66 



Garden and Forest. 



[Pefruary 6, 1889. 



seem any good reason why we should not have Chrysanthe- 

 mums that flower from January to June, just as we have them 

 now from July to January. 



Growers of hardy plants here ai- turning their attention 

 again to Hollyhocks, which a few years ago were as great 

 favorites as Single Dahlias are now. Then came disease, and 

 the stately, many-colored Hollyhock was almost given up in 

 despair by English horticulturists. Modern growers say cow 

 manure will keep away the disease from these plants. 



January nth, 1889. W. WatSOn. 



I 



, Cultural Department. 

 Leaf Spots of Green-house Plants. 



T is usually the case, when black spots appear on the leaves 

 of ornamental plants, that they are supposed to be due to 

 the attacks of insects or the growth of fungus parasites. There 

 is, however, one form of black spot to which my attention has 

 been several times called, which, although due to a fungus, is 

 not caused by a parasitic species which infests the leaves 

 themselves, and the apots cannot be considered as indications 

 of any disease, but merely as accidental disfigurements. The 

 spots to which I refer are about as large as the head of a pin, 

 and are scattered without order, and sometimes very pro- 

 fusely, over the surface of the leaves. They can easily be 

 removed by mashing or be picked off, when they leave a 

 slight circular depression, as a rule. A microscopic examina- 

 tion shows that there is no fungus mycehum, but merely a 

 mass of ellipsoidal, orange-colored cells covered by a black, 

 structureless membrane of a flattened, hemispherical shape, 

 which adheres to the leaf by its free edge. In short, the black 

 spots are nothing but the discharged spores of a species of 

 Pilobolus with their sporangial cap. 



The species of Pilobolus are small moulds which grow on 

 dung of various kinds, and look like minute white or pale 

 orange-colored, glistening sacks, with a black tip when ma- 

 ture. The spores are ejected with considerable violence, and 

 I have known them to be shot off to a distance of several feet. 

 It is only when the Pilobolus grows on the manured soil of hot 

 frames and green-houses, or other small-sized compartments 

 where plants are grown, that it is likely to attract popular 

 notice. When plants are crowded in a small space over fresh 

 m.anure the Pilobolus is likely to appear and discharge its 

 spores over the leaves and stems of any plants which are 

 near. Some years ago the Roses in a green-house at Cleve- 

 land were found to be thickly spotted with Pilobolus spores, 

 and the black spots were supposed to be due to a new fungus 

 disease. More recently the Roses in a small green-house at 

 Whitinsville, Massachusetts, were similarly affected, and an 

 examination showed the presence of a quantity of Pilobolus, 

 M'hose spores not only formed spots on the Roses, but also on 

 the wood-work of the green-house for a considerable extent. 

 The most recent case to which my attention has been called- 

 was at Newton, Massachusetts, where the leaves of Geranium 

 were thickly spotted by spores of Pilobolus. The spots, of 

 course, are merely a form of dirt, and cause no disease of 

 either Roses or Geraniums, for the Pilobolus spores do not 

 develop on living leaves and stems. It is a little singular 

 that, while this particular form of black spot has attracted 

 the attention of gardeners in this country, it has not been 

 noticed in European green-houses either as a supposed 

 cause of disease or disfigurement to any extent, if one can 

 judge by the absence of any reference to the subject in the 

 common works on plant diseases. IV. G.Farlow, 



Cambridge, Mass. ' 



Ferns. 

 TOURING tiie dull days of mid-winter it is essential that suf- 

 J-^ ficient ventilafion should be given to this class of plants. 

 Tor if the moisture in the atmosphere is condensed on the 

 fronds to any great extent, the plants soon become disfigured. 

 If the weather is severe, a httle addidonal fire-heat may be 

 given, so that the ventilators may be opened enough to allow 

 the superfluous moisture toescape, though at the same time 

 excessive firing-should be avoided, the present being the sea- 

 son of rest for a majority of species. 



Some judgment should also be exercised in the matter of 

 watering, so that the deciduous kinds may receive no excess, 

 which would be sure to injure their roots, and this would 

 mean a weakened growth the following season. Of course the 

 evergreen species will take much more water, and, in fact, 

 should not be allowed to become actually dry at any time 

 during the year. 



These caufions are specially applicable to old-established 

 plants, as young seedlings of many species can be readily 



kept in a growing condition during the first year, or possibly 

 eighteen months, of their existence, but the period of rest 

 will become more marked during the second year. As the 

 most suitable time for repotting most of the species will soon 

 be upon us — that is, in February or the beginning of March — 

 it may be well to give that matter some consideration here. 

 In repotting some ot the large plants, it will be found more 

 convenient to reduce the old ball, so that the plant may be re- 

 placed in a pot of the same size, provided this operation can 

 be done before active growth begins. Otherwise the result 

 might prove a disappointment ; and if necessary to increase 

 the stock, division of the crowns or rhizomes, as the case may 

 be, can best be made at the same time. The soil for potting 

 should be rather coarse, but the plants should be potted 

 firmly, and given free drainage, though until they begin to 

 root freely water should be given rather sparingly, not allow- 

 ing them, however, to become very dry. 



The practice followed by some growers, of cutting off all 

 the old foliage at the time of repotting, may not be very in- 

 jurious to some species, and if the plants are infested with in- 

 sects it is a very good way of disposing of much of the ver- 

 min ; but in my experience this radical treatment has not 

 proved entirely satisfactory, on account of the weaker growth 

 resulting from it, so that the plants recover their beauty much 

 later in the season than when a portion of the old growth is 

 left until the new appears. 



If it is desirable to raise some plants from spores, these 

 may be sown at any time when they are ready, but the most 

 successful sowing is usually that made about the beginning 

 of March. After that time there is not so much danger of the 

 yoimg plants damping off, and being the natural season of 

 active growth with many of the species, it is quite reasonable 

 to suppose that they will make more rapid progress if sown 

 at that time than at any other. 



But apart from the economic side of the question, the rais- 

 ing of Ferns from spores will be found a most interesting di- 

 version for any one so inclined, not only on account of their 

 peculiar mode of development, but because novel forms and 

 unexpected hybrids often appear in a collection of seedlings. 



Holmesburg, Pa. W. H. TapUn. 



Girdling Grape Vines. 



ON the 13th day of September last an excellent opportunity 

 was afforded to a Committee of the Massachusetts Horti- 

 cultural Society to observe the effects of the process of girdling 

 the branches of the Grape for the purpose of hastening ihe 

 maturity of the fruit. Among other vineyards, we visited 

 one situated in the south part of the town of Concord. On the 

 southern slope of a hill which runs down to the river we 

 found a plantation of several acres of the Concord Grape. 

 The elevation was about seventy-five feet above the level of 

 the river. The plants in the eastern half of the vineyard had 

 been girdled for this and the two preceding seasons, while 

 those in the western half were growing in their natural way. 

 The girdled plants were more irregular and thinner in foliage, 

 and, upon general view, did not look as vigorous as the 

 normal growth. A closer inspection showed that the girdling 

 process had been severely practiced upon every fruit- 

 bearing branch, producing a very niarked effect in develop- 

 ing the size and hastening the maturity of the fruit.. Though 

 the season was so late and imfavorable that we found the 

 Moore's Early, in this and in other vineyards, to be barely 

 ripe, yet the girdled Concords were in quite as good condi- 

 tion. On the other hand, the Concords of normal growth 

 were much smaller in size and hopelessly behind time. It 

 was evident then, as the event proved, that the natural crop 

 would be ruined by frost. Here was an instance of a crop 

 saved by girdling, and of another, side by side, which was lost 

 by neglect of this process. 



Without going further, it is then evident that, under some 

 circumstances and with some varieties, there are decided 

 advantages in the process. Such excellent varieties as the 

 lona and the Jefferson may be hastened to maturity by gird- 

 ling. But in ordinary seasons we should scarcely think it 

 worth while to be at the trouble to hasten the Concord, when 

 we have equally good varieties like the Worden and the 

 Moore, which are early without this treatment. Yet there 

 is a larger development of the fruit by the process, which is 

 of much importance to the marketman. This is so material a 

 consideration, that it would be likely to govern were it not for 

 another consideration which must be taken into account. 

 What will be the permanent effect upon the vineyard of a con- 

 tinuation of this process ? In the instance before us the work 

 had been so thorough, not to say severe, that the effect 

 upon the future of the vine could be predicted with confidence. 



