Recent studies of the olive-tubercle organism / by Erwin F. Smith.

  • Erwin Frink Smith
Date:
1908
Catalogue details

Licence: In copyright

Credit: Recent studies of the olive-tubercle organism / by Erwin F. Smith. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    When taken from ven' young Ijoiiillon cultures made from similar cultures, i. e., in such a way as to obtain spore-free material, the organism is readily killed by drjTng. Cloudy bouillon from sucli tubes when spread on glass cover slips and preserv^ed in ordinary' covered Petri dishes for from five to nine days in a closet at room temperatures failed to cloud tubes of bouillon when thrown into them. That part of Scliiff-Giorgini’s paper distinguishing two distinct forms of olive tubercle—the primary', due to external infection, and the metastatic or secondary, developing from within—is well worked out and marks a distinct advance in plant jiatholog}'. THE DISEASE IN THE FIELD. It has been obser\'ed over and over again in Italy and elsewhere that rich .soil, hea\y manuring, and excessive use of water favor the spread' j of this organism, bj' producing a gnuit quantity of juicy tissues suit- | able for infection. This is also tnie of pear blight. Some varieties I of olives seem to he mon> subject than others. VerA' sensitive ones ! should be discarded. Ohl tubercles are often eaten by various insects, and it is possible'! that some insect carrier plays a part in the distribution of this disease. | This can he determined only by a prolonged inA’estigation of field con-’ dilions supplemented by laboratorA* studies. The skillful use of the pruning knife offers some hope. Specially knives should be jirovided for the pnming of diseased trees, or else alii j the knives should be disinfected after each tree is gone over. In>j ])runing it should be remembered that in some instances the organisnii |! may occur in the interior of the stem, .some distance below the tubercle.^ j It is wise, therefore, ti) cut .several inches beloAV visible signs. A dab' of disinfectant on the cut surfaces, if they are not too numerous, is^ also to be recommended. Of germicidal sprays, two may be recommended for trial on a small- scale at first, i. e., until it is known definitely whether or not the foliage of the olive will be injured by them. These substances are Bordeaux mi.xture and the self-boiled lime-sulphur mixture recently deA’ised by Scott for the treatment of peach diseases. If the oliA'e tree Avill bear either of these germicides, then thorough tests for the control of the disease should be made by giA'ing a half dozen sprayings in the actively growing part of the season. “ .See Circular No. 1, Bureau of Plant liidustrj', 1908.