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It has been conceived that the quality of forage crops is generally inferior in the warmer areas than that in the colder areas of Japan, though scarcely reliable proofs for the fact having been given hitherto. In the present study, the authors investigated the effects of various growing seasons in Kyushu on the growth behavior, structure and chemical composition of corn plants the samples of which were seeded April 15, June 15, and August 15. respectively. A good many reports given in the past on the physiological studies of environmental effects upon such crop plants seem to have more or less unduly neglected the problems of the age of the plant materials for experiments. In the study by the present authors, an early variety, Northwestern Dent Corn, were conveniently used as material, because the final number of leaves on the main stem showed only a very little variation among individual plants of this variety, and so the growth stages could be identified so clearly that the effects due to the environments were distinguished from those due to the age of the plant. Internodes of a definite position from the sample plants were used in the physical, histological and chemical examinations. It was found as the result that the period from planting to tasselling was shortened by late planting, and that the leaf emerging in the main stem was faster when planted June 15 or August 15 than when planted April 15. The plant was tallest when planted June 15. The period, from planting to beginning of elongation of internode was longer when planted April 15 than, when planted June 15 and August 15. The lower internodes of corn plant were longer, and the middle internodes were short when planted April 15. The internodes were harder in the lower portions of stem than those in the higher portions. The hardness of internode increased with advance of growth stage. However, there was not remarkable difference between the hardness of internode of each plot at the same growth stage. When corn was planted August 15, the internode was harder at the former part of growing stage than those of the other two plots. The degree of lignification of internode was approximately parallel to the hardness. Crude protein content and crude ash content were higher through out the growing season when planted August 15 than when planted April 15 and June 15, but crude fiber content was not lower in the former case than that of the latter cases.

AT least one mid-Western seed company has asserted that 'round-grade' dent corn (maize) seeds withstand more than 'flat-grade' seeds the cold weather after early spring sowings.

A study of the habits of the rice weevil, Sitophilus oryzae (L.), as related to infestations in dent corn, yielded several observations which help to explain the spotty nature of field infestations.

Larvae of the European corn borer, Ostrinia nubilalis (Hubner) (Lepidoptera: Pyralidae), reared continuously on a meridic diet lost their ability to survive on a susceptible inbred line of dent corn, but survival equal to that of wild borers could be recovered by 1 backcross to the wild parent. The trait is therefore genetically controlled.

Yao, B., and Tuite, J. 1989. The effects of heat treatment and inoculum concentration on growth and sporulation of Penicillium spp. on corn genotypes in storage. Phytopathology 79:1101-1104. The effects of heat treatment and inoculum concentration of Penicillium was greater for the resistant hybrids but the disease rankings among the brevi-compactum, P. cyclopium, and P. viridicatum on storability of corn genotypes remained. The heat-treated resistant hybrids did not support kernels were determined in separate tests for 10 genotypes of dent corn significantly more sporulation of Penicillium than the unheated, susand a visual flint (VF) selection. Hand-shelled corn grown during ceptible genotypes. In three tests, a total of I I corn genotypes were 1983-1985 was used. Kernels of B73 X Mo17 and Dekalb XL67, resistant, inoculated with 2 X 10' to l04 or 2 X 103 to l0' spores of Penicillium and H95 very susceptible and VF, moderately susceptible to storage spp. per gram of corn and stored at 13-14 C and 88% RH. Increasing Penicillia were heated at 80 C for 20 min, then inoculated with 2 X 103 the inoculum to either 104 or l05 spores/g generally had no significant spores/g and stored at 88% RH and 14 C for 49 days. Host reaction effect on relative resistance as measured by propagules and visible mold, was determined by a visible mold rating on individual kernels and number although there was an increase in propagules with an increase in the of propagules isolated after dilution on a modified potato-dextrose agar. amount of inoculum, particularly when 2 X 104 or 10 spores/g was used. Molding was substantially increased by the heat treatment as measured There appeared to be a more defined separation of hybrids with inoculum by propagules and less so by visible mold for all four genotypes. Increase at 2 X 104 and 105 than at 2 X 103 spores/g. Additional keywords: maize, storage molds.

Samples of high-temperature-dried yellow dent corn stored in the laboratory at moisture contents of 14.5-19.5% suffered increasing invasion by storage fungi, increasing loss in dry matter, and an increasing percentage of damaged (brown to black) germs with increasing moisture content and increasing time of storage. Invasion of the germs by storage fungi (especially Aspergillus glaucus) preceded any detectable weight loss and change in germ color. By the time the dry matter loss had reached 0.5-1.0% the germs of the corn kernels had been extensively invaded by storage fungi

plants to the east and west of these Knoke, J. K., Louie, R., Madden, L. V., and Gordon, D. T. 1983. Spread of maize dwarf mosaic mares in eah row were surveye virus from johnsongrass to corn. Plant Disease 67:367-370. resulting in 200 10-plant samples per plot. Spread of maize dwarf mosaic virus (MDMV) from introduced virus-infected johnsongrass to Disease incidence was recorded as the adjacent susceptible corn in experimental plots was evaluated during 1979 and 1980. The proportion of plants in each sample that relationship between MDM incidence in corn and distance from the source was adequately showed disease symptoms. Straight-line described by the model Y = a(exp(-bD)), where Y is disease incidence at distance D from the distances from the johnsongrass to the source, b is the spread coefficient, and a is the scaling factor. In both years, b was significantly center of each 10-plant sample were greater than zero, demonstrating that MDMV spread to the corn test plots. In control plots with no calculated. For regression analysis, intentionally placed virus source, b values and disease incidence were lower than in test plots. For a incidence data in each plot were grouped single planting in 1979, the steepness of the gradient of disease incidence from the source (quantified in 1-m intervals, eg, all observations by b) decreased with time as fewer plants remained uninfected. For two successive plantings in 1980, no significant difference in b values was observed. MDMV spread also was not related to 20-21 m from johnsongrass were prevalent wind direction. No spread of maize chlorotic dwarf virus (MCDV) to corn was observed averaged to calculate incidence at 20.5 m. by symptomatology even though 90 and 50% of the johnsongrass plants were infected in 1979 and In 1980, PAG 246006 and Agway 1980, respectively, as indicated by enzyme-linked immunosorbent assay. The leafhopper vector of XP708 were each machine-planted in MCDV, Graminella nigrifrons, was also present during both years. The presence of MDMV in the four plots on 11 June, 15 July, 8 August, control plots indicates that there were virus sources other thanjohnsongrass or that MDMV moved and 4 September. The sweet corn hybrid more than 400 m from johnsongrass to the control plots. Agway XP708 is susceptible to MDMV and MCDV, whereas the dent corn

Temperature and moisture requirements for germination of conidia and growth on agar were determined for 14 species of Penicillium isolated from corn kernels. Species isolated mainly from unharveste...

The older maize varieties of the southern United States are of interest for two reasons: (1) Some of them were extensively used in developing the more highly derived varieties of the United States corn belt. (2) They show a strong affinity to the dent corns of central Mexico. When their history can be worked out in more detail, it should shed significant light on the relationships of the brilliant civilizations of central Mexico and the lands to the north. In the states east of the Mississippi, maize has had, on the whole, a relatively simple history. As we have demonstrated (Brown & Anderson, 1947), the northern flints were widely distributed in pre-Columbian times in the northeastern states where they were the only type of corn grown over a considerable area. In the Gulf States and spreading northward from them, there were at least two other major types of maize: (1) the old white dents, and (2) the Caribbean flints. We do not yet have any exact knowledge of when the intermingling of these southern types began. We do know that by the early nineteenth century the old southern dents were, on the one hand, being intentionally crossed with the Caribbean flints and, on the other hand, with the northern flints. From the latter union there was eventually developed the distinctive, cylindrical dent corn of the United States corn belt. Today in the southern states one may still find authentic samples of such old dent varieties as Gourdseed and Shoepeg. They are not easy to come by and require extensive searching among conservative families in more or less isolated neighborhoods. Along with them are more modern varieties derived from crosses with the northern flints, with Caribbean flints, and with corn-belt varieties from farther north. For the purpose of this study we have made a rough grouping of the material under observation as: (1) old southern dents, (2) derived southern dents. Our collections of these corns were reasonably complete and our survey is a comprehensive one, particularly in relation to the role played by these varieties in the development of the maize of the United States corn belt. The Caribbean flints, although undoubtedly involved, were peripheral to the area covered by our studies and have therefore been omitted from this survey. These tropical flints, because of their wide distribution in both hemispheres, deserve exhaustive analysis, but to be carried on effectively such a study would require adequate experimental fields in a subtropical environment. The methods used in this study were essentially those applied to previous surveys of maize in the United States and Latin America. A few selections were