Pest management strategies based on crop losses from single stress factors may be inadequate where multiple stresses occur. Consequently, experiments were conducted in 1989, 1990, and 1991 to quantify interactive effects of stresses from soybean cyst nematode (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 green cloverworm [Plathypena scabra (F.)] on seed yield of soybean [Glycine max (L.) Merr.]. Treatments were combinations of at‐planting soybean cyst nematode soil density, acifluorfen plus bentazon rate, and green cloverworm defoliation level. Herbicides were applied at V6 soybean development, while green cloverworm feeding was simulated during R2 to R4 soybean development. Plot yield and yield components (pods per plant, seeds per pod, and weight per seed) were determined. Herbicide injury and defoliation independently reduced yield in 1990 and 1991. Yield reductions from defoliation were attributed to fewer pods per plant, while herbicide injury decreased pods per plant (1990) and weight per seed (1990 and 1991). Moreover, herbicide injury and defoliation interacted over 1990 and 1991 to decrease yield. Although stress from soybean cyst nematode alone never affected yield, interactions with herbicides and with defoliation reduced yield in 1990. No treatment effects on yield were found in 1989, probably due to uncontrolled environmental factors. Because of the 2‐yr herbicides × defoliation effect, lower economic injury levels for green cloverworm were developed for soybean treated with acifluorfen plus bentazon. To account for potential interactions involving soybean cyst nematode, growers will be advised to consider adjusting weed and insect management strategies for soybean fields infested with soybean cyst nematode.

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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.

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Infant rats deprived of food, maternal care, and the opportunity to suckle display a dramatic behavioral activation and vigorously ingest when provided milk through oral cannulas. These experiments assessed which components of deprivation are important in producing these responses to milk. Nutritional deprivation alone, with or without the presence of an active maternal female, appears to be sufficient to produce ingestion. Behavioral activation, on the other hand, appears to require both nutritional deprivation and deprivation from a maternal female. The effect of maternal stimulation on later behavioral reactivity was not a function of the pups' opportunity to suckle. However, active maternal stimulation was more effective in preventing activation than was passive maternal stimulation (e.g., thermotactile and olfactory stimulation). Stimulation provided by an active, nonlactating mother was effective in preventing behavioral activation, but the effect was short-lived, lasting only 2 hr after the pup was removed from the mother's care. This series of studies thus reveals that identified components of maternal separation have dissociable effects on appetitively motivated behaviors in infant rats.