15 — 



The Diseases of the Grape-vines 



are principally occasioned by animal or vegetable 

 parasites. I leave others, who are more conversant 

 with the subject, to treat of the former, and will mere- 

 ly state here that our species have all grown up with 

 the Phylloxera, and would have long ago been extin- 

 guished, or rather never could have lived, if that insect 

 had such power over them ; but they as well as the 

 insect live on, the latter having no other nourishment 

 than the grape-vines and their. roots : you may call it 

 an accommodation between them. 



More important for us in America are the fungus 

 diseases, which do our grape crops more harm than the 

 Phylloxera. It is said that in Europe they have dis- 

 covered over 200 kinds of fungi which live on the differ- 

 ent parts of vines, but fortunately only a few of them 

 are really injurious. These are, above all, the mildew of 

 the leaves and the black rot of the berries. In Europe 

 they have, besides our mildew, which has lately been 

 introduced, the Oidium and the Anthracnose. 



The Mildew, Peronospora viticola, appears in frost- 

 like white spots on the under side of the leaves, hairy 

 as well as glabrous ones, here in Missouri generally 

 from the beginning of June, fostered by the sultry and 

 damp or wet weather, usual at that season ; in the East- 

 ern States it seems to come on later in summer and in 

 the fall. Though most common on the leaves, it some- 

 times also infests the petioles of the leaves, the stems 

 of the bunches, and the very young berries. But, even 

 if it does not attack the latter, the effects on the leaves 

 alone, which turn brown in spots and are eventually 

 partially or completely killed, destroys the fruit, the 

 berries shrivelling from the base, turning light brown 

 without falling off. This is here sometimes termed 

 "brown rot." 



The fungus at first pervades the cellular tissue of the 

 leaf; then, a few days later, the minute fungus stems 

 protrude through the stomats (breathing pores) of the 

 lower surface, forming little upright branching plant- 

 lets, which might be compared to a miniature spruce 

 tree, singly not visible to the naked eye ; they bear at 

 the end of the branchlets the summer spores (conidia), 

 which mature, are discharged, spread by wind or other- 

 wise, and, when moistened, germinate with astonishing- 

 rapidity. Late in the season the fungus produces what 

 are called the resting spores (oospores) in the interior 

 of the leaf-tissues, and, while the others propagate the 

 parasite in summer, these larger and more enduring- 

 ones keep alive through winter and insure its growth 

 in the following summer. Thus it is seen that the dead 

 mildewed leaves, containing the resting spores, really 

 do preserve the germs for the next season's mildew. 

 These leaves ought to be destroyed by carefully ga- 

 thering and burning them, or by burying them deeply 

 in the ground. The direct destruction of the fungus 

 lias been often attempted, and by different means, 

 especially by sulphur - sprinkling, but without any 

 marked effect ; a dry spell of weather, however, arrests 

 it most effectually for the time being. 



The Peronospora has since 1878 made its appearance 

 I in Europe — like the Phylloxera, accidentally intro- 



duced from this country— and has added another terri- 

 ble infliction on the wine-growers there, which threat- 

 ens to be worse than the Oidium, which years ago used 

 to decimate the grape crops of Europe. 



A few words about this Oidium may be in place 

 here. This is a mildew-like fungus which appears on 

 the outside of theupper surface of the vine-leaves, and 

 bears its fewer spores on smaller, not much branebed. 

 stemlets; it destroys the vitality of the leaves, and 

 with it the crop, just as our mildew does. Its resting 

 spores are unknown and with its life-history we are 

 not so well acquainted, but we know that sulpbur 

 sprinkled over the leaves will destroy it. It made its 

 first appearance, as far as it is known, about 1845, in 

 graperies at Margate, near London, and spread rapid! y 

 and destructively over a great part of Europe and the 

 islands, especially Madeira, where the grape culture 

 was almost annihilated by it ; but it seems to be now 

 less common or less injurious than it was years ago, 

 and may possibly have run its course, just as other epi- 

 demics are apt to do. It is unknown where it origi- 

 nally came from ; some suppose that it originated in 

 America, but it has' never appeared here in the form 

 under which it is known in Europe ; whether in 

 another form, is still questionable among our best 

 mycologists ; at all events we have thus far only one 

 destructive form of mildew here, the Peronospora. 



The second great fungus pest of our vineyards is the 

 Black Rot, Phoma uvicola. On the berries, but never 

 on the leaves or stems, generally about the time that 

 they are full grown, in July or August, very rarely on 

 half-grown berries in June, a light brown spot with a 

 darker central point is observed on the side and not 

 near the stem ; this spot spreads, and darker, shining 

 nodules or pustules, plainly visible with the naked 

 eye, begin to protrude above the epidermis ; at last the 

 whole berry shrivels up, turns bluish-black and the 

 pustules roughen the surface, and each one opening at 

 its top emits a whitish worm-like thread, which con- 

 sists of innumerable spores glued together with a mu- 

 cilaginous coating. In this condition the spores are 

 inert, but rain will dissolve the mucilage and liberate 

 and wash down the spores, or they will with the dead 

 berries fall to the ground. What then becomes of 

 them, whether they enter the soil, or how they propa- 

 gate the fungus, is as yet unknown. At all events it 

 seems advisable to gather all the affected berries, if 

 such a thing can be done, and destroy them. 



In Europe they have another fungus disease of the 

 grape, called in Germany Brenner, in France Anthrac- 

 nose, and described under the name of Sphacelorn a am- 

 pelinum, which by some authorities has been supposed 

 to be another form of development of our Black Rot, 

 above described ; this, however, seems very doubtful. 

 We have, as it seems, never had the Sphaceloma, nor 

 they the Phoma. The former attacks all the green 

 parts, leaves, young stems, or green berries, and forms 

 open wounds which might be compared to ulcers 

 while our Phoma is restricted, as far as known, only to 

 green berries, without breaking up the tissues or form- 

 ing ulcers. The Sphaceloma seems to be an old disease 

 in Europe, known already in the last century. Mycol- 

 ogists are now carefully studying these questions. 



