LIME-SULPHUE NOT A GOOD POTATO SPRAY.* 



F. H. HALL. 



From a spraying test made at this Station in 

 Lime-sulphur ion and reported in Bulletin No. 347, the con- 

 dwarfs elusion was reached that " lime-sulphur cannot 

 potato plants. replace bordeaux mixture as a preventive of 



potato diseases." A similar test made in 1912 

 strengthens this conclusion. The lime-sulphur treatments caused 

 dwarfing of the plants as in 1911, did not repress but seemingly 

 increased the damage from tipburn, did not keep off flea-beetles, 

 apparently did not check late blight and rot, and resulted in 

 greatly decreased yields as compared with rows sprayed with 

 bordeaux mixture. 



The rows under test were arranged in sections, 



Plan of as in other potato-spraying work at the Station. 



test. The first row in each of the five sections was 



sprayed with bordeaux mixture (6-4-50), the 

 second row with concentrated lime-sulphur solution diluted to 

 give the standard strength for foliage (1 to 40), and the third 

 row was left untreated. Potato beetles were combated by the 

 use of arsenate of lead, and were well controlled on all rows. 



Flea-beetle injury was slight, but decidedly least 

 Troubles. on bordeaux-sprayed rows ; tipburn appeared 



in August and affected the checks and lime- 

 sulphur rows badly, the latter much the worst, so that nearly all 

 the plants on the lime-sulphur rows were dead several days before 

 very many had died on the check rows, while the plants 

 sprayed with bordeaux showed little of the trouble at any time ; 

 dwarfing of the plants treated with lime-sulphur was noticed by 

 Aug. 20 and the difference in size grew more pronounced as the 

 season advanced ; late blight appeared very late in this field, the 

 attack not being noticeable until most of the plants on the lime- 

 sulphur rows were dead from dwarfing and tipburn, so that the 

 subsequent rot did less harm on these rows than on the check 

 rows owing to the few living blighted plants to serve as_ centers 

 of rot infection. 



The check rows yielded at the rate of 240^/^ bu. 

 Gams and to the acre, of which only 165 bu. were market- 

 losses, able owing to the large amount of rot. The 



lime-sulphur rows gave 39 bu. less of total yield 

 than the checks, but because rot had not spread so fast gave a slight 

 increase (6 bu.) in marketable tubers; and the bordeaux-sprayed 

 rows outyielded the checks by 48 bu. in total product and 111^2 

 bu. in marketable potatoes. 



*A reprint of "Popular Edition" of Bulletin No. ."52; >nte p. 201 for the 



Bulletin. 



[850] 



