its own specialist field. The remainder are stationed at substations, disease problems of field crops being studied by three professional officers at Lincoln in the South Island, while diseases of pasture plants are investigated by an officer at Palmerston North, and tobacco diseases by one at Nelson.

In addition to those employed by the Plant Diseases Division, there are about 12 other plant pathologists practising their profession. Within the Department of Scientific and Industrial Research, the Crop Research Division employs a pathologist to investigate virus diseases of potatoes, the Fruit Research Division takes part in the investigation of fruit tree viruses, and a nematologist is attached to the Entomology Division. To assist with plant quarantine and advisory and extension work, the Department of Agriculture also employs several plant pathologists. In addition to their servicing work, these officers undertake research on diseases of vegetables and berry fruits and on chemical control of diseases. Research on diseases of forest trees is carried out by the plant pathologists employed by the Forest Research Institute of the State Forest Service. At Massey and Lincoln Agricultural Colleges, students are trained by qualified scientists who also undertake investigation of plant diseases. At least one plant pathologist is employed by a chemical-manufacturing firm.

Scientists in other fields also contribute to work in plant pathology. Thus plant breeders at the Crop Research and Grasslands Divisions of the Department of Scientific and Industrial Research are concerned with the breeding of disease-resistant varieties of field crop, vegetable, and pasture plants, and chemists of the Dominion Laboratory assist with studies on therapeutant chemicals.

An extension and advisory service concerning plant diseases is provided by the Farm Advisory and Horticultural Divisions of the Department of Agriculture, whose officers make substantial contributions to plant pathology with their field observations and by carrying out plant-disease surveys and conducting field trials on disease control. They also assist pathologists by drawing to their attention new disease problems, collecting disease material for identification and study, and by assisting in the selection of disease-resistant varieties. The Department of Agriculture also provides a plant quarantine service and administers seed certification schemes which have as one of their aims the production and distribution of disease-free seed.

Introduction and use of control measures have been successful in greatly reducing losses caused by plant diseases, but in spite of this and the fact that hundreds of thousands of pounds are spent annually on disease control, direct losses greatly exceed £10,000,000 and are probably considerably in excess of £20,000,000 a year. Also of major importance are indirect losses brought about by the inability, because of disease, to grow economically certain crops, such as brassicas and cereals, in many parts of the country. At a moderate estimate the combined ravages of fungous, bacterial, and virus diseases reduce the value of our brassica crops, which are widely used as supplementary stock food, by £5,000,000 a year, while diseases of fruit crops take an annual toll of more than £1,000,000. In some seasons losses in cereal crops also amount to more than £1,000,000, and diseases in vegetables regularly cause losses of the order of millions of pounds a year. No crop grown in the Dominion is unaffected.