FIRE BLIGHT.

Taranaki Daily News, 20 November 1920, Page 11 (Supplement)

FIRE BLIGHT.

A TERRIBLE FRUIT DISEASE. Orchards in some parts of Auckland Province have for some time been infested with a disease known as "iireblight." As it is a recent invader, and ia not known to JNew Zealand fruit-growers generally, a description of it may be useful. The fruit affected are apples, pears, and quinces; but the disease finds a comfortable—and for the or'charaist most inconvenient—home in the hawthorn. The first sign of infection is usually seen in the flowers, which become discolored and die, so that the fruit does not form. The disease travels down the twigs, and forms cankers" in the bark; and if this effect is serious enough for the patches to extend right round the twig, it is in effect and wilts suddenly- If a tree is badly affected, it takes on a scorched appearance, from which the blight gets its name. Aphides help to spread the disease bp suckin" the juices from diseased parts and later migrating to clean shoots, which they mfoet. The events .described constitute only the actively destructive period of one season. The bacteria which cause the disease remain inactive during the cold of winter, under the bark, but in the spring they begin to multiply at an enormous rate and cause little swellings, which burst and exude a gummv substance. This consists partly of sap, but a minute quantity of it contains myriads of the bacteria Flies are very fond of this "ooze," and if after feeding upon it they visit fruit trees for honey, the infection of the flowers is almost certain. For this reason the spread of the disease to healthy trees is apt to bo disastrousy rapid. It has been found that the hawthorn is a prolific source of the "ooze," and it is regarded by experts as especially dangerous, because it is not, like fruit treeis, under supervision. The blight is caused by a minute bacillus, or vegetable organism, which propagates with enormous rapidity. A single bacillus in perfectly favorable condition could produce a colony of about 10,500,000 bacilli in 24 hour's. The fighting, of the fireblight bacillus is engaging attention, but so far the cures are of the heroic type. The method recommended is to cut badly-in-fected branches off and destroy them; and where the infection is noit so severe as to make complete removal of (the branch necessary, the cankered bark should be eut out down to the wood, and the wood sterilised with a per cent formalin solution.