DISEASES OF PT.ANTS. 747 



Tho disease iiiny oceiir in isnlatt'd Iri'os. Irinii w liidi it spreads eitlirr alou;; 

 file rows or radially from the center ol' int'ectinn. 



An examination of the dead trees siiows lliat Hhm-o are two parasites, which 

 are usnally associated, althoufih SDiiictiuies nccni-rinK separately. The first 

 is a niushrooni. prolmhlx A nnilhnin inclltti. wiiicii (levelo|(s on fli(> mots and 

 forms a white felt between the hark and the wood of the tree. It also pro- 

 duces rhizomorphs, hy whicii new phnn trees, irrajtevines. .ind otiicr I'liiit or 

 forest trees are attacked. 



The insect associated with this disease is one of tlic fiiiit tree Itark horers 

 ( .s'co/,(//».\- nifniloKiix)- It is most fretinently fcmnd on trees where there is a 

 diN-ided dinnmition in tlH> How of sajt. such as follows an attack of tlie funjrns 

 on the roots. 



In oriler to comhat this dist'a.se the author ivconnnends the hnrninj; of all 

 infested trees, the difr^ins of trenches about .30 in. deej) around the trees, and 

 disinfect iuf,' the soil with carbon bisulphid. Care should be exercised not to 

 replant plum or other susceptible trees in the infected areas. In it)mb;itinj; 

 the bark borer, in addition to the su.wi'stions j^iven. the author reconnnends 

 vif,'orons pruniufj, buriuuir the infested branches and bark, and sprayini; with 

 various insecticides. It will be found that anythinjr that increases the vifior 

 of the trees, such ;is the removal of mosses, lichens, and funjii. thinidiif; the 

 fruit, etc.. will aid in combatiiii; this di.scase. 



An outbreak of the European currant rust, F. V. Stkwaut {\cii- )'(/rh- ,slat<' 

 &7fl. Tech. Hid. J. ///(. (!l-l'i. Ills. .i). — During: Sept<MnlK>r. liHiC. the author 

 observed an unusual appearance of the foli.-isie of currant bushes at the station. 

 and an examination showed that they were infested by the Kuroiie.iii eurrant 

 rust (Cron art i 11)11 rihicolu). 



In the plantation there were about 1T."> jilants. includini,' ."4 v:irietii>s of ditfer- 

 ent species of Ribes. 4S of which were more or less infested with the rust. In 

 si)ite of a very .severe attack on the black currants, the jilants were in full 

 foliajie. and the red and white varieties seemed only sli;j:htly affected. In 

 another portion of the station firoinuls ;i number of currants of different species 

 were .crowinj;, but only two plants were found to be attacked. 



CronurtiiiDi ribicohi appears during the sunnner and autumn as a conspicuous 

 orange-colored powder on the under surface of the leaves of various species of 

 currants and gooseberries. The jecidial form occurs on the trunks and branches 

 of species of pine, particularly the white i)ine il'iiniK si roll hk). where it pro- 

 duces a disease known as blister rust. 



The fungus occurs throughout a number of Enro|)ean countries, but has never 

 been rejiorted from Australia or South America, and only once previous to this 

 lime from North America. From the information at hand it appears that as a 

 currant disease. Croiiartitnii rihicola is regarded as of little importance in 

 those regions where it is abundant, but as a disease of white pine it causes much 

 damage. 



The author has undertaken to trace the origin of the outbreak at Geneva, but 

 with little success. It appears that some of the varieties of currants were 

 imported from Europe a few years ago, and that some pini^s which are near by 

 are also of European origin, so that the fungus possibly was introduT-ed with 

 either the currants or the pines. 



In order to stamp out the rust, if possible, every i)lant of the different species 

 of Ribes on the station grounds has been destroyed. The white pines standing 

 near the currant |)lantation will be kept under observation to see if the disease 

 appears upon them, in which case they too will be destroyed. It is lujssible 

 that the rust might be controlled on currants and gooseberries by spraying with 



