less subject to it than those from heavy soils, and the disease spreads most rapidly in a damp, warm, and close cellar.

2. Due to bacteria.' The tubers may be wholly or partially soft, and exhale a disagreeable odor. Butyric acid may be liberated and the destruction of the tubers is slow. Contact with other potatoes should be avoided. If to be used for seed, in some cases depending on the cause, soaking the tubers in formalin before planting is beneficial.

DRY ROT may be the evidence of the presence of one or more of several troubles.'

1. Stem rot, bundle blackening, dry end rot, is believed to be due to a fungus (Fusarium oxysporum); the leaves curl, and the foliage wilts and dies. The tubers show brown or blackened bundles at the stem end under an apparently sound skin. The disease spreads rapidly in storage, especially if the rooms are warm. Some investigators advise that diseased tubers should not be fed to stock, thrown on the manure-pile, or planted, and that all such potatoes should be destroyed at harvest-time or as soon as discovered. No remedy is known.

2. Due to bacteria. The tubers may be free from odor, moderately firm, but more or less soft in spots, showing in places a loose skin, which yields to the finger, and under which are white, gray, or brownish blotches. Soaking unaffected tubers in formalin before planting is suggested.

1 Ill. Bul. 40, p. 140.

2 Ill. Bul. 40, p. 139. Tex. Bul. 42, p. 926.

3 U. S. D. A. Bureau of Plant Industry Bul. 55. (N. Y.) Geneva Bul. 101, pp. 83, 84; Bul. 138, pp. 632, 634.

4. Insects.-THE FLEA-BEETLE (Crepidodera (Epitrix) cucumeris) (Fig. 39).-These small insects often

cause more loss than the potato beetles. They perforate the leaves (Fig. 40) during a critical

period of the plant's life. The holes produced are used by the

FIG. 40-LEAFLET OF POTATO, SHOW

spores of both early ING OVER A HUNDRED HOLES MADE

BY FLEA-BEETLES

and late blight for entrance into the leaf. Arsenical poisoning is usually first noticed of disease, and pave the way for the rapid on the margins of

The ease with which this damage might be overlooked is evident. These holes make suitable avenues for the entrance of spores

destruction of the plant.

these holes. At no time in their life history can these insects be readily destroyed. They dislike Bordeaux

mixture; hence, the only known means of reducing their ravages is to spray the plants with this material.

NUMBER OF FLEA-BEETLE PUNCTURES IN 50 LEAFLETS FROM 1 12 ADJACENT ROWS

Punctures

Row 1.-Sprayed with very weak Bordeaux mixture I,794 Row 2.-Sprayed with very weak Bordeaux mixture and

I, 194

1,090

Row 4.-Sprayed with strong Bordeaux mixture
Row 5.-Sprayed with strong Bordeaux mixture and

soap.

Row 6.-Sprayed with weak Bordeaux mixture
Row 7.-Sprayed with weak Bordeaux mixture and soap
Row 8.-Not sprayed

1,295

901

2,287

The grubs of the flea-beetle infest the tubers and roots of potatoes, doing some damage and causing the trouble known as "pimply potatoes."""

In the Pacific Coast the flea-beetles (Epitrix subcrinita, Lec., and E. hirtipennis, Mels.) sometimes reduce the yield 50 per cent. by their ravages. As they are leaf-eaters, the foliage should be sprayed or dusted with an arsenical poison. One pound of Paris green to 150 gallons of water per acre is suggested,' but it is better to apply the Paris green in Bordeaux mixture.

THE POTATO BEETLE, COLORADO POTATO BEETLE, OR POTATO BUG (Doryphora decemlineata).—Until 1850 this insect was confined to Mexico and the Rockies. In 1859 its eastward movement was noted, and it is now well distributed. A related species (D. juncta)

1 Vt. Bul. 72, pp. 6-9. Cal. Bul. 135, p. 29.

2 (N. Y.) Geneva Bul. 113, pp. 312–317.

retreated before its advance, and is now more common in the South. In New Mexico' a parasite lives on the eggs and larvæ. The eggs are laid on the potato leaves, on which the young "bugs" live, chewing holes in or eating the whole of the leaf. The insects are most active about blossoming-time, and do considerable damage if left alone.

Modes of Combatting.-The leaf should be thoroughly coated with a poison, generally an arsenical compound being used. The poison should be applied as soon as the "bugs" hatch, because the younger the "bugs" the more easily they are destroyed. Various arsenical compounds are used—as, Paris green, arsenate of lead, and others. "Bugs" object to Bordeaux mixture, hence in applying the poison it is found to be good practice to apply Bordeaux mixture at the same time. The whole of the plant should be covered, because if badly sprayed the bugs live on the unsprayed foliage. The standard application is 1⁄4 to 1⁄2 pound of Paris green to 50 gallons of mixture. Generally I pound of Paris green is sufficient per acre, and if it is desired to apply more than 100 gallons, the proportion of Paris green should be varied accordingly. If desired, Paris green may be applied in the dry form by means of a powder gun, the Paris green being mixed with flour, land plaster, etc., as desired. About 50 cents per acre

should cover the cost of one application.

THE POTATO WORM,' also known in the South as the tobacco-leaf miner (Gelechia operculella, Zell.), is estimated to destroy 25 per cent. of the potato crop

1 American Naturalist, 1899, pp. 927-29. New Mexico Bul. 33, PP. 47-51. 2 Cal. Bul. 135, pp. 5-29.

on the Pacific Coast. Great losses often occur in storage as well as in the field. The moths fly at night, and lay eggs on the stalks and tubers. Destruction of the moths by trap lanterns, the destruction of infested stems, careful hilling of potatoes, getting them under cover as soon as dug, cleaning up the refuse of the field, and a rotation of crops is recommended. In storage, fumigation with 11⁄2 pounds of carbon bisulphide per thousand cubic feet of air-space will destroy all the larvæ if repeated five times at intervals of two weeks. This gas is inflammable, and no lights must be taken near. It is a heavy gas, and sinks from the top of the building.

POTATO STALK WEEVIL' (Trichobaris trinotata).— This beetle attacks the stalks, causing them to wilt. It is found from Canada to Texas and Florida. The vines should be destroyed as soon as attacked, and weeds belonging to the potato family kept down.

Another insect has caused similar trouble in Maine.' GRASSHOPPERS (Melanoplus sp.) do much damage during some seasons, especially after the hay crop is cut, by severing parts of the leaves. Bordeaux mixture containing an arsenical poison is the best deterrent, being better than the arsenical compound alone.

THE JUNE BUG (Lachnosterna sp.).-The big white larvæ of these beetles often eat the tubers. They are most prevalent on land which has been in grass, although if land is in clover but one or two years less trouble may be expected.

1 Consult U. S. D. A. Div. of Entomology, Bul. 33, 6. Ind. Report, 1895. Kan. Bul. 82. Pa. D. A. Report, 1896. N. J. Bul. 109, pp. 25-32.

2 Me. Report, 1897, p. 173.