TREE SURGERY

Hawke's Bay Tribune, Volume XVIII, Issue 21, 6 January 1928, Page 7

TREE SURGERY

AMERICAN EXPERT’S VISIT TO TOUR THE DOMINION. CARING FOR NATURE’S HERITAGE “Tree-surgery,” a highly specialised branch of horticulture, is th© profession of Mr. James A. G. Davey, of Ohio, U.S.A., who came to Auckland by the Niagara for a two-months’ stay in the Dominion. Mr. Davey is making a world pilgrimage in the cause of forest? (states the Auckland “Star”). He will travel by way of Australia and the East to Europe, concluding his tour in Paris and London. Each country h e visits will afford him special opportunities of arboreal study, and lie is looking forward with keen interest to his stay in New Zealand, where, he says, the native trees are of unique importance to scientists. The art of tree-surgery is best described as that ot maintaining trees in full and healthy growth, of repairing their injuries, and of cheeking and preventing decay. It is primarily work in the cities, for. as Mr. Davy points out, a tree in its natural surroundings has every chance of growing to healthy maturity and of continuing to obtain the requisite supply of food. In large towns it is different. Accidents will occur; a tree is often deprived of one or more of the ten elements which it requires as food, and insects and blight find it an easy prey.

Mr. Davey is chief adviser to the Parks Department of New York municipality where he has charge of many thousands of trees, chiefly elms, lindens, oaks, and maples. Last spring and summer wag a particularly busy time for him owing to the ravages upon the trees of the parasite known as red mite. Despite the most strenuous efforts of Mr Davey and the staff of the Parks Department, about 75 per cent of the trees were defoliated, many being stripped absolutely bare of leaves. Finally, however, the cause of the trouble was definitely ascertained, and Mr. Davey is confident that there will be no such disaster next spring or summer. The street trees of Paris, he says, were similarly attacked, and he has reason to believe that the same pest was responsible. On his visit to the French capital he hopes to lx- able to advise the municipal authorities as to the best methods of preventing the ravages of red mite and of curing its effects. MOTOR FUMES NOT INJURIOUS. For a long time, said Mr Davey, it was believed that the exhaust fumes and gases from motor car engines were injurious to trees, but, after long and careful investigation he has come to the conclusion that, in the open-air at all events, they are harmless to growth. Sulphur dioxide when present in the air in a proportion of over live parts in a million is definitely injurious, but carbon monoside, the principal gas constituent of exhaust fumes, cannot do harm in the open. “FEEDING”' CITY TREES. The feeding of city trees was another interesting branch of his work to which Mr. Davey referred. Of the ten elements which a tree needs, he said, six were available in all soils, and one. namely carbon, was taken from the air, but it was frequently necessary to provide the remaining three, namely nitrogen, phosphorus and potassium, by the use of fertiliser. “Yon have not needed tree surgeons in New Zealand so far,” said Mr. Davey, “but the time may come when you will need them. It is a great profession, and one which already provides splendid work in the open air for many young Americans,” On the subject of re-afforestation he also had something of interest to say. “We have found ourselves at the danger-point m the United States,” he remarked, “and the same thing applies to most of the other countries of the world. We have moved slowly, but I think there is now a great and general public desire for a wise and prudent policy.”