More than 70% of all14C-bentazon absorption occurred within 4 h after herbicide application regardless of adjuvant Moisture stress reduced14C-bentazon absorption by common cocklebur and velvetleaf. Mature (second true leaf) and moisture-stressed leaves of velvetleaf had 50 and 17 μg cm−1more epicuticular wax (ECW) than did juvenile and unstressed leaves, respectively. Common cocklebur had less14C in the ECW and lower total14C in treated mature leaves compared to juvenile leaves. The use of 28% urea ammonium nitrate (UAN) or crop oil concentrate (COC) increased14C in ECW samples of both plant species, regardless of leaf age or moisture stress. More14C in the ECW did not always correlate with more14C in the leaf tissue. Adjuvants increased14C-bentazon absorption into leaves of plants that had been stressed.

The effect of herbicides applied to V3 soybeans on race 3 soybean cyst nematode (SCN) reproduction and glyceollin production in roots was measured. Soybeans were treated postemergence with 1 × and 2 × rates of herbicides plus adjuvants or with adjuvants alone, and SCN development was measured. Acifluorfen, bentazon, lactofen, crop oil concentrate (COC), and nonionic surfactant (NIS) applications reduced SCN egg population densities 50 to 60% compared with the untreated control 4 and 8 wk after application. The SCN reproduction on plants treated with fluazifop-P, sethoxydim, and imazethapyr was similar to the untreated control. Crop oil concentrate or NIS applications alone were as effective as acifluorfen, bentazon, or lactofen applications for reducing SCN reproduction. However, no additive effect of adjuvant-herbicide combinations was observed, nor did herbicide rate affect SCN reproduction. Treatments reduced SCN reproduction only when applied to soybeans and had no effect on SCN reproduction when applied directly to the soil. No treatment stimulated SCN reproduction relative to the untreated control. Soybeans treated with COC, NIS, acifluorfen, and bentazon also had more glyceollin detected than the untreated control. Herbicide-induced glyceollin production may have increased the resistance of soybean to SCN.

Soybean [Glycine max (L.) Merr.] responses to combinations of stress factors generally are unknown. Research was conducted in 1989, 1990, and 1991 to quantify growth responses to stresses from soybean cyst nematode (SCN; Heterodera glycines Ichinohe), acifluorfen {5‐[2‐chloro‐4‐(trifluoromethyl)phenoxy]‐2‐nitrobenzoic acid} plus bentazon [3‐(1‐methylethyl)‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide] herbicides, and simulated green cloverworm [GCW; Plathypena scabra (F.)] defoliation. Treatments were combinations of at‐planting SCN soil density, acifluorfen plus bentazon rate, and simulated GCW defoliation level. Herbicides were applied at V6 soybean development, and GCW feeding was simulated from R2 to R4 soybean development. Plant growth was quantified at V4, R2, and R4 developmental stages. Herbicide stress was assessed by leaf stomatal conductance and visible foliar injury. Herbicides reduced conductance and caused visible injury each year, and limited growth (plant height, leaf area, pod number, and dry weight of leaf, pod, and stem plus petiole) in 1990 and 1991. Likewise, defoliation reduced leaf area each year, but reduced growth (plant height and leaf dry weight) in 1990 and 1991 only. Uncontrolled environmental factors probably confounded growth responses in 1989. Although no herbicide × defoliation effects on growth were found, defoliation caused greater reductions in canopy quantity and quality for herbicide‐injured plants in 1990 and 1991. Targeted stress from SCN was achieved in 1990, and interaction with herbicides decreased conductance, increased visible herbicide injury, and reduced leaf area, plant height, pod number, and pod dry weight. These data support the potential for stresses from SCN and acifluorfen plus bentazon to cause more‐than‐additive reductions in soybean growth.

Absorption of14C-bentazon from the leaf surfaces of common cocklebur and velvetleaf was rapid and most occurred within 4 h after foliar application. Greater14C in the epicuticular wax (ECW) did not correlate with higher radioactivity in the leaf tissue. There was significantly less ECW on the “mature” leaves of common cocklebur and “juvenile” leaves of velvetleaf. However, the “mature” leaves exhibited greater14C absorption for both species. The use of 28% urea ammonium nitrate increased14C-absorption when compared with crop oil concentrate and with no adjuvant.

A new soil water retaining technology, designed to increase vegetable production and improve water use efficiency (WUE), was field tested on sand soil. Green bell pepper (Capsicum annuum) and cucumber (Cucumis sativus) were planted on previously installed U-shaped troughs of impermeable membranes designed to double soil water content in plant root zones. These soil water retention technology (SWRT) membranes significantly increased volumetric water content (VWC) in plant root zones promoting both crop production and improved water use efficiency (WUE). Greater vegetable production was attained when SWRT membranes significantly increased the low 9% to 10% water holding capacity by control sands. Membrane improved VWC to 15% and 18% increased yields of green bell pepper by 20% and cucumber by 24%. These newly optimized root zone water contents also increased WUE 19% and 41% for cucumber and bell pepper crops grown on SWRT transformed sands. SWRT membrane installations also provide an early return on investment (ROI) for the sand soils that auto control optimal soil water contents in plant root zones. This new technology offers new opportunities for establishing greater profits for the long-term vegetable production on sand soils. Anticipated positive impacts by SWRT on natural resource management and crop production offers new opportunities for enhanced profitability while protecting the environment in rural America. These SWRT improvements for vegetable production including greater yields, higher WUE, and very brief ROI should encourage adoption of this technology across irrigated vegetable production located on highly permeable sand and loamy sand soils.