During 1950-1957 investigations of sorghum midge (Contarinia sorghicola (Coq.) ) were made with respect to hosts, sorghum varietal susceptibilities, life history and seasonal populations, with particular reference to the factors influencing development from diapause. All major hosts recorded are members of the genus Sorghum. Minor hosts include several native grasses, of which Dichanthium sericeum is the most common, but these hosts have no real influence on pest populations in sorghum crops. Differential varietal susceptibilities amongst commercial sorghums are not evident, although preferences in sites for oviposition are shown under certain conditions.

SynopsisIn zero-tillage wheat stubble plantings, seed firmer press wheels significantly increased sorghum stands in one trial but not in another. Seed firmer and driver-press wheels were evaluated alone and in combination in wheat stubble plantings (5 trials). Mean stand increases varying from 8 to 34% were obtained. Press wheels were valuable in increasing stands and yields of grain sorghum grown under zero tillage. Fall disking of sorghum stubble increased stands and grain yields.

SynopsisIn laboratory studies, the relation between soil strength and grain sorghum emergence was established for 6 soils. Soil moisture tension, planting depth and plant species affected the emergencea t specified soil strengths. Soil temperaturea ffected the rate of sorghum emergence but not the relation between soil strength and final emergence.

Each ton of high quality manure was equivalent to 22 lb of nitrogen from ammonium nitrate as measured by equivalent grain sorghum (Sorghum vulgare Pers.) yields over a 4-year period. Phosphorus level of the soil by the Bray and Kurtz no. 1 procedure was increased by 1 ppm for each ton of applied manure. Commercial phosphorus fertilizer did not increase grain yields. Total N content of the surface soil was increased by all manure treatments. Nitrogen uptake by grain was correlated with relative yield of grain. The forage portion of sorghum appeared to take up N in excess of needs for maximum grain yield.

SynopsisWheat, sorghum, sudangrass, and tomato yields were reduced by compacting a silt loam soil to a bulk density of 1.6 g./cm.³. Severe compaction delayed maturing of wheat by several days and tomato ripening by two weeks. Soil condition was ameliorated in one year to the extent that second and third crop wheat yields were not reduced significantly by the initial compaction treatments.

SynopsisSeeding rates in excess of 4 pounds per acre generally reduced grain sorghum yields under dryland conditions in southeastern Colorado. The RS 610 hybrid yielded highest at the 2-pound seeding rate. Grain yields from 21-inch and 42-inch row spacings were not significantly different when the same amount of seed per acre was planted. Plant populations apparently have more effect on yield than do row spacings.

SynopsisTen grain sorghum hybrids were treated in 1961 and 1962 with 3 pounds per acre propazine preemergence, 3 pounds per acre atrazine postemergence, and cultivation. Each year differences among hybrids were significant, but the hybrid ✕ treatment interaction was not significant. Chemically treated plots significantly outyielded cultivated plots in 1961; they bloomed slightly earlier and were slightly taller in 1962.

SynopsisIn 34 trials, grain yields in 20-inch rows exceeded those in 40-inch rows by 10% in eastern Kansas and 7% in central Kansas. Grain yields were remarkably constant across stand densities because of intercompensations among individual components of yield. Little tendency for row width and stand density interaction was noted.