NOTES AND ABSTRACTS. 



819 



the disease, which makes its appearance early in the spring before the new 

 leaves are mature. A number of grey or bluish spots appear on the leaf, 

 with the surface concave on one side and convex on the other. These 

 depressions vary from 0*25 to 1 cm. in diameter, and are isolated or 

 confluent. The rapid spread from one leaf to another may lead to a partial 

 or complete defoliation in early summer. 



The fungus causing this disease is one of the ascomycetes, and is 

 closely related to the Peach-curl, Pear-leaf blister, and Poplar blister, under 

 the name of Exoascus or Taphrina. In some species the spots occur on 

 the lower surface of the leaves, and in others on both the lower and upper 

 surfaces. 



The species implicated in this disease is stated to be that which 

 was described by Desmazieres in 1848 under the name of Ascomyces 

 ccernlescens, of which it is affirmed that Ascomyces quercus (Cooke) and 

 Ascomyces alutaceus (Thum.) are only synonyms. 



A tree of Quercus nigra was selected and sprayed with the ordinary 

 Bordeaux mixture about ten days before the buds opened, and then at 

 intervals of ten days for three times. Although the sprayed tree was in 

 close proximity to unsprayed trees which were badly infected, the sprayed 

 tree was only very slightly affected by the disease. — M. C. C. 



Oaks Of Iowa. By Prof. B. Shimek {U.S.A. Hort. Soc. Iowa, Bep. 



1902, pp. 228-232 ; 10 figs.). — Contains notes on the Oaks of Iowa, with 

 a key to the species. — F. J. C. 



Oat Smut and its Prevention. By R. A. Mcore (U.S.A. Ayr. Exp. 

 Stn. Wisconsin, Bull. No. Ill, March 11)04 ; 2 plates).— Oat smut is pre- 

 valent throughout the State. During the past three years the destruction 

 of the Oat crop of Wisconsin farmers by smut amounted to twelve and a 

 half million dollars. The support of the rural public schools in the State 

 has cost for three years eleven and a half million dollars, or two millions 

 less than the estimated value of Oats destroyed by smut. 



Where farmers have used the formaldehyde treatment, or secured seed 

 Oats from farmers who have used the treatment, the crop was free from 

 smut, or only a trace could be found, and the smut in the State has thus 

 been appreciably lessened. 



The increase of smut checked and retarded during wet seasons. This 

 is especially true w T here Oats lodge and subsequent rains wash the im- 

 mature smut spores on the ground. When Oats lodge before maturity 

 the vitality of the grain is greatly impaired, and if retained for seed will 

 usually result in producing only a partial crop. 



Barley smut can be eradicated by submerging the seed grain for ten 

 minutes in a solution made by using one pint of formaldehyde to twenty 

 gallons of water. 



By constant vigilance it seems that smut can be practically controlled 

 by the farmer. — M. G. C. 



Ochnacese, The. By Ph. van Tieghem (Ann. Sc. Nat., Bot. xviii. 



1903, pp. 1-60). — This is a supplement to the monograph already noticed 

 (Journ. R.H.S. xxviii. p. 270).— -Four new genera and eight species are 

 described, and their systematic position in the group discussed. — \V. G. S. 



k K 



