206 



THE DICTIONARY OF GARDENING, 



Potato continued. 



are also burnt substances, such as wood and peat ashes, 

 wood and peat charcoal, burnt clay, &o. Common salt is 

 sometimes used beneficially as manure where the soil is 

 unusually light and dry. Lime used occasionally for 

 Potatoes has a marked effect, particularly on land already 

 rich in decayed vegetable substances, the constituent 

 parts of which require to be set free. Lime is also of 

 use in killing slugs of various descriptions, which live 

 in the earth, and frequently eat holes in, and partially 

 destroy, the tubers. Guano, gypsum, bone-dust, nitrate of 

 soda, and various other manures, have also been employed 

 for the Potato, with more or less satisfactory results. 



Digging and Storing the Crop. Before the destructive 

 Potato disease made its appearance, the main crops 

 could be allowed to ripen naturally, and their produce 

 lifted for storing, in any suitable weather, and at any 

 convenient opportunity, before the appearance of frost. 

 Of late years, however, it has often been necessary to 

 lift the successive crops, from the earliest onwards, so 

 soon as the foliage indicates that the ripening process 

 is approaching completion. After the appearance of 

 disease in anything like an extensive form, the quicker 

 lifting is commenced, the better, provided the produce 

 is sufficiently matured to insure its keeping afterwards. 



Exposure to light has a very injurious influence on 

 Potatoes intended for food. It causes them to assume at 

 first a yellowish tinge, and then a green colour, and 

 materially impairs their flavour. The crop should, there- 

 fore, never be allowed to lie in the open air after being 

 dug, except, perhaps, for an hour or two to dry ; even 

 this is unnecessary if the ground is in proper working 

 order, and the weather fine ; and from wherever the tubers 

 are stored for the winter, or until required for use, light 

 must be rigidly excluded. The most common plan of 

 storing a stock of Potatoes is that of keeping them in 

 pits ; these, preferably, should never be made very large. 

 A dry situation, or, at least, one where there is no 

 possibility of water collecting, should be selected, and the 

 soil dug out about 9in. deep, and 3ft. wide at the base. 

 The Potatoes may then be piled up in a ridge as high as 

 convenient, and covered with 9in. of soil, dug out from 

 either side. The ridge, after being beaten flat with a 

 spade, will be complete ; it is then a good plan to thatch 

 it with straw or dry fern, with a view to excluding frost 

 and wet. It is advisable to make Potato pits with their 

 ends pointing north and south. Thus arranged, a part of 

 the contents may bo taken out from the southern end, 

 on a frosty day, without injury, when the sun shines, 

 and the remainder made secure. 



Culture in Pots, Frames, Sfc. An early supply of new 

 Potatoes is always considered an essential in the kitchen 

 garden, and various methods are adopted to secure it- 

 first, from under glass ; and next, from the most favoured 

 positions outside which the garden affords. Pots Sin. in 

 diameter are sufficiently large for one set each ; they 

 may be filled half full of soil at first, and top-dressed 

 when the plants have grown. Potatoes grown under 

 glass must not be subjected to much heat, nor must they 

 be kept in a confined atmosphere. A light position in a 

 frame, or on a shelf in a house where there is a little 

 warmth, and plenty of air is admitted during favourable 

 weather, is that best suited. Ordinary hotbeds in deep 

 pits are well adapted for early Potato culture ; to utilise 

 all the space, the sets may be planted in rows 12in. or 

 15in. apart, and additional soil provided when earthing-u^ 

 becomes requisite. Only dwarf, compact varieties should 

 be grown under glass, and so soon as the weather allows, 

 and after the plants are up, the sashes may be pulled 

 off during the best part of the day, and put on again at 

 other times. Potato plants are extremely tender. It is 

 essential, in forwarding early crops, that protection from 

 frost should always be secured. To succeed those grown 

 under glass, other supplies should be brought on in warm, 



Potato continued. 



sheltered spots outside, choosing the same dwarf varieties 

 for the first, and protecting them with fern, dry litter, 

 or other substance, should unfavourable weather occur. 



FUNGI. By far the most destructive of the Fungi 

 parasitic on Potatoes is that which causes " Potato Eot," 

 and which is described under the heading Phyto- 

 phthora infestans (which see). It is unnecessary to 

 repeat what has already been said, and therefore the 

 reader is referred to the above-named article for an 

 account of this Fungus. The tubers suffer greatly from 

 its action on them, though the action is less speedy than 

 it is on the green 'parts of the plants. But even where 

 the Fungus has not itself severely affected a tuber, the 

 latter is rendered a suitable food for various species of 

 Fungi which grow on it, and cause its decay by either Dry 

 Eot or Wet Rot. The Fungi that grow on Potatoes under 

 these conditions have been carefully studied by the German 

 botanists, Eeinke and Berthold ; and they, in 1879, pub- 

 lished an account of their researches (" Zersetzung der 

 Kartoffel durch Pilze"). Of the many Fungi that they 

 found on rotting Potatoes, they attribute the chief share 

 to a few viz. : in Dry Eot, to Fusisporium (Hypomyces) 

 Solani, Nectria Solani, Verticillium cinnabarinum, Chae- 

 tomium crispatum, and C. bostrychodes ; and, in Wet Eot, 

 to Bacteria (Bacterium navicula and Baccillus amylo- 

 bacter), although the Fungi of the Dry Eot were also pre- 



FIG. 257. PEZIZA POSTUMA a, Small Specimen (natural size), with 

 two Cups on slender stalks, which rise from an oval Sclerotimn 

 (c) ; 6, Cup, cut lengthwise ; c, Section of Half of Cup, showing 

 surface-layer of Asci ; d, Two Asci, each with eight Spores, 

 arising from small-celled Tissue of Cup (magnified about 250 

 times). 



sent. They recommend exposure to air and heat, either 

 of the sun or of artificial origin, to check the decay, by 

 drying the substance, and to save as much of the starch 

 as possible for conversion into dextrine, in which form it 

 is now largely used. But other Fungi besides Phyto- 

 phthora infestans attack growing Potatoes. One of the 

 more dangerous of these is described in W. G. Smith's 

 " Diseases of Field and Garden Crops " (pp. 15-29) under 

 the name of Peziza postuma ; but this Fungus is so like 

 some others (Peziza ciboroides, P. sclerotiorum, &c.) 

 that its specific rank is doubtful. Mr. Smith states that 

 Potatoes in the West of Ireland were observed, in 1880, 

 to suffer from a peculiar disease ; but this was not fully 

 traced to its cause in that year. It appeared at Stavanger, 

 in Norway, in 1883, and also in the North of Scotland, 

 where Mr. A. S. Wilson has grown the Fungus to ma- 

 turity, i.e., till the production of the Peziza. The diseased 

 plants become covered with a dense coat of white my- 

 celium ; and, in a week or two from its first appearance, 

 this kills the plants, withering up and drying the leaves. 

 In the mycelium upon the stems there appear very many 

 oval or rounded, hard masses, of all sizes up to in. 

 across. They become black externally, but remain white 

 inside. These bodies are sclerotia, and consist of very 

 compact masses of mycelium, and the black coat is made 

 up of small, angular cells, with dark, thickened walls, 

 closely united in growth. The sclerotia pass the winter 



