Additions of surfactants to the isooctyl ester of (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) and the dimethylamine of 3,6-dichloro-o-anisic acid (dicamba) generally did not increase absorption or translocation of the herbicides when they were applied to foliage of five hardwood species and loblolly pine (Pinus taeda L.). Adjusting pH of the formulations to 3, 6, or 9 with a buffering solution had small and inconsistent effects upon absorption and translocation.

Treatments were applied to heavily infested johnsongrass [Sorghum halepense (L.) Pers.] in the field for 3 years. Half of each treated plot was cultivated 5 weeks after planting soybeans [Glycine max (L.) Merr.]. Dalapon (2,2-dichloropropionic acid) applied to johnsongrass foliage 7 to 10 days before plowing plus either of the following three preplant incorporated herbicides, trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], or vernolate (S-propyl dipropylthiocarbamate), gave 85, 68, and 82% johnsongrass control, respectively, at the end of a 3 year study. The preemergence incorporated herbicides applied following plowing and two diskings resulted in poor (35 to 50%) johnsongrass control with significant yield reductions in 2 of the 3 years. When the preemergence incorporated herbicides were applied following two diskings and eight rototillings, johnsongrass control was 62% after 3 years which was significantly less than the 79% control resulting from dalapon plus preemergence herbicides. Cultivation 5 weeks after planting soybeans increased johnsongrass control 22, 35, and 36% and soybean yields 439, 370, and 320 kg/ha in 1969, 1970, and 1971, respectively, over comparable plots without cultivation.

The combination of the herbicide 2-chloro-2′,6′ diethyl-N-(methoxymethyl) acetanilide (alachlor) with the insecticide 2,2-dimethyl-2,3-dihydrobenzofuranyl-7-N-methyl-carbamate (carbofuran) interacted synergistically to reduce barley [Hordeum vulgare L. ‘Larker’] but not corn [Zea mays L. ‘Michigan 400’] growth. Alachlor alone increased the respiration rate of barley. Accumulation of 14C from 14C-alachlor was greater in the plant roots than shoots. The increased accumulation of alachlor in the roots was accentuated by a reduced rate of alachlor metabolism. The basis for the observed interaction appeared to be greater alachlor uptake by barley plants grown from seed treated with carbofuran. A statistical procedure for pesticide combinations in experiments with a completely randomized design was developed for the calculation of interaction significance.

Trumpetcreeper [Campsis radicans (L.) Seem.] grown from 10-cm root sections was more susceptible to foliar applications of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and dicamba (3,6-dichloro-o-anisic acid) than trumpetcreeper grown from 45-cm root sections. Dicamba controlled trumpetcreeper better than did 2,4-D, particularly trumpetcreeper grown from 45-cm root sections. More 14C-dicamba than 14C-2,4-D was absorbed through the foliage and translocated to the roots of trumpetcreeper grown from 10-cm roots. No 14C-2,4-D was detected in the 45-cm roots; however, 14C-dicamba was recovered from both the upper and the lower sections of the 45-cm roots.

Wild watermelon (Citrullus vulgaris Schrad. var. citroides Bailey) is a widespread problem in cotton (Gossypium hirsutum L.) and grain sorghum [Sorghum bicolor (L.) Moench] planted on sandy soils. Preplant herbicide treatments did not suppress wild watermelon emergence, dry matter, or melon production. Preemergence application of fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] suppressed growth and controlled the weed. However, propazine [2-chloro-4,6-bis(isopropylamino)-s-triazine] controlled and nearly eliminated melon production. Although postemergence application of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] was effective, most postemergence treatments gave erratic control, probably because of differences in vigor from seedlings emerging from varying depths. There was no difference in emergence from seed planted 2.5 to 10 cm deep. However, emergence was lower from seed planted 20 cm deep and seedlings were less vigorous from seed buried 10 cm or deeper.

Weed control and sugarbeet (Beta vulgaris L.) injury from applications of methyl m-hydroxycarbanilate m-methyl-carbanilate (phenmedipham) were influenced by additives, volume of additive, and species in both field and greenhouse experiments. Oils were more effective than the surfactant as additives to phenmedipham on green foxtail (Setaria virdis (L.) Beauv.), yellow foxtail (Setaria glauca (L.) Beauv.), redroot pigweed (Amaranthus retroflexus L.), or common lambsquarters (Chenopodium album L.). Herbicidal activity of phenmedipham on kochia (Kochia scoparia (L.) Schrad.) or wild mustard (Brassica kaber (D.C.) L.C. Wheeler var. pinnatifida (Stokes) L.C. Wheeler) was not enhanced by any additive. Linseed oil (2.34 L/ha) enhanced the herbicidal activity of phenmedipham on green foxtail, yellow foxtail, and redroot pigweed more than petroleum (2.34 L/ha) or sunflower (Helianthus annus L.) oil (2.34 or 9.35 L/ha). However, linseed oil reduced the herbicidal activity of phenmedipham on kochia.

Investigations of the behavior of 3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one 2,2-dioxide (bentazon) in water solutions have shown that it was anionic in neutral solutions by exhibiting a strong movement toward the anode in an electrical field. The herbicide was not adsorbed by any of twelve selected Illinois soils or by the cation exchange resin, carboxymethylcellulose (CMC), but was almost completely adsorbed by charcoal and by the anion exchanger, diethylaminoethylcellulose (DEAE). Bentazon moved with the water front on soil thin-layer plates as well as through soil columns.

Seeds of yellow foxtail [Setaria lutescens (Weigel) Hubb.], ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.], common cocklebur (Xanthium pensylvanicum Wallr.), jimsonweed (Datura stramonium L.), velvetleaf (Abutilon theophrasti Medic.), and giant ragweed (Ambrosia trifida L.) were buried in the soil November 20 and 21, 1966 at Urbana, Illinois for noting emergence of seedlings from April 1 through August 18, 1967. Similarly, seeds of yellow foxtail, ivyleaf morningglory, jimsonweed, velvetleaf, giant ragweed, common ragweed (Ambrosia artemisiifolia L.), and Pennsylvania smartweed (Polygonum pensylvanicum L.) were buried on October 25, 1968 for emergence observations from April 1 to August 18, 1969. Pennsylvania smartweed, giant ragweed, and common ragweed had large flushes of germination from early April through early May, with no emergence after June 1. Velvetleaf displayed similar early flushes and had additional small flushes of emergence in late May or June. Yellow foxtail seedlings also emerged in April and May in 1969 and in May and June during both years. Common cocklebur seedlings emerged abundantly in April and May but less abundantly in June. Ivyleaf morningglory and jimsonweed displayed flushes of emergence sporadically after May 1. Flushes of emergence for all species which occurred after May 1 were preceded by sufficient rainfall to bring the surface 10 cm of soil to field capacity. Cumulative heat units in the soil above 10 C were not correlated with initiation of emergence for any species. The early emergence was attributed to stimuli from general soil warming while emergence after May 1 was stimulated by favorable soil moisture from rainfall.

Treatments with the herbicide 3-(4-bromo-3-chlorophenyl)-1-methoxy-1-methylurea (chlorbromuron) were combined with seed treatments with the insecticide, 2,2-dimethyl-2, 3-dihydrobenzofuranyl-7-N-methylcarbamate (carbofuran), to measure phytotoxic interaction effects on barley (Hordeum vulgare L. ‘Larker’) and corn (Zea mays L. ‘Michigan 400’). The combination synergistically reduced radicle length in barley seedlings and reduced the leaf area and dry weight of 7-day-old corn seedlings grown in sand culture. The chlorbromuron-carbofuran combination reduced net photosynthesis in barley and corn and increased respiration in barley. The 14C from 14C-chlorbromuron preferentially accumulated in barley and corn shoots. The carbofuran seed treatment resulted in a reduced level in barley shoots and corn roots but increased the accumulation of 14C in barley roots and corn shoots. The basis for this interaction appeared related to the increased accumulation of chlorbromuron in corn and barley shoots and reduced chlorbromuron metabolism.

A 6-year study was conducted to compare the influence of 1,1′-dimethyl-4,4′-bipyridinium ion (paraquat), a mixture of paraquat and 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine), frequent mowing, hay mulch, and cultivation on growth, yield, and nutrition of peach (Prunus persica (L.) Batsch ‘Jerseyland’) trees. The growth and yield of trees which received two annual applications of paraquat or one application of paraquat plus simazine were comparable to those of trees maintained under cultivation or hay mulch. Hay mulched and cultivated trees responded comparably. Hay mulched trees had higher leaf potassium (K) and lower leaf magnesium (Mg) than the other trees. Where grass was controlled only by mowing, trees were generally lower in nitrogen (N), made less growth, and produced less fruit.

The absorption of 14C-labeled herbicides by soybean (Glycine max (L.) Merr. ‘Lee’) seed from aqueous solutions and treated soil was investigated. A comparison of the absorption of the various herbicides from aqueous solution showed that differences existed in the rate and amount of herbicide absorbed by the seed. Calculations showed that the concentration of herbicides at the seed coat surface varied with absorption time which indicated that the permeability of the soybean seed to these herbicides changed during the absorption process. The rate of absorption of isopropyl m-chlorocarbanilate (chlorpropham) and 2-chloro-4-(ethylamino)-6-(iso propylamino)-s-triazine (atrazine) by soybean seed in soil was rapid for the first 4 hr and then decreased steadily until the event of germination at which time the rate increased. When the amount absorbed by the soybean was compared with that predicted by the perfect sink equation, it was found that the soybean was a better sink during the first few hours than afterwards. The amount of herbicide moved to the seed in the imbibed water could not account for the total amount of chlorpropham absorbed indicating considerable contributions from diffusive transport. Only during the initial 4-hr period was uptake of atrazine greater than that moved to the seed by mass flow.

Qualitative and quantitative oil content of corn (Zea mays L.) kernels as influenced by herbicides was measured by gas-liquid chromatography. Alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl) acetanilide] at 0 to 6.7 kg/ha, atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] at 0 to 5.6 kg/ha, linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] at 0 to 3.4 kg/ha, prometryne [2,4-bis(isopropylamino)-6-(methylthio)-s-triazine] at 0 to 3.4 kg/ha, and cyanazine [2-[4-chloro-6-(ethylamino)-s-triazine-2-yl]amino-2-methylpropionitrile] at 0 to 7.8 kg/ha were evaluated. Oil quantity was not greatly influenced by any of the herbicides; however, percentage corn oil fatty acid composition was altered to a minor but statistically significant degree by each of the herbicides. The use of alachlor, cyanazine, atrazine, linuron, or prometryne on corn at recommended rates or at rates greater than currently recommended field application rates did not induce serious changes in either total oil content or fatty acid distribution in corn.

Radicle length of barley (Hordeum vulgare L. ‘Larker’) seedlings was greatly reduced by the combination of the herbicide S-ethyl diisobutylthiocarbamate (butylate) applied in combination with the insecticide 2,2-dimethyl-2,3-dihydrobenzofuranyl-7-N-methylcarbamate (carbofuran). Corn (Zea mays L. ‘Michigan 400’) seedlings were not similarly affected. Carbofuran interacted with butylate to reduce synergistically the root and shoot growth of barley but not that of corn. The combination of these two carbamate pesticides synergistically increased respiration in barley. The basis for these interaction effects in barley appeared to be decreased metabolism of butylate and increased respiration in the presence of carbofuran. Although the same metabolism trend was apparent in tolerant corn, the butylate level was much lower since the absorption of butylate was reduced by the carbofuran seed treatment. The 14C from 14C-butylate preferentially accumulated in barley shoots and corn roots.

Tubers of yellow nutsedge (Cyperus esculentus L.) were buried in the field 2.5 to 30.5 cm below the surface in November 1969 and 1970 at Urbana, Illinois. In both years, shoots began to emerge the following May and continued emergence until July. Very few additional shoots emerged after July. Shoots emerged from less than 2% of the tubers buried at 2.5 cm; the maximum number of shoots emerged from tubers at the 10.2 and 20.3-cm depths. Tubers at the 2.5 and 5.1-cm depths were more susceptible to winterkill than tubers at lower levels, probably because of the differences in soil temperature at these levels during cold periods. Kinetic analysis of laboratory-determined tuber viability for periods up to 22 months revealed that the half-life was 4.4 and 5.7 months for tubers buried at 10.2 and 20.3 cm, respectively. The extrapolated minimum temperature required for initiation of tuber germination in the laboratory was 12 C. This temperature minimum could not readily be related to initial shoot emergence in the field. The temperature at which 50% of the tubers survived a cold treatment for 4 to 48 hr was −7 C.

The competitiveness of annual weeds in irrigated sweet Spanish onions (Allium cepa L.) was studied at North Platte, Nebraska, during 1969 and 1970. Weeds allowed to grow in the row for 2, 4, 6, and 8 weeks after onion emergence reduced onion yields 20, 20, 40, and 65%, respectively. When plots were kept weed-free until onion emergence and 2, 4, 6, 8, 10, and 12 weeks after emergence, onion yields were reduced 100, 99, 87, 75, 46, 25, and 5%, respectively. Redroot pigweed (Amaranthus retroflexus L.), kochia (Kochia scoparia L.), and grass weeds accounted for 54, 21, and 21%, respectively, of the total weed yield.

Seasonal variation in flowering of common dandelion (Taraxacum officinale Weber) was studied in 1969 and 1970 at Bowling Green, Kentucky. At this location the dandelion flowered throughout the year. Maximum flowering occurred during April and a secondary peak occurred in September and October. Number of flower stems per square meter was not significantly correlated with precipitation, temperature, or day length. Length of stem was positively correlated with temperature and day length. The plants exhibited diurnal variation in flowering habit. Number of times (or days) the heads opened and closed, length of time in which the heads remained open each day, and length of time heads remained closed before opening into mature heads (white balls) varied with time of year.