18G ON POTATOES. 



and I had the satisfaction to observe, that not a single curled leaf was 

 produced ; though more than nine-tenths of the plants, which the same 

 identical tubers subsequently produced, were much diseased. 



In the spring of 1 808, Sir John Sinclair informed me that a gardener 

 in Scotland, Mr. Crozer, had discovered a method of preventing the curl, 

 by taking up the tubers before they are nearly full grown, and conse- 

 quently before they became farinaceous. Mr. Crozer, therefore, and 

 myself, appear to have arrived at the same point by very different routes ; 

 for by taking his potatoes, whilst immature, from the parent stems, he 

 probably retained the sap nearly in the state to which my mode of 

 culture reduced it. I therefore conclude, that the opinions I first 

 formed, are well founded ; and that the disease may be always removed 

 by the means I employed, and its return prevented by those adopted by 

 Mr. Crozer. 



XX. ON THE CONSTRUCTION OF PEACH-HO USES. 



[Read before the HORTICULTURAL SOCIETY, April 3rd, 1810.] 



SCARCELY any fruit can be raised in greater abundance, or with fewer 

 chances of failure, than the peach in a forcing-house ; where the insects, 

 which often prove so formidable in the open air, are easily destroyed, and 

 where the tree is subject to scarcely any other disease than the mildew ; 

 and I have reason to believe, that the appearance of this disease may, in 

 general, be very easily prevented by selection of proper soil, and by 

 proper management. But though a crop of peaches, or nectarines, is 

 very easily obtained under glass, experience seems to have proved that 

 neither of these fruits acquire perfection, either in richness or flavour, 

 unless they be exposed to the full influence of the sun, during their last 

 swelling, without the intervention of the glass. It has consequently been 

 the practice, in some gardens, to take off the lights wholly before the 

 fruit begins to ripen ; and in warm seasons, and favourable situations, 

 this mode of management succeeds perfectly well. But in the colder 

 parts of England this cannot be done ; and if the weather, in any part, 

 prove cold and wet, just after the lights are taken off, the growth of the 

 fruit is suddenly checked, and its quality greatly injured : and I have 

 never met with the peach in so much perfection, as when it has been 

 raised in a house where it could be conveniently exposed to the sun in 



