JUNB 7, 1917. 



The Rorists' Review 



19 



iHE investigations covered 

 more or less briefly in this 

 report were begun August 

 1, 1916, During the first 

 four months much time was 

 spent in visiting rose plant- 

 ings in northeastern United 

 States, making a survey of diseases. 

 This seemed desirable in order to ac- 

 quaint us with the various diseases, to- 

 gether with their range and the extent 

 of injury caused by them in this coun- 

 try. "With these facts in mind, suitable 

 plants and materials have been col- 

 lected for experiments now under way 

 which will prove of the greatest value 

 to growers of roses. 



Old Diseases. 



The survey and correspondence with 

 growers has shown the most important 

 rose diseases, in order o2 importance, to 

 be (1) black spot, (2) mildew, (3) 

 crown gall, (4) stem canker, (5) Phyl- 

 losticta leaf spot, (6) rust, (7) bud rot, 

 (8) other leaf spots. Practically all of 

 these diseases are always present and 

 take from the growers yearly tolls of 

 surprising magnitude. It is not uncom- 

 mon to find houses with all the plants 

 completely defoliated by black spot. It 

 is unnecessary to mention the damage 

 done by mUdew, while there is an ever- 

 increasing demand for information re- 

 lating to crown gall, stem canker, rust 

 and bud rot. Unfortunately, little is 

 known regarding the control of most of 

 these diseases and many points remain 

 to be investigated concerning the con- 

 trol of such common and well-known 

 diseases as black spot and mildew. 



A New Disease. 



A new, and what appears 

 to be one of the most im- 

 portant diseases of the rose, 

 has been observed by the 

 writer in visits to rose 

 houses. We are calling it 

 the crown canker. Speci- 

 mens have been sent by 

 growers from many parts 

 of eastern United States 

 and from as far west as 

 Missouri. It was first ob- 

 served by the writer in Sep- 

 tember, 1916, but talks with 

 growers indicate that the 

 disease has been present for 

 possibly four or five years. 

 All varieties seem to be 

 susceptible to the disease. 

 The plant is attacked just 

 below the surface of the 

 soil and although the dis- 

 ease advances slowly, the 

 death of the plant is sure, 

 with an ever-decreasing 

 number and quality of flow- 

 ers. 



This disease, which has 

 never been described, is 

 considered of such import- 

 ance that a large part of 



the writer's time is being devoted to a 

 study of the life history of the causal 

 fungus and the development of a method 

 of control. Several large growers have 

 stated that unless help is obtained they 

 will be forced out of business. 



Will Soon Be Distributed. 



With the disease already known to be 

 present in the houses of ten large grow- 

 ers, it is safe to assume that other grow- 

 ers have plants similarly affected and 

 that the disease will be widely distrib- 

 uted and increase rapidly in importance. 

 Steps must be taken immediately to 

 control this disease. Not only is it im- 

 portant that growers who already have 

 the disease shall be furnished with con- 

 trol methods, but it is even of greater 

 importance that the method of dissem- 

 ination of the fungus be worked out in 

 order that the further spread of the 

 disease be checked. 



What appear to be other new diseases 

 than the one mentioned above have been 

 brought to the writer's attention, but 

 too little progress has yet been made in 

 this investigation to give definite state- 

 ments at this time. 



Work on Leaf Diseases. 



The following investigations are un- 

 der way: 



(a.) Black spot. It is planned to con- 

 duct extensive experiments for the con- 

 trol of this disease during the coming 

 season. Plants at the Cornell test gar- 

 den and at the nursery of Chase Bros., 

 Honeoye Falls, N. Y., will be treated 

 with various fungicides along the lines 

 of recent developments in plant disease 

 control. One of the most important 

 fungicides to be tried is that of finely 



Statement by Rose Society's Secretary 



Last year. In response to a letter from President Pennock, of the 

 American Rose Society, thirty-two florists generously contributed 

 toward the investigations in rose diseases which were carried on by 

 Dr. L. M. Massey. of the Department of Plant Pathology, at Cornell 

 University. Dr. Massey has put in considerable work on this problem 

 during the last year and has several lines of investigation well under 

 way. It is the feeling of the officers of the American Rose Society that 

 Dr. Massey should continue his work during the coming year, as was 

 outlined in the project of a year ago. At that time it was stated that 

 it was expected the investigation would be on a two-year agreement, 

 Last year the American Rose Society pledged itself to support Dr. 

 Massey while in the fleld one-fourth of the time, and that the co8t 

 would not exceed $1,000, of which sum $300 the first year and $250 

 the second year would be for traveling and other special expenses. 

 The rest of the expenses of the investigation have been borne by 

 Cornell University. 



Dr. Massey carries on the major part of the outside work during 

 his vacation periods, when he is free from college duties, and can 

 visit commercial ranges. Laboratory research is carried on during the 

 college year. 



On this page there appears a summary of a preliminary report of 

 Dr. Massey's work. It will be understood from the natut« of the 

 project that definite results cannot be given In so short a time. It 

 seems, however, that Dr. Massey's work during the last year has 

 opened up some wonderfully valuable lines of investigation, which 

 should be continued. 



It is hoped that a large number of men interested in rose growing, 

 who did not contribute to the work last year, may feel interested to 

 do their part this year. All subscriptions should be sent to £. A. 

 MTiite, secretary, American Rose Society, Ithaca, N. Y. 



ground sulphur applied in the form of 

 dust. Suitable plants have been ob- 

 tained and are now growing in the 

 greenhouse at Cornell for similar experi- 

 ments for the control of black spot un- 

 der glass. 



(b.) Mildew. Experiments for the 

 control of mildew through the use of 

 finely ground sulphur used as a dust on 

 both indoor and outdoor roses. 



(c.) Phyllosticta leaf spot. A study 

 of the life history of the causal organ- 

 ism is now being made. This is one of 

 the most important leaf -spot diseases of 

 ramblers and methods of control will be 

 tried during the coming season. 



Work on Boot Diseases. 



(d.) Crown gall. Some 200 healthy 

 plants have been obtained to be inocu- 

 lated with bacteria causing this dis- 

 ease. These plants will be grown to de- 

 termine the effect of the disease upon 

 the plant, there being a divergence of 

 opinion as to just how much damage is 

 done. 



(e.) The new root or crown disease, 

 crown canker. Extensive experiments 

 for the control of this disease are now 

 under way. It is probable that the fun- 

 gus lives in the soil and that successful 

 treatments will be along the line of soil 

 sterilization and the practice of sanita- 

 tion in the houses. Some 300 rose plants 

 have been obtained and are now grow- 

 ing in the greenhouses at Cornell for 

 these experiments. Much time is being 

 spent in working out the life history of 

 the causal organism, as such informa- 

 tion is essential for a comprehensive 

 study of control methods, 



(f,) Fungi and bacteria causing other 

 diseases of roses are being studied in 

 culture. These organisms 

 have been isolated from 

 diseased material obtained 

 from growers. Their patho- 

 genicity will be tested and 

 control experiments c o n - 

 ducted where the organisms 

 prove parasitic and the im- 

 portance of the disease war- 

 rants such action. 



Can't Stop Now. 



It will be seen from the 

 above statements that while 

 there is but little yet to re- 

 port in the line of results in 

 control, still considerable 

 progress has been made and 

 the foundation laid for ex- 

 periments for the control of 

 diseases which are of ex- 

 treme importance to the 

 growers of roses. There is 

 every reason to expect that 

 another year's work will 

 bring results upon which 

 proved and definite advice 

 may be furnished the grow- 

 ers for the solution of their 

 rose-disease problems. 1 1 

 is hardly necessary to add 



