August, 1908.] 



137 



PLANT SANITATION. 



SELP-BOTLE D LIME-SULPHUR 

 MIXTURE AS A PROMISING 

 FUNGICIDE. 



Introduction. 

 The well-known toxic action of Bor- 

 deaux mixture on peach foliage, which 

 renders it practically useless for the con- 

 trol of peach diseases in the growing 

 season, led the writer to investigate 

 other possible fungicides that might 

 prove less caustic. Moreover, Bordeaux 

 mixture, although remarkably beneficial 

 in the control of fungous diseases, even 

 stimulating the growth of plants in 

 addition to its fungicidal effect, is un- 

 fortunately often injurious tu the fruit 

 and foliage of the apple and some other 

 plants. The fruit russetitig and foliage 

 injury caused by Bordeaux mixture in 

 the case of the apple has been the sub- 

 ject of much complaint in recent years, 

 thus increasing the demand for a fungi- 

 cide that can be used in growing plants 

 without danger of injury. 



The investigations of fuugicides in 

 which various sulphur compounds as 

 well as other substances were tested, 

 have extended over several years, but no 

 satisfactory results were obtained until 

 last season, when the self- boiled lime- 

 sulphur wash was tried and proved to 

 be sufficiently active to prevent fungous 

 diseases without injuring the plauts 

 treated. Although the results reported 

 are exceedingly encouraging, it should 

 be distinctly understood that this fungi- 

 cide in the self-boiled form is in its 

 experimental stage, aud has not been 

 sufficiently tested to justify its general 

 recommendation. For the present, its 

 use is advised for trial only, aud the 

 object of this preliminary paper is to 

 show the rather striking results so far 

 obtained and make them available to 

 investigators and fruit growers as a basis 

 for further experiments, in order that 

 the value of the mixture may be more 

 speedily determined. The Bureau of 

 Plant Industry will continue the investi- 

 gations, and it is hoped that at the end 

 of another season definite recommenda- 

 tions can be made for the use of this 

 wash or some modification of it in the 

 treatment of orchard diseases. 



A similar self-boiled wash has some 

 slight reputation as a dormaut treat- 

 ment for the San Jose scale, and a few 

 fruit growers have used it rather exten- 

 sively for this purpose, but it seems to 

 have had very little consideration as a 



fungicide and has apparently never been 

 recommended for use on plants in 

 foliage. Curiously enough, however, as 

 early as 1833, before the general use of 

 fungicides, Dr. William Kenrick recom- 

 mended for mildew ou graoes a mixture 

 of sulphur (l£ pints), quicklime (a piece 

 the size of thu fist), and boiling water, 

 (2 gallons). This mixture, after cooling, 

 was diluted wich cold water and allowed 

 to settle. The clear liquid was then 

 drawn off and diluted to m dee a barrel- 

 ful before using. In 1885 William Saun- 

 ders also recommended for pear-blight a 

 self-boiled lime and sulphur wash con- 

 sisting of 8 pounds of sulphur and one- 

 half bushel of lime with boiling water ; 

 the mixture to be applied as a white- 

 wash with brushes ; and for mildews he 

 advised applications of the pure sulphur 

 liquid d'awu off from this wash and 

 greatly diluted. 



Sulphur as a Fungicide. 



Sulphur has long been known to have 

 fungicidal properties, and has played an 

 important part in the treatment of 

 several plant diseases, notably the grape 

 powdery mildew, rose mildew, and 

 asparagus rust. Previous to 1880 it was 

 almost the only fungicide in use, and it 

 is to-day one of the best remedies for 

 various mildews. In the form of potas- 

 sium sulphide it has for years been the 

 chief remedy recommended for goose- 

 berry mildew and to a less extent for a 

 few other diseases. The boiled lime- 

 sulphur wash used as a dormant spray 

 ranks close to Bordeaux mixture in the 

 treatmeut of the peach leaf-curl and 

 the California peach blight (Coryneum 

 beyerinckii, Oud.), a serious disease of 

 tlie peach on the Pacific Coast. On 

 account of its caustic effect on the foli- 

 age of plants this boiled wash cannot 

 be used during the growing season, and 

 its usefulness as a Fungicide is therefore 

 restricted to diseases that can be reached 

 in the dormant period; but the self- 

 boiled mixture used in the experiments 

 reported in this paper was entirely 

 uninjurious to the foliage and fruit of 

 both the peach and the apple. 



The Self-Boiled Lime-Sulphur 

 Mixture. 



At intervals during the past several 

 years the writer has made experiments 

 with sulphur aud various sulphur com- 

 pounds with the object of finding a 

 fungicide that could ba used during the 

 •growing pariod on fruits trees, especially 

 the peach, without injury to the foliage 



