Palmer amaranth (Amaranthus palmeriS. Wats. # AMAPA) planted in a field at monthly intervals from March through October at Shafter, CA, began to emerge in March when soil temperatures at a depth of 5 cm reached 18 C. With the exception of March and April plantings, at least 50% of the seed of later plantings produced seedlings within 2 weeks after planting. Although growth of plants was initially slower for early plantings, plantings from March to July reached 2 m or greater in height by fall. Due to longer growing times, plantings from March to June eventually produced more dry matter and a greater number of inflorescences than later plantings. Plants began flowering 5 to 9 weeks after planting in March through June and 3 to 4 weeks after planting in July through October. Some viable seed was produced as early as 2 to 3 weeks after flowering began. Total seed production in the fall ranged from 200 000 to 600 000 seed/plant for the March through June plantings, and 115 to 80 000 seed/plant for the July through September plantings. Killing frosts in November prevented Palmer amaranth planted in October from producing seed.

In 1982 and 1983, CGA 82725 {2-propynyl-2-[4-[(3,5-dichloro-2-pyridinyl)oxy] phenoxy] propanoic acid}, fenoxaprop {(±)-2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxyl]propanoic acid}, fluazifop {(±)-2-[4-[[5-trifluoromethyl)-2-pyridinyl] oxy]phenoxy] propanoic acid}, haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, and sethoxydim {2-[1-(ethoxyimino-(butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} were evaluated as postemergence treatments for the control of rhizome johnsongrass [Sorghum halepense(L.) Pers. # SORHA] in cotton (Gossypium hirsutumL. ‘Acala SJ-2′). Applications of fluazifop or haloxyfop, and the higher rates of sethoxydim or CGA 82725 or fenoxaprop, controlled 90% or more johnsongrass 20 and 52 weeks after application and prevented cotton yield losses.

River channel and harbor dredging activities in the eastern USA generate hundreds of millions of yards of dredge materials annually with very little used beneficially. The Woodrow Wilson Bridge project across the Potomac River at Washington D.C. generated in excess of 450,000 m 3 of silt loam, high pH, low salt dredge materials. The materials were barged to Shirley Plantation on the James River in Charles City Co. Virginia, and placed into an upland utilization area atop a previously reclaimed sand and gravel mine. The strongly reduced inbound sediments were very low in sulfides, pesticides, and other contaminants. The materials were dewatered, treated with varying rates of yardwaste compost and planted to wheat (Triticum vulgare) in the fall of 2001 and corn (Zea mays) in 2002 and 2003. Winter wheat yields in 2001 were similar to local agricultural lands despite animal damage and less than ideal establishment conditions. Average corn yields in 2002 were greater than long-term county prime farmland yields in a severe drought year ( 2002) and equaled county averages in a wet year (2003). Soil pit and auger observations revealed significant oxidation and formation of a deep Ap-AC-C profiles with coarse prismatic structure within two years after placement. Overall, the chemical and physical properties of these materials are equal or superior to the best topsoils in the region, supporting federal initiatives to utilize suitable dredge materials in upland environments whenever possible.

Yellow nutsedge (Cyperus esculentusL. # CYPES) was treated with unlabeled and14C-labeled glyphosate [N-(phosphonomethyl)glycine] to study the toxicity and translocation of glyphosate into parent tubers of this weed. When plants of 2 and 4 weeks of age were treated with 0.6 kg ai/ha of glyphosate, fewer parent tubers from treated plants resprouted (14 and 32%) than tubers from control plants (73 and 59%, respectively) of equal age. Also, fewer tubers resprouted from 2-week than from 4-week-old treated plants. The radioactivity of parent tubers from plants treated at 2 weeks of age, which exceeded that of tubers from plants of 4 and 6 weeks of age, indicated that translocation of14C into parent tubers decreased as the treated plants increased in age. The differential amounts of14C translocated appear to explain why applications of glyphosate were more effective in suppressing resprouting of parent tubers from 2-week than 4-week-old plants.

When postemergence applications of sethoxydim {2-[1-(ethoxyimino) butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} were compared with DSMA (disodium salt of methylarsonic acid), MSMA (monosodium salt of methylarsonic acid), and glyphosate [N-(phosphonomethyl)glycine] for control of johnsongrass [Sorghum halepense(L.) Pers. # SORHA] in cotton (Gossypium hirsutumL. ‘Acala SJ-2′), repeated annual applications of sethoxydim were more successful than other herbicides in protecting yields of cotton and reducing populations of rhizome johnsongrass over time. After the first year of treatment with sethoxydim in 1982, when an 18% yield loss of cotton occurred, populations of rhizome johnsongrass were reduced to the extent that they were no longer a threat to yields in plots treated with sethoxydim in 1983 and 1984. Although DSMA and glyphosate improved yields when compared to cultivated control plots, substantial yield losses occurred every year, and populations of johnsongrass remained unchanged after 3 yr of treatment. Averaged over 3 yr, plots treated with sethoxydim produced 94% as much cotton as weed-free plots, compared to 60 and 45% for plots treated with glyphosate and DSMA/MSMA, respectively.