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tissues of the twigs. More rarely large branches are killed through cankers in the bark. Cutting off the infected twigs, when dormant, some distance below the diseased tissue and wiping the pruning tool each time with a cloth saturated with carbolic acid or corrosive sublimate, to kill adhering germs, has been the common method for control.

Cankers: When a fungus enters a branch or trunk of a tree, it usually becomes perennial there and, gradually killing the bark, makes a cankered spot which, if it encircles the branch, causes death of the parts above. Fortunately, few of the fungi thus invade large limbs or the main trunk.

Chestnut Blight, Endothia parasitica (Murr.) Anders., is one of these canker fungi that has proved destructive in this way. Its action has been unique in tree history in this state, as it has practically eradicated not only all forest chestnuts but ornamental ones as well. All that are left are the sprouts that come up from the cut trees and occasional small seedlings, both of which are still subject to attacks. Treatment of any kind, so far, has been unsuccessful with this disease. This and the forestry department, however, expect soon to start small seedling plantations for future observation.

Poplar Cankers, Dothichiza populea Sacc. & Bri., is another, apparently European, importation that has recently been producing havoc with our ornamental poplars, especially the Lombardy. Not all the injury, however, is due to this fungus, as insects and winter injury have played their part. The remedy for this trouble seems to be to start with a young tree entirely free from the disease, as we have seen large isolated trees that continue to escape any injury.

Nectria Cankers, Nectria cinnabarina (Tul.) Fr., and N. galligena Bres., are apt to produce more localized cankers, especially the latter. The former, in our opinion, is not a serious trouble as it seems to follow winter injury only, and is especially prominent on those trees least hardy. The clustered bright-red fruiting pustules are conspicuous on the dead bark. The latter species makes a distinct canker that slowly enlarges year after year, in time showing a series of concentric rings of denuded wood with the canker deepest at the center. It is especially prominent on black birch in the woods but is occasionally found on cultivated trees of this species as well as on apple, maple and oak.

Treatment: Treatment of leaf destroying fungi by spraying depends upon prevention rather than cure. Hence the sprayings must begin before infection and continue while this danger lasts. This usually takes from two to five treatments according to the disease. With the anthracnoses and leaf curls, these treatments usually have to be started quite early, in some cases as soon as the buds begin to swell in the spring; with the leaf spots and mil

dews, some time in the late spring or summer, before the first signs of injury show. With rusts, spraying is usually of little or no value. In deciding whether spraying is desirable, one must take into consideration how injurious or obnoxious the fungus has proven, especially the preceding year, and how frequently it causes trouble. The 4-4-50 Bordeaux mixture, on the whole, is the best fungicide to use; in some cases where conspicuous sediment is objectionable, commercial lime and sulphur, 1 to 50 gallons of water, can be used. When necessary, an insecticide can be added to either. See the Station's Spray Calendar for further information.

Treatment for the Blights, Cankers, and Blister Rust is chiefly, as already indicated, through pruning off the invaded parts. Occasionally, under certain conditions, spraying is also given.

WOOD DESTROYING FUNGI

Nature: Almost all of the wood destroying fungi, whether on living or dead wood, belong with that class known as shelf fungi and toadstools. These represent the larger and more conspicuous fungi. Some of them are real parasites on the trees, killing the living tissues first and later causing decay of the dead wood; others are saprophytes, occurring only in the heartwood and causing its decay. Many, while not strictly parasites, are semi-parasitic as they cause some injury to the living tissues though usually confined to the dead. Therefore, it is not always easy to distinguish the parasitic from the saprophytic forms. We treat them together here, dealing, however, only with those saprophytic forms, that, in our experience, commonly occur on the dead wood of living ornamental trees. Most of the fungi discussed belong to that group known as Polypores, so-called because their spores are borne in pores that form the lower surface of the conspicuous fruiting bodies. Some have their spores borne on spines, teeth, gills, etc. Many other species are more prominent as agents of decay in dead forest trees than those mentioned here. There are others that are more important as parasites of living trees, but we have not met with them on ornamental trees in this state.

Trunk Forms: Daedalea quercina (L) Pers. confines itself largely to oaks and is rarely seen fruiting on living trees though on dead stumps in the forest it is common. It occasionally causes a heart rot of the ornamental oaks even if rarely fruiting on the same. The fruiting body shows as a conspicuous bracket, light brown in color and of a semi-corky texture. The lower fruiting surface has very large irregular or labyrinthiform pores.

Fomes applanatus (Pers.) Wallr., like all the species of the genus Fomes, is a perennial fungus developing a new poroid fruiting layer each year over that of the preceding year, so that when

cut through these show as a series of stratified tubes. This species is one of the largest and most common of the shelf fungi. It is not found fruiting on living trees as commonly as on the dead ones. The woody shelf varies in size from a few inches to even a foot or more in width, and projects out from the trunk horizontally almost as far. Its upper surface is a light brown and its fruiting surface is white, minutely poroid and easily etched; the tissues within are chocolate-brown. We have found it occasionally on living maples, poplars, willows, apples and peaches, and believe it to be the common heartwood rot of the maple.

Fomes connatus Fr. is a whitish, semi-fleshy or finally somewhat woody, species less than a foot wide and consists usually of several irregular shelving and overlapping brackets. The fruiting surface develops flesh-colored, small, thin-walled pores having a satiny lustre. We have found it fruiting on hickory and hard maple where it caused heartwood rot.

Fomes igniarius (L.) Gill. is a single, woody, roundish to hoofshaped bracket four to eight inches wide. It is at first light brown and smooth above but with age dark brown and more or less concentrically zoned and rimmed. Below, the minutely poroid surface is a rusty-brown color. It has been found on oaks and apples, where it seems to injure somewhat the living tissues as well as cause rot of the wood.

Polyporus squamosus (Huds.) Fr. is a semi-fleshy mushroomlike fungus with a side stem. The upper surface is covered with conspicuous patches of rusty scales and the lower is coarsely poroid. It has been found a few times on living maples where heart rot was present.

Polyporus sulphureus (Bull.) Fr. is a striking species with adhering and overlapping brackets of considerable size that are at first fleshy but on drying corky in texture. The upper surface is orange-red while the lower is a sulphur-yellow with moderate sized pores. While commonly a saprophyte on stumps and logs, at times, it is parasitic on living trees especially, as seen here, on oak.

Polystictus conchifer Schw. is a small, papery, conch-like species found on elm limbs where it produces slow rot and causes the branches to break off easily in storms. Some writers consider it semi-parasitic.

Pleurotis sapidus Kalch., P. ostreatus Jacq., oyster mushroom, and P. ulmarius Bull. are all evident, fleshy, gill fungi of the mushroom type. The two former occur as large, usually clustered or overlapping, brackets with the individual parts narrowed backward to a more or less distinct base down which the gills run for a short distance. The last species consists of a single fruiting body with a much more pronounced stem, arising near the center of the cap, to which the gills are attached by a notch. All are white forms with the tops often more or less brownish, especially

toward the center. They are most frequently found on the elm and hard maple and are associated with a heart rot of the wood. All three species are edible.

Hydnum septentrionale Fr. is a very conspicuous but rather uncommon, semi-fleshy when young but leathery when old, bracketed form with the overlapping irregular shelves joined to the trunk by a united but not distinct base. The tops of the shelves are whitish, often somewhat scabrous and the lower fruiting surfaces are differentiated quite markedly from other fungi by the very crowded, pinkish, fine, fruiting spines about half an inch in length. It has been found here, so far, only on hard maple and hickory and is apparently semi-parasitic.

Root Forms: It is not always easy to determine whether roots have been killed by these larger fungi, since the fruiting bodies are not usually present. Even when either the mycelial threads or the fruiting bodies are seen it is still a possibility that the fungus is a secondary agent following winter or some other injury. The only two species we have found here apparently injuring the roots of ornamental trees are of the toadstool type.

Armillaria mellea (Vahl) Quel. is the most important of the mushrooms attacking the roots of living trees. The umbrella-like cap is usually a honey-yellow with patches of brownish scales; the gills are white and the central stem has a more or less evident ring. They occur in clusters on the ground with the mycelium forming conspicuous, dark colored, rounded strands running over the roots and flattening out under the bark where the woody tissues are invaded. It is more likely to attack coniferous than deciduous trees.

Collybia velutipes Curt. is a yellowish to tawny mushroom, somewhat smaller than the preceding, that is especially distinguished by the velvety brown stems of the clustered fruiting bodies. It is claimed by some to cause injury to the roots of trees though commonly found on dead wood.

Treatment: For further statements concerning the control of wood-destroying fungi, the reader is referred to the articles by Collins and Filley elsewhere in this Report. We shall mention here only the fundamental requirements. The first is the complete removal of all decayed or infected wood and bark to prevent, or at least to arrest, further decay. The exposed wood is usually given an antiseptic and waterproof coating or coatings. The cavity should be properly shaped and the bark so left that rapid callus formation is favored. Whether or not the cavity should be filled is a matter of opinion, but, if filled, there is no question that it should be done properly. This means that the filling should be permanent, semi-flexible, waterproof, non-injurious to the living tissues, especially the cambium layer, tight fitting or better adherent to the wood, and so shaped that the callus readily grows over its exposed surface.

[graphic]

Black oak on Station grounds, broken by ice on February 5, 1924. A tree surgeon is needed in such a case.

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