DISEASES OF PLANTS. 84l 



The root I'ot of tobacco caused by Thielavia basicola, W. W. Gilbert (Bol. 

 Tec. Coltiv. Tahacchi [Scafati], 11 (1912), No. 1, pp. 9-54, P^s. 5).— This is a 

 translation of Bulletin 158 of the Bureau of Plant Industry of this Department, 

 previously noted (E. S. R., 22, p. 49). 



Tomato leaf rust (Jour. Bd. Agr. [London], 18 (1912), No. 11, pp. 920, 92J, 

 pi. 1). — The tomato leaf rust (Cladosporium fulvum), which has proved very 

 destructive to tomatoes grown under glass in England, is described. Spraying 

 with fungicides has not proved satisfactory unless the applications were made 

 early. When the plants are young it is recommended that they be sprayed 

 with half-strength Bordeaux mixture, to be followed by a solution of potas- 

 sium sulphid, 1 oz. in 4 gal. of water, when flowers and fruit are present. 



European and American Gloeosporium fructigenum, O. Schneider-Orellt 

 (Ccntbl. Bakt. [etc.], 2. AM., 32 (1912). No. 13-19, pp. 459-467).— The work 

 here reported on an outgrowth of a previous investigation by the author 

 (E. S. R., 26, p. 749), is a comparative study of the G. fructigenum of middle 

 Europe with that found in North America. In this it was found that, while the 

 two are too nearly alike morphologically to class as separate species, the 

 American kind is more active physiologically and as a parasite, attacking twigs 

 as well as fruit in its habitat. A connection is suggested between this activity 

 and the fact that the American fungus inhabits a climate some 5° C. warmer 

 than does that of middle Europe. 



Monilia on fruit trees, E. Voces (Ztschr. Pflansenkrank., 22 (1912), No. 2, 

 pp. S6-105, figs. 2). — The author gives an account of his studies on Monilia in 

 relation to tip burn and die-back in apple and cherry trees, attributed to at- 

 tacks of M. cinerea and M. fructigena. While moisture was found to play an 

 important role in infection, these fungi readily attacked wounded twigs, flowers, 

 or ripe fruit. Conidia of M. fructigena lost their power of germination early 

 in winter. The behavior of M. fructigena on apple trees was very similar to 

 that of J/, cinerea on cherry trees. 



Different wintering over of two species of Monilia and its biological sig- 

 nificance, R. Ewert (Ztschr. Pflanzenkrank., 22 (1912), No. 2, pp. 65-86). — la 

 continuation of the author's investigations on the wintering over of fungi 

 (E. S. R., 23, p. 346), he studied for 2 winters the behavior of Monilia fruc- 

 tigena and M. cinerea on mummified fruit. 



According to tbe findings here announced, the spores of tbe former lose their 

 power of germination early in the winter even when colonized on plums, a very 

 favorable situation; while spores of the latter remain all winter capable of in- 

 fection and awaken early to activity if given warmth and moisture. This 

 difference in these otherwise closely similar fungi is not attributed to a differ- 

 ence in resistance to cold. 



A study of diseases of olives, L. Petri (Studi sulle malattie delV olivo. 

 Rome, 1911, pp. 151, pis. 2, figs. 25; noted in Riv. Patol. Veg., 5 (1911), No. S, 

 pp. 37-39). — An account is given of the establishment of a laboratory for the 

 study of olive diseases, with a detailed report on a study of the " brusca " of 

 olives. 



This disease appears to be a constitutional one that is not affected by soil 

 conditions but seems to be dependent on temperature and moisture as well as 

 factors that tend to destroy the mycorrhiza on the roots and reduce their ab- 

 sorbing power. Such conditions bring about a weakened state of tbe olive 

 trees and render the leaves subject to fungus attack. In the case of the brusca 

 disease it becomes possible for weakly parasitic fungi to attack the trees, and 

 such fungi as Stictis panizzei, Phyllosticta insulana, and Coniothgrium olece 

 readily attack the foliage. 



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