Spraying with tank mix combinations of the fungus Colletotrichum coccodes and the plant growth regulator thidiazuron increased mortality, decreased biomass and height of velvetleaf, and increased soybean yield in field experiments. The velvetleaf isolate of C. coccodes was compatible with thidiazuron, and tank mix combinations consistently improved control over either component alone. In the moist 1986 season the fungus and the growth regulator interacted synergistically to increase velvetleaf mortality. In the drier 1987 season no significant interaction was detected between the two components.

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.

Field experiments were conducted in central Missouri in 1989 and 1990 to evaluate weed control practices in conjunction with cover crops and cover management systems in reduced tillage corn. There was no difference in weed control among soybean stubble, hairy vetch, and rye soil cover when averaged over cover management systems and herbicide treatments. However, mowed hairy vetch and rye covers provided greater weed control in the no-till plots than soybean stubble when no herbicide was used. Differences in weed control among cover management systems were reduced or eliminated when a PRE herbicide was applied. corn population and height were reduced by hairy vetch and rye soil cover. Corn grain yield was reduced in rye plots both years. There was no difference in grain yield between tilled and no-till plots.

Growth room and field studies were conducted to determine if increasing use of forage aeschynomene may lead to new weed problems in rice and soybeans and to identify possible control measures in these crops. In a growth room study, flooding of ‘Florida Common’ and ‘LSU 1147’ forage aeschynomene did not reduce yield. However, forage aeschynomene seedlings did not emerge from a flooded seedbed, and 1-week-old seedlings were killed by 2.5 or 7.5 cm of flooding. Competition from interseeded forage aeschynomene reduced ‘Centennial’ soybean yields by 81%. Acifluorfen, fomesafen, and lactofen, labeled for soybeans, control forage aeschynomene. Acifluorfen, labeled for rice, may control forage aeschynomene in that crop. Forage aeschynomene might become a weed problem in rice if plants are past the seedling stage when flood water is applied and could cause weed problems in soybeans; but, in most situations, cultural and chemical control practices should provide adequate control.

Agricultural production in China occurs via three distinct organizational units: the countryside farmer, state farms, and military farms. The countryside farmer in northeast China carries out most production operations with hand tools, some animal and tractor power, and little additional mechanization. Most weeds in row crops are controlled by hand, although a high percentage of the rice crop is treated with herbicides as is about 20% of the wheat. Countryside farmers independently manage small plots of land. State and military farms, the majority of which are located in China's northeastern-most province of Heilongjiang, are highly mechanized and accomplish most weed control with herbicides. Military farms range from ~500–2,500 ha, and state farms generally occupy 50,000–100,000 ha, with some much larger. Primary crops on the military farms are soybeans, oilseed rape, and wheat. State farms generally have more diversity in crops. The need for herbicide adjuvants to increase postemergence (POST) herbicide efficacy and for reduced tillage practices to combat soil erosion are recognized concerns, as is the threat of herbicide resistance.