An in vivo ALS assay was used to differentiate between susceptible and resistant kochia biotypes from Idaho and Montana. Experiments were also conducted using this assay to determine the effect of the timing of herbicide application on ALS activity in resistant and susceptible cocklebur biotypes from Mississippi. When treated with chlorsulfuron, resistant kochia biotypes demonstrated 160-and 170-fold resistance at the whole plant level for the Idaho and Montana biotypes, respectively, compared to susceptible biotypes. Using the in vivo ALS assay, the Idaho and Montana biotypes showed 70- and 490-fold resistance, respectively, based on I50 values. The biotypes also demonstrated a low level of cross-resistance to imazethapyr using the in vivo technique. Resistant cocklebur biotypes showed approximately 200-fold resistance to imazaquin compared with susceptible biotypes. This research demonstrated that the in vivo assay can be used effectively to identify resistant biotypes 6 and 24 h after treatment, and to determine the extent of cross-resistance.

Two sulfometuron-resistant biotypes of Italian ryegrass were identified from rights-of-way of U.S. Highway 49E in Holmes County, MS, and State Highway 14 in Humphreys County, MS. Sulfometuron at 5.2 g ai/ha applied PRE or POST reduced shoot fresh weight of these selections 20% or less at 4 wk after treatment. A susceptible ‘Gulf’ Italian ryegrass was reduced 52% or more in shoot fresh weight by 0.5 g/ha sulfometuron applied PRE or POST The biotype from Highway 49E was reduced 47% or less in shoot fresh weight by 520 g/ha sulfometuron applied PRE or POST.

A study was conducted to evaluate effects of application timing and sulfometuron rate on weed control and bermudagrass tolerance. Sulfometuron was applied at rates from 13 to 105 g ai/ha and compared to 1120 g ae/ha 2,4-D amine. Control of Italian ryegrass and common vetch was not affected by October, November, December, or March application dates and 39 to 105 g/ha sulfometuron provided equivalent control of both species 6 mo after the initial treatment. Percent green cover of bermudagrass at 6 mo after the initial treatment was 22% or less following March applications compared to 36% or greater when applied in October, November, or December. More bermudagrass injury occurred following March treatments of 52 g/ha or greater sulfometuron where green cover was 14% and less compared to 22 and 30% green cover following 13 g/ha sulfometuron or 1120 g/ha 2,4-D amine, respectively.

‘Lemberger’ wine grape response was evaluated when chlorsulfuron, tribenuron, thifensulfuron, chlorsulfuron plus metsulfuron, thifensulfuron plus tribenuron, and 2,4-D were applied up to three times at weekly intervals in 1992 and 1993 at rates simulating drift. All herbicides injured grapevines visibly. Symptoms increased and total leaf area and grape pruning weight decreased as the herbicide rate and number of applications increased. Grapevines generally recovered within 45 to 60 d from symptoms caused by single exposures to low levels of sulfonylurea herbicides. Multiple exposures of grapevines to 2,4-D, tribenuron, and chlorsulfuron plus metsulfuron at 1/100 of the maximum use rate for wheat caused the greatest injury, which persisted throughout the entire growing season and reduced pruning weight. Based on potential use rate, the order of herbicide phytotoxicity was 2,4-D > tribenuron > chlorsulfuron plus metsulfuron > thifensulfuron plus tribenuron > chlorsulfuron > thifensulfuron. Rates that slightly injured grapevines did not reduce growth as measured by pruning weight. However, multiple exposure to high rates of 2,4-D, tribenuron, and chlorsulfuron plus metsulfuron adversely affected growth.

Field experiments were conducted from 1993 to 1995 to evaluate control of annual weeds with glyphosate applied at rates of 560 to 2800 g ai/ha in spray volumes of 93 and 187 L/ha. Glyphosate controlled 100% of giant foxtail, fall panicum, redroot pigweed, and velvetleaf (in 1993) regardless of rate, spray volume, or application timing. Ivyleaf morningglory, velvetleaf, and common lambsquarters control was greater with glyphosate applied early POST than late POST. Ivyleaf morningglory, velvetleaf, and common lambsquarters control increased as glyphosate rate increased with both spray volumes. Velvetleaf control with glyphosate applied late POST was greater with glyphosate in 187 L/ha water compared with 93 L/ha water.

In the 1990s, citizens regard green lawns and golf courses with attitudes ranging from pleasure for their beauty to dismay caused by concerns for environmental consequences. Citizens concerned with environmental consequences describe fertilizers or pesticides that may be harmful to groundwater or other organisms while others worry about the harm caused by more bee stings or economic and aesthetic losses caused by unsightly weeds. Both sides of an issue can be supported by facts. The listener may have difficulty forming an opinion since many issues do not have a clearly right or wrong approach. How should educators deal with this sort of dilemma? Are learning methods available to explore people's values, data, assumptions, and practices?

The Office of Pesticide Programs (OPP) within the United States Environmental Protection Agency (EPA) has initiated several programs to reduce risks associated with the use of pesticides. Examples include accelerated registration of new products (including biological pesticides) that offer reduced risk to human health and the environment, and regulatory relief for products posing virtually no risk to provide replacement for more problematic pesticides. In addition, efforts are being undertaken to reduce pesticide resistance in target pests, develop joint “Environmental Stewardship” efforts between the EPA, United States Department of Agriculture (USDA), and the United States Food and Drug Administration (FDA). The new Biopesticides and Pollution Prevention Division (BPPD), established as a pilot in October 1994, has responsibility for many above functions, with special emphasis on registration of biological pesticides and development of the new Pesticide Environmental Stewardship Program (PESP). This program is designed to recognize achievements already made by farmers to reduce conventional pesticide use and to find further improvements through cooperative efforts with growers.

Food safety concerns involving pesticide residues continue to receive widespread public, legislative, and scientific attention. The National Research Council's 1993 report Pesticides in the Diets of Infants and Children concluded that significant improvements in the U.S. government's pesticide risk assessment and food tolerance establishment procedures were needed. Strict interpretation of the Delaney Clause by the U.S. Ninth Circuit Court of Appeals has led to the projected elimination of several pesticide uses due to statutory, rather than scientific considerations. Congressional “solutions” to the Delaney problem may have broad impacts upon future pest management practices if adopted. Emerging issues include the safety of imported produce and the potential effects of trade agreements such as NAFTA and GATT upon U.S. pesticide residue standards.