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weeks or months before the pustules appear, for these are merely indications of the last stage in the life of the fungus, and with the throwing off the spores from these pustules the old parasite perishes.
The pustules, when fully open, are from one-sixteenth to one-eighth of an inch in diameter, usually round, but sometimes slightly oval in form, and placed mainly in almost straight rows length ways of the branch, as shown in Fig. 44. These pustules appear on wood of all ages, from two years upward, and in what may be termed patches, ranging from a few inches to a foot or more in length, and more frequently on the upper side than the underside of the branches.
This fungus is undoubtedly indigenous, and its host plant is the common American hazel (C. Americana). From a very careful search, I have not been able to find any clump of these bushes of any considerable size that was entirely free from pustulous stems. But on these wild plants it seems to do but little harm, for if a stem is killed, another soon springs up from the roots to take its place; but when this fungus invades our orchards and gardens and attacks filbert trees, we recognize it as an implacable enemy. How far the spores of this fungus are likely to be carried by the wind, transported on the clothes of a person, or the hair of domestic animals, I do not know, but it certainly is not safe to FIG, 44. plant the susceptible species and varieties HAZEL FUNGUS. within a mile of the wild hazel bushes, unless the planter is prepared to use fungicides freely on his trees. There are certain phases of this filbert blight that are rather obscure and scarcely explainable; as, for instance, its virulence among some species and varieties, and almost if not total absence among others. So far as my observation extends, I have never found it attacking the native beaked hazel (Corylus rostrata), and my correspondents in the Northwest and in the Pacific States assure me that no blight on the hazel has, as yet, been found there, and its absence is probably due to the fact that the common hazel (C. Americana) is not an inhabitant of these regions.
In a neighbor's garden just across the highway from my own, there are, at this time, four old Europea. hazelnut trees, fully twenty feet high and as many years old. They are of two varieties : one a small round nut, the other a long, slender nut, but neither of much value, because of their small size. The trees, however, are perfectly healthy, never having suffered from the blight, although these four are all that remain of a long row of choice European varieties all planted at the same time. Blight destroyed the better varieties, while these inferior ones continue to thrive and are exceedingly productive.
This native fungus that causes blight in the hazels is but one of a large number of similar maladies which have appeared and often worsted the horticulturist, in his endeavor to introduce and cultivate foreign species and varieties of plants, and like the tropical fevers, they may pass unnoticed among the natives, but are terribly fatal to immigrants from cooler climates. The disease so well known as the black knot (Otthia morbosa, Schu.), and widely destructive to the European varieties of the plum, and Morello cherries, has existed for ages among our native plums and black cherries, doing comparatively little harm; but it seems to protest, by its virulence, against the introduction of some foreign species. The same is true with various blights and rusts which
attack the exotic pear, apple, quince, peach, and other of the larger fruits, and we have only to ascend he scale a few degrees from the microscopic fungi to the microscopic insects, to meet on the very threshold of this realm the minute but unconquerable grape Inuse (Phylloxera vastatrix), which for more than two ca turies has prevented the successful cultivation of the European varieties of the grape in the open air everywhere east of the Rocky mountains in North America; although this minute insect has ever been present and a constant parasite of the indigenous species of the grape, but scarcely affecting the health of its host. The plum curculio, chestnut and hickory weevils, bean weevil, and many other similar species of insects appear to be ever protesting against the introduction of exotic plants, as well as the improvement of our indigenous kinds.
It is this blight, and nothing else, that has prevented the extensive cultivation of the improved varieties of the European filbert and hazelnut in this country, and not the uncongenial soil and climate, as has been so often “officially” proclaimed by men whose theories are far greater than their practical knowledge of such subjects. Men whose experience with these nuts has been limited to a few isolated bushes or trees in gardens or nurseries, where they were protected, or beyond the reach of the spores of the blight fungus, as bas already been noted in the experience of Prince, Downing, Barry, and my neighbor Butler, of Brooklyn, could scarcely understand why others should remain so indifferent to such a promising industry, or why the demand for the trees remained so limited, with scarcely an attempt to plant filbert orchards anywhere in this country. Nurserymen have continued to offer the choice varieties at low prices per plant, and to advise their customers to cultivate filberts extensively, even to setting them in hedgerows; and yet home-grown filberts remain
as rare in our markets as they were a hundred years ago, and all due to the simple reason that the insidious filbert blight still scatters its spores unrestrained.
With the present almost universal employment of various fungicides for the destruction of blights, mildews and rusts on cultivated fruits and vegetables, we may confidently assert that the diseases of the filbert may be readily controlled by the same means. The spraying of the trees with Bordeaux mixture and other copper solutions will certainly destroy the fungus spores, and with these out of the way filbert culture may become of as much importance and as popular here as it is in certain countries of Europe. In my own experience I have found no other nut tree (barring always the blight) that has been more satisfactory. The plants come forward rapidly, fruiting freely and abundantly when young, and if properly trained, the crop can be gathered with little labor, and as it is ready for use a month or more in advance of the arrival of fresh nuts from abroad, the home market during the time is at our command.
The number of applications of the fungicides that will be necessary during the season to rid the trees of blight, or the strength of the copper solution used, will depend somewhat upon circumstances and the condition of the subjects operated upon. If the trees are growing near hedges of wild hazels, where there is a constant or annual influx of the fungus spores, then greater care will be required to suppress them than if the trees are some distance from such sources of contagion; and it may be well for those contemplating planting filbert orchards, to examine their surroundings carefully in advance, in order to avoid local blight-breeding plants, and have these destroyed if any are found. I would also warn the cultivator against collecting branches of the wild hazel in the spring, carrying pollen-bearing catkins
Ontired with little properly traineely and abundants
to be employed in fertilizing the pistillate flowers of the cultivated varieties, for by such means blight spores may be readily introduced into orchard and garden.
It will seldom be necessary to practice artificial fertilization, where any considerable number of trees are grown near together, because if ninety per cent of the male catkins are winterkilled, the few remaining will be sufficient to supply pollen for the pistillate flowers. In my grounds filberts have never failed to produce annual crops after reaching a bearing age, although they have been subjected to great extremes of temperature in winter. One year the trees were in full bloom the last week in February, and although cold weather followed, the protected pistillate flowers were not injured. The winters of 1894 and 1895 were among the severest, in the way of continuous low temperature, I have ever experienced here, and while the filberts did not bloom until the first week in April, the crop proved to be abundant.
Insects Injurious to Filberts.--My personal observations lead me to believe that the filberts and hazels are, in this country, remarkably free from the depredations of noxious insects. Two species of nut weevils have been reported as breeding in the wild hazelnuts, viz., Balaninus obtusus, and B. nasicus, but among the many bushels of the European varieties of the filbert produced in my grounds I have never found one infested by a weevil or other insect. In Europe a nut weevil (B. nucum) is said to be very destructive to the wild hazel, often invading the filbert orchards, and this we can readily believe, because they are not at all uncommon in the imported puts, but fortunately have not, as yet, become naturalized in this country.
The great hazel-leaf beetle, or as more generally known, elm-leaf beetle (Monocesta coryli), has been known in a few instances to attack and defoliate large