A cropping system of soybeans and rice grown in alternate years for 4 yr controlled red rice when combined with effective herbicide treatments applied to the soybean crop. Effective herbicide treatments in soybeans were preplant incorporated applications of alachlor, metolachlor, or alachlor plus trifluralin each followed by postemergence over-the-top applications of bentazon plus mefluidide, postemergence directed applications of paraquat, or sequential applications of postemergence over-the-top bentazon plus mefluidide and postemergence directed paraquat. Control of red rice in soybeans reduced red rice infestations in the subsequent rice crop. Red rice infestations were lower in rice grown the fourth year than in rice grown the second year. Postemergence over-the-top or directed herbicide treatments used alone or combined with preplant incorporated applications of trifluralin did not control red rice in soybeans with subsequent red rice infestations in the rice crop.

The methods used to teach weed identification at 20 U.S. universities were obtained for comparison through a telephone survey in December, 1986, and January, 1987. Weed identification is taught as a portion (30%) of the laboratory section in introductory weed science courses. Only five have a separate weed identification course. Field trips frequently are used to teach weed identification. Students must learn from 50 to 125 weed species with some seedling identification. Pressed plant collections of approximately 50 weed species normally are required. Most instructors strongly suggest using live plants and repetition for long-term learning.

Studies were conducted to determine the usefulness of HOE-39866 (HOE-00661) in chemical fallow systems on the Canadian prairies. HOE-39866 at 0.5 to 1.0 kg ai/ha controlled Russian thistle, kochia, green foxtail, wild oats, and wheat comparable to paraquat, glyphosate, and glyphosate plus the isopropylamine salt of 2,4-D. However, control of barley with HOE-39866 was unacceptable. HOE-39866 was compatible in tank mixtures with ammonium sulfate, paraquat, chlorsulfuron, and metsulfuron. Ammonium sulfate improved weed control when HOE-39866 was applied at 0.25 kg/ha but not at 0.75 kg/ha. Adding paraquat at 0.07 to 0.21 kg ai/ha to HOE-39866 improved control of grass species over HOE-39866 alone. Adding chlorsulfuron and metsulfuron to HOE-39866 provided greater initial control of certain species as well as residual control of many weeds. HOE-39866 alone or in conjunction with other herbicides is an alternative to the herbicides used in chemical fallow systems.

Larvae of the leafy spurge hawk moth were sprayed with and/or were fed leafy spurge plants sprayed with 2,4-D or picloram. Larval survival was not affected from contact with the chemicals, from feeding on contaminated foliage, or from a combination of both. Viable second-generation adult moths were produced in all treatments. Thus, leafy spurge infested with the leafy spurge hawk moth can be sprayed with 2,4-D or picloram without injury to larvae that have reached the fourth or fifth instar stages.

Organic matter is the soil constituent most often associated with herbicide adsorption. Structural diversity makes humified organic material an ideal substrate for the adsorption of many pesticides, but variability in composition and distribution in situ complicates interpretation of its quantitative effect on adsorption. Variability in the adsorption distribution coefficient (KD) of a herbicide among soils often is due to differences in organic matter content and can be reduced by adjusting KD for soil organic carbon content and computing the organic carbon partition coefficient (Koc). Koc can be estimated from the octanol-water partition coefficient (Kow) of organic compounds, but the correlation weakens as compound polarity increases. Koc also can be correlated with aqueous solubility if a correction is made for the melting point of compounds that are solids at 25 C. Relative adsorption can be estimated from parachor and molecular connectivity indices; but corrections are needed for polar compounds, and correlations with KD or Koc have been variable. Such predictive methods may be useful for broad classification purposes, but accurate extrapolation generally requires site-specific adsorption measurements. Empirical models which accommodate the multiple regression of organic matter content and other soil properties such as clay content, pH, and cation exchange capacity on herbicide adsorption can increase accuracy, but interpretation may be restricted to a small number of sites.

Bermudagrass [Cynodon dactylon (L.)Pers. #3 CYNDA] probably originated in tropical Africa; however, Australia, Eurasia, the Indo-Malaysian area, and the Bengal region of India/Bangladesh also have been proposed as its home (11). Although many early writers believed that bermudagrass started in India, most improved strains of Cynodon have been developed from Africian stock (15).

Dinitroaniline herbicides are absorbed readily by roots and emerging shoots, but shoot exposure is more phytotoxic. Translocation within the plant varies by specific herbicide but commonly is minor. Dinitroaniline herbicides injure plants by binding to tubulin, a dimer protein in the ceil that polymerizes to form microtubules (MTs). MTs form the major part of the mitotic apparatus, including spindle fibers, which enable chromosomes to separate during cell division. Dinitroaniline herbicides prevent tubulin from polymerizing into MTs, thus arresting mitosis. This leads to abnormal cells with more than the normal complement of chromosomes and, frequently, lobed nuclei. MTs also are responsible for orienting cell wall microfibrils in such a way that they prevent lateral enlargement of cells. Treatment with dinitroaniline herbicides leads to disorientation of the microfibrils, leading to one of the common symptoms—spherical cells instead of rectangular ones. Studies on the metabolism of trifluralin in plants have shown that amination, dealkylation, and cyclization all can occur. However, metabolites often amount to a small percentage of the original herbicide. In general, trifluralin seems quite stable within the plant.

Tansy ragwort (Senecio jacobaea L.), commonly called stinking willie and sometimes incorrectly called ragweed, is an abundant weed in many parts of Prince Edward Island and Nova Scotia. It is found in pastures, hayfields, waste areas, clearings in woodland and along roadsides. This species is extremely poisonous to cattle and horses and thus is a problem in pastures.

Jimsonweed, Jamestown weed, datura, stramonium, thornapple, tolguacha. These are some of the more than a score of common English names used for jimsonweed (Datura stramonium L. #3 DATST), a cosmopolitan weed of worldwide distribution. The above names are those used most widely in the United States. Jimsonweed is a corruption of Jamestown weed, the name given the plant in colonial days because it first grew in and around Jamestown, VA (2). It had been brought from England as a medicinal plant. Boiled with hog's grease, jimsonweed made a healing salve for burns from “fire, water, boiling lead, gunpowder, and lightning” (2).