DISEASES OF PLANTS. 59 



Boils are most subject to its attacks. Au excessive nse of manures rich iu nitrogen 

 encourages the disease. Late-sown grain crops are the most liable to the attack. 

 Thinly sown crops are most liable to rust." 



A report is given of the experiments made in Anstralia on the 

 growth of resistant varieties. The most promising results are along 

 two lines: 



"Rust-resisting wheats, by which are meant wheats which, in localities suited to 

 their growth and under normal conditions, resist at all seasons of the year either the 

 entrance of the rust mycelium into their tissues or its subsequent growth and out- 

 burst. Of this class many examjiles are known. . . . 



"Rust-escaping wheats, that is to say, Avheats which are rust liable, but which if 

 sown at the proper time ripen so early as to be ready for harvest before the rust of 

 au ordinary season can prevent a paying crop." 



In the first group the following characteristics have been found by an 

 examination of 12 varieties: 



"The possession of a thick and tough skin, so tough that though the mycelium may 

 enter the plant by means of the open stomata. yet it can not breakthrough the skin 

 in order to mature and shed its spores, so that its further development is prevented. 

 And, secondly, the presence of waxy exudation on the surface of the jdants similar 

 to the bloom of fruit ; this waxy covering, when present about the mouth of the 

 stomata, prevents the rust mycelium from entering. Wheat plants possessing tough 

 skins, and especially if j>ossessing toughness of the skin in conjunction with the 

 waxy bloom, may be grown under all conditions suitable to their normal growth 

 without suffering seriously from rust. On the other hand, rust-liable wheats, which 

 are characterized by the possession of a thin and tender skin, and often by the 

 absence of waxy bloom, can be grown successfully during a rusty year only in one 

 way, namely, by sowing at such time as the plant shall be only for a short time sub- 

 ject to the attacks of the rust fungus." 



Brief reports are given of the occurrence of rust in Germany, India, 

 Japan, and the United States. The life history of the rust is given in 

 detail. 



The means suggested for the repression of rust are burning infested 

 straw and spraying the infested plants. The spraying of wheat with 

 copper and other solutions has giv^en conflicting results. 



A detailed report on the investigation of rust-resistant varieties of 

 wheat is given, in which it appears that a thick epidermis and glaucous 

 or waxy bloom, preventing the entry of the sporidia or the emergence 

 of the mycelium to form sori for the furtlier propagation of the fungus, 

 are the essentials for such varieties. The report concludes with a 

 chapter on the spring rust, Puccinia ruhigo-vera. 



Report of the horticulturist, S. A. Beach {Neiv York State Sta. 

 Rpt. 1893, pp. 530-585, 642-677, pis. 9, Jigs. 16). — Some bean diseases 

 (pp. 531-556). — A reprint from Bulletin 48 of the station (E. S. E., 4, 

 p. 557.) 



Leaf spot of chrysanthemums (pp. 557-560). — A report on a disease of 

 chrysanthemums prevalent in the station greenhouse during 1891. The 

 disease first appeared in small dark-brown spots Avhifli increased iu size 

 and number until the leaf tissue died and the foliage dropped oft". In 

 badly diseased ])lants nearly all the leaves withered and fell away j evcji 



