called the corn-stalk disease. The first indication of the disease is the dwarfed condition of the young plant. This commonly occurs in spots of various sizes, and is found in rich places, rather than in those of poorer quality. The young diseased plants, besides being smaller than the healthy ones, are uniformly yellowish in color, the lowest leaves showing worst. Affected plants are easily pulled from the ground on account of the death of the lower roots. The inner tissue of the lower part of the stalk has a uniform dark color, while on the surface there are brownish corroded spots. After midsummer the leaf-sheaths become spotted with various sized patches of a watery-brown, half rotten in appearance, which are most conspicuous from the inner surface. The ears are at least occasionally affected. Internally, in the worst stage, the whole ear reduced to a moist state of corruption. Very often these ears subsequently become mouldy, penetrated through and through by a close, very white, felt-like fungus. These mouldy ears are, in certain seasons, very numerous, and are readily recognized by the husker. No remedy is known. There appears to be in a considerable number of cases more injury on land which has been planted with maize the preceding year.

324. BACTERIAL Disease of SWEET MAIZE.-Plants affected by this disease wilt and dry up very much like plants suffering from lack of moisture, except that there is little or no rolling of the leaves. Diseased plants are intermingled with healthy ones. The woody strands of the plant are filled with a multitude of short, yellow bacilli, which, when the stem is cut across, exude as a yellow viscid substance. The disease is confined to sweet maize, and is most destructive to early varieties. It is disseminated chiefly by means of the germs which cling to the seed. No remedy is known. The principal measures of prevention are selection of seed and the planting of resistant varieties.1

Uredo stage or red

rust on maize leaf, Disease

produced by inoculation by Kellerman

325. MAIZE RUST is found wherever maize is grown, but principally in regions of considerable rainfall. The rust does not differ materially in appearance from rusts of other grasses, particularly Puccinia graminis of wheat and oats; the surface of the affected leaf and sheath displays small oblong or elliptical spots, which contain reddish-brown spores. Kellerman has shown that only the uredo and teleuto stages may be included in the life cycle, although Arthur has identified the aecidial stage on oxalis. 2 It passes the winter in the teleuto stage. Though fungicides are effective, the rust is of such little economic importance as not to warrant treatment. Pammel reports decreased yields of sweet maize due to the rust. The rust also occurs on sorghum and teosinte.

326. THE LEAF BLIGHT FUNGUS has been reported in maize, causing extended or elliptical brown (dead) areas in the leaf blades, not distinguishable by the unaided eye. The disease is of little economic importance.

1 N. Y. (Geneva) Bul. 130.

2 Botanical Gazette, July, 1904.

327. Insect Enemies.-Two hundred and fourteen species of insects are known to be more or less injurious to the maize plant. Insect injuries are more common and more extensive in the Southern States than in the Northern States. Except, however, for those insects which attack the young plant and make replanting necessary, destruction of the crop is seldom complete. The larger number of the injuries to maize occur after plowing up grass land of long standing, or are due to continuous culture of maize upon the same land several years in succession. Some of the insects also pass a portion of their life on or can use weedy plants for food. Generally, therefore, the most effective remedies against insect attacks are short and systematic rotations, accompanied by clean culture of the maize field and the surrounding territory. Where the land is neither in grass nor maize more than two years in succession the attacks of insects are comparatively limited; except, perhaps, in the case of certain migratory insects, such as the chinch bug, locusts and army worms, whose increase in numbers has been brought about by special conditions. The insects of most economical importance to growing maize are as follows:

(1) Wireworms (Elateridae). (2) Cutworms (Noctuidae).

(3) White grubs (Lachnosterna spp.)

(4) Corn root worms (Diabrotica longicornis Say and D. 12-punctata Oliv.). (5) Corn root web-worms (Crambus spp.).

(6) Corn root louse (Aphis maidi-radicis Forbes).

(7) Corn bill bugs (Sphenophorus spp.)

(8) Corn ear-worm (Heliothis armiger Hubn.)

(9) Stalk borers (Noctuidae and Pyralidae).

(10) Chinch bug (Blissus leucopterus Say) (151).

The insects most injurious to the stored grain are the same as those affecting stored wheat. (156)

328. WIREWORMS are the larvae of the large family of click beetles or " 'Jumping Jacks," eight species of which are known to be injurious to maize.1 The worms vary in length from one-half to one and one-quarter inches, have a hard,

1 Ill Bul. 44, p. 224.

smooth, shining surface, varying in color from yellowish to reddish-brown. They pupate in July and August, and transform to beetles three or four weeks later. The beetles remain in the soil and emerge the following spring. Eggs are then laid in the earth in grass land, where they soon hatch, the larvae requiring at least two years to become fully grown. The larvae are very destructive by attacking the seed in the ground before it is sprouted, and also by eating and boring the roots and stems of the young growing plant. The injury is likely to be greater the second year, after sod has been broken up. All cereal crops may be attacked. No successful remedy has yet been proposed, although fall plowing is believed to be helpful. When replanting injured maize it is customary to put the new seed between the attacked rows, which are left to stand as a food supply until cultivation becomes necessary.

Beetle and larva of wire

worm, enlarged two times. (After Forbes.)

same.

329. CUTWORMS.-There are at least fourteen distinct species of moths whose larvae have the cutworm habit. The life history of the different species, of course,

varies somewhat, but in general their injuries and treatment are substantially the The moths lay their eggs upon the leaves of grasses in meadows and pastures and the larvae feed upon the growing vegetation. The fully grown cutworm is one and one-quarter inches to two inches long and varies in color with the species from dull brown to gray or green and is variously marked with longitudinal or oblique stripes and dashes and dots. The moths lay their eggs during midsummer and partially grown larvae pass the winter in the ground. Thus when grass lands, especially of long standing, are plowed up and planted to maize, the cutworms, being deprived of other vegetation, attack the young maize plants when only a few inches high, cutting them off just above the ground. The larvae pupate during late spring and summer, some species on the fortieth parallel as early as the fourth week in May, thus permitting late planted maize to escape their attacks. Late fall plowing is measurably effective by disturbing and exposing the worms and by destroying the food on which they would feed during spring. They may also be poisoned by a mixture of wheat bran, forty pounds; molasses, two quarts; paris green, one pound, mixed with enough water to moisten. A tablespoon of this mixture placed near each hill will attract the cutworms and prove fatal.

White grub, about natural size. (After Forbes.)

330. WHITE GRUBS.-White grubs are the larvae of May beetles or June bugs, of which a number of species are known to attack maize. The beetles lay their eggs mostly during June in the earth, commonly in grass lands but not infrequently in maize land also. The eggs hatch in ten to eighteen days and the grubs are supposed to live over two full years, the complete life cycle being three years. White grubs do their injury by feeding upon the roots of the young maize plant, sometimes causing immediate destruction,

These grubs

In other cases causing prolonged and a more or less partial injury. are also extremely destructive to grass lands, in some cases causing complete destruction of the sod. The adult beetles also frequently cause considerable injury by feeding upon the leaves of deciduous trees. No thoroughly satisfactory remedy has yet been proposed for this insect.

331. CORN ROOT WORMS.-There are two species: the western corn root worm and the southern corn root worm. The larva of the western corn root worm is two-fifths of an inch long, about as large as a pin, body somewhat cylindrical, colorless, except the head, top of the first segment and a little patch on the last segment of the body, which are yellowish-brown. The injury is done by the larva, chiefly during July and August, by beginning in the tip of the maize root and working towards the plant, devouring the inner portion of the root as it goes. It pupates in the earth among or near the roots of maize. The pupae emerge in August or September as grass-green beetles about one-fifth of an inch long and half as wide. The beetles feed upon the pollen, silks and in some cases upon the soft grains at the top of the ear, but usually the injury done by the beetle is trivial. The beetle lays clusters of five to a dozen dirty-white eggs one-fortieth of an inch long in the ground, one inch to six inches deep, about the maize plant during October and November. Only the eggs survive the winter, hatching in May and June. The southern corn root worm is distinguished by the beetle being larger and having three transverse rows of four black spots on the wing covers. Since the larvae of these two species have no other host plant and since the eggs are usually laid about the hills of maize plants, a rotation of crops furnishes a simple and effective remedy for these insects. It is likewise destructive only in those sections where maize is cultivated on the same land several years in succession.

Western corn root worm, enlarged three times. (After Forbes.)

332. CORN ROot Web-Worms.-They are the larvae of at least five species of moths which lay their eggs among the grass in the summer, the larvae passing the winter in a half-grown condition. They attack the young maize plant just above ground, and when not at work they remain in a silken web just underneath the ground at the base of the plant. The fully grown larva is about half an inch long, somewhat hairy, varying in color from brown to dirty white. They pupate about June first, on the fortieth parallel. They may also attack oats.1 Their injuries to maize may be avoided by late planting. Ordinarily, injury is to be expected only where maize follows grass; the longer the land has been in grass the greater the danger.

333. CORN ROOT LOUSE.-All plant lice are enormously prolific. During the summer the wingless females of the corn root louse reproduce continuously, without the intervention of the males, living young which, when a few days old, also begin to multiply. Winged females appear from time to time and establish new colonies, while in the fall large numbers of individuals of both sexes appear. Generally the last brood lays eggs from which the spring brood is produced. Ants apparently

■ Ohio Bul 68, p. 48.

protect and care for the plant-lice in return for their secretions which they consume They are held in check by carnivorous and parasitic insects. The corn root louse does its greatest injury to the young maize plant during May and June, causing the

Corn root louse on the left and its caretaker, the ant, on the right, both enlarged. (After Forbes.)

plant to wither and die by sucking its juices. Usually these attacks are in spots throughout the field and are likely to be most injurious during unfavorable weather conditions. The injury done by these insects is variable and fitful, owing, doubtless, to their great prolificacy and the enemies which keep them in check, so that remedial measures are usually of slight avail. The corn plant louse (Aphis maidis) attacks the plant above ground, but it appears to be less injurious than the corn root louse, whose attacks are confined to the roots.

334. CORN BILL BUGS.-Several species of bill bugs are known to be injurious to maize. The adults are black beetles one-fourth to three-fourths inch long, which do their damage by puncturing the stalks and the young leaves of maize as they are unfolding. Eggs are usually laid during the spring and summer and reach the pupal stage in about one month. In some species the larvae live in the interior of the stalk, bulb or roots of small grain or timothy, and in other cases in the maize plant itself. They pass the winter in the adult form. The damage is generally comparatively slight. There is no specific remedy.

335. CORN EAR-WORM.-The larva, one and one-half inches long, varies in color from pale green to dark brown, is marked with longitudinal stripes of the same color, with eight round shining black spots on each segment of the body from which arise short hairs; the head and neck are brown. It is two to seven-brooded, depending upon the latitude. The last brood passes the winter in the pupal stage, emerging as a moth in the spring. In the Northern States the most destructive brood lays its eggs in the silk when the ears are young, and the larvae feed upon the grains at the tip of the ear, often doing great damage, not alone on account of the grain actually eaten, but also through subsequent decay by access of moisture and through destruction due to other insects. In the Southern States the earlier broods are also destructive by feeding upon the leaves and stalks. This insect is injurious to cotton by feeding upon the bolls; hence is known as the boll worm. Disturbance of the pupa by late fall plowing or early spring plowing appears to be of some value, although no remedy has been found which is entirely efficient.

336. STALK BORERS.-There are at least three species of insects which injure maize by boring in the stem, although they are often equally injurious to other plants, including weeds; namely, the stalk borer (Gortyna nitela Guen.), the smaller stalk borer (Pempelia lignosella Zeller) and the larger stalk borer (Diatraea saccharalis Fab.). The most serious injury is usually done by the latter, which in the South Atlantic States occasionally amounts to twenty-five to fifty per cent of the crop. IU. S. Dept. of Agr., Div. Ent. Cir. 16, 2d Ser.