Herbicide soil/solution distribution coefficients (Kd) are used in mathematical models to predict the movement of herbicides in soil and groundwater. Herbicides bind to various soil constituents to differing degrees. The universal soil colloid that binds most herbicides is organic matter (OM), however clay minerals (CM) and metallic hydrous oxides are more retentive for cationic, phosphoric, and arsenic acid compounds. Weakly basic herbicides bind to both organic and inorganic soil colloids. The soil organic carbon (OC) affinity coefficient (Koc) has become a common parameter for comparing herbicide binding in soil; however, because OM and OC determinations vary greatly between methods and laboratories, Koc values may vary greatly. This proposal discusses this issue and offers suggestions for obtaining the most accurate Kd, Freundlich constant (Kf), and Koc values for herbicides listed in the WSSA Herbicide Handbook and Supplement.

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Cockroach suppression is fundamental to cockroach allergen mitigation in infested homes. The effects of various cockroach control strategies on cockroach populations and allergen concentration have not been examined in schools. This study was conducted to compare the effectiveness of integrated pest management (IPM) and conventional pest control in controlling German cockroach (Blattella germanica L.) infestations and concentrations of the cockroach allergen Bla g 1 in public school buildings. Two school districts included six schools that used conventional pest control and one district included seven schools that used IPM to control pests. Cockroach traps were deployed to assess the level of infestation, settled dust samples were collected in food service areas, classrooms, and other school areas, and the Bla g 1 allergen was quantified by ELISA. Both cockroach counts and Bla g 1 concentrations were dependent on the pest control approach, with highly significant differences between IPM-treated schools and conventionally treated schools in both the cockroach mean trap counts (0 versus 82.6 +/- 17.3 cockroaches/trap/wk, respectively) and in the amount of Bla g 1 in dust samples (2.8 +/- 0.3 versus 30.6 +/- 3.4 U/g dust). Cockroaches and Bla g 1 were primarily associated with food preparation and food service areas and much less with classrooms and offices. Our data extend recent findings from studies in homes, showing that cockroach allergens can be reduced by cockroach elimination alone or by integrating several tactics including education, cleaning, and pest control. IPM is not only effective at controlling cockroaches but also can lead to long-term reductions in cockroach allergen concentrations, resulting in a healthier environment for students and school personnel.

Large crabgrass is a problem weed in horticultural crops, particularly in turfgrass in the southeastern United States. If growth of large crabgrass could be suppressed via soil pH or calcium levels, control of this weed in turfgrass might be improved while minimizing herbicide usage. To determine the effect of soil calcium and pH on germination and growth of large crabgrass, seeds were sown in a loamy sand soil amended with calcium carbonate (CaCO3) or magnesium carbonate (MgCO3) that established a range of soil pH from 4.8 to 7.8. Seeds were also sown in soil amended similarly with calcium sulfate (CaSO4), which does not affect pH, that established a range of exchangeable Ca levels corresponding to the Ca range in CaCO3from pH 4.8 to 7.8. Seed germination of large crabgrass was unaffected by pH when soil was amended with CaCO3, whereas seed germination decreased with increasing pH when soil was amended with MgCO3. Crabgrass germination was not affected by Ca (CaSO4) independent of pH changes. Increasing soil pH reduced shoot and root dry weights of seedlings regardless of material used to raise pH. Maximum shoot dry weights occurred at pH 4.8 in the unamended soil, whereas maximum root dry weights occurred at ranges from pH 5.8 to 6.3 for CaCO3and pH 5.3 to 5.8 for MgCO3. Shoot and root dry weights were not affected by Ca when soil was amended with CaSO4. By raising soil pH levels, the growth of large crabgrass and its ability to compete with turfgrass may be reduced. Raising exchangeable Ca does not appear to be an effective management tool for control of this weed species.

The objective of this research was to evaluate the influence of different initial weed densities on weed control effectiveness in no-tillage corn at two locations in North Carolina during 1994 and 1995. Different weed densities were established over a 4-year period (1989–1992) by using various weed management strategies. Resultant density levels were estimated and used to establish high and low weed density plots. Treatments applied were PRE, POST, at-planting, and an untreated control. Weed density estimates were made 37 and 57 DAP. Common lambsquarters at low densities (20 to 40 weeds/m2) was controlled with the cover crop alone, but common lambsquarters at high densities (150 to 170 weeds/m2) and redroot pigweed at any density were not controlled. POST herbicides reduced weed densities as well as the PRE herbicides, regardless of initial weed densities.