19101 



DISEASES OF PLANTS. 845 



Becent studies on the treatment of grape downy mildew, L. Ravaz (Prog. 

 Agr. et Yitic. [Ed. VEst-Centre), 40 (1919), No. 2, pp. 25-32).— Damage due to 

 grape downy mildew during the year is said to have been comparatively slight. 

 An account of the weather is given in this connection. 



For a given percentage of copper, Burgundy mixture has the same fungicidal 

 efficacy, whether mildly acid, mildly alkaline, or neutral. The scorching ef- 

 fect On the leaves caused by Burgundy mixture at 1 to 10 per cent, as here 

 tabulated, shows a somewhat uniform increase of injury with strength. 

 The effects due to causticity differ according to state or age of the foliage, 

 earliness of the treatment, and concentration. The preparation, composition, 

 and behavior of several mixtures intended to be fungicidal are described. 



Treatment of downy mildew, A. Mazotta {Prog. Agr. et Yitic. {Ed. VEst- 

 Centre), 40 {1919), No. 3, pp. 5^-56). — In this article, which is said to have been 

 translated from another source, it is stated that good results were obtained in 

 tests with a treatment consisting of a commercial mixture consisting chieliy 

 of sulphur and copper sulphate in different given proportions. 



The action of polysulphld on Oidium, J. Capus {Prog. Agr. et Yitic. {Ed. 

 VEst-Centre), 39 {1918), No. 47, pp. J,91, 492).— Employment of alkaline poly- 

 sulphids at 0.5 per cent strength and an equal proportion of soap, both dissolved 

 in water, gave satisfactory results as regards grape OiYlium. Favorable re- 

 sults from the use of this preparation in compariscm with those from an in- 

 secticidal preparation are also noted. An account is given of the employment, 

 as far back as 1853, of alkaline polysulphids against grape Oidium. 



Recent views regarding* arricciamento (roncet) in grapevines, li. Petri 

 {Atti R. Accad. Lined, Rend. CI. Sci. Fis., Mat. e Nat., 5. ser., 21 {1918), II, 

 No. 9-lQ, pp. 271-275, fig. J).— Previous work (E. S. R., 28, p. 749; 29, p. 349; 

 31, p. 245) has been followed by this account of later study and observation 

 regarding any causal influence of soil and climate in relation to grape roncet. 

 The facts discussed are considered to show that roncet is probably due to the 

 presence of a living organism. 



Distribution of Fusarium cubense, the cause of banana wilt, E. W. Brandes 

 {Ann. Rpt. Mich. Acad. ScL, 20 {1918), pp. 271-275).— The author sketches the 

 history of banana wilt or Panama disease in various banana producing coun- 

 tries of America. It is claimed that this disease is due to F. cubense, of which 

 the author has furnished'previously an amplified technical description (E. S. R., 

 38, p. 757). 



A study of susceptibility to this disease brings out the fact that in any par- 

 ticular country this disease attacks most severely, and sometimes exclusively, 

 the variety most widely planted. This is said to be true in mixed plantings. 

 Varieties which are not attacked, or which are slightly attacked in a given 

 locality, may in some other locality suffer severely from banana wilt. The 

 facts cited suggest biological specialization on the part of the organism. 



The parasite enters the plant from the soil, failure resulting from all at- 

 tempts by the author to inoculate portions above ground. The disease is also 

 carried in the propagating rhizomes and in the water in the form of spores. 

 Sterilization, though a problem of considerable difficulty, is claimed to be pos- 

 sible. 



Banana wilt increases excessively within a mouth or so after the beginning, 

 and increases to the end of the rainy period after which plants which are 

 slightly attacked may improve and produce fi'uit. 



Notes on the general treatment of fungus diseases, A. C. Tunstall {Indian 

 Tea Assoc, Sci. Dept. Quart. Jour., No. 4 {1918), pp. 122-128) .—The informa- 

 tion and advice contained herein are concerned chiefly with tea culture. 



