The methyl ester of diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} mixed with soil at 1, 2, and 3 ppmw reduced the growth of Bromus species in the greenhouse as follows: downy brome (Bromus tectorum L. ♯ BROTE) more than Japanese brome (Bromus japonicus Thunb. ex Murr. ♯ BROJA) more than cheat (Bromus secalinus L. ♯ BROSE). The decrease in herbicide effect (decay) over time was described better using a second-order equation than a first-order equation. Plant response-herbicide dose relationships were described best with a cubic polynomial equation.

Bermudagrass [Cynodon dactylon (L.) Pers. ♯ CYNDA ‘Vamont’, ‘Midiron’, and Cynodon dactylon X Cynodon transvaalensis Burlt-Davy ♯ CYNTR ‘Tifway’] cultivars were tolerant to oxadiazon [2-tert-butyl-4(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1, 3,4-oxadiazolin-5-one] applied at rates up to 4.5 kg ai/ha during sprig establishment. The rate of shoot growth from sprigs after oxadiazon treatment was excellent and provided adequate ground cover within 3 months. Oxadiazon applications adversely affected root development of the Midiron cultivar as measured by the force required to uproot the sod. Root development of Vamont and Tifway after oxadiazon application was equal to that of untreated bermudagrass. Oxadiazon plus bensulide [O,O-diisopropyl phosphorodithioate S-ester with N-(2-mercaptoethyl)benzenesulfonamide] was inhibitory to both root and shoot growth of all cultivars. Metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] applications at 3 and 5 weeks after sprigging caused severe root injury to Vamont and Midiron bermudagrass.

Roller-applied picloram (4-amino-3,5,6-trichloropicolinic acid) at a concentration of 30 to 60 g ae/L gave similar control to leafy spurge (Euphorbia esula L. ♯ EPHES) as spray-applied picloram at 1.1 to 2.2 kg ae/ha. Leafy spurge control was most effective when the roller applicator was adjusted to treat a maximum amount of stem tissue with a 60 g/L picloram solution. Control was not improved by including a petroleum oil or surfactant additive. Fall applications of roller-applied picloram tended to provide better control than spring applications. When used on dense leafy spurge stands, the roller applicator applied only 40% as much picloram as spray treatments of 2.2 kg/ha. However, picloram residues in soil following roller application were similar to those from picloram at 0.3 to 1.1 kg/ha applied as a spray.

Invasion of rootplowed rangeland by blackbrush acacia (Acacia rigidula Benth. ♯ ACARI) is a problem in south Texas. Low-energy grubbing uprooted plants 1 to 2.5 m tall in densities of 50, 150, and 300 plants/ha at rates of 3.0, 1.6, and 1.0 ha/h, respectively, yielding an average plant kill of 85%. Plants grubbed above the second major lateral root sprouted. A grubbing depth of 20 to 30 cm was necessary to assure plant death. A grubbing blade modified by the addition of ripper teeth facilitated grubbing under dry soil conditions and extended the grubbing season. Contract cost for grubbing the average density of 169 plants/ha was $20.80/ha adjusted to 1983 dollars.

The rates of degradation of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] were determined in an untreated Portneuf silt loam, in soil with added organic amendments, and in soil previously treated with metribuzin. While first-order rate kinetics generally described the degradation of the metribuzin in the soil, a quadratic expression was superior. Organic amendments were found to inhibit or accelerate the rate of breakdown of metribuzin depending upon the kind of amendment. Neither a lag phase nor an enrichment was observed from prior treatment with metribuzin.

An isolation and screening procedure was developed to identify soil actinomycetes that can produce germination and growth inhibitors on agar plates. Eight of 120 isolates tested demonstrated severe toxicity on cress (Lepidium sativum L. ‘Curly’) and barnyardgrass [Echinochloa crus-galli (L.) Beauv. ♯ ECHCG]. Several isolates were observed to stimulate growth. In replicated tests using the agar screening procedure, compounds produced by microorganisms significantly inhibited germination and growth of indicator plants. Organisms shown to produce toxins in agar media did not always produce toxins when grown in submerged culture.

Emergence of sugarbeets (Beta vulgaris L. ‘MonoHy D2’) from soil was reduced by germinating kochia [Kochia scoparia (L.) Schrad. ♯ KCHSC] seed at densities greater than 1 seed/cm2 when the fungus Rhizopus sp. was present. Water-soluble exudates from germinated kochia seed did not influence Rhizopus growth in vitro or sugarbeet germination. Cell-free culture extracts of Rhizopus reduced sugarbeet germination and radicle elongation. There appeared to be an interaction between kochia and Rhizopus, but the responsible compounds were not identified.

The chemical composition and the utilization by domestic goats (Capra hircus L. ‘Saanen’) of alfalfa (Medicago sativa L.) hay and silage that contained or did not contain hoary alyssum [Berteroa incana (L.) DC. ♯ BEFIN] was studied. Alfalfa was higher in quality than hoary alyssum; crude protein (CP) was 38% higher, and the neutral- and acid-detergent fiber (NDF and ADF) were 18 and 29% lower, respectively. Less CP and more ADF were found in weedy hay than in other forages. Animal utilization, as measured by the dry-matter intake, digestible dry-matter intake, relative intake, and nutritive value index were greater for weed-free than for weedy forages. Hoary alyssum was more deleterious in chopped silage than in long hay, because of selective refusal of the weed by goats that were fed hay. The presence of hoary alyssum in alfalfa decreased its utilization by ruminants.