CERCOSPORA MALI E. & E. On Pyrus Malus, Apple. Burl., Aug. 1891; J. 2473. Walden, Aug. 1898; 0. 2781. CERCOSPORA MICROSORA Sacc. On Tilia Americana, Basswood. Providence Island, June, 1898; O. 2931. Snake Mountain, July, 1898; O. 2932. CERCOSPORA SAGITTARIÆ E. & K. On Sagittaria variabilis, Arrowhead. West Townshend, Aug. 1894; G. 617. CERCOSPORA SQALIDULA Pk. On Clematis Virginiana, Virgin's bower. Newfane, Sept. 1892; G. 2333. Beaver, Aug. 1897; 0. 2335. CERCOSPORA VIOLE Sacc. On Viola sp., Cultivated violet. Burl., Sept. 1898; O. 2800. CERCOSPORELLA CANA (Pass.) Sacc. On Erigeron annuus, Daisy fleabane, Isle La Motte, Oct. 1898; 0. 3007. CLADOSPORIUM FULVUM Cke. On Lycopersicum esculentum, Tomato. Burl., Jan. 1893; J. 275. Injurious in the greenhouse. On Solanum tuberosum, Potato. Burl., July, 1893; J. 2934. Dorset, July, 1894; Tracy, 2933. CLADOSPORIUM HERBARUM (Pers.) Lk. On Populus tremuloides, Poplar. Newfane, Sept. 1892; G. 288. On dead wood of Tilia Americana, Basswood. Johnson, June, 1895; G. 274. CLADOSPORIUM RAMULOSUM Desm. On Populus tremuloides, Poplar. Burl., Aug. 1897; O. 2483. FUSICLADIUM DENDRICTICUM (Wallr.) Fckl. On Pyrus Malus, Apple. Burl., Sept. 1894; J. 2968. Isle La Motte, Oct. 1898; O. 2967. Walden, Aug. 1898; O. 2782. FUSICLADIUM DEPRESSUM (B. & Br.) Sacc. On Angelica atropurpurea. Johnson, Sept. 1893; G. 2970. FUSICLADIUM PYRINUM (Lib.) Fckl. On leaves and fruit of Pyrus communis, Pear. No. Calais, Aug. 1898; O. 2971. Burl., Sept. 1898; O. 2972. HETEROSPORIUM GRACILE (Wallr.) Sacc. On Belamcanda Chinensis, Blackberry lily. Charlotte, July, 1896; G. 299. On Iris sp., Cultivated iris. Charlotte, Sept. 1897; O. 2975. Burl., Sept. 1898; 0. 2976. MACROSPORIUM PORRI Ell. On Allium Cepa, Onion. Milton, June, 1896; G. 2979. MACROSPORIUM SARCINULA Berk. var. PARASITICUM Thům. On Allium Cepa, Onion. Milton, Sept. 1896; Herrick, 301. MICROSTROMA JUGLANDIS (Berang.) Sacc. On Carya alba, Shellbark hickory. Burl., July, 1897; O. 2796. MONILIA FRUCTIGENA Pers. On Prunus domestica, Plum. So. Hero, Oct. 1898; O. 3005. OVULARIA SOMMERI (Eichelbaum) Sacc. On young stems of Myrica Gale, Sweet gale. Burl., May, 1897; J. & O. 2736. PENICILLIUM GLAUCUM Grev. On fruit of Pyrus Malus, Apple. Burl., Jan. 1892; J. 376. PIRICULARIA GRISEA (Cke.) Sacc. On Setaria glauca, Pigeon grass. Burl., July, 1897; O. 3008. RAMULARIA ACTEE E. & H. On Actea alba, White baneberry. Newfane, June, 1892; G. 308. RAMULARIA ARMORACIAE Fckl. On Nasturtium Armoracia, Horseradish. Milton, Sept. 1896; G. 3023. RAMULARIA ARVENSIS Sacc. On Potentilla Norvegica, Cinquefoil. Burl., June, 1898; O. 2727. RAMULARIA CELASTRI Pk. On Celastrus scandens, Bittersweet. Newfane, Sept. 1895; G. 310. Burl., Aug. 1897; O. 2370. No. Calais, Aug. 1898; O. 2712. RAMULARIA DECIPIENS E. & E. On Rumex crispus. Dock. Burl., Aug. 1897; O. 2986. RAMULARIA IMPATIENTIS Pk. On Impatiens fulva, Jewel weed, Beaver, Aug. 1897; O. 2797. RAMULARIA NEMOPANTHES Pk. On Nemopanthes fascicularis. Burl., July, 1898; O. 3020. RAMULARIA OXALIDIS Farl. On Oxalis acetosella, Woodsorrel. Stratton, July, 1894; G. 692. RAMULARIA PLANTAGINIS E. & M. On Plantago major, Plantain. Stratton, Aug. 1894; G. 691. RAMULARIA RANUNCULI Pk. On Ranunculus acris, Buttercup. Walden, Aug. 1898. O. 3019. RAMULARIA RUDBECKIAE Pk. On Rudbeckia laciniata, Cone-flower. Vernon, Aug. 1895; G. 690. 1897; O. 3013. RAMULARIA TARAXACI Karst. On Taraxacum officinale, Dandelion. Burl., July, RAMULARIA URTICAE Ces. On Urtica gracilis, Nettle. Burl., Sept. 1897; O. 2795. SCOLECOTRICHUM GRAMINIS Fckl. On Dactylis glomerata, Orchard grass. Burl., Sept. 1896. G. 3011. KILLING WEEDS WITH CHEMICALS Since the publication in a recent bulletin1 of the successful results from the use of salt in killing the orange hawkweed many inquiries have been received as to the possibility of destroying a variety of other weeds with chemical agents. The great difficulty in the practical use of chemicals as weed killers is in managing to kill the weeds without either destroying neighboring useful plants or leaving the soil so impregnated with the chemical as to interfere with the growth of useful plants thereafter. These difficulties interfere with the general usefulness of chemicals as weed destroyers. There are two cases where chemicals may be resorted to in spite of them. First, where an especially dangerous or obnoxious weed occurs in a limited locality and it is desired to destroy it quickly and utterly; and, second, where the soil to be freed from weeds is not thereafter to be used for the growth of other plants, as in the case of gravel walks and roads, or those paved loosely with stone or wooden blocks, and also in tennis courts and similar areas. Since numerous inquiries have concerned such cases it was decided to make a comparative test of a number of chemicals for these purposes. These tests have included the following: common salt, copper sulphate, sulphide of potassium, kerosene, arseniate of soda, and a mixture of white arsenic and sal soda, in addition to two proprietary articles described later. The details of this work were carried out at this station by Messrs. T. E. Hazen, a graduate student in its employ, and A. W. Edson. The chemicals were tested by marking off areas in gravel walks, roadways, tennis courts and similar dry beaten soils, noting the character of the weed growth and observing the effect upon this of the applications of various chemicals. These applications were begun about July 1st and observations continued until autumn. In some cases the walks were occupied by weeds of considerable size, in others they had recently been hoed and raked over. The solutions were applied in all cases with an ordinary water 1. Vt. Exp. Sta. Bul. 56, (1897.) ing pot. It was found by experience that about eight gallons of solution was required effectively to wet down one square rod of such soil and that amount was used in most of this work. The results may best be presented topically as follows: Nature of the weeds.-The knot-weed or knot-grass (Polygonum aviculare Linn.) was the most troublesome weed in the areas under observation. White clover and several of the annual grasses occurred commonly also (setarias and panicums especially) and in certain of the plots the perennial grasses, Kentucky blue and quack (Agropyron repens) were abundant. Purslane, plantains, blue-curls, dandelion and some other weeds occurred in some of the plots. Of these the knot-weed was distinctly the most troublesome, and the efficaciousness of a chemical in destroying this was considered the best gage of its value. SALT Common salt, sodium chloride, was tried upon gravel containing the knot-grass (Polygonum aviculare) and some of the coarser grasses (panicums, etc.) It was applied dry in amounts varying from four to twenty pounds per square rod, and in one case it was used in a larger but unmeasured quantity. It was found to be slow and imperfect in its action as a weed killer under these circumstances. Moreover, it washed into the grass borders and injured them considerably in case of rains. We are led to decide for these reasons that salt is not to be recommended for such weed killing. It has heretofore been shown that salt has a distinct practical value for killing the orange hawkweed, and that the larger of the amounts cited above is sufficient to eradicate that weed. There may be exceptional circumstances when the use of salt on roadways may be wise. Thus the superintendent of the Boston parks writes us that he obtains refuse salt at $1.00 per ton, which he uses freely and successfully on such of their roadways as permit of no danger to adjacent lawns or trees. True1 finds that salt has slight toxic (poisonous) effects upon some plants, but most of its value as a weed killer depends upon the fact that it rapidly draws the water out of plant tissues with which it comes in contact. It is more effective, therefore, when applied dry (not as a brine) and also when applied on a dry, hot, sunshiny day. COPPER SULPHATE Copper sulphate or blue vitrol has been recommended as a weed killer,2 and we began these experiments with the idea that it possessed considerable value for this purpose. Three strengths of solution were tried: one 1 True, Am. Assn. Adv. Sci., Proc. 47, p. 410 (1898). 2 Canada Exp. Farms, Bul. 28, p. 9 (1897). pound in three gallons of water (4% solution); 1 pound in one and onehalf gallons of water (8% solution); and one pound in one gallon of water (12% solution). In no case was the result satisfactory. For example, in one plot containing plantain, purslane and various grasses the results following the application of a 5% solution were as follows: At at the end of one week some of the purslane leaves were dead, but no plants entirely killed. The purslane and grass leaves were but slightly affected. At the end of two months most of these plants had recovered their vigor. All our trials agree in showing that copper sulphate is inferior as a weed killer to other chemicals to be mentioned later. It is worthy of note in this connection, however, that copper sulphate may have decided value as a weedkiller under other circumstances. It has been found by recent trials in Europe that a weak solution of this chemical sprayed over a grain field infested with kale may destroy the weed without injuring the grain. H. L. Bolley of the North Dakota experiment station writes that experiments made by him indicate that it is possible to destroy the common annual weeds in a grain field by such use of a 3% solution and that this strength does not injure the grain. In the light of our own experiments we are led to believe it probable that such results as he describes are due to the killing by the solution of the tender upper portions of the weed plants. The grain in its rapid growth would soon overtop and smother the weeds thus weakened. Further investigations of the practical usefulness of this chemical as a weed killer may therefore be awaited with interest. KEROSENE This was used diluted with water in the proportion of one part kerosene to three parts water (25% mixture). When so diluted and applied at the rate of 8 gallons to the square rod it failed to kill the weeds. It became evident, therefore, that the herbicidal activity of the kerosene is so slight in proportion to its cost as to preclude its practical use as a weed killer. POTASSIUM SULPHIDE (LIVERS OF SULPHUR) One pound in three gallons of water (4% solution) when applied at the rate of eight gallons per square rod, in one trial was not effective in destroying the weeds. It gave so little promise of practical value that no further trials were made. CARBOLIC ACID The crude liquid was added to water in proportions varying in different trials from one pint per gallon (12% sol.) to one-fifth pint per gallon (21% sol.). This was mixed with the water by agitation and was applied |