Diseases of forest and shade trees, ornamental and miscellaneous plants in the United States in 1924 /

csd;.r blig-ht caused by ph(mopsis junipbrovopu.}um (prepared by Glonn Garc^-Hcr Hahn, Office of Investigations in P:)rj:St Pathology) Cedar blight was first observed by P. G. Stcwr.rt as r.destructive dis- ease of young rod cedar trees caused by a Phonia in a nursery at Kent, Iowa, 1896-7.^(Phytopn.thology8: 35-34.^^^7 I918)...t that time specimens v/crc scaat to B. M. Duggar (1897^^vho obtained the Phona in pure culture but did not proceed further v/i th the investigation.Tlio dcs tructivonoss of this blight organian as a virulent parasite of young red cedar trees xr.s later observed by G. G. Hedgcook (1903-4) v^ion he surveyed heavy infections in nursery seed- ling stock at i'.lbcrt Lea, Minnesota; Charles City and Shenandoah, Iov;a • and Missouri.Ho reports one nursery in lov/a as being practiorJ.ly'v iped out v/ ith the disease.In l^l^-li> R. G. Pierce observed the cedar blight as an importr.ntdisease causing large drjnage in nurseries at Cedar Bluff nnd North Bcaid, Neb- raska; Hays, Kajisas; Dundee and Glenview, Illinois; and Charles City, lovvra* He states that one nursery in Nebraska growing a million seedlings of eastern red cedar was practically v/i pod out by the blir^t.C Hartley end the v/riter in- vestigated the disease at nurseries in IllinDis (1916-I7) isolating and prov- ing a crusal parasite whidi v/as assigned tentatively to the genus Phoma.(jour./^ric.Res.10; 533-539.Sept. I917).This Phoma v/as a little later definitely identified and described as Phomopsis .junipcrovpran. sp.Hahn.(Phytopathology 10: 249-253.Apr.1920).V^erc the blight has been under observation it lias proven a most impor- tant parasitic dis'easc.Certain of the horticultural cedar varieties are pa rticulxirly susceptible.In behavior the blight is typic?!.The scalier twigs first sfcoir up brovm and dead.The disease iia y move downv/ard into the older p£rts causing cankers to form which may completely girdle or kill only one side of the stem.V/hcro girdling occurs all the parts beyond die.Cedar blight may be the cause of serious loss in coniferous nursery seedling bods.The blight and cankers may also appear as a destructive disease in older stock both in nurseries and in ornamental plantings.PLants affected with the blight arc often not rccogniacd as diseased and consequently have been widely dis- anl CDntinurlly CDVcrod thrxigh^ut tho ::rowin:, soiSDn, the initial spraying, boins pcrf ormc-"'.very cr.rly in the sprir^to prevent the lUi^^lit frxi {^r.inin^: r. f jDthold in tiic seedling beds, seems to bo the most likely ircans of control, Scr.sons of exceptional rainfall v/hen excessive moisture is present are con- ducive to the spread of the disease.Metlixls of cutting dov/n an unc'-ue moisture supply are therefore of benefit.Cankers should be pruned out of lar^c trees to prevent tho further spread of the parasite.No systematic survey to dotcrmino the ^e Oi:;raphical distribution of cedar bli^lit has boon made, but from a study of the specirat^ns mentioned below and from reports it is definitely known to extend in certain states rl on{3 the Atlantic Seaboard from Nev/ Yoik to Florida; throuohout tlic Middle 'Jest from southern Minnesota, to ..labajna; and it is not knov/n far tlx cr ;7est than eastern Nebraska and Kansas.Diagnoses of the disease has been mrjfl.cf rom s pec imcns of tlic fUngus on affected stems and leaves received from the follov/ing states: ^;iabamr.-Young native red cedar reported badly infected, October 10, 1924.Speoliiens not personally examined by the '.vriter.District of Co lun^> ifi -Infected ornamontal plant big of Juniperus chin - ens is var.procumbens , and J. sabina .May 3> I92O.Coll^oti:)ns rcr, do by G. G. Haha.Infected ornQmcntal planting of J. chincnsis var.