48 EXPERIMENT STATION BECORD. [Vol. 37 



phid solutions should be attributed, the authors carried out a study duriug 

 1914 and 1915 with powdery mildews (Erysiphaceae), the materials and methods 

 of which ai-e discussed in detail. 



Such fungicides as liver of sulphur and ammonium sulphid when used against 

 powdery mildews require some such substance as suft soap to insure adequate 

 wetting of tlie folia!,'e by the spray. Liver of sulphur was not effective when 

 used at concentrations below 0.6 to O.S per cent. Yellow aranwnium sulphid 

 proved to be eflicacious against hop mildew in the greenhouse and against 

 American gooseberry mildew in the open. Unlike lime sulphur it leaves no 

 disfiguring deposit, and at definite fungicidal strength it does not scorch the 

 foliage. Iron sulphid at O.G per cent quickly destroys hop mildew. When so 

 made as to contain a trace of ammonium sulphid. it is in a condition in which 

 it can be reduced to a tine sjiray and is harmless. 



Free alkali is not the determining fungicidal factor in alkaline sulphid solu- 

 tions, nor is the i)ropurtion of sulphid sulphur present an index of their fungi- 

 cidal value. Apparently the polysulphids in yellow ammonium sulphid act 

 fungicidally as such, and not by virtue of the sulphur deposited when they 

 decompose. 



The effect of covering' winter crops, L. Hiltnei: (I'rakt. Bl. Pflanzenbau u. 

 Schutz, n. scr., 14 (1916), Xo. i, pp. S-10). — A report Is given of experinii-uts 

 conducted in 1914-15 to determine the effect of mechanical winter covering of 

 cereals on the development of Fusarium diseases. Most of the experiments 

 were carried out with winter rye, although winter wheat and clover were also 

 tested. Seed treated with formnldehyde and uulrcated seed were employed, 

 the mechanical ciiverings being straw, manure, various chemical fertilizers, etc. 

 The results for rye are tabulated, marked varietal differences due to the treat- 

 ment being noted. In practically every instance the harvest was greatest from 

 the treated seed. 



The general conclusion drawn from the experiments is that any form of 

 covering, even snow when the ground is unfrozen, is injurious when Fusariums 

 are present, as It produces conditions favorable for the development of the 

 fungus. 



Notes on some diseases of collards, B. B. Higgins {Georgia Sta. Rpt. 191ti, 

 pp. 21-27. fiijs. 6). — Attention is called to black mold of collards due to Alter- 

 tuiria. bras.'iivw, which is said to have been very destructive during several years. 

 The funi,'iis attacks the more tender parts of the plant, causing their destruc- 

 tion, and ill many instances it is associated with soft rot bacteria which enter 

 through I lie fungus lesions. As a result of ob.servations, it was suspected that 

 tbe harlequin bug plays an importiint part in the spreatl of the disease and this 

 suspicion was confirmed by investigations carried on in 1916. In connection 

 with the study of the role of this insect in spreading the disease, an investiga- 

 tion was made to determine whether the fungus entered through insect punc- 

 tures, but all the evidence obtained seemed to indicate that the germ tube of 

 the fungus entered through the stomata of the plant. For the control of this 

 disease, one or two applications of Bordeaux mixture are recommended, though 

 no experiments in control have been undertaken. The destruction of harlequin 

 bugs is also considered important. 



In addition to the above disease, Sclcrotinia libcriiana also attacks collards, 

 considerable damage being done, especially to young plants. 



A new sweet corn disease in Kentucky, H. Garman (Kentucky Sta. Cirt . 

 IS, pp. 4< fiff- i)- — ^ description is given of a destructive bacterial disease at 

 tacking sweet corn, first noted at the Kentucky Station in June, 1916. The 

 disease is considered the same as that previously described by Stewart (E. S. R.. 

 9, p. 1056). In addition to the usual characteristics of this disease, the author 



