The uptake, translocation, and fate of (2,4-dichlorophenoxy)acetic acid (2,4-D) were compared in nightflowering catchfly (Silene noctiflora L.) and common lambsquarters (Chenopodium album L.), resistant and susceptible species, respectively. Nightflowering catchfly leaf sections absorbed more 2,4-D from 5 × 10-4 M and 5 × 10-6 M 2,4-D solutions at pH 3.0 than did leaf sections of common lambsquarters. Intact plants of both species accumulated 2,4-D in the stems and leaves below the treated leaf. At 72 hr after treatment, nightflowering catchfly released 2,4-D through the roots into the nutrient solution while common lambsquarters continued to accumulate 2,4-D. Nightflowering catchfly metabolized 2,4-D and the metabolite was recovered in the roots 24 hr after treatment, whereas common lambsquarters did not metabolize 2,4-D.

Lithium salt of (2,4-dichlorophenoxy)acetic acid (2,4-D) (1000 ppm) was sprayed on plants of curly dock (Rumex crispus L.) 12 days before anthesis, at an thesis, 7 days after anthesis, and 34 days after anthesis. Treatment 12 days before anthesis completely prevented the formation of viable seeds. Two percent of the seeds had minute embryos after treatment at anthesis, but even these seeds did not germinate. Embryos were present in 91% of the seeds from plants treated 7 days after anthesis. These embryos ranged in size from 0.5 to 2.5 mm. The total weight of seeds obtained was significantly less than the control and only 5 to 15% of these seeds were capable of germination. Spraying the inflorescences 34 days after anthesis did not affect the number of seeds produced or seed viability. Almost all plants remained alive after the harvest.

Neutron-activation analyses of arsenic were reproducibly quantitative at 10 ng As and might be extended as low as 3 ng As with extended counting periods. The method was tested on soil and cotton (Gossypium hirsutum L., var. Atlas 67) leaves treated with repeated applications of monosodium methanearsonate (MSMA). Leaves from untreated plants contained 55 ng As/g whereas leaves from treated plants showed higher levels of arsenic. Translocation of As was demonstrated and analysis of arsenic in the soil was valid.

Granular 4-amino-3,5,6-trichloropicolinic acid (picloram) was effective in controlling live oak (Quercus virginiana (Mill.), huisache) (Acacia farnesiana (L.), Willd.), and yaupon (Ilex vomitoria Ait.), but not honey mesquite (Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockerell) in south Texas. Granular 5-bromo-3-sec-butyl-6-methyluracil (bromacil) controlled live oak and huisache. Herbicides applied to soil were usually most effective in spring and fall during periods of active brush growth. Picloram granules applied in May to a mixed stand of woody plants in Puerto Rico usually were effective. However, rates up to 30 lb/A were ineffective on some species.

Four substituted pyridazinone compounds inhibited the Hill reaction and photosynthesis in barley (Hordeum vulgare L., var. Dayton C.I. 9517). These inhibitions appeared to account for the phytotoxicity of 5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone (pyrazon). The pyridazinone chemicals were weaker inhibitors than 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine). Two substitutions onto the molecular structure of pyrazon result in a new experimental herbicide, 4-chloro-5-(dimethylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone (hereinafter referred to as 6706), which retains the action mechanism of pyrazon but also has two additional biological properties. It is resistant to metabolic detoxication in plants, and it possesses a second mode of action involving interference with chloroplast development. The second action is like that expressed by 3-amino-s-triazole (amitrole) and by 3,4-dichlorobenzyl methylcarbamate (dichlormate). However, the new chemical is 100 to 1000 times more effective. The trifluoromethyl substitution on the phenyl ring and the dimethyl substitution on the amine are both required to give either of the two additional physiological properties. Analogs with only one of the two substitutions behave like pyrazon rather than like 6706.

Chemical fallow with 2,2-dichloropropionic acid (dalapon) reduced the yield of non-seeded perennials more than mechanical fallow with sweep blades in the year of treatment. However, plants derived from seed left at the soil surface resulted in greater yields of nonseeded perennials on chemical than on mechanical-fallow plots the year following treatment. Each fallow method increased annual herbage yields the year after treatment as compared with directly-seeded plots. Litter was greatly reduced in the year of and in the year after mechanical fallow. However, the amount of litter on the chemical fallow plots was very high in the year of treatment and declined in the succeeding year. Success of seeding crested wheatgrass [Agropyron desertorum (Fisch, ex Link) Schult.] was slightly better after mechanical than after chemical fallow. Yield of crested wheatgrass in the year after planting was about the same for the mechanical fallow and the higher rate (10 lb/A) of dalapon. There was more available soil moisture to a depth of 30 inches in fallowed than in non-treated plots; but the small amount of moisture saved by fallow probably is immaterial to seeding success.

Evaluations were made of the α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) distribution patterns produced by eight incorporating implements. The power rotary cultivator concentrated the trifluralin in the top inch when operating at a 4-inch depth, while the disk, operated at the same depth, concentrated the trifluralin at a point 2 to 3 inches below the surface. All the remaining implements resulted in more than 80% of the recovered trifluralin in the top inch, except for isolated treatments with the Richardson and Lilliston tools. Surface applications resulted in less trifluralin recovery than from any implement. The disk resulted in the highest recovery and was two to three times greater than the recovery from the surface application. The recovery from the Richardson, Lilliston, and Ro-Wheel was 1.5 to 2 times greater than the recovery from the Mix-A-Product, field cultivator, and spike harrow.