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.

In field studies 0.1 ppmw ae or less 2,4-D [(2,4-dichlorophenoxy)acetic acid] applied by sprinklers in 5.1 cm of water over 8 h did not affect the number or dry weight of leaves or length of canes of 1-yr-old Concord grape plants (Vitis labrusca L.). A second application at 0.01 ppmw or higher to the same plants 1 yr later reduced growth of leaves, canes, and trunk. Combined effects of root pruning (required to position plants for treatment the second year) and 2,4-D probably account for this apparent anomaly. When 2,4-D was applied annually at 1.0 ppmw or less to established plants for three consecutive years, growth, yield, and fruit quality were not affected. No residues of 2,4-D were detected in the fruit at harvest (detection limit 0.05 ppmw). Grapes treated with 1.0 ppmw 2,4-D developed moderate injury symptoms.

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.

Acid-scarified hogpotato (Hoffmanseggia densiflora Benth. ex. Gray # HOFDE) seed incubated in distilled water germinated at least 94% when incubated at constant 15, 20, 30 C, and at alternate 20/30 C (20 C for 16 h and 30 C for 8 h) temperatures. Highest germination in buffered solutions occurred at pH 5.0 and 6.0 with reduced germination at lower and higher pH levels. Sodium chloride concentrations of 50 mM and greater reduced the germination rate. Percent germination after 9 days was reduced at NaCl concentrations of 100 mM and greater. Radicle lengths measured after 3 days were significantly reduced with increasing NaCl concentration. Twenty-day-old hogpotato seedlings having three true leaves were able to resprout after topgrowth removal. Regrowth occurred on 15% of the seedlings approximately 15 days after top removal.

The dispersion of ethylene in the soil after application from a backpack ethylene applicator (BPEA) was determined using a bioassay of witchweed [Striga asiatica (L.) Kuntze # STRLU] seed germination. Witchweed seed were buried in packets in ridged seedbeds under field conditions. Ethylene dispersion was better when injected into the furrow than into the ridge top. Injections 30 cm deep were more effective in causing seed germination than injections 15 cm deep. Seed germination induced by ethylene injection into the furrow 30 cm deep was 13% more than that obtained from the ridge top injection 15 cm deep. Seed germination as high as 90% was obtained at soil depths to 75 cm at a horizontal distance of 100 cm from the point of ethylene injection. Ethylene diffused up to 300 cm horizontally and to 75 cm vertically to cause at least 45% seed germination in a field of Lakeland soil (Typic Quartzisamment). The BPEA was found to be an effective application tool in witchweed control operations.

Velvetleaf (Abutilon theophrasti Medic. ♯3 ABUTH) and Powell amaranth (Amaranthus powellii S. Wats. ♯ AMAPO) control with pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] was dependent on proper timing of application. Preemergence and early postemergence pendimethalin treatments provided effective control, but control rapidly diminished with later postemergence treatments, particularly on Powell amaranth. Time-course studies on the effects of pendimethalin on the growth of these species indicated that pendimethalin inhibited shoot growth by slowing or stopping the production of leaves and branches, as well as reducing leaf size and internode length. Pendimethalin appeared to have its greatest effect on portions of the shoot undergoing cell division.

The absorption, translocation, and metabolism of 14C-ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] in sugarbeet (Beta vulgaris L.), common ragweed (Ambrosia artemisiifolia L.), redroot pigweed (Amaranthus retroflexus L.), and common lambsquarters (Chenopodium album L.) were studied as possible bases for selectivity of preemergence-applied ethofumesate. The sensitive redroot pigweed and common lambsquarters plants translocated more 14C-ethofumesate from nutrient culture to the leaf tissue than did the tolerant sugarbeet and common ragweed. The radioactivity was more highly concentrated in sugarbeet and common ragweed roots. The rapid metabolism of ethofumesate by sugarbeet and common ragweed, particularly that which accumulated in the leaf tissue, appeared related to tolerance.

We are meeting near the Boston Common, an historic 50-acre public park that was set aside in 1630 for “common use as a cow pasture and training field.” Records show that 100 people (pirates, Indians, Quakers, and suspected witches) were hanged on the Common by the early Puritans who established the Massachusetts colony.

There were no farmers or scientists on this list. Hopefully, after this presentation, my name will not be added to the Puritans' “hit” list.

Experiments were conducted to examine morphological variation among hemp dogbane populations. Rootstocks collected from 16 sites throughout Michigan and Illinois were used to establish nurseries in East Lansing, MI, and Champaign, IL. Growth, stem characteristics, and leaf characteristics were measured for each ecotype at both nurseries. Differences among ecotypes were observed for all measurements except emergence date and growing degree days to emergence. The number of shoots per plot produced by the ecotypes ranged from 5 to 54 and shoot height ranged from 69 to 126 cm. Ecotypes spread laterally at different rates, with the most aggressive covering 19 times more ground area than the least aggressive. Total shoot dry weight accumulation varied greatly among ecotypes. Some ecotypes could be identified from others by their unique leaf shape. Shoot number, shoot height, and ground area covered were greater for plants grown in Michigan than in Illinois. Differences in growth and morphological characteristics among ecotypes were not correlated with the geographical region where they were collected. Differences in measurements between the two nurseries illustrate the role of environment and genetics in the growth and morphology of this plant species.

Herbicides have been used to control tall larkspur to prevent cattle deaths. There is some evidence that tall larkspur may become more toxic and more palatable during the desiccation process following herbicide treatment. A series of studies were conducted to measure toxic alkaloid concentration in tall larkspur following treatment with metsulfuron, picloram, and glyphosate. Herbicides were applied to larkspur plants grown in a greenhouse (1990), to field plots infested with larkspur (1993), and to individual larkspur plants in the field (1995). Leaves were harvested up to 14 or 28 d following treatment, and toxic alkaloids were measured. Metsulfuron increased toxic alkaloid concentration in the 1990 greenhouse study and in 1993 field plot studies, and increased both concentration and absolute amount of toxic alkaloids in 1995 individual plant treatments. Alkaloids in plants treated with picloram either remained unchanged or declined slightly in all three studies and were similar to control plants. In the 1995 study, glyphosate caused the relative concentration of alkaloids to increase as the plants desiccated, but the absolute amount of alkaloids was similar to control plants. Picloram and glyphosate did not reduce alkaloid concentration; thus, the risk of poisoning remains until plants desiccate. Metsulfuron increased alkaloid concentration, thus increasing the risk of poisoning. Cattle should not be allowed to graze sprayed areas until larkspur desiccates and withers.

The phenology and biomass dynamics of Typha subulata were studied for 2 yr under two natural conditions, a marsh and an irrigation channel. Populations demonstrated a spring to summer growth pattern, with peak aboveground biomass in spring. The phenological phases identified for both populations were identical, but plants growing in the marsh averaged 38 and 28% less aboveground biomass and height, respectively, than plants growing in the channel. Noticeable differences were found in the timing of both phenological phases and biomass cycle between growth seasons, suggesting that the susceptibility of cattail to weed control during the seasons could vary between years.

Field and greenhouse studies were conducted on S-21634 (1-methyl-4-phenylpyridinium chloride) for control of purple nutsedge (Cyperus rotundus L.) and tolerance of several turfgrass varieties and species. Purple nutsedge was controlled during the initial year of treatment with single applications of 3.4 and 5.6 kg/ha rates. All turfgrasses were injured following treatments, however, all except centipedegrass [Eremochloa ophiuroides (Munro) Hack.] had recovered in 7 to 8 weeks. In general, the injury to centipedegrass was higher and the turf density was lower in the treated plots at the final ratings. None of the treatments applied as a single S-21634 application affected root growth of bermudagrass (Cynodon sp.), ‘Emerald zoysia’ (Zoysia japonica x Z. teniuflolia), centipedegrass, St. Augustine grass [Stenotaphrum secundatum (Walt.) Kuntze], or tall fescue (Festuca arundinacea Schreb, ‘Ky 31′).

Pronamide [3,5-dichloro-(N-1, 1-dimethyl-2-propynyl) benzamide] phytotoxicity was compared in 10 Wisconsin soils and the relationship of activity to soil physical and chemical properties appraised. Twelve soil properties were measured and correlated with pronamide I50 (50% fresh weight inhibition) values using oats (Avena sativa L. ‘Portal’) as the indicator plant in bioassays conducted under greenhouse conditions. Organic matter was the soil variable most inversely correlated with pronamide phytotoxicity. Cation exchange capacity, field moisture capacity, and Mg content were also inversely correlated with pronamide phytotoxicity, but probably reflect changes in soil organic matter levels. Clay content did not significantly affect pronamide phytotoxicity.

Nine substituted dinitronaline herbicides were studied to determine their effectiveness in controlling common root rot of peas (Pisum sativum L.) caused by Aphanomyces euteiches Drechs. under field conditions. Most of the dinitroaniline herbicide treatments increased plant stand, plant fresh weight, and shelled pea yield due to root rot suppression in each of the three years studied. Weed control was good in all plots and did not contribute to yield differences. Root rot suppression and crop injury were the primary determinants of yields. The greatest yield increases when compared with the weeded control were 82% for 0.56 kg/ha of dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) in 1974, 80% for 0.84 kg/ha of fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl) aniline] in 1975, and 26% for 1.68 kg/ha of pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] in 1976. The best average yield increases over all years were 54% for the combination of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) at 0.56 + 0.56 kg/ha, 49% for fluchloralin at 0.84 kg/ha, and 43% for pendimethalin at 0.84 kg/ha. Annual applications of 0.84 kg/ha of trifluralin delayed the rate of pathogen infestation of a field repeatedly planted to peas.

In greenhouse studies, soil organic matter reduced the herbicidal activity of ethalfluralin (N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl)benzenamine). Fifty percent inhibition (I5.0) values for barnyardgrass [Echinochloa crus-galli (L.) Beauv.] stand, injury, and shoot fresh weight increased as the soil organic-matter level increased. No difference in ethalfluralin tolerance was found among 16 cucumber (Cucumis sativus L.) cultivars. When grouped according to market type, fresh market cultivars tended to be injured more than pickling cultivars by excess ethalfluralin. Both shoots and roots of cucumber absorbed the herbicide, but exposure of roots to ethalfluralin was more toxic than exposure of shoots. Field studies indicated that with certain edaphic and environmental conditions, cucumbers can be injured by preemergence applications of ethalfluralin. Injury was greatest in a low organic-matter soil following a heavy rain. Ethalfluralin at 1.3 kg/ha gave adequate weed control in 1 and 3% organic-matter soils, but not in a 9% organic-matter soil.

Occurrence of various growth stages of major pasture plants near Lincoln, NE, were recorded for 15 yr, 1958 to 1973. The phenology of 31 perennial and 16 biennial, winter annual, and annual broadleaf species and 18 grasses was determined. Phenological stages of broadleaf species were recorded as: emergence, stem elongation, first bud, first bloom, and seed firm. Events recorded for the grasses were: emergence, culm elongation, head exserted, anthesis, and seed firm. Much variation existed in phenology among and within life habit groupings of species. Year-to-year variability in phenology of these plants was dependent on temperature patterns of specific years. Studies of this nature are useful in developing more efficient control methods for weeds, insects, and diseases.

Several herbicide antidotes were used with barban (4-chloro-2-butynyl m-chlorocarbanilate) in the field and greenhouse. The seed treatments of R-25788 (N,N-diallyl-2,2-dichloroacetanilide) and NA (1,8-naphthalic anhydride) at 0.12 or 0.5% by seed weight reduced wheat (Triticum aestivum L. ‘Waldron’) injury with barban in the field and greenhouse. R-25788 and R-28725 (2,2-dimethyl-3-dichloroacetyloxazolidine) applied at 0.14 kg/ha as a spray with barban or R-28725 applied as a seed treatment at 0.06 or 0.25% by seed weight were ineffective in reducing wheat injury. S-449 (4-chloro-2-hydroxyiminoacetanilide) at 0.06 or 0.25% by seed weight reduced wheat injury with barban in the greenhouse; however, in the field these treatments increased wheat injury and reduced wild oat (Avena fatua L.) control.

The persistence of napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] applied at 2.24- and 4.48-kg/ha was studied for 2 yr at two locations in the field. Wheat (Triticum aestivum L. ‘Arthur 71′) was severely injured when sown in the fall following a spring application of napropamide. A wheat root bioassay also showed that napropamide was persistent for more than 180 days. The yield of sweet corn (Zea mays L. var. rugosa Bonaf. ‘Gold Cup’) was not significantly reduced when grown 1 yr after the initial application of napropamide.

There were no apparent herbicide-insecticide or herbicide-fungicide interactions when two pesticides were used on peanuts (Arachis hypogaea L.) in the greenhouse. In field studies, O,O-diethyl s-(2-(ethylthio)-ethyl)-phosphorodithioate (disulfoton), O,O-diethyl s-((ethylthio)-methyl)-phosphorodithioate (phorate), 1,2-dibromo-3-chloropropane (dibromochloropropane), and pentachloronitrobenzene (PCNB) had little influence on phytotoxicity of the herbicides 3-amino-2,5-dichlorobenzoic acid (chloramben) and α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) to peanuts. There was no phytotoxic effect or yield reduction as a result of application of chloramben or trifluralin combined with the use of fungicide-treated seed in the field. However, in the greenhouse, top growth of the fungicide-treated checks was greater than that of the herbicide-fungicide seed treatments. Dibromochloropropane nematocide alone was injurious to peanut seedlings grown in the greenhouse, but the application of a herbicide did not increase the injury.

Southern Root-Knot nematode and common cocklebur interfere with cotton growth and yield. A greater understanding of the interaction of these pests with cotton growth and yield is needed for effective integrated pest management (IPM). An additive design was used in outdoor microplots with five common cocklebur densities (0, 1, 2, 4, and 8 plants per plot) growing in competition with cotton, with and without the presence of southern Root-Knot nematode. Differences in cotton height could not be detected among common cocklebur densities or nematode presence at 3 wk after transplanting (WAT); however, differences in crop height were observed at 5 WAT between nematode treatments. In the absence of nematodes, the relationship between cotton yield loss and common cocklebur density was described by a rectangular hyperbolic regression model (P < 0.0001). Maximum yield loss from common cocklebur in the absence of nematodes exceeded 80%. In the presence of nematodes, there was a linear relationship between cotton yield loss and common cocklebur density (P = 0.0506). The presence of nematodes at each common cocklebur density increased cotton yield loss 15 to 35%. Common cocklebur plant biomass was 25% greater in nematode treatments, likely because of the reduced competitiveness of the cotton plants in these plots. This study demonstrates that multiple pests can interact to cause an additive reduction in crop yield.