July, 1915. 



THE CANADIAN HORTICULTURIST 



171 



Troublesome Rose Pests and Their Cure 



J. M. Bryson, Moore Park, Toronto 



MILDEW is one of the worst and 

 most prevalent diseases to 

 which the rose is subject. It is 

 known to most lovers of roses, forming 

 as it does a white du.st like mycelium, 

 first of all, usually, upon the young 

 foliage. The portions of the roses at- 

 tacked cause the rest of the bushes to 

 curl up their leaves. In some cases 

 where mildew has been allowed to go 

 unchecked for any length of time, the 

 leaves begin to drop, and, where it at- 

 tacks the buds, they open to a very 

 hard flower, looking very much as 

 though they had been blistered. 



Methods of cultivation are often the 

 direct cause of mildew, as, for instance, 

 an excessive use of fertilizer or turn- 

 ing the hose on the bushes on a liumid 

 morning, especially if the bushes are 

 not robust in character. The most 

 common cause of mildew on outdoor 

 roses, however, is rapid changes of 

 temperature, from hot days to cool 

 nights. This disease is rarely trouble- 

 some until August, when night fogs 

 are prevalent, although such varieties 

 as pink and white Killarney, Harry 

 Kirk, His Majesty, Her Majesty, and 

 Mrs. Sharman Crawford, usually are 

 subject to this pest from the outset of 

 their growth. 



For a mild attack of mildew, equal 

 parts of quick lime and flowers of sul- 

 phur dusted over the affected parts 

 will in most eases be found effective, 

 or the use of grape dust in the same 

 maimer, but these remedies ituist be 

 applied in such a Avay that they come 

 into actual contact with the mildew. 

 For a bad attack of mildew, use sul- 

 phite of potassium or flowers of sul- 



phur, on heavy bushes, at the rate of 

 half an ounce to one gallon of water, 

 applied cold with a sprayer or syringe. 

 Give weak bushes half the above quan- 

 tity. Abol is another excellent remedy 

 for mildew, the directions for whi-;h 

 are supplied with each carton. This 

 is a non-poisonous preparation, and it 

 will cure mildew. 



Black Spot. 



Black spot is caused by an entirely 

 different fungus from that which 

 causes mildew. As the mycelium is 

 underneath, or, to be more correct, 

 partly inside the leaf, it is hard to 

 reach it by spraying, unless a fungicide 

 be used, which, besides destroying the 

 black spot, also causes the loss of the 

 foliage. However, defoliation usually 

 follows in the wake of this disease. 

 The leaves should be carefully gather- 

 ed and burned forthwith. 



The symptoms of this disease arc 

 broAvnisli-black spots, some round and 

 some large and oblong, which cover 

 half of the leaf. A solution of sulphide 

 of potassium, the same strength as for 

 mildew, is a corrective only if it is 

 applied weekly throughout the growing 

 season, at the same time spraying the 

 ground under and around the bushes. 

 It is best to use this mixture on a dull 

 day, as if used persistently in the sun, 

 scorching of the foliage is apt to re- 

 sult. 



The most effectual remedy I know of 

 for this disease is to drop three or 

 four, not more, crystals of permangan- 

 ate of potash into a gallon of water 

 and water the plants at the root with 

 this mixture once a month, giving each 



bush affected one pint of the mixture, 

 and apply it after sundown. I am con- 

 vinced that this disease must either be 

 treated from the root or else sprayed 

 with a solution strong enough to kill 

 the foliage, which will of course begin 

 to grow again, but if an early, severe 

 frost should happen to strike them 

 during the growing period, which, by 

 the way, is during September and Oc- 

 tober, it would simply mean that the 

 weakening of the bushes consequent 

 upon the disease and also the use of 

 strong fungicides, combined with the 

 frost, would likely cause some of them 

 to wither and die. 



The Carpenter Bee. 



This is a small black fly with a 

 pointed sting which is used with dead- 

 ly effect upon not only roses but any- 

 thing of a thorny nature. In some 

 stages, the effect that the sting from 

 this bee has upon rose foliage re- 

 sembles the Irish gooseberry blight. 

 The rose is attacked in the following 

 manner. On the extreme end of a 

 shoot from which a bloom has been 

 cut, it makes a small puncture, where 

 it deposits its larva, which when in- 

 cubation starts, works down the pith 

 section, drawing the sap from the 

 leaves to sustain it during the cocoon 

 stage, which results in black spots ap 

 pearing upon the leaves, and the ul 

 timate drying up of the rose bush. 



This insect will kill an acre of ro.se 

 bushes in a week's time if it is not at 

 once checked. The only method I know 

 of to combat it is to cut below the spot 

 where the cocoon has penetrated. This 

 can easily be determined by slicing the 

 shoot lengthwise, and if it has been 

 penetrated to union or callus, the bush 

 must be takeii up, root and branch, 

 and at once burned, and a strict watch 





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I^HP 



%~ 



Dr. Frank E. Bennett, president oC the St. Th(>ma.^ Horticultural Society, among his tulips. At a sprinir exhibition this year Dr. Bennett showed 125 



varieties of tulips, winning a silver cup tor the second year in succession. 



