20 CIKCULAK NO. 127, BUEEAU OF PLANT INDUSTRY. 



that year at the station." It should be noted that he beheves the 

 disease was introduced into Connecticut on imported varieties. 



The disease was first found by tlie writer in the fall of 1912 in two 

 barrels of potatoes shipped from western New York to Washington, 

 D. G. No count was made, but it was estimated that at least 10 

 per cent of these potatoes was infected. Later it was found on 

 Irish Cobblers bought in the local market early in December, 1912. 

 These potatoes were raised in Maryland about 15 miles from Wash- 

 mgton. Each tuber was examined and it was found that 56 per cent 

 of this collection (2 bushels) was infected with silver- scurf. More 

 recently the disease has been found on potatoes from Virginia, Ver- 

 mont, Maine, Kansas, West Virginia, New York, Florida, and Wis- 

 consin, which tends to show that it may be quite generally distrib- 

 uted throughout the eastern half of the United States. This is espe- 

 cially interesting as showing its rate of spread, since it was first 

 observed in this country in 1907 by Clinton and could hardly have 

 existed long prior to this date without being observed by patholo- 

 gists. 



IS IT INJURIOUS? 



It has been quite definitely estabhshed by earlier workers that 

 Spondylocladium does not attack the fohage of the potato plant, but 

 is confined cliiefly to the potato tuber. Although the morphology 

 of this fungus has been beautifully pictured and well described, 

 very little is known regarding its eft'ect on the tuber further than 

 a few general statements occurring in the literature, none of which 

 are based on experimental evidence. It is not probable that silver 

 scurf is as destructive as our common Oospora scab, yet the following 

 statements tend to show that some damage does occur from this 

 disease. 



According to Frank, silver scurf has the same effect on the potato 

 as the Fusaria. This comparison is hardly justifiable in the fight of 

 our recent contributions on the various parasitic species of Fusaria, 

 although it conveys some idea as to its destructiveness. Appel and 

 Laubert are of the opinion that Spondylocladium has Uttle destruc- 

 tive effect on the potato. It has already been pointed out that the 

 fungus studied by Appel and Laubert may be different from the one 

 common on the potato in America. Johnson, of Ireland, befieves 

 that "it is a true parasite, and apparently may do considerable 

 unsuspected damage to the potato crop in Ireland. It may give rise 

 to a skin disease or 'scab' of the potato tuber, and in a more advanced 

 stage of attack to a 'potato rot'." Massee recommends that infected 

 tubers should not be used for seed purposes. By Bohutinsky it has 

 been stated that a species of llelminthosporium is the cause of leaf-roll. 

 The fungus reported as causing leaf-roU has since been identified by 



[Cir. 127] 



