(Muehlenbeckia spp.).

Of the dock family or Polygonaceae, there is in New Zealand a genus Muehlenbeckia, plants of which are mostly climbing or scrambling. The genus has in all about 20 species which are found in this country, Australia, the Pacific Islands, and South America. Pohuehue (a Maori name applied to other climbing plants as well) or M. australis, is a stout liane which climbs up trees to heights of 30 ft or more. It is found from the Three Kings to Stewart and Chatham Islands, also in Norfolk Island, and is closely related to an Australian species. It has greatly increased under settlement and is one of the commonest plants, forming impenetrable tangles in second-growth forest. Leaves of pohuehue grow up to 3 in. long and are about ovate in shape. There are dock-like stipules around the stems at the junction of the leaves. The fruit is a smallish, black triangular nut with a succulent covering. Birds eat it readily and pass the nut through, thus spreading the plant rapidly. The Maoris also included M. complexa in pohuehue. This plant has much the same distribution as M. australis, is a scrambler rather than a climber, forms masses of tangled, tough, wiry stems, and sometimes climbs over bushes and rocks. The leaves are up to three-quarters of an inch long, about orbicular, and are sometimes constricted in the middle. There are many forms of this species. M. ephedroides is a sprawling, usually leafless plant and, when leaves are present, they are linear. It occurs in sandy or gravelly places from sea level to montane altitudes and from about the middle of the North Island to Otago. M. axillaris is usually a prostrate, matted plant with stems and branches creeping under the surface. Sometimes it forms a straggling shrub.

by Alec Lindsay Poole, M.SC., B.FOR.SC., F.R.S.N.Z., Director-General of Forests, Wellington.

(1864–1920).

Sixteenth Governor of New Zealand.

The Fifth Baron Plunket of Newton, County Cork, in the United Kingdom, was born in Upper Pembroke Street, Dublin, on 19 December 1864, son of the Fourth Baron, who was Archbishop of Dublin and Primate of Ireland. His mother was Annie Lee, daughter of Sir Benjamin Lee Guiness, and sister of Lord Ardilaun and Lord Iveagh. Lord Plunket was educated at Harrow (1879–81) and at Trinity College, Dublin, from which he graduated B.A. (1889), where he was captain of the rowing club. He joined the Diplomatic Service in 1889, serving (1889–92) as an honorary attaché to the Embassy at Rome, after which (1892–94) he transferred to a similar post at Constantinople.

He was married at the British Consulate in Paris and at the Rue d'Aguessau Church, on 4 June 1894, to Lady Victoria Alexandrina Hamilton Temple-Blackwood, youngest daughter of Frederick Temple-Blackwood, First Marquis of Dufferin and Ava, and by her had three sons and five daughters.

Retiring from the Diplomatic Service in 1894, Lord Plunket became private secretary to Lord Cadogan, the Lord Lieutenant of Ireland, where, for special services, he was awarded in 1900 the C.V.O. From 1900-04 he acted as private secretary to Lord Dudley, the new Lord Lieutenant, and in this connection undertook the arrangement of two visits of King Edward VII who in 1904 raised him to K.C.V.O.

On 9 February 1904 he was appointed to succeed Earl Ranfurly as Governor of New Zealand, arriving in Wellington on 20 June 1904. His services here gained him increasing recognition at Home, and he received in succession K.C.M.G. (1905), G.C.V.O. (1909), and G.C.M.G. (1910). He completed his term as Governor on 8 June 1910. His last official connection with New Zealand came in 1911, when he carried the Dominion's standard at the Coronation of King George V.

Lord Plunket was a freemason in the Irish Constitution, and served a term as grand master in New Zealand. He was also a Knight of Grace in the Order of St. John, and while in New Zealand took a leading interest in the affairs of the order. His life after leaving New Zealand was fairly uneventful. He was Deputy Lieutenant, County Dublin, but his family estates in England and Ireland took up most of his time. On the institution of the Order of the British Empire, he was created K.B.E. (1918). He died at 40 Elvaston Place, Gloucester, on 24 January 1920.

Coming as he did from a family with strong Anglican traditions, Lord Plunket always took a close interest in Church affairs. A Conservative politically, Plunket's Vice-Royalty coincided with the crest of the Liberal movement in New Zealand. He preserved excellent relations with his Prime Ministers, Seddon, Hall-Jones, and Ward, in part because he did not essay more than his constitutional role as the King's personal representative, as had some of his predecessors. Lord Plunket possessed a strong conception of his office as Head of the New Zealand State, and in the course of his multifarious duties penetrated to almost every corner of the Dominion. He is perhaps best remembered for the interest he took in Sir F. Truby-King's early work, and gave his name to the Plunket Society. He also donated New Zealand's premier cricket trophy, the Plunket Shield, as well as the Plunket Medal competed for annually by the Victoria University of Wellington Debating Club.

by Bernard John Foster, M.A., Research Officer, Department of Internal Affairs, Wellington.

• The Times (London), 26 Jan 1920 (Obit).

Although there have been local ploughing matches in New Zealand for many years, there was no national championship until the Atlantic Silver Plough trophy was instituted in 1956. In the earliest recorded competitions, which were held on a local or district basis, horse-drawn ploughs were used, but, since the late 1920s, tractors have come into favour in most competitions. In New Zealand the first move towards forming a national organisation to control ploughing as a sport followed the establishment in 1952 of the World Ploughing Organisation (W.P.O.). One of the principal objects of W.P.O. is to promote world championship ploughing contests, and as participation in these is confined to countries which possess “a national organisation which organises an Annual Championship Ploughing Match at which competitors have qualified for entry by being successful in local or regional ploughing matches”, it was necessary that a New Zealand controlling body should be constituted. Accordingly, about 1955, the New Zealand Ploughing Association was formed and affiliated with the world body. The New Zealand Ploughing Championships were inaugurated in July 1956, and have been held each year since. The contest is sponsored by the Atlantic Union Oil Co., which donated the championship trophy, the Atlantic Silver Plough. This trophy is an exact replica of the first plough in New Zealand, which was used by the Rev. J. G. Butler on 3 May 1820 at Kerikeri, Bay of Islands. The silver model is mounted on a kauri plinth and the engraved plates and carved frieze at the base were executed by E. Mervyn Taylor.

Each year the New Zealand champion ploughman is sent overseas to compete in the W.P.O. “Golden Plough” Championships. In 1961, at Grignon, France, H. A. Magson won second place in the world championship contest. The final for the 1967 World Ploughing Championships will take place at Lincoln College, Canterbury, in May 1967.

The following are the winners of the Atlantic Silver Plough since the inception of the competition:

(1812–1905).

Early settler, businessman.

John Plimmer was born on 28 June 1812 at Upton-under-Amon, near Shrewsbury, Shropshire, the youngest but one of the 12 children of Isaac Plimmer, a builder and timber merchant, and of Mary, née Roden. He was educated at the local parish school and intended for the teaching profession; however, he preferred to train as a master builder and plasterer. When his father moved to Willenhall, Staffordshire, Plimmer plied his trade there until he was attracted by the colonising activities of the New Zealand Company. On 31 October 1841 he arrived at Port Nicholson in the Gertrude and settled at Te Aro, Wellington, where he commenced a prosperous timber and charcoal-burning business and a small limeworks. In 1850 he purchased the Inconstant (586 tons), which had been wrecked at Pencarrow Head. After towing the hull to Lambton foreshore, to a point opposite the present Barrett's Hotel, he converted it into a wharf, business offices, and a bonded warehouse. Plimmer's wharf or “Noah's Ark”, as it became popularly known, proved a most profitable concern and continued to be used until 1883. Over the years Plimmer invested much of the money he made from the “Ark” in various local public companies. After the 1855 earthquake he devoted himself to his building and contracting business, became a foundation member of the Wellington Chamber of Commerce, and was elected to the first Town Board (1867–71). He represented Wellington City in the Provincial Council (1856–57) and opposed the sale of the city's reserved lands. During his term he introduced, and successfully piloted through the Council, a Bill to vest these in the city authorities. Possessing keen business foresight, Plimmer became a strong advocate of railways, the reclamation of portions of Wellington's waterfront, and improved harbour facilities. For many years he urged the construction of the North Island Main Trunk railway and was prominent in the agitation which preceded the formation of the Wellington and Manawatu Railway Co. Plimmer was a foundation member of the company, remaining on its board until 1900. He was also a director of the New Zealand Times Co. for many years and contributed many letters and articles on current topics to that and other Wellington newspapers. During the Boer War he conducted vigorous press campaigns to aid the patriotic funds. In 1901 the Government appointed him one of the Wellington Commissioners to welcome the Duke and Duchess of Cornwall and York.

Partly because of his extreme longevity and partly because his firm was responsible for erecting many of the well-known commercial buildings in the city, John Plimmer has been called “the Father of Wellington”. More justly, perhaps, this title should belong to Colonel Wakefield.

Plimmer was twice married: first, in 1833, at Birmingham, to Mary Roden, who was probably a cousin; and, secondly, in 1864, at Wellington, to Janet, a sister of John Anderson, editor of the Wellington Independent. He died at his home at Plimmer's Steps, Wellington, on 5 January 1905, survived by four sons and three daughters of his first marriage and a son of his second. One of his sons, Isaac Plimmer (1834–1908), was associated with his father in business and represented Wellington in the Provincial Council (1869–71). A grandson, William Harcus Plimmer (1874–1959), was the musical and dramatic critic on the Dominion for many years; and a great-grandson, Clifford Ulric Plimmer, was a member of the Royal Commission of Inquiry into the State Services of New Zealand (1962).

by Bernard John Foster, M.A., Research Officer, Department of Internal Affairs, Wellington.

• Life of John Plimmer, Young, J. (1901)
• The Merchants Paved the Way, Millar, J. H. (1956)
• Evening Post, 5 Jan 1905 (Obit)
• New Zealand Times, 6 Jan 1905 (Obit).

Poisonous plants native to New Zealand are not numerous but, with the many toxic species now naturalised here, plants poisonous to man and animals must be seriously considered.

The Maoris recognised that the kernels of karaka (Corynocarpus laevigatus) caused paralysis and took steps to prevent these poisonings; they realised, too, that tutu (Coriaria arborea) was toxic. Severe, if not fatal, stinging must have been experienced from ongaonga, the tree nettle (Urtica ferox), while the poisonous nature of green poroporo berries (Solanum aviculare and S. laciniatum) would have been recognised.

The introduction of livestock with European colonisation soon revealed the toxicity to animals of tutu, ngaio (Myoporum laetum), Strathmore weed (Pimelea prostrata), waoriki (Ranunculus rivularis), and bracken (Pteridium aquilinum var. esculentum). With the expansion of agriculture and the introduction of many species that soon became widely naturalised, hemlock (Conium maculatum), St. John's wort (Hypericum perforatum), and ragwort (Senecio jacobaea), the cause of Winton disease, were additional important poisonous plants. Increasing horticultural importations yielded such poisonous plants as yew (Taxus baccata), laburnum (Laburnum vulgare), and Jerusalem cherry (Solanum pseudocapsicum). Toxic species which have escaped from horticulture and are now naturalised include Cape tulip (Homeria collina), oleander (Nerium oleander), and species of cestrum. The most recent addition to the list of poisonous plants is the fungus Pithomyces chartarum, the spores of which are responsible for facial eczema of sheep, a photosensitivity disease of quite long standing in New Zealand.

Connor (1951) lists almost 200 species of known and suspected poisonous plants. Of 118 species definitely known to be poisonous only 12 are native, the remainder being naturalised species. Some 72 species have been suspected of causing plant poisoning, and these include 22 indigenous species. Plant families with large numbers of toxic species include Ranunculaceae (14), Papaveraceae (8), Euphorbiaceae (8), Papilionaceae (15), Umbelliferae (8), Compositae (14), Solanaceae (8), Gramineae (8); the remaining 43 families are represented by a few species each. Most species are toxic only when eaten, but nettles are contact poisons, as also are the cultivated poison ivy (Rhus toxicodendron) and primula (Primula malacoides).

A wide range of poisonous principles is present – alkaloids in hemlock, laburnum, ragwort, poroporo, yew, and Jerusalem cherry; glycosides in karaka, buttercups (Ranunculus), and foxglove (Digitalis purpurea); cyanogenetic glycosides (those which yield prussic acid) in cherry laurel (Prunus laurocerasus) and titoki (Alectryon excelsus). The poisonous principle in tutu is tutin, a picrotoxin-like substance which is found in all parts of the plant except the black, swollen petals. Tutin, on passing through the passion vine hopper (Scolypopa australis), is converted to mellitoxin and other honey toxins, which remain in honey dew secreted by the hopper on tutu plants. Honey dew, when gathered from tutu by bees and incorporated into honey, is poisonous to man. St. John's wort contains hypericin, a photo-sensitising pigment. Buttercup glycosides yield protoanemonin, a volatile substance which causes acute irritation and inflammation of the stomach; this toxin is destroyed when the plants dry. Nitrates accumulated by such plants as oats (Avena sativa), mangels (Beta vulgaris), and variegated thistle (Silybum marianum) may be broken down in the stomach by bacterial or enzyme activity into toxic nitrites. Ngaio contains a toxic essential oil.

Toxic properties may be restricted to specific parts of plants – in some members of the Cruciferae only the seeds, which contain mustard-oil glycosides, are poisonous. The kernels of karaka are toxic, but only when uncooked. Ripe seeds of laburnum are the most toxic part of this plant, while in many species all parts of the plant are poisonous.

by Henry Eamonn Connor, M.SC., Botany Division, Department of Scientific and Industrial Research, Lincoln.

• New Zealand D.S.I.R. Bulletin, No. 99 (1951), “The Poisonous Plants in New Zealand”, Connor, H. E.

The Maori brought the kumara and taro to New Zealand. Without these plants they would have been hard put to it for vegetable foods. Apart from fern root, New Zealand yielded little in the way of fruits or of plants which could be cultivated, harvested, and stored. Laborious and often lengthy processing was necessary to make the native plants edible, but even so several plants were utilised.

“Fern root” or aruhe, the staple food, is the creeping underground stem or rhizome of the common bracken (Pteridium aquilinum var. esculentum). The rhizome is extremely hard and fibrous, requiring steaming in an umu or earth oven to soften it, followed by pounding or chewing to extract the relatively small amount of starchy material. Aruhe was used even in the areas where kumara and taro could be grown. Only well-grown fern plants with thick rhizomes would yield sufficient food to warrant the effort of preparation.

Only three berry fruits were used to any extent, hinau, karaka, and tawa. Children would eat these, and several others, in the raw state, but usually considerable effort was expended on preparation for general consumption. Hinau (Elaeocarpus dentatus) was prepared by pounding or soaking the fruits to separate the flesh from the stones, the flesh being dried and made into cakes which were steamed in an umu. With tawa (Beilschmiedia tawa), the kernel was the part used for food. The berries were steamed in an umu for two days, then washed to remove the turpentine-flavoured pulp. The dried kernels were stored. When required, they were soaked in hot water and pounded, sometimes flavouring being added to the mashed meal. Karaka (Corynocarpus laevigatus) was prepared in a similar way, the edible pulp being largely rejected in favour of the kernel, in spite of the presence of a poisonous glycoside, karakin. This poison is also present in the unripe pulp. To remove the poison the berries were cooked by steaming and then washed in running water. The washing also removed the pulp. Further steaming prepared the kernels for eating. Karaka trees and groves were highly prized and were usually family or tribal possessions. Many groves found far inland were probably planted near pa sites, as the trees are normally found only on the coasts.

Tutu (Coriaria spp., especially C. arborea) also yielded food from its berries, but again a dangerous poison is contained in the seeds. The fruits were crushed and strained through the flower heads of toetoe grass (Cortaderia spp.) to remove the seeds. The juice formed a thin jelly or was allowed to ferment into a “wine”. Other foods were often soaked in tutu juice to improve their flavour. Numerous other berries were eaten raw, especially by children, but they did not form any appreciable part of the Maori diet except for special occasions. Examples are kahikatea or white pine (Podocarpus dacrydioides), rimu (Dacrydium cupressinum), poroporo (Solanum aviculare and S. laciniatum), konini, the fruit of the tree fuchsia (Fuchsia excorticata), and kawakawa (Macropiper excelsum).

The only non-berry fruit of significance was that of kiekie (Freycinetia banksii), the flavour of which has been likened to that of a pear. The fleshy bracts surrounding the flower head were also prized for food. The upper leaves were often tied over the young heads to protect them from rats.

Mamaku or black tree fern (Cyathea medullaris) was an important source of starch food, but to obtain it the plant had to be cut down and killed. Slow growth of the trees thus restricted the supply. The trunk was split and the thick, slimy pith extracted, the upper third of the trunk being preferred. The pith was steamed for about two days, by which time the sliminess had disappeared and the resulting sago-like substance could be eaten cold or dried for future use. The stalks of young, still curled fronds were also eaten after cooking.

Very young leaves of nikau palm (Rhopalostylis sapida) and ti or cabbage tree (Cordyline ausstralis) were eaten, also the pith of the stems, especially that of the cabbage tree. This plant has the advantage over mamaku and nikau of regenerating well after being cut. Considerable ceremony was involved in the annual collecting of cabbage tree stems. These were stripped of bark and cooked in trenches, then dried. The starchy edible material was rubbed or beaten from the fibres and then soaked in water.

Raupo (Typha muelleri) yielded enormous quantities of pollen which was collected and made into cakes. The rhizome also provided a starchy food.

“Greens” were obtained from quite a number of plants, such as rauriki (Sonchus oleraceus and S. asper), pohue (Calystegia sepium), and raupeti or black nightshade (Solanum nigrum). The word puha was applied to many edible greens, but is now confined in popular usage to Sonchus oleraceus. Young leaves of five-finger (Neopanax arboreum) also make a palatable food when cooked.

The best-known “greens”, the scurvy grass (Lepidium oleraceum) of Captain Cook and New Zealand spinach (Tetragonia tetragonioides, T. trigyna), do not seem to have been used, at least not extensively, by the Maori. The former is now almost extinct on the mainland because of its being eaten out by stock. Spinach is perhaps the only contribution the New Zealand flora has made to the European diet, although its popularity has diminished considerably in recent years.

Minor food products include fungi, only eaten in times of stress, and masticatories or chewing substances. Gums and resins for these were obtained from kauri (Agathis australis), tarata (Pittosporum eugenioides), kohuhu (Pittosporum tenuifolium), rangiora (Brachyglottis repanda), and wharangi (Melicope ternata). The juice of rauriki (Sonchus oleraceus), a latex, was also used.

by Bruce Gordon Hamlin, Botanist, Dominion Museum, Wellington.

New Zealand has a comprehensive literature on plant diseases and their control. Most of the earlier papers appeared in annual reports of the Department of Agriculture and in the New Zealand Journal of Agriculture. For the past 25 years, however, the more technical papers have been published in the New Zealand Journal of Science and Technology and, more recently, in the New Zealand Journal of Agricultural Research. Popular papers have continued to appear in the New Zealand Journal of Agriculture and also in the Orchardist of New Zealand, the New Zealand Commercial Grower, and other growers' journals. Articles on the classification of fungi have been published, mainly in the Transactions and Proceedings of the Royal Society of New Zealand, and some papers have appeared in overseas journals. Articles on plant pathology are too numerous to be cited but a few of the more important books and bulletins are given here.

by Edward Edinborough Chamberlain, D.SC., Director, Plant Diseases Division, Department of Scientific and Industrial Research, Auckland.

• Fungous Diseases of Fruit Trees in New Zealand, Cunningham, G. H. (1925)
• Rust Fungi of New Zealand, Cunningham, G. H. (1931)
• Plant Protection by the Use of Therapeutants, Cunningham, G. H. (1935)
• Tomato Diseases and Pests in New Zealand and their Control, Atkinson, J. D., Brien, R. M., Chamberlain, E. E., Cottier, W., Jacks, H., Reid, W. D., and Taylor, G. G. (D.S.I.R. Information Series, No. 2) (1949)
• Plant Virus Diseases in New Zealand, Chamberlain, E. E.(1954)
• Plant Protection in New Zealand, Atkinson, J. D., Brien, R. M., Chamberlain, E. E., Cottier, W., Dingley, J. M., Jacks, H., Reid, W. D., and Taylor, G. G. (1956).

The main concern of plant pathologists in New Zealand is to gain an understanding of our diseases and their significance in the country's economy and to minimise the losses they cause, generally in one or more of the following three ways: (1) By preventing the introduction of diseases not already here; (2) By eradicating those not fully established; and (3) By control of those which cause damage with chemical or cultural methods or by the development of resistant varieties.

Some serious plant diseases now confined to other countries, if established here, could cause losses amounting to millions of pounds annually. Hence plant quarantine regulations are enforced. Plants and seeds not known to carry diseases or pests which could be dangerous to our crops may be imported without restriction but are inspected at the port of entry. Others require an entry permit, must be grown for one season in a specified area and kept under observation by officers of the Department of Agriculture who certify them as disease-free before distribution. The introduction of plants of a third category is prohibited except in small numbers under special licence. These are grown under strict quarantine conditions at the Plant Diseases Division, Mount Albert, and released only after they have been declared free from disease.

Although eradication has been attempted on a number of occasions, it is rarely practicable because a disease is usually well established by the time it is recognised. An attempt to eradicate fire blight (Erwinia amylovora) failed but others have been gratifyingly successful. Citrus canker (Xanthomonas citri) has been eliminated from the large orchard areas at Kerikeri and Otumoetai, but there are still small pockets of infection in Taranaki, while an outbreak has recently been located in Auckland. Again, though onion yellow dwarf, a serious virus disease of onions, was well established by 1939 in the onion-growing area of Marshland, Christchurch, it has not been observed there for the last 20 years. Regulations enforcing sanitation and prohibiting the growing of onion-seed crops, and alternative hosts brought about the eradication of this disease from the district. Even if not completely eliminated from the country, onion yellow dwarf has been successfully kept out of the major onion-growing areas. Attempts to eradicate Verticillium cinerescens of carnations, and the virus diseases Moorpark mottle of apricots and plum fruit crinkle appear to have been successful. Hot water treatment of barley, introduced during the 1920s, together with the production of mother seed and certification of seed crops, has eliminated the serious diseases of loose smut (Ustilago tritici) and covered smut (Ustilago hordei) from our malting barleys.

There are many ways of keeping diseases in check. Their incidence and severity may be greatly influenced by cultural factors such as soil type, date of sowing, size of plantings, crop rotation, sanitation, etc. Knowledge of these factors is used to reduce losses. Perhaps the most satisfactory way is to use resistant varieties, to the selection and breeding of which much attention has been given, with marked success in increased production of field crops and vegetables.

Heavy losses can occur through the use of diseased stocks of vegetatively propagated plants. A seed potato certification scheme introduced in 1928 has done much to increase potato yields. Similarly, the health of fruit-tree nursery stock has been greatly improved by selection of disease-free root stocks and scion wood.

Work begun by New Zealand pathologists in the 1920s contributed much to knowledge of seed-borne diseases and their control. Since that date the general application of seed treatment to many field and vegetable crops has been of considerable benefit to the country's economy.

There are some serious soil-borne diseases particularly dangerous in glasshouses. Successful investigations on soil treatment have led to control of many of the more important of these, thereby achieving much heavier yields of tomatoes and other crops. Treatments have also been evolved and successfully applied for control of soil-borne organisms in the field.

Control of the majority of fungous and bacterial diseases is achieved by the application of therapeutant sprays. A great deal of research work has gone into finding the most effective material for specific diseases, the optimum concentrations, and the times and number of applications needed. As materials of high quality are essential for best results, the extent of control was greatly improved in 1938 by the introduction of a therapeutant certification scheme; but with increasing numbers of therapeutants becoming available it was not possible with limited scientific resources to maintain this. In 1959 it was replaced by an approval and registration scheme administered by an Agricultural Chemicals Board.

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.

The temperate, moist climate of most of New Zealand, where temperature and rainfall do not vary markedly with the seasons, is ideal both for the growth of fungi and bacteria and for the increase of many of the insects responsible for dissemination of plant viruses. Numerous endemic fungi occur in the Dominion, some causing damage to our native pasture plants and forest trees, but none is of major economic importance probably because few of our native plants are cultivated as commercial crops. Endemic plant bacteria appear to be rare as only one bacterial disease, a leaf spot of the forest tree Dysoxylum spectabile caused by Pseudomonas dysoxyli has been recorded and is of no importance economically. Phormium yellow leaf of New Zealand flax (Phormium tenax) spread by a native plant hopper (Oliarus atkinsoni) is the only known endemic plant virus – one which has caused widespread death of large areas of phormium, a valuable fibre plant.

The development of fungous and bacterial diseases is determined by the presence of pathogens, susceptible host plants, and suitable climatic conditions. Many of the fungi and bacteria which thrive in temperate climates have been introduced to New Zealand and most of these have become established. Surprisingly, however, others which might be expected to thrive under our climatic conditions have not been found here. These include important fungous diseases like potato wart (Synchytrium endobioticum), tobacco blue mould (Peronospora tabacina), apple rust (Gymnosporangium juniperi-virginianae) and hop downy mildew (Pseudoperonospora humuli), and serious bacterial diseases such as potato ring rot (Corynebacterium sepedonicum), bean blight (Xanthomonas phaseoli), bacterial blight (X. translucens) of cereals, and Stewart's disease (Bacterium stewartii) of maize and sweet corn.

Less dependent on climatic conditions are the plant viruses which often owe their existence to the presence of insect vectors. Aphids which have found the climate favourable have established themselves, together with many of the viruses they carry. Leaf hoppers, however, have been established less readily and we still do not have some of the viruses they transmit such as aster yellows, beet curly top, lucerne dwarf, and western-X virus of stone fruits.

Common in some localities are trace-element deficiency diseases due to lack of boron, manganese, zinc, copper, and molybdenum. Although shortage of these elements may result from a low content in the parent rock, it is often brought about by a relatively high rainfall leaching the minerals from the soil.

Diseases of major economic importance in New Zealand include the fungous diseases dry rot (Phoma lingam) of swedes and turnips, late blight (Phytophthora infestans) of potatoes and tomatoes, verticillium wilt (Verticillium albo-atrum) which is most serious in tomatoes but also causes losses in potatoes, tobacco, stone fruits, gooseberries, raspberries, straw-berries, and a wide range of ornamental plants, and the rusts (Puccinia coronata and P. graminis) of cereals and grasses which greatly restrict the growing of wheat and oats in the North Island and reduce pasture production through their effect on ryegrass. Bacterial diseases of particular importance are blast (Pseudomonas syringae) of stone fruits, tomatoes and many other hosts, black rot (Xanthomonas campestris) of brassicas, and soft rot (Erwinia carotovora). The latter causes heavy losses in brassicas and also attacks the storage organs of many plants including potatoes, onions, and carrots. Of major importance amongst the virus diseases are cauliflower mosaic of swedes, turnips, rape, cauliflower, and cabbage, cereal yellow dwarf of wheat, barley, oats, and grasses, tomato spotted wilt which is particularly serious in tomatoes and also causes losses of lettuce, peas, and many ornamental plants, and the endemic virus phormium yellow leaf which has prevented the use of New Zealand flax for developing a major fibre industry.