The Banana.

Its Behaviour and Diseases in Storage and Transport.

(By C. W. Wardlaw and L. P. Maguire, in the “Fiji Times and Herald.’')

THE research dealt with in this pub lication was carried out by the authors at the Low Temperature Station, Imperial College of Agricul ture, Trinidad, 8.W.1.

Panama disease, which first appeared in Central America in 1903, has caused heavy losses in the West Indies, and has been responsible for the abandon ment of thousands of acres of planta tions. In view of the fact that the export of bananas from the British West Indies amounts to about £2,000,000 annually, the success of the research work indicated above is of great mo ment to the Empire.

The prevalence of Panama disease, to which the Gros Michel banana, the chief variety of commerce, is susceptible, has not only necessitated a study of the disease in question, but also the breed ing of suitable immune or highly dis ease-resisting hybrids, and the selec tion of the most suitable varieties of proved immunity or high resistance. In addition it has been necessary to de termine the precise set of conditions suitable to the successful transport overseas of each such hybrid or variety and to its subsequent ripening to an attractive colour.

The principal causes of wastage in banana shipments are due to main stalk rot resulting from the attacks of various fungi diseases, and “finger dropping,” which may be due to the advanced stage of main-stalk rot, to mechanical injury to individual fingers, or to late maturity.

The Gros. Michel, Lacatan and Caven dish were found to be varieties of de cided value. The earlier trials estab lished the following facts: correlation between the conditions in respect of soil and climate under which the fruits were grown before storage and the be haviour in storage and ripening, exces sive tenderness and susceptibility to bruising usually attributed to the Cavendish variety, and believed to ne cessitate its cratings were not con firmed, careful handling obviating the major objection of breaking off of fin gers; and, thirdly, much of the irre gular colouring up of fingers and pre mature ripening of lower hands was found to be due to fungal attack as a result of insect punctures or mechani cal damage during harvesting and transport.

There is a wide range of maturity at which the Cavendish variety may be picked, so that it will stand, uncrated, the usual bulk storage conditions for as long as 18| days. While on being ripened it has not the rich hue of the Gros Michel, the better and more vig orous bunches were extraordinarily systematised and attractive, especially before the onset of freckling, concomi tant with late maturity in this variety.

If these results are confirmed in later storage trials, a hopeful note may be sounded regarding the possibilities of

the West Indian Cavendish as a sub stitute for the Gros Michel.

Experimental work on various fungi was carried out to determine the gen eral behaviour of such infection on the banana under commercial storage con ditions. Such infections were con sidered from the point of view of the rate of growth of the fungi at different temperatures and their parasitic be haviour, as determined by inoculation experiments.

As a preliminary, observations on the rate of growth of six fungi affecting the banana were carried out by cultur ing the fungi. In this manner the rate of growth of fungi at different tem peratures was ascertained, an im portant consideration in connection with these investigations.

Inoculation experiments with various fungi were carried out to observe the effect of each fungus on the bunch.

It was found that wastage in banana cargoes or in stored fruit is due mainly to the activities of a number of fungi or moulds. These are responsible for an important downward rotting of the main-stalk, for “finger dropping” and the blemishing and rotting of fruit, L. fections may become established in the field or during storage. Rough hand ling of fruit, with the consequent bruising, greatly accentuates the amount of disease. Further, tempera ture plays an important part in the growth activities of moulds. Low stor age temperatures curtail the amount of disease.

The next stage in the investigation was to consider the nature and inci dence of diseases in large consign ments of fruit during ocean transport.

P’or some years main-stalk rot has been prevalent in cargoes on arrival at the English port. It was found that the length of time that elapsed in ships before refrigeration of the cargoes en couraged the early development of main-stalk rot.

The authors recommend the follow ing to reduce losses attendant on main stalk rot. First, cutting stalks long— about 10 inches—when reaping bunches.

Secondly, that after inspection at quayside the stems be fresh cut with a sharp instrument and thoroughly treated with vaseline. In this wav' the fungal organisms which have become established in the long interval between reaping and loading will be eliminated.

Thirdly, commencing refrigeration as soon as possible after loading; and, fourthly, rapid cooling of the cargoes.

The use of brown paper in other countries has made it possible to en sure that the fruit shall arrive at its destination with the minimum of blem ishes. The use of such bags, however, affects very materially the composition of the air around the fruit and the temperature of the fruit itself. These factors may affect the fruit consider ably with serious consequences, espe cially when the ship is delayed. The danger from these causes was obviated to a large degree by punching holes i-inch diameter, set four inches apart.

A comparison of the condition of the fruit in bags so treated with untreated bags demonstrated that while over 60 per cent, of the bunches in the un punched bags showed acute main-stalk rot, there was an incidence of six per cent, only in the corresponding punched set. Furthermore, cooling with the latter method was more rapid.

Bananas for certain markets are cut into hands and crated. This tends to uneven and more rapid ripening. As a result of investigation, the authors em phasise the necessity for careful selec tion of fruit at the correct stage of maturity; shortening as much as pos sible the interval between harvesting and transference to the cool-storage chamber; thorough pre-cooling of the whole bunch prior to cutting into hands and the application of vaseline for journeys of ten days or longer; rapid transference, in insulated conveyors if necessary, from the pre-cooling station into the ship’s hold; the maintenance of a temperature of 50 degrees P, —55 degrees F. in the case of Cavendish and Gros. Michel varieties; the complete change of the storage atmosphere at least once per day; the use of “dun nage” on crates, and the provision of vertical breaks in the cargo stacks, when these are large.