Application of 10-8 M 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine) to the roots of 10-day old barley (Hordeum vulgare L. ‘Coho’) seedlings grown in nutrient cultures increased the water-soluble protein content when grown at 20 C day, 15 C night with 3 mM nitrate nitrogen. The water-soluble carbohydrate content decreased with increases in water-soluble protein. In a time-course study simazine increased 14C-leucine incorporation into protein prior to increasing nitrate uptake, indicating that simazine may have a direct influence on protein synthesis. The nonherbicidal metabolite of simazine, 2-hydroxy-4,6-bis(ethylamino)-s-triazine (hydroxysimazine), did not affect 14C-leucine incorporation into protein.

Seven cultivars of spring wheat (Triticum aestivum L.) and one hybrid (Triticale hexaploid Lart. ‘Rosner’) were evaluated in seven field experiments and one greenhouse test for tolerance to the postemergence application of the sodium salt of trichloroacetic acid (TCA) for the control of green foxtail (Setaria viridis (L.) Beauv.). The control of green foxtail and broadleaf weeds was also studied. Of the seven cultivars, ‘Pitic 62’ and ‘Stewart’ were most susceptible to injury from TCA. All other cultivars were tolerant to 0.56 kg/ha. ‘Selkirk’ appeared to be most resistant. With ‘Manitou’ 0.56 kg/ha of TCA gave about 50% control of green foxtail. Higher rates permitted increased growth of broadleaf weeds as a result of reduced competition from injured wheat and green foxtail. Control of all weeds was improved by 10 to 30% when TCA was applied with one of the phenoxy herbicides. Satisfactory crop tolerance and good weed control was achieved with 0.56 kg/ha TCA and 0.56 kg/ha of the amine salt of (2,4-dichlorophenoxy)acetic acid (2,4-D).

Autoradiographic studies showed that regardless of whether 5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone (pyrazon) was applied to the leaves or to the roots of sugar beet (Beta vulgaris L.) plants, it moved in the apoplastic system. The pattern of pyrazon distribution from root absorption in sugar beet seedlings was identical at either 35 or 18.3 C. However, root absorption at 35 C was twice as great as at 18.3 C; and translocation of pyrazon into the shoot was more rapid at the high temperature. A major metabolite of pyrazon, a pyrazon-glucose conjugate, was produced in leaves and cotyledons but not in roots of sugar beets. A minor metabolite, less than 5%, was found in sugar beet leaves. Pyrazon was not metabolized by the susceptible species common lambsquarters (Chenopodium album L.). The rate of pyrazon-glucose conjugate formation in pyrazon-infiltrated sugar beet leaf discs was practically identical at 35 and 18.3 C. Therefore, it was concluded that the increased susceptibility of sugar beets to pyrazon at higher temperatures was due to an increase in absorption and translocation of the herbicide at higher temperatures which was not accompanied by a parallel increase in the conversion of pyrazon to its glucose conjugate.

Investigations were undertaken to ascertain whether residues of soil-applied carbaryl (1-naphthyl N-methyl carbamate) and diazinon [O,O-diethyl-O-(2-isopropyl-4-methyl-6-pyrimidyl) phosphorothioate] insecticides may be absorbed from the soil and translocated to foliage of rice (Oryza sativa L. ‘Nahda’) and to determine the phytotoxic interaction between them and foliar-applied propanil (3′,4′-dichloropropionanilide). Results from greenhouse studies showed that carbaryl and diazinon were translocated and affected hydrolytic activity in rice shoots at all rates of application. Carbaryl was more inhibitory but diazinon persisted longer in the soil. When propanil was applied in the presence of diazinon, no additive phytotoxicity occurred on rice plants over that occurring from propanil alone. Synergistic effects in rice, resulting in dry weight loss, were marked when soil was treated with 5 mg of diazinon per kilogram of soil and subsequently sprayed with propanil. Synergistic phytotoxicity was apparent when propanil was applied 1 day after carbaryl treatment and most plants were killed. Slight injury was noticed on plants treated with propanil 2 weeks after carbaryl treatment at 1 and 5 mg/kg.

Effects of herbicide combinations on aquatic invertebrates were evaluated in Inglis Reservoir, which is located in west coastal Florida. The addition of 6,7-dihydrodipyrido [1,2-a: 2′1′-c]pyrazinediium ion (diquat) plus the triethanolamine complex of copper sulfate (TAC) and diquat plus copper sulfate pentahydrate (CSP) for control of hydrilla (Hydrilla verticillata Casp.) decreased the number of invertebrates inhabiting the treated areas. The diquat plus CSP combination exerted the greatest effect upon invertebrate numbers. Both herbicide combinations, however, did alter significantly the number of taxonomic groups in the areas. Invertebrate declines were due more generally to resultant habitat changes (i.e., loss of hydrilla) than to direct herbicide toxicity. The response of fish to the effects of the herbicide treatments on invertebrates could be ascribed to dietary changes, decreased growth rates, and possible mortality.

Thirteen soil-incorporated herbicides, mainly of the dinitroaniline and carbamate groups, were evaluated in the greenhouse for selective control of hemp broomrape (Orobanche ramosa L.) in tomato (Lycopersicon esculentum Mill. ‘Rutgers’). Hemp broomrape readily parasitized tomato roots and competed vigorously with the host. Shoots of the parasite emerged within 6 weeks after inoculation. Herbicides at 0.1 to 10.0 ppmw, with one exception, significantly reduced shoot dry weight of tomato measured at 10 weeks after treatment, in comparison with untreated, noninoculated controls. Generally, the degree of inhibition of establishment of the parasite was correlated with herbicidal injury to tomato. None of the treatments prevented the establishment of the parasite without causing severe crop injury. However, N-n-propyl-N-tetrahydrofurfuryl-4-trifluoromethyl-2,6-dinitroaniline (CGA-14397, ER-9063) at 3.3 and 6.6 ppmw exhibited some degree of selectivity as indicated by relative shoot dry weights of the host and parasite. Activated charcoal applied as a root dip on tomato or in soil admixtures prior to transplanting had no effect on parasitism and growth of hemp broomrape.

Fall-applied 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine) and α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) satisfactorily controlled annual and biennial weeds in tall bearded iris (Iris germanica L.). Increased application rates improved control of semitolerant weeds. Trifluralin controlled grass weeds better than simazine. Simazine caused leaf tip and root necrosis, and trifluralin prevented root growth of iris plants when incorporated in the root zone at high rates of application.

Proso millet (Panicum miliaceum L. ‘Turghai’, ‘M28’, and ‘Panhandle’) was planted at three or four dates from late April to late June in 1970, 1971, and 1972 on silt loam soil and in 1972 on sandy soil. A single spray application of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) at 2.24 kg/ha on half of each date plot was preemergence to the first date and preplanting to the last two or three dates of planting. Proso millet was not injured by atrazine. At each date, weed control was better on sprayed than on untreated plots. Foxtails (Setaria spp.) were the only weeds present after all plots on silt loam soil were sprayed postemergence with (2,4 dichlorophenoxy)acetic acid (2,4-D). Millet planted early produced higher yields than millet sown at normal planting dates if foxtail competition was not serious. Use of selective herbicides and spring planting offer a potential major gain in the profitability of millet production in areas where annual weed problems now relegate millet to summer planting.

Preemergence flame weeding followed by postemergence herbicide treatment was the best procedure found for controlling weeds in field plantings of two Dioscorea species. Of eight herbicides tested in one or more of five experiments, norea [3-(hexahydro-4,7-methanoindan-5-yl)-1,1-dimethylurea] gave the best weed control without crop injury. Two applications of norea (3.8 kg/ha each) controlled most weeds for one growing season. Better control resulted when plots were flamed one or two times before crop emergence and treated one or two times subsequently with norea. Although new growth developed in most cases when emerged Dioscorea shoots were destroyed by flaming, yields from plots so treated were low.