242 ON THE DAHLIA, 



they may be due, but to notice some particulars necessary to be 

 attended to in the cultivation of this national favourite. I have 

 been stimulated to send you this communication by the reflection 

 that any thing however trifling that would tend to improve the 

 cultivation of the Dahlia, would find a ready acceptance both 

 with you and your numerous readers. 



I wish, then, to direct the attention of your subscribers to a 

 particular disease incident to the Dahlia and other plants, at the 

 same time allow me to say, that were gardeners to pay more at- 

 tention to the pathology of plants, sending you accounts of {he 

 causes and cures of the various diseases happening to these 

 objects of their care, there would be fewer disappointments 

 and greater perfection attained. In heavy soils the Dahlia is oc- 

 casionally subject to the disease generally called " curl," the in- 

 fant leaves as they are unfolded, are perforated with numerous 

 holes, the margins of which are brownish as if burnt,' they then 

 become rigid, curled, and succulent, and the whole plant un- 

 healthy and dwarfish. The principal stem almost ceases to in- 

 crease in height, and numerous suckers and lateral branches rise 

 from below, forming a dense bush, the summits of these growths, 

 in their turn, also become diseased. The flowers of such plants, 

 as might be expected, are small, irregular, and unsymetrical, and 

 however excellent the variety may be, they yield nothing but dis- 

 appointment to the anxiously expectant cultivator. Kings and 

 queens, dukes and lords, and the numerous gentry that show off 

 their splendors in the Dahlia ground, will put on a mean ragged 

 and most plebean aspect, conferring no honour either on the cul- 

 tivator, or the personages they represent. I have, for several 

 years, been puzzled as to the cause of this disease. Loudon has 

 afforded me no hint in his Cyclopaedia, Paxton's Treatise on the 

 Dahlia I have not seen, and as the complaint has become very 

 general in this neighbourhood during the present season, I have 

 attended more particularly to the disease. I find it to be occa- 

 sioned by an insect, the Cymix chloroterus or green bug of Lin- 

 naeus ; a transparent winged insect, about one-fourth of an inch 

 in length, with a large probosis generally folded under the tho- 

 rax. It inhabits the extremities of the Dahlia, grows and feeds 

 upon the under surface of the unexpanded and infantine leaves, 

 thrusting down its long probosis amongst those which are most 

 tender ; I find the same insect commiting similar devastation on 

 a variety of other plants the Potentilla formosa, ntrasanguinea, and 



