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OR, BOTANICAL DICTIONARY. 



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593 



of which were so minute as not to be discovered when the 

 roots were taken up, and so have grown the following season, 

 to the great injury of the crop then on the ground. The 

 haulm of these Potatoes is generally killed by the first frost 

 in the autumn ; and the roots should be taken up soon after, 

 and laid up in sand in a sheltered place, where they will 

 keep dry, and be secured from frost. The growers near 

 London do not wait lor the decay of the haulm, but begin 

 to take up part of them as soon as their roots are grown to a 

 proper size for the market, and so keep taking up from time 

 to time, according to the demand. There are also others, 

 who do not take them up so soon as the haulm decays, but 

 let them remain much longer in the ground ; in which there 

 is no hurt done, provided they be taken up before hard frost 

 sets in, which would destroy them ; unless where the ground 

 is wanted for other crops, in which case the sooner they are 

 taken up the better, after the haulm decays. When laid up, 

 they require a good quantity of sand or earth between them, 

 to prevent their heating; and on that account also they ought 

 not to be laid up in very large heaps. Diseases. The Potato 

 is subject to a disease commonly called the curl, and in this 

 state is sometimes called frizzled, or rose-headed. These 

 names are given it from the obvious appearance of the leaves 

 in this disease ; but the destructive effect of it falls upon the 

 bulbs of the root, which become worse and diminish in size 

 in proportion to its influence. A variety of causes are assigned 

 for this disease. 1. That the sets are unsound. 2. Forcing 

 the plants from which the sets are taken, by too much fresh 

 dung, and earthing them up too deep, on land too rich and in 

 a southern aspect, and choosing sets from bulbs rendered large 

 by this management. 3. Planting the same sorts too long 

 on the same land. 4. Taking the sets from such bulbs as 

 have been heated or frosted in the heaps. 5. The first shoots 

 being broken off before planting, by which means the sets 

 are weakened. 6. Planting too near the surface, and in old 

 worn-out ground. 7. Planting indiscriminately sets of new 

 sorts raised from the seeds. 8. Insects attacking the sets' or 

 roots, or young shoots. 9. Unfavourable soils and seasons. 

 One or more of the above causes may operate in producing 

 this disease ; and anyor all of them, in different circumstances. 

 He must be a careless cultivator indeed, who will plant dis- 

 tempered or vitiated sets ; and he deserves to have a bad 

 crop, who sells or eats all his best Potatoes, and plants the 

 worst. Forcing Potatoes by setting them late in a rich soil 

 well manured, having a southern aspect, especially if the 

 summer be hot and dry, or covered with green fern or other 

 litter before the plants appear, is found, by a series of expe- 

 riments, to produce the curl. The set will be exhausted in 

 feeding the plant; but should the weather become moist and 

 warm towards the end of summer, the plants, especially if 

 they should be earthed, may then produce a plentiful crop 

 of large Potatoes, which will be lit for eating, but, being 

 produced from the stalk after the set was exhausted, will be 

 defective in vegetative power, and the plants from them will 

 be curled. It' they were covered, the rain would rot the fern 

 or litter, and penetrate as a manure to the roots : thus the 

 plants are forced to the second growth, and the sets from 

 these bulbs will produce curled plants. Large crops may be 

 raised by earthing and manuring; but these are not fit' for 

 planting. A portion of ground should therefore be allotted 

 r raising sets. Planting repeatedly on the same land, or 

 the same sort on similar soils, is very unadviseable, and con- 

 trary to general practice with other crops. Potatoes have 

 been grown for several years together on the same spot of 

 rich land with high manuring; and labourers frequently do 

 in their confined gardens. But unless the sort be changed, 





it is found frequently to produce the curl ; and, on a large 

 scale, they are seldom planted two years together on the same 

 land. Whether the curl be occasioned, as some pretend, by 

 being frost-bitten before or after planting or, as by others, 

 by being heated in the heaps ; or not no prudent person 

 would use such sets in planting; for they must be weakened, 

 and produce an inferior crop, and will probably suffer by the 

 curl. When the sets have been suffered to exhaust them- 

 selves by sprouting, they are unfit for planting. If the Potato 

 be planted too near the surface, or where the staple is very 

 shallow, they will be exposed to frost, and by that means to 

 the curl, besides wanting proper nourishment, and therefore 

 be weak : now weakness, from whatever cause it arise, will 

 probably produce disease. For the same reason, old worn- 

 out varieties are unquestionably improper for plants, as no 

 one can reasonably expect a sound crop from such seed. On 

 dry soils, in a very dry season, Potatoes are very subject to 

 the curl. On the contrary, a very wet season in strong reten- 

 tive land, though it has not been ascertained to produce that 

 disease, is nevertheless very unfavourable to the growth of 

 these roots. Mr. Marshall adopts the idea, that the old vari- 

 eties formerly in cultivation, dwindling in produce till they 

 were entirely worn out with disease, new varieties were intro- 

 duced, and that the disease vanished with the old ones. In 

 confirmation of this, he observed in Rutlandshire, in a large 

 piece of Potatoes, two stripes, which were almost wholly 

 curled ; whilst the rest of the ground appeared to be free 

 from the disease. Inquiring into the reason of this difference, 

 he was told, that the healthy plants were a new sort, called 

 Manleys ; and the diseased ones, Red-nosed Kidneys, which 

 were heretofore the prevailing sort. The circumstance of the 

 old sorts being now almost entirely cut off by the curl, renders 

 it probable that the disease is incident to declining varieties 

 of Potatoes, as the canker is to declining varieties of fruit. 

 Not only copious dunging is thought by some to bring on the 

 curl, but manuring well with lime or ashes, either of coal or 

 wood. On a deep loarn, limed, nearly three-fourths of the 

 crop were curled ; whilst a few drills adjoining, not limed, 

 and planted with the same sort of Potato, were perfectly free. 

 The experiment was repeated the year after, with the same 

 result; and the curl has been since observed to prevail most 

 in the districts where much lime or ash manure is used. A 

 moderate quantity, however, of lime, made into a compost 

 with earth, will not injure the root, but be useful in destroy- 

 ing the wire-worm, and other insects which attack the sets. 

 The method of cure is pointed out by the causes of the 

 disease. If it be owing to the soil, that should be improved 

 by sufficient manuring and good management; or it should 

 be given up, if found wholly unfit for Potatoes. If the dis- 

 order be occasioned by any defect or weakness in the sets, 

 arising from their having been heated, or frozen, or over- 

 forced, or exhausted by shooting, or from whatever cause, 

 care should be taken to procure proper sets, and to change 

 the sorts occasionally. If the land be rich and warm, the 

 crop ought not to be over-earthed ; if it be dry, poor, and 

 shallow, it should be well earthed up: for the roots must 

 neither be parched in the sun, nor removed beyond its 

 influence. If very rich dung, by forcing them too much, 

 bring on the curl, spread it over the field and plough it in, 

 rather than put it immediately over or under the sets in the 

 furrows, especially as the latter mode is apt to make the 

 Potatoes scabby. In a proper soil, with good management, 

 planting in the best season, and due attention to procure 

 good sorts in a sound healthy condition ; changing the land, 

 or bringing this in with other crops in a regular rotation; 

 changing alsp the sorts which are intended for sets, or plant- 



