18 



The Florists^ Review 



MabCh 13, 1919. 



as has been found to be true of many 

 fungi, this fungus is carried through the 

 winter on fallen leaves in which the 

 ascosporic stage develops the following 

 spring. 



Although when mature the asci dis- 

 charge the spores through an apical pore 

 formed by the rupture of the wall, the 

 spores are apparently not discharged 

 with violence. Wolf states that they 

 merely pile up in a whitish heap in the 

 opened perithecium. How they reach the 

 unfolding leaves of the plant has never 

 been definitely determined, but it is 

 probable that insects, splashing rain and 

 possibly the wind play an important 

 part. Man, in cultivating, may also 

 serve as an agent of inoculation. 



The maturity of the ascospores and 

 the occurrence of rainy periods when 

 the spores are mature are factors gov- 

 erning spore discharge. 



The ascospores which are probably 

 distributed during a rainy period re- 

 quire moisture to germinate and pene- 

 trate the host. They germinate within 

 twenty-four hours. Wolf found the pe- 

 riod of incubation to be about ten days, 

 small black areas being evident May 

 7 from inoculations made April 27. 



Infection occurs by the entrance of 

 the germ-tube directly through the cu- 

 ticle of the leaf. The resulting mycel- 

 ium remains for some time immediately 

 beneath the cuticle, later penetrating 

 the tissues below, first filling the epi- 

 dermal cells and only in advanced stages 

 of the disease penetrating the meso- 

 phyll. The black appearance of the 

 spots is not due to the fungus, which 

 is almost colorless, but to the disinte- 

 gration of the cells below the spot. 



EnyiToiuiiental Relations. 



Temperature and especially moisture 

 are factors which may influence the se- 

 verity of the disease by their effect on 

 the parasite and the host. It is a matter 

 of common observation that greenhouse 

 roses are more subject to this disease in 

 the spring and autumn, when extremes 

 of temperature are most likely to occur. 

 Frequent rains and general cloudiness 

 are important factors at these times. 

 Many growers of indoor roses claim that 

 if the plants can be carried through late 

 summer and autumn prior to the time 

 when firing begins without suffering an 

 epiphytotic of black spot there is little 

 danger of plants being badly diseased 

 during the winter. No doubt excep- 

 tions occur, but the most badly diseased 

 houses noted by the speaker in visits to 

 growers were those where firing was be- 

 gun late. The natural heat of summer 

 and artificial heat of winter quickly 

 dries off the foliage and must thus be in- 

 strumental in lessening infection. It is 

 very improbable that the ascigerous 

 stage develops in the fallen leaves un- 

 der glass. 



Outdoors, where primary infection is 

 initiated by ascospores formed during 

 the winter in old leaves left lying on 

 the ground, it is obvious that the spring 

 rains are important factors, as moisture 

 is necessary for the discharge of these 

 ascospores from the perithecia. Moisture 

 supplied either by rainfall or by dew is 

 probably necessary for the germination 

 of both the ascospores and conidia, so 

 that a greater amount of disease may be 

 expected during rainy seasons. It is a 

 matter of common observation that 

 whereas more or less black spot is pres- 

 ent every year, epiphytotics on outdoor 

 plants only occur during seasons of 



heavy rainfall. The precipitation of 

 dew on the foliage during the autumn 

 when cold nights and warm days prevail 

 may account for the increased amount 

 of disease at this time. Lesions on the 

 leaves are more numerous and perhaps 

 larger in rainy, cloudy seasons than in 

 dry seasons. When conditions favorable 

 to black spot are known a big step will 

 have been taken toward the control of 

 this disease, especially under glass. 



Ck>iitrol. 



Since the fungus lives over winter in 

 fallen leaves, where the ascospores are 

 produced which serve as the source of 

 primary infection in the spring for out- 

 door roses, it follows that these should 

 be carefully collected and burned late in 

 the autumn. It is also advisable to keep 

 the benches free from old leaves affect- 

 ed with the disease, for they bear the 

 summer spores and thus serve as sources 

 of infection. Where a rose garden con- 

 sists of only a few plants much may be 

 accomplished by picking and burning 

 every leaf as soon as it shows signs of 

 disease. 



Protection by spraying is the usual 

 recommendation for the control of the 

 disease of roses caused by Diplocarpon 

 *rosae Wolf. Of the numerous fungi- 

 cides recommended in literature prob- 

 ably Bordeaux mixture and ammoniacal 

 copper carbonate are the two most often 

 mentioned. Statements to the effect that 

 the latter fungicide is as efl&cacious as 

 the former are common in literature. Re- 

 sults of experiments conducted in 1917 

 indicate that ammoniacal copper car- 



bonate is not as efiicient as Bordeaux 

 mixture for the control of the disease.' 

 A mixture of ninety parts finely ground 

 sulphur and ten parts powdered arsenate 

 of lead dusted upon the plants proved 

 to be as efi&cient as Bordeaux mixture 

 and its use rendered the plants far less 

 (insightly than the latter fungicide. 

 Lime-sulphur solution, on© part of the' 

 commercial concentrated solution to 

 fifty parts water, was found to be more 

 efficient than ammoniacal copper carbon- 

 ate and probably as much so as Bor- 

 deaux mixture and the sulphur-lead 

 dust. However, lime-sUlphur discolors 

 the foliage almost as much as Bordeaux 

 mixture. 



ADVERTISINa WITH OBDEBS. 



Dobbs & Son, of 140-150 South Divi- 

 sion street. Auburn, N, Y., have made 

 use of an idea which is worth the con- 

 sideration of every retail florist. With 

 every letter and bill sent out by this 

 concern is sent a neat card, upon which 

 is printed the verse which follows, as 

 well as the, firm name, its address and , 

 telephone number: 



"A few flowers, a sick friend to cheer. 

 Do more good than all the drugs you can buy 



In a year; 

 'Tis better to bring a single flower 

 To a living friend at any hour, ' 



Than to heap up roses, white and red. 

 Upon his co£9n when he's dead." 



Florists could vary the idea by using 

 appropriate quotations of prose or 

 poetry, instead of original verse. The 

 card serves as a reminder to the cus- 

 tomer when he wishes to order again 

 and is an inexpensive method of adver- 

 tising. 



Natick, Mass. — Robert Montgomery 

 has been unwell for some time, but feels 

 that with the advent of spring he will 

 be as vigorous as ever. Roses are his 

 specialty and have cropped well when 

 they were worth most. A fine crop is in 

 sight for Easter. 



Watertown, Mass. — A. Davenport 

 makes a specialty of ferns and reports 

 a good demand, especially for the 

 crested forms of nephrolepis, as it is 

 found they make better house plants 

 than the plain-leaved kinds. A miscel- 

 laneous stock for Easter looks promising. 



Natick, Mass. — James Wheeler, 

 though forced to close two of the largest 

 houses, has been well compensated by 

 the heavy crops of carnations, Benora, 

 Pink Delight and Matchless, the last 

 named, in his opinion, unequaled for 

 productiveness, both in grass and bloom, 

 and one of the easiest to propagate. A 

 pink sport promises much. Aviator is a 

 favorite. Mr. Wheeler believes it well 

 worth trying by all growers, as it does 

 finely here. Close by it is a failure, 

 evidence that it is not confined to a cer- 

 tain location. Junior Wheeler made 

 what he believes a record when he 

 picked and bunched 1,150 blooms in one 

 and three-quarter hours. Anybody 

 equaled or beat this feat? The empty 

 houses will be planted to Comet toma- 

 toes for a spring crop. 



Waverley, Mass. — ^Manager Hermann 

 Bartsch, of W. W. Edgar Co., is hav- 

 ing his usual success in producing stock 

 for Easter, regardless of the date. Mr. 

 Farmer, father of Mrs. W. W. Edgar, is 

 being congratulated upon having passed 

 the seventy-sixth milestone, as spry as 

 ever, full of "pep," a valuable help to 

 the business and proud of being asso- 

 ciated with the only John Evans and 

 Lloyd-George by kinship through the 

 land of their birth. 



Bosllndale, Mass. — Antoine Leuthy, 

 speaking from experience as an old-time 

 importer, says that we cannot compete 

 with Belgian growers of palms and 

 azaleas, and gives as the reason that a 

 closed car is either too hot or too cold 

 and that the journey across the conti- 

 nent is fatal to this class of stock. On 

 the other hand, the Belgians pack for 

 the voyage and rarely, if ever, fail, un- 

 der ordinary conditions, to get the plants 

 through in good shape. The same ap- 

 plies to bay trees and boxwood. More- 

 over, palms grown under lath houses are 

 open to attacks from grasshoppers. 

 These are a bane to our confreres in 

 Louisiana. Mr. Leuthy relates one of 

 his experiences as a youthful palm 

 grower in Algiers, when ditches were 

 dug and kerosene sprayed and lighted to 

 burn up the pests. 



