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JOUENAL OF HOETICULTUEE AND COTTAGE GAEDENEB. 



[ October 24, 1872. 



tinued at intervals of about three weeks up to the middle of 

 February ; they mature before the disease manifests itself. 



The true cause of the disease appears to me to be too moist 

 an atmosphere and soil, which induce over-luxuriance or a 

 gross growth ; the tissues of the plant are consequently gorged 

 with crude sap, requiring light and heat, with dryness, for its 

 due digestion or elaboration. When a close, moist, dull atmo- 

 sphere prevails and the soil is wet — when, too, there is but 

 little range of temperature — the leaves are unable to digest or 

 elaborate the sap impelled into them, and the descending sap 

 by which the tubers are formed (I know that Potatoes will 

 form tubers without the presence of leaves, but in this case 

 the elaboration of the sap takes place by the skin of the tubers 

 in course of formation, and they are very deficient in starch, 

 being mere waxy lumps of matter) not being perfectly elaborated, 

 it is conveyed by the stem to the tubers along the root-stem, 

 and reaches them in a crude state, and thus a fitting medium 

 is prepared for the spores, mycelium, and development of the 

 fungus (Botrytis infestans), or Potato disease, which spreads 

 until it destroys every part of the diseased tuber, or that part 

 of it containing but little starch. The disease attains a greater 

 degree of development in some tubers than in others. Some 

 are entirely destroyed by the fungus, and become rotten ; 

 others are only diseased in part, the disease commencing at 

 the core, and manifesting itself on the surface or skin in 

 specks or blotches. 



The parts of the tuber which resist the attack contain starch, 

 which those which are diseased do not contain, or only in 

 small quantity. It is also desirable to notice that a Potato 

 diseased, but having the growing parts or eyes not affected, 

 will on exposure to light have the parts not diseased greened. 

 Those in which the growing parts or eyes are diseased will not 

 green, even in the sound parts, but will retain their original 

 colour as dug from the soil ; ulceration sets in, and a peculiar 

 unpleasant smell, the accompaniment of putrefaction, is emitted. 

 In some instances the tubers do not rot, but the parts dry in. 

 This is commonly the case with those having the eyes (though 

 in some parts diseased) unaffected by the disease. 



If the disease originates from the imperfect elaboration of 

 the sap, or the crude matters taken up by the roots from the soil, 

 or by the leaves from the atmosphere, how does it happen that 

 the leaves first show evidence of the disease, the stem next, 

 and the tubers last of all ? The leaves are the seat of the 

 imperfectly elaborated juices of the plant ; by the leaves the 

 sap is drawn up or derived, in them it is digested or fitted for 

 the formation of the tubers, and from them it is conveyed 

 to the stem and tuber. This imperfectly elaborated sap is 

 diseased in the stomach and lungs — i.e., the leaves are dis- 

 eased with the greatest virulence and first — they are first 

 attacked, simply because they present a proper state of the 

 plant to receive the spores or mycelium of the fungus ; next to 

 the leaves the stems are attacked, they acting as conduits of the 

 imperfectly elaborated juices and receiving the diseased matter 

 after the leaves ; and lastly, the roots receive it, but with less- 

 ened virulence. Here we have an instance of the care taken 

 by Nature and her All- wise Originator for the preservation and 

 perpetuation of everything of its kind. The tuber, being the 

 continuation of the Potato, were the disease to originate in it 

 there is every reason to believe that a diseased tuber would 

 communicate the disease to its progeny. On the other hand, 

 a diseased tuber gives a stiff sprout and stiff sturdy haulm , 

 ripens its tubers off in good time — a considerable time before 

 those that are planted quite sound; and whilst the latter have, 

 if the season be favourable to the development of the disease, 

 many diseased tubers, those resulting from the diseased set 

 are quite free, perfect in every way for the perpetuation of 

 the kind. In this I see the care of Providence for the con- 

 tinuance and preservation of everything ; also that the Potato 

 disease is not hereditary. 



If the above premises are just, and the theory established, 

 it will follow — 1st, That the disease is producible ; 2nd, That 

 it is avoidable. With the view of proving the correctness 

 of the first proposition, let us suppose that we plant a 

 frame, say a three-light one, with Potatoes in February, with 

 the avowed intention of producing diseased tubers. The soil 

 shall be rich, in garden phrase " full of manure," such being 

 conducive to free growth. Let the frame stand in the open 

 ground, and let the sets be of a land that has never been known 

 to be diseased, or let them be of any kind whatever, due regard 

 being paid to planting them at a distance suitable to the full 

 development of the variety. We shall not put on the lights 

 until the haulm is strong and tubers have begun to form ; then 



we will raise the frame 13 inches on bricks placed under the 

 corners, and put on the lights. Over the frame let a wooden 

 framework be formed 4 feet larger than the frame every way, 

 and high enough for a man to walk erect round the frame, and 

 let it have a span-roof with an angle of 45°, and a door. This 

 framework of wood must be covered with tiffany No. 3, and 

 made close-fitting. The frame shall be kept close, except when 

 the Potatoes are watered, which must be with rain or pond 

 water to which half an ounce of sulphate of ammonia has been 

 added to every hundred gallons. Let five gallons be given per 

 square yard with a rose watering-pot throughout the whole 

 extent of the covered space, both over the Potatoes and the 

 tiffany enclosure, replacing the lights at once. Water twice 

 in the following week, giving half the quantity at the week's 

 end, and the other half in three days. The haulm to be made 

 thoroughly wet — leaves and stems — four times a-day, not con- 

 fining the sprinkling to the frame, but applying it to the 

 enclosed space, and it must be impregnated with the ammonia. 

 The sprinklings to be continued until the haulm is quite 

 decayed or the leaves fallen, the waterings also — viz., one 

 watering at first with five gallons per square yard, second 

 week five gallons, but at twice, third week five gallons at once, 

 and fourth week five gallons at five times, to be continued at 

 this rate until the leaves and haulm perish. Be sure that the 

 tubers are diseased after about four or six weeks of this treat- 

 ment. The rainfall will be equal to (with the sprinkling) 

 nearly 6 inches per month; the atmosphere close, moist, such 

 as we experience in dull wet weather, and perceptibly impreg- 

 nated with ammoniacal vapours. This treatment, I believe, 

 will induce a state of the plant suited to the disease, of which 

 it, along with the tubers, will inevitably perish. — G. Abbey. 



HYBRID VIOLAS. 



In a season like the present, unprecedented for its wetness, 

 it is a great matter to have something to depend upon to em- 

 bellish the flower garden besides our usual Geraniums, &e. 

 Leaves rather than flowers were the characteristics of beds com- 

 posed of these, and almost all other bedding plants were equally 

 disappointing, with the exception of hybrid Violas. It is in 

 praise of the latter class of plants that I wish to direct attention. 

 Mr. Williams has conferred a great boon on the flower gardener 

 in giving Viola Perfection, Enchantress, and Magnificent, which, 

 when better known, will be universally cultivated. The late 

 weather seems to have suited' these Violas well, as they have 

 flowered most profusely since the month of May till this late 

 period of the autumn. Many persons are engaged in trying 

 to improve the race, and obtain new colours between the 

 Pansy and Viola eornuta, and in consequence of this Viola 

 Perfection is surpassed both in quality of petal and dwarfness 

 of growth. The two principal objects to be aimed at in obtain- 

 ing improvements on existing varieties, are dwarfness of growth, 

 and profusion of bloom, with variety in colour. 



Although many crosses have been obtained from Viola 

 Perfection with various coloured Pansies, I have my own doubts 

 if they will prove as useful as the seed-bearer. Blooms from 

 this cross are more like Pansies than Violas ; but they all 

 possess the botanical distinction which gives the name to the 

 race V. eornuta, " the horn " projecting, and in some instances 

 curling behind the footstalk. If the seed-bearer is the Pansy, 

 the progeny are simply hybrid Pansies, and want the distinc- 

 tion mentioned above, as the spur or horn hardly reaches the 

 footstalk. No doubt some of these hybrid Pansies will prove 

 useful bedders ; but I am doubtful if they will not take more 

 after the Pansy than the Viola, and lack the robustness of 

 growth of the latter. In the first instance, then, it is desirable 

 to have the Viola eornuta for the mother. Mauve Queen and 

 Purple King are both excellent in growth and shade of colour 

 in the flower. The white variety, as far as I know, has not 

 been tried as a seed-bearer, but would, doubtless, yield white 

 and yellow hybrids crossed with self Pansies of these colours. 



The Violas are easily fertilised, as a rule, if the following 

 precautions be used. A fine sunny morning is the first re- 

 quisite. About eleven or twelve o'clock remove the under 

 petal carefully from the Viola to be operated on, and examine 

 the pistil with the glass to ascertain that the bees have not 

 anticipated you, and that there is no pollen already there ; next 

 very carefully remove the under petal of the Pansy, and ob- 

 serve in the sulcus or furrow with the glass and you will per- 

 ceive the fine dust or pollen there — that is to say, if the 

 flower is in a proper state, and apply this under petal so that 

 the top of the pistil may be drawn through the furrow among the 



