581 



light and dark-skinned varieties; (3) barn-yard manure vs. commercial 

 fertilizers; (4) effect of tobacco dust iu drill; (5) scabby vs. smooth 

 seed. The (juality of seed, variety of potato, method of manuring and 

 planting, and amount of scab on the crop are tabulated for each of 28 

 plats. The results are summarized as follows : 



(1) Deep phiutiiig iii>])o;ir.s to tend to cUiiiiuisU the (lovelopniont of scab, tboiij;h 

 further exporiiiioiits iu this direction are very desirable. (2) Wiiile the very dark 

 jiotatoes were wholly free from scab, little or no difference was to be noticed iu the 

 susceptibility of the three light varieties planted ; it is to be regretted that none of the 

 best red varieties were available for the couiparisou. (15) The ])otatoes raised on 

 barn-yard manure were markedly more scabby and more deeply scabbed than the rest. 

 (4) Tobacco dust iu the drill had no appreciable effect iu increasing or diminish- 

 ing the scab. (5) Scabby seed produces a crop ueitlier better nor worse than 

 that grown from smooth potatoes. None of these results are new, but they may 

 serve as further material on which to base general conclusions, aud as continuatory 

 of tlie results of most previous similar experiments. But all such results are com- 

 paratively without significance so long as the cause of the trouble remains unknown, 

 and we are as much as ever iu the dark so far as any basis of rational experimenta- 

 tion or treatment is concerned ; therefore the most atteution has been given to the 

 study of the development of the scab. 



Observations on the development of the scab indicated that there 

 were " superhcial" and "deep" forms of the disease, but no organism 

 was discovered as its cause. The forms of scab described by European 

 writers are discussed and illustrated in comparison with those exam- 

 ined at the station. 



Fungous diseases on the station farm (pp. 223-227). — Notes on the smut 

 of barley and oats (Ustilago scfjetnm, Pers.), spot disease of beets (Sej)- 

 toria beta', West, aud Cercospora beticola, Sacc), and rot of potatoes 

 {Phytophthora infestans, De B.). 



Notes on material referred to the station (pp. 227-230). — Brief notes 

 on a fungus found in a cellar, black spot of rose leaves (Actinonema 

 roscc, Fr.), and a disease of cucumbers caused by nematodes. 



Special work of the chemical laboratory (pp. 231-313). 



(1) Commercial fertilizers (pp. 232-283). — General remarks on com- 

 mercial fertilizers and their inspection, the trade values of fertilizing 

 ingredients for 1889, the text of the Massachusetts fertilizer law, and 

 list of licensed dealers ; and the analyses of 138 samples of licensed fer- 

 tilizers, including compound fertilizers, bones, tankage, ground fish, 

 cotton-hull ashes, aud nitrate of soda. Besides these, the analyses 

 are given of numerous materials sent to the station for examination, 

 among which are wood ashes, cotton-seed hull ashes, cotton-seed meal, 

 sulphate and muriate of potash, gypsum, lime. South Carolina phos- 

 phate, Mona Island guano, dissolved bone-black, bone coal, ground 

 bones, dried blood, sul[)hate of ammonia, nitrate of soda, saltpeter waste, 

 wool waste, "mud crab," tobacco dust, gluten meal, linseed refuse, 

 cotton-seed fertilizer, oak leaves, chaff from grain elevator, jute waste, 

 hemp waste, cranberry vines, salt hay, barn-j'ard manure, silage liquor, 

 "nicotinia," hellebore, "peroxide of silicate," and 74 samples of well- 

 water. 



25909— No. 10 4 



