1042 EXPERIMENT STATION RECORD. 



DISEASES OF PLANTS. 



Examples of the use of the microscope in investigating' plant diseases, 

 (). Ari'Ki. (lirisiiiclc ziir inikroskDitiscIti n. L ntciHiuhung von J'ftanzcnhnink- 

 heitcti. lirrliii. tHOS, 2. ed.. nr. and ml., pii. 5), /igs, 6S). — This is a second edi- 

 tion of tho jiuthor's contribution on the use of the microscope in the study of 

 plant diseases, and is issued as a separate from Haj^er and Mez's Das Mikroskop 

 uiid seine Aiiweiiduu};. 



In this pul)lication the author describes tlie principal microscopic characters 

 of a number of couinion and destructive diseases, among them the bacterial 

 rot of potatoes, the bacterial disease of cherries, club root of Cruciferoe, the 

 I'hytopbthora disease of potatoes, grape mildew, leaf spot of clover, cereal 

 mildews, smuts and rusts of grain, etc. In addition notes are given on a num- 

 ber of insects that cause diseases of plants, such as nematodes, plant lice, scale 

 insects, etc. 



Two little known Myxosporiums, C. W. Edgerton {Ann. Mi/roL, 6 {1908), 

 Xo. J, pp. J/S-o.i, figs. 2). — During a study of fungi which have a Glnposporium- 

 like fructif]cati<»n. the author noted two parasites which should be placed in the 

 genus ^Myxosporium. One of these occurs ou the branches of the tulip tree 

 {Liriodcndrnn tulipifera). while the other is found on the living branches of 

 apple and pear trees. The latter produces a canker on the old bark and has 

 been frequently confused with another fungus, Spharropsis malornm. 



After a careful study of the bark canker and that caused by the black rot 

 fungus, the author concludes that the two forms may be readily distinguished. 

 The bark canker is produced, as indicated above, by a species of Myxosporium, 

 and the name .]/. corticoUnn n. sp. is given it. The fungus is iierennial, living 

 fi-oni year to year in the bark, and forming a new ring of growth each year. It 

 grows rapidly in the direction of the main axis, causing the formation of a long 

 narrow canker. It does not penetrate deeply into the host, the mycelium ex- 

 tending only about one-third to the cambium zone. The outer portion of the 

 cortex is killed and dries out much faster than the healthier tissues, and, as a 

 result, this area becomes slightly sunken. During the second year the fungus 

 grows out into the unaffected bark surrounding the canker and this region 

 becomes the spore-bearing one for that season. 



Notes are given on the relation of this fungus to others, with a discussion of 

 its synonymy, and a technical description concludes the study of this species. 



The second species, which attacks the tulip tree in a somewhat similar man- 

 ner, is also due to a new sitecies, M. longisporum, which is technically described- 

 Investigations on diseases of cereals in 1908, K. Stormer {Landw. 

 Wchnschr. Hachscn. 10 {1908), ^^os. 35, pp. 306-309; 38, pp. 331, 332; 39, pp. 

 3.'fO. 3-'il ; J/O, pp. 3.'i7-3.'i9). — A report is given of studies carried on at the plant 

 jiathology station on the occurrence of cereal diseases in Saxony in 1908. The 

 most inii)ort;int diseases were the smuts of barley and wheat {Ustilago Jtordei 

 and U. tritiei), the stinking smut {TiUetia caries), the stem disease due to 

 Opiiioholus licrpot rich lis, and the leaf and stem disease caused by Hclminthos- 

 poriiini gramincum. 



Different treatments for the prevention of these diseases were tested. The 

 modified hot-water treatment for smut prevention as well as the treatment by 

 means of dry hot air recommended by Kiihle (E. S. R.. 20, p. 947). which con- 

 sists of a preliminary soaking of the seed in cold water for several hours, fol- 

 lowed by drying in a drying machine heated to 60° C. or more, are recommended 

 as the most elhcient treatments for smut. 



Notes are given on other diseases, among them rust, mildew, etc. 



