204 ON THE CULTURE OF ERICAS. 



applied upon the very first appearance of the disease, by dusting 

 the plants all over with the dry flour of sulphur, or by making up 

 a thick lather of sulphur, mixed with soap, and laid on the plants 

 with a painter's brush. It is difficult to trace the real cause of 

 this disease ; some attribute it to the practice of exposing them 

 during summer to the power of the mid. day sun ; others, to the 

 excess of water given them towards autumn ; while many think it 

 is an atmospheric disease, and that some situations are more 

 liable to its effects than others. It is said to be of a rare occur- 

 ence in Scotland, owing, probably, to the summers being cooler 

 there than in England. Whatever may be the cause, the effect 

 is in general fatal, for heaths, once attacked by the disease seldom 

 recover. 



It is said that "the best preventive is placing the plants during 

 summer, behind a wall, hedge, or other shelter ; so that they may 

 be shaded from the rays of the sun five or six hours in the hottest 

 part of the day, without having recourse to awnings of any kind ; 

 likewise, to house them early in autumn, in houses where the 

 sashes can be drawn off in fine weather, and put on to protect 

 them from heavy rains. For the more delicate species, generally 

 kept in pits and frames in summer, the best preventive is to use 

 lights glazed with green glass, keeping the lights on from nine 

 o'clock in the morning till six o'clock in the evening, and giving 

 plenty of air, by tilting the lights up at the back of the pits and 

 frames, but never to use shading of any description. The lights 

 to be drawn entirely off during the night, except in rainy weather. 

 With this mode of treatment, slight waterings over head occa- 

 sionally are beneficial." 



Heaths are not very subject to the attacks of insects ; the green 

 fly, however, sometimes assails them, but these are readily got 

 rid of by slight fumigations of tobacco. 



General Treatment Out of Doors. — A want of sufficient accom- 

 modation induces many to place a part if not all their heaths, as 

 well as other greenhouse plants, out of doors ; and habit, we believe 

 induces many more. The hardier and more free-growing; kinds 

 may not suffer much from this practice, but the finer and more 

 delicate sorts evidently do. I believe the rationale of turning ex- 

 otic plants into the open air, is to adopt the least of two evils ; 

 for if they be kept under glass during the growing season, and 

 closely crowded together, they suffer as much for want of fresh 

 air as they would do if placed in a sheltered situation in the open 



