LOSSES OF FRUIT

New Zealand Herald, Volume LXXV, Issue 22971, 24 February 1938, Page 17

LOSSES OF FRUIT

TOLL OF BROWN ROT AUCKLAND RESEARCH WORK COSTLY CONTROL METHODS SEARCH FOR IMPROVEMENTS Continued experiments are being conducted in Auckland by officers of the Plant Research Division to determine an effective and economic method of controlling the incidence of brown rot, an infection which has again played havoc this season in the stone fruit orchards of Auckland growers. It was estimated earlier this month that about 70 per cent of the nectarines and peaches grown for the city markets had been destroyed. With tlie cause of the disease known, it is said to be possible to reduce losses by the application of a scientific spraying programme, but, in a wet season, the costs involved in the extra work that is required are more or-less prohibitive. Brown "rot is a fungus disease which carries over from one season to the next on the rotten fruit that has fallen to the ground. It also gains a lio'd in cankers in the tissue of the wood itself and, in the spring, spores are produced from both sources which infect the blossom with the disease. Infection in Cases The director of the newly-established Plant Research Station at Mount Albert. Dr. G. H. Cunningham, said' yesterday that one member of the staff was fully occupied in attempting to make further improvements on the methods of control. He was investigating the merits of new types of sprays, and was making variations in the times of application and in the quantities applied to each .tree. One of the most serious aspects of the problem of brown rot losses, particularly with peaches, has been the spread of infection in packed fruit. Al-' though apparently healthy and in good condition at the time of picking, when the fruit is opened, perhaps two days later, it is often found to be greatly affected owing to the extremely humid conditions which prevail in the case. It is in this direction that a good deal of the research is addressed. Little to Announce Although geueral throughout the Dominion, brown rot is most prevalent in districts where high humidity is common. The Alexandra area, in Central Otago, is one of the very few localities relatively free from the disease, but, even there, control is rendered difficult during a wet and humid season. Nor are losses confined to New Zealand, but they are common the world over/and Dr. Cunningham said that careful research suggested that the infection had been introduced into New Zealand from North America.

"Research has extended over the past three seasons and this year methods of 'post-picking' control have been more particularly investigated," Dr. Cunningham explained. ".Results cannot be achieved in a day or a month and this type of work is essentially a long-term investment. There is really little to announce at the present time." Peach Growing Problem

From several, growers the opinion has been heard that peach growing is an uneconomic proposition in the Auckland district. In a wet season, so many sprays are required to combat the incidence of brown rot that the ultimate returns do not justify the expenditure, and it is onlv when effective methods can be applied more cheaply that this phase of orchard work will be practio able for northern growers. One of the objectives of the workers at the Mount Albert research station, according to Dr. Cunningham, is to tackle the problem from two angles. Many varieties of fruit will be grown in an effort to develop types possessing the greatest' resistance to the disease and, at the same time, experiments will continue with forms of tree treatment to reduce its toll. "At the present time, we can control brown rot, but in a wet, humid season the cost of the special spraying plan is too high for commercial growers," Dr. Cunningham added. "It is our aim to modify the system in such a way as to make it thoroughly economic and practicable."