Morphological and chemical characteristics of 11 warm season pasture weed species were defined. Goldenrod (Solidago altissima L.) was significantly taller and common ragweed (Ambrosia artemisiifolia L.) had the largest canopy diameter of the 11 species studied. Species ranged from 14 to 134 cm in height with canopy diameters of 25 to 70 cm. No direct correlation was found between individual leaf size and total leaf area. Macro- and micromineral content varied widely among species but all values obtained were considered high enough to meet the requirements of ruminant animals. Redroot pigweed (Amaranthus retroflexus L.) and horsenettle (Solanum carolinense L.) contained potentially toxic levels of nitrate. Five of the 11 species contained sufficient crude protein for ruminants and six of the 11 species were more than 50% digestible. Digestible energy values averaged 1.9 Mcal/kg for the 11 weeds evaluated.

Tall morningglory [Ipomoea purpurea(L.) Roth] seeds were germinated at various temperatures and dry weight conversion measured at 24, 48, 72, 96, and 120 hr. Germination and dry weight conversion were slower at the lower temperatures although both occurred. Tall morningglory could germinate and become established over a wide range of temperatures. Some herbicides were effective in reducing germination, and dry weight conversion was reduced most with the dithiocarbamates followed in sequence by the amides, benzoic acids, uracils, dinitroanilines, phthalamic acids, triazines, and ureas.

Electrophoretic analysis of storage protein accumulation in developing cowpea [Vigna unguiculata(L.) Walp. ‘Mississippi Purple’] seed indicated that a large increase in protein content per seed occurred between 10 and 11 days after flowering (DAF). Polypeptides with molecular weights of 54, 49, and 41 kilodaltons (kD) accumulated first, and one with a molecular weight of 59 kD appeared 2 days later at 13 DAF. Treatment of plants with glyphosate [N-(phosphonomethyl)glycine] when pods were 7 and 10 DAF prevented accumulation of the major storage protein polypeptides. The accumulation of these polypeptides was not inhibited as much when pods were 11, 12, or 13 DAF at the time of treatment with glyphosate. Pod length and seed fresh weight were inhibited by glyphosate treatment of plants bearing pods 7, 10, 11, and 12 DAF. Pod width, seed dry weight, and seed length were inhibited by glyphosate when plants bearing pods 7, 10, and 11 DAF were treated.

Emergence of tall morningglory [Ipomoea purpurea(L.) Roth] seedlings was delayed and reduced as planting depths increased from 1.3 to 5.0 cm. Development of seedlings emerging from 3.8 cm or greater depth was delayed for up to 4 weeks as indicated by dry weight accumulation. In both greenhouse and field studies, chemical control of tall morningglory was generally greater when seedlings emerged from planting depths of 2.5 cm or greater. The competitive ability of tall morningglory, as indicated by yield reduction of cowpea [Vigna sinensis(L.) Endl], was dependent upon both planting depth and duration of infestation. Cowpea yields were reduced more by the tall morningglory plants that emerged from 1.3 cm than by those that emerged from greater planting depths for a given infestation period.

Smutgrass (Sporobolus poiretii Roem and Schult.), a prevalent and increasingly serious weed problem in pasture areas of the southeastern United States, cannot be selectively controlled in swards containing desirable forage species with the available recommended procedures. Dallisgrass (Paspalum dilatatum Poir.)‐bermudagrass (Cynodon dactylon (L.) Pers.) pasture swards, the most prevalent type of pastures in our region, were selected for uniform infestation of smutgrass and treated with atrazine [2‐chloro‐4‐(ethylamino)‐6‐isopropylamino)‐s‐triazine] at 4.48 and 8.96 kg/ha; bromacil (5‐bromo‐3‐sec‐butyl‐6‐methyluracil) at 2.24 and 4.48 kg/ha; and MSMA (monosodium methanearsonate) at 2.24, 4.48, and 8.96 kg/ha in the fall of 1970 and 1971. From 83 to 97% smutgrass control was obtained with a single application of atrazine or bromacil with no more than 38% injury to bermudagrass and 28% injury to dallisgrass. Maximum smutgrass control obtained with MSMA application was 63% which also resulted in 89% dallisgrass control. Forage quality determinations in the spring following smutgrass control indicated that total forage was more acceptable when smutgrass was controlled.