trees in the United States, the fungus occurring in all of the fruit-growing regions east of the Rocky Mountains and practically every orchard in the State of Nebraska being more or less infected.

The symptoms vary, being affected by variety, age of trees, available water and soil nutrients, and general weather conditions. They may resemble those accompanying sun scald, winter injury, collar rot, and the so-called arsenical poisoning. The organism is a wound parasite attacking either roots or branches, and it may be present for several seasons before becoming visible externally. It is disseminated by means of infected wood, conidia, or ascospores, both of these reproductive bodies being produced throughout the growing season under favorable weather conditions. Conidia usually appear during the season in which the canker first appears, ascospores one or more seasons later, and both may be borne on the same stromata for many seasons thereafter. Ascospores are much more viable than are conidia, but the latter are also important agents in the spread of the disease.

Infection occurs rarely in case of rapidly growing tissues, but readily in case of inactive xylem tissues. The cellular structure is not destroyed, as the fungus penetrates by way of the pits in the cell walls, making more rapid progress longitudinally through the trachea than transversely, though the medullary rays facilitate the advance in a radial direction. The characteristic brown discoloration is always associated with the presence of the hyphæ, though sometimes extending some distance beyond their advance. The fungus usually grows faster below than above the point of entrance, if that be aboveground. If inoculated below the surface of the ground, the reverse is true. Susceptibility depends largely upon variety, the vigor of the tree, the available supply of water and of nutrient solutes, and the season in which inoculation occurs, being less in early spring and summer during rapid growth. Fertilizing experiments have shown little or no benefit. Variation in resistance may be due to chemical as well as to anatomical and physiological factors.

It is thought that control must depend upon prevention, as cures of trees once affected are possible in very few cases. Heavy pruning aggravates the disease. Either copper sulphate or lime sulphur applied to the cankers is effective. All wounds should be covered. Liquid asphaltum appears to be about as effective as white lead and oil for this purpose. The first coat should be thin, the second heavier.

Methods of controlling blister canker, J. R. COOPER (Nebraska Sta. Bul. 161 (1917), pp. 18, figs. 8).—This is a popular edition of the bulletin noted above. Apple or cedar rust, R. C. WALTON (Mo. Bul. Ohio Sta., 3 (1918), No. 3, pp. 86-88, figs. 3).—It is stated that of the Ohio counties reporting apple rust 91.3 per cent are in the southern half of the State where the red cedar is more abundant as a native tree, though both this tree and the disease exist more or less in all parts of the State. In some apple varieties, as Rome Beauty, infection of the fruit is frequently severe in addition to the leaf infection. Winesap, Stayman Winesap, and Maiden Blush are named as resistant, Ben Davis and Grimes Golden as moderately so. The best method of control is destruction of all cedars within one mile of the orchards.

Dusting for cedar rust, F. D. FROMME and H. E. THOMAS (Virginia Sta. Rpts. 1915-16, pp. 179–183, figs. 2).—Having used successfully a dusting mixture containing copper for late blight of tomato (E. S. R., 36, p. 750), the authors tested this plan, employing a dust mixture containing sulphur, hydrated lime, and lead arsenate in the ratio of 15:5:4, for cedar rust (Gymnosporangium juniperi-virginianæ), on apple trees adjacent to cedars. Treatments were applied either before each important rain, after such rains, or on the regular spray schedule.

No constant decrease of infection could be found on any of the plats receiving dust applications.

Control of cherry leaf spot in Wisconsin, G. W. KEITT (Wisconsin Sta. Bul. 286 (1918), pp. 11, figs. 8).—This is a report based on work done by the author during two seasons with cherry leaf spot (said to be the most serious fungus disease of cherry in Wisconsin) in the attempt to ascertain the times and numbers of sprayings which would give the best and most economical results under present conditions as regards prices of labor and materials.

The most obvious feature of the disease is the loss of the leaves, resulting in a lowering of vitality and failure of the fruit to attain its normal growth and maturity. The disease also affects the fruit and fruit stems. The causal fungus overwinters in dead leaves on the ground, giving up spores in spring which repeat the infection.

Early and clean cultivation greatly aids control by reducing the number of spores set free.

As a result of comparative tests in 1916 and 1917 it is found that while Bordeaux mixture is safe at a strength of 2:2:50 in case of good sanitation and timely applications, the 1:1:50 strength is not to be recommended for commercial use, but the 3:3:50 formula may be used with full confidence in Wisconsin. Lime-sulphur at a specific gravity of 1.2946 diluted at the rate of 1:40 or 1:30 was also satisfactory, especially when containing lead arsenate (to 1 lb. in 50 gal. water, or if in the form of paste, 1 to 2 lbs.).

Dusting for peach scab, H. E. THOMAS (Virginia Sta. Rpts. 1915–16, pp. 184-186, figs. 2).—A preliminary trial was made of a dry lime and sulphur mixture (1:3) on peach scab (Cladosporium carpophilum) at Blacksburg during the season of 1916. The applications were made with a power dusting rig from both sides of the row on June 29, July 14 and 31, and August 14, the amount averaging 0.8 lb. per tree for each application. The dust adhered well to the fruit, but not to the foliage.

The efficiency of the dust application was rated as remarkably high, considering that the scab had become well established before the first application was made. The mixture prevented the spread of the scab to noninfected fruit, 78.6 per cent of the fruit being clean on the dusted tree, as compared with 0.4 per cent on the check. It also checked the development on infected fruit or prevented reinfection, 73 per cent of the fruit on the check tree being classed as heavy scab, as opposed to 0.1 per cent on the dusted tree. This treatment is therefore considered a promising means of control for peach scab. Fungus diseases [of cranberries], H. J. FRANKLIN (Massachusetts Sta. Bul. 180 (1917), pp. 186-198).-These investigations were conducted as in previous years (E. S. R., 36, p. 51) in cooperation with the Bureau of Plant Industry of the U. S. Depatment of Agriculture.

Comparison of the tabulated results of spraying experiments with Bordeaux mixture showed that as a rule the areas sprayed in 1915 were less productive in 1916 than were the checks, also that the fruit from the sprayed areas was inferior as regards keeping quality. Apparently injury from Bordeaux mixture weakens the resistance of the berries to disease. Blackleaf 40 solution (0.25 per cent) with fish-oil soap (2 lbs. to 50 gal. water) affected but little the quality of the fruit and showed no fungicidal value in the storage tests, but these experiments are not regarded as conclusive. Corona arsenate of lead (3 lbs. to 50 gal. water) gave little if any increase in yield, but an improvement was noted in the keeping quality of the fruit. Most of the rot in berries of the variety Early Black was found to be due to anthracnose (Glomerella rufomaculans vaccinii). Areas treated by putting copper sulphate in the flowage

showed no definite advantage, either in the quantity or in the keeping quality of the fruit.

False blossom was unusually abundant on the station bog this season, the moist conditions supposedly favoring greatly the development of Exobasidium oxycocci, the cause of this disease, which this year attacked blossoms as well as leaves.

Observations on the spoilage of cranberries due to lack of proper ventilation, C. L. SHEAR, N. E. STEVENS, and B. A. RUDOLPH (Massachusetts Sta. Bul. 180 (1917), pp. 235–239.)—Tests made with cranberries of several varieties from different sources kept in an atmosphere of nearly pure carbon dioxid resulted in the spoilage of almost all such berries, which also showed a dull red color. The controls kept in the air showed very little rot even at the end of two weeks. Confirmatory tests are described. Humidity appears to have no influence on the effect of the carbon dioxid, and the same is true of the different fungi present, which are usually also unfavorably affected by the carbon dioxid. The importance of ventilation is indicated.

Downy mildew in vines, H. E. LAFFER (Jour. Dept. Agr. So. Aust., 20 (1917), No. 12, pp. 970-977).-In a report dealing with insect injury and reconstitution of vineyards in New South Wales, it is stated that for the first time in Australia grape downy mildew (Plasmopara viticola) has been identified in the vineyards of Victoria, the infected area being spread over some 400 square miles in the northeastern portion of the State. It is thought that the disease may possibly have been present for several years, but only in the past season have the frequent summer rains and other weather conditions favored sufficient development of conidiophores to enable the fungus to be identified with certainty. The development of the conidiophores is greatly increased by the proximity of even small areas of water surface, as dams or drains.

Citrus diseases, J. A. STEVENSON (Porto Rico Dept. Agr. Sta. Rpt. 1917, pp. 78-83).-Notes are given on citrus scab due to Cladosporium citri, fruit rots caused by Penicillium spp. and Diplodia sp., crown rot of seedlings due to Sclerotium rolfsii, and on the parasitism of mistletoe (Dendropemon spp.). Progress Texas is making toward the eradication of citrus canker, E. L. AYERS (Bul. Agr. and Mech. Col. Tex., 3. ser., 3 (1917), No. 7, pt. 1, pp. 37, 38).— In an address to the Texas Farmers' Congress in 1916 the author stated that rapid progress had been made toward eradicating citrus canker. Though at one time scattered through the entire citrus-growing area of the State, this disease has been almost entirely confined to the three counties where it was first prevalent, and it is decreasing in that area.

Comparative studies on soils affected or not affected with gummosis.—I, The soil reaction, S. TIJMStra (Bul. Deli Proefstat, Medan, No. 9 (1917), pp. 41).—An extension of studies previously noted (E. S. R., 33, p. 22) is reported to have shown no distinct difference in reaction between soils carrying the infection responsible for gummosis and those which were free from such infection. Melanose, II, H. E. STEVENS (Florida Sta. Bul. 145 (1918), pp. 101–116, figs. 7). In continuation of a report made in connection with Floyd (E. S. R., 28, p. 651), the author states that melanose of citrus leaves, fruits, and young stems, previously shown to be due to Phomopsis citri, is found chiefly in dead twigs and branches. These constitute the principal sources for the spread of this disease, which does not extend itself from either foliage or fruit, though the fruit is subject to injury by this fungus during several months.

Removal of dead wood is thought to offer the most practical means at present available for reducing the ravages of melanose, which is thought to be the

most injurious disease attacking citrus fruits and to cause increasing loss each year in Florida.

Diseases and pests of tea on the east coast of Sumatra, C. BERNARD (Dept. Landb. Nijv. en Handel [Dutch East Indies], Meded. Proefstat. Thee, No. 54 (1917), pp. 1–15).-The author briefly discusses, along with animal enemies of tea, a Fomes causing root disease, also other causes of loss or injury, as red rust (Cephaleuros virescens), brown blight (Læstadia sp.), gray blight (Pestalozzia palmarum), and sooty blotch (Capnodium sp.).

Nematode diseases of narcissus, J. RITZEMA BOS (Tijdschr. Plantenziekten, 23 (1917), No. 3, pp. 99–135).—The author describes a stem disease of narcissus ascribed to a nematode (Tylenchus devastatrix) which is said to be parasitic on many other plants. A list of these plants is given along with a discussion of the possible specialization of this nematode.

Biological observations on Puccinia vincæ, F. VINCENS (Bul. Soc. Path. Veg. France, 4 (1917), No. 1, pp. 30-36, fig. 1).—A brief account of study of P. vince concludes with the statement that the teleutospores found on Vinca major will not cause infection of V. minor. From this fact it is inferred that there exist two biological species of P. vinca.

A practical method of preventing the damping-off of coniferous seedlings, C. A. SCOTT (Jour. Forestry, 15 (1917), No. 2, pp. 192-196, pls. 2).-A method said to be practical and highly satisfactory is described for sterilizing forest nursery seed beds with steam delivered at 120 to 160 lbs. pressure for from 35 to 45 minutes under inverted pans previously weighted down. This plan has stood the test of use for two seasons very favorable to the fungus causing the damping-off of coniferous seedlings, except in the case of the Engelmann spruce. The unsterilized beds of all species showed almost a total loss.

Germination in the sterilized beds occurred from two to four days earlier and was more nearly complete, giving a considerable saving in the cost of seeds. This method also destroys all weed seeds, thus eliminating the cost of weeding and counterbalancing thereby the entire expense of sterilizing the beds. The seedlings in the sterilized beds made a much more vigorous growth, attaining before the close of the growing season from two to four times the size of those on the untreated beds.

Effects of mistletoe on young conifers, J. R. WEIR (Jour. Agr. Research [U. S.], 12 (1918), No. 11, pp. 715–718, pl. 1).-In the course of work done in the Bureau of Plant Industry on injury to conifers by mistletoes of the genus Razoumnofskya (Arceuthobium), in part noted previously (E. S. R., 34, p. 547; 35, p. 459; 37, p. 458), the author was able to demonstrate the suppression of growth in young trees by this parasite. In Pinus ponderosa the internodes as well as terminal and lateral buds of the main shoot were greatly reduced by the action of the mistletoe. In case of Pseudotsuga taxifolia the buds were greatly reduced, the food normally stored therein going elsewhere to form brooms and burls, this fact probably bearing an important relation to the stunting of the tree and a staghead appearance. The actual storage of food materials in mistletoe brooms became apparent in the production of needles on detached brooms kept in damp situations, normal branches showing very little disposition to throw out needles, though kept in the same damp, shady situation.

The author concludes that false mistletoes are seriously injurious to the young conifers in the forest, especially as these, when infected on the main stem (the usual way), do not recover so as to produce merchantable material. The young tree does not pursue the usual plan of excurrent growth in such cases. It may become practically a continuous witches' broom or else die 71629-185

outright. All infected trees, especially those overtopping other trees, should be destroyed.

A disease of walnut due to Armillaria mellea, P. GUINIER (Bul. Soc. Path. Veg. France, 4 (1917), No. 1, pp. 27-29).—Armillaria mellea is noted as causing the death of walnut in certain regions which are named.

ECONOMIC ZOOLOGY-ENTOMOLOGY.

Report of the entomological department, J. TROOP (Indiana Sta. Rpt. 1917, pp. 39, 40). The grape colaspis is said to have shown great activity in corn fields, particularly in the southern counties of Indiana. On one farm examined, a field which had been in timothy the previous year was so badly infested that it had to be disked under and replanted, while in an adjoining field, which had been in wheat the previous year, no infestation could be found.

During June, 1917, several carloads of potatoes which were received in the Indianapolis market from Australia were found to be badly infested with the potato tuber moth.

Report of the entomological department, E. C. SMYTH (Porto Rico Dept.. Agr. Sta. Rpt. 1917, pp. 99–106).—This statement of the work of the year deals particularly with plant inspection and quarantine and the fumigation of imported cane for grinding. The importance of preventing the introduction of the cane butterfly Calisto archebates in cane from Santo Domingo is again pointed out (E. S. R., 36, p. 753). In addition to the cane butterfly three cane beetles are annually intercepted by the hundreds through fumigation with sulphur dioxid, namely, the Santo Domingo cane weevil root borer (Diaprepes quadrivittatus), the Santo Domingo cane weevil stalk borer (Metamasius sericeus), and a large black histerid beetle that seems to work in cane, Hololepta quadridentata.

Report of the assistant entomologist, R. T. COTTON (Porto Rico Dept. Agr. Sta. Rpt. 1917, pp. 107-122, figs. 8).—This consists largely of a report of investigations of several tobacco insects, including the tobacco leaf folder (Pachyzancla periusalis), the large tobacco suck fly (Dicyphus luridus), and the small tobacco suck fly (D. prasinus). A heavy infestation of slugs (Veronicella lapas) at the time of planting is said to have resulted in considerable damage to the young plants. This pest, however, is fairly easily controlled, the most effective and cheapest method consisting of collection with the aid of lanterns when they come out to feed at night. Flea-beetles, which are the worst insect pests of tobacco in Porto Rico, are being controlled by lead arsenate in powder form applied with small dust guns at the rate of 50 lbs. of arsenate of lead to 50 lbs. of dry, leached, wood ashes. Two plant bugs which are abundant in all sections of the tobacco district and damage the leaves were found to be new to science and have been described by Gibson under the names D. luridus and D. prasinus (E. S. R., 37, p. 561), both of which have been studied and are here reported upon.

The tobacco leaf folder (P. periusalis) is of wide occurrence in Porto Rico and has been recorded as occurring in the United States and Brazil. It feeds exclusively on solanaceous plants, tobacco being its favorite among cultivated plants, although the weeds Solanum torvum and S. nigrum are undoubtedly its main food plants. It is abundant in all localities throughout the tobacco districts, but attacks the plants only when they are young and tender. The young larvæ on hatching out commence to feed on the leaf near the midrib and after some growth form a feeding shelter by folding over a portion of the edge of the leaf and fastening it down with silk strands, within which they