Rejuvenating Pip-fruit Trees

New Zealand Journal of Agriculture, Volume 71, Issue 4, 15 October 1945, Page 371

Rejuvenating Pip -fruit Trees

"Inarching" to Promote Vigour

IN most orchards there are some trees that, through various causes, have stopped growing and appear weak and unhealthy. No matter what treatment, such as manuring and adequate cultivation, is given to some of these trees, little response in growth can be secured. The orchardist is faced, therefore, with the problem of replanting, or of accepting the position, hoping that something will eventually add vigour to these trees. Replanting with pip-fruit trees where the old ones have been removed is unsuccessful in most cases, and no grower desires poor trees on the orchard provided some remedy can be secured.

AN unhealthy tree indicates a poor root system, while a healthy tree has a vigorous and extensive root system. The “inarching” of a new stock into unthrifty trees to give an additional well-developed root system and promote growth has been practised on pear trees in Hawke’s Bay with satisfactory results. Marked Response Seven years ago a line of Louise Bonne de Jersey pear trees propagated on quince stock were given a new root system by inarching pear stocks

into the existing trunk. These trees were then 12 years old and, as frequently occurs with pears propagated on quince stocks, they were very poor specimens. Three years after treatment some improvement was visible, and today all of these trees, where the inarching has been successful, have responded in a marked degree and now have the advantages associated with both types of stock, namely, vigorous growth as usually supplied by the pear stock, and a heavy crop of fruit of excellent quality attributed to the quince stock. ,

Inarching Technique The accompanying photographs illustrate the methods adopted and the results obtained. The technique of the operation, which is purely one of grafting, was to procure young pear stocks, not budded to any variety, from a nursery and plant them during the month of July approximately 9in. from the existing tree trunk. Two stocks per tree were used, one on either side of the trunk. At the normal grafting period a strip of bark 6in. long, the exact width of the young stock, was removed from the original tree trunk, the top of the strip being approximately 16in. from ground level. The stock was then prepared with a 6in. slanting cut so that it fitted into the groove in the trunk, cut surface to cut surface, bringing together the two cambium layers, without which no graft can be successful. Using two or three fin. tacks, the stock was tacked into place and the operation finished by sealing with some suitable grafting wax. Great care must be taken to ensure that an air- and water-tight seal is secured. Several variations, such as an inverted T and L cut on the tree trunk, have been tried, but the best results were secured

by the removal of the strip of bark as described above. On one tree only one of the inarches made a union, the other being damaged by implements shortly after treatment. The results are interesting. /)n the side of the tree where the union was successful there is abundant growth, while on the side of the tree where there is no union there is no growth, the condition typical of all the trees prior to treatment. The stock that did not take is still alive, and, although it is exactly the same age as the successful one, there has been practically no growth, due to the lack of influence of the established tree top to promote sap circulation and because of shade of the larger tree preventing its development by itself. This emphasises the

mutual assistance which obtains between the inarching stock and the main tree. More Vigorous Stocks The successful i practice of inarching would appear to depend entirely on securing stocks that are much more vigorous than the original ones. The degree of vigour of the pear stock relative to that of the quince stock is high, and good * results have been secured by using the former for inarching. To secure comparable results on apple trees a stock such

Hail Damage to Apple Trees

SOME indication of the severity of the damage caused to many of the apple trees in the Loburn district by the hail storm last season may be obtained from the accompanying photograph of wood taken from Cox’s Orange trees in the orchard of Mr. D. Hoskin. The pruning of these trees was recently the subject of a demonstration by the local Orchard Instructor, who advised the cutting back to base buds of all light type wood showing injury as extensive as that illustrated, as healing over is not likely to be satisfactory and breakage of shoots will occur in many instances if fruit is produced on such damaged wood. Callusing of the bark appears to be taking place rapidly on the heaviest wood shown, so that this type may be retained if required. Although nearly all last year’s shoots will have to be removed, there are sufficient fully-developed fruit buds on short spurs to allow for a moderate crop next season. There will, however, be a shortage of wood on which normally the fruit buds for the following season would develop. The pruning of these trees will be somewhat laborious, as although the damage is very severe, it is readily noticed from only one side of the tree. ' - A. R. GRAINGER, Orchard Instructor, Christchurch.

as East Maling No. 12, with a much higher degree of vigour than Northern Spy, the most common stock of existing orchards, should be selected for use. Further evidence of the success of the inarching of pear stock into trees on quince stock has been noted recently on another orchard, the increase in crop being considerable. By the application of inarching to unthrifty, weak trees other growers could also obtain similar benefits without much effort. —K. C. HOCKEY, Orchard Instructor, Roxburgh.