Many acid herbicides must be methylated before analysis by gas-liquid chromatography. Several reagents were evaluated for the esterification of substituted acid herbicides. Esterification by the different methods was determined on 2,3,6-trichlorophenylacetic acid [fenac], 2,3,6-trichlorobenzoic acid [2,3,6-TBA], 4-amino-3,5,6-trichloropicolinic acid [picloram], 2-methoxy-3,6-dichlorobenzoic acid [dicamba], and 3,6-dichlorosalicylic acid, a possible metabolite of dicamba. The effect of substituent size and position is discussed in relation to esterification. The best methylating reagent for acid herbicides was diazomethane although it is toxic, explosive, and more costly than the other methods. BF3-methanol was equally as good when the compound was not sterically hindered. Water interfered with the esterification efficiency of all reagents. Diazomethane esterified the ammonium salt but not the sodium salt of the acids used.

Preemergence applications of 5-bromo-3-sec-butyl-6-methyl-uracil (bromacil) and mixtures containing bromacil controlled both broadleaf and grass weeds best, and increased seed production and quality in side-oats grama [Bouteloua curtipendula (Michx.) Torr.] fields. Other herbicides significantly reduced broadleaf weeds but did not control grass weeds. The most troublesome grasses were foxtails; bristly foxtail [Setaria verticillata (L.) Beauv.] was the most prominent. Weed competition, in plots where herbicides were ineffective, significantly lowered seed production. Excessive rainfall after treatment was probably responsible for decreased weed control and increased crop damage from some of the herbicides. Applications of 2,3,5-trichloro-4-pyridinol (pyriclor) resulted in early crop chlorosis.

Visible symptoms of injury in susceptible oat plants were not apparent until 4 days after initial exposure to 1 ppm 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) solution. However, the herbicide affected normal absorption and translocation over this period of time. The expected translocation and uniform distribution of xylem transported atrazine-C14 was stopped after 2 days of exposure to atrazine. The reduction in translocation of atrazine-C14 to the shoot apices in early stages of herbicidal injury was not due to reduced asborption but very likely to some other factor such as reduced transpiration. Reduction in atrazine-C14 absorption reduced translocation to the shoot apices, but this probably was not an important factor in the early stages of injury. Absorption of atrazine-C14 by oat plants was not reduced until 3 days of exposure to atrazine. A reduction in carbohydrate concentration, resulting in injury to root tissues, may be responsible for reduction in total atrazine-C14 absorption.

Virginia chain fern (Woodwardia virginica (L.) Smith) was controlled by 2,6-dichlorobenzonitrile (dichlobenil) in cranberry bogs on a St. Johns soil at Chatsworth, New Jersey, in experiments conducted during 1960, 1961, 1962, 1963, and 1964. The treatments were applied at emergence of the weed. Stalk counts of the fern were recorded the year following treatment. Excellent control was obtained at either 4 or 8 lb/A of dichlobenil. No re-growth occurred in subsequent years.

Experiments were conducted to evaluate the preplant incorporation and preemergence activity of several herbicides for weed control in southern peas (Vigna sinensis (L.) End.). The selectivity of 4,5,7-trichlorobenzthiadiazole-2,1,3 and 4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline has been demonstrated. Eight other chemicals generally gave good weed control but resulted in injury to the peas.

Herbicides which contain primary or secondary amino groups may be detected on thin layers of silica gel G or silica gel H with 1% tert-butyl hypochlorite, followed with an aqueous solution of 1% KI and 1% soluble starch. Detection limits range from approximately 1 μg to less than 0.05 μg, depending upon the herbicide in question. The technique also appears to be effective for aromatic or aliphatic iodides.