The response of yellow nutsedge (Cyperus esculentus L. #3 CYPES) and Canada thistle [Cirsium arvense (L.) Scop. # CIRAR] to combinations of low rates of fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone} and bentazon [3-(1-methylethyl)-(1H)-2,l,3-benzothiadiazin-4(3H)-one 2,2-dioxide] was determined in a controlled environment chamber and on Canada thistle in the field. In the growth chamber, injury to yellow nutsedge was increased with 24 g ai/ha fluridone combined with 323 g ai/ha bentazon. Either 2.7 or 5.4 g/ha fluridone combined with 27 g/ha bentazon caused uniform injury to Canada thistle. In the field, the combinations of 5.6 g/ha fluridone with either 28 or 2800 g/ha bentazon was phytotoxic to Canada thistle.

Leafy spurge causes economic loss by reducing both herbage production and use. Herbage use by grazing cattle in various densities of leafy spurge (Euphorbia esula L. #3 EPHES) was evaluated over a 3-yr period in North Dakota. Forage production and disappearance were estimated in four density classes of leafy spurge. Use of cool- and warm-season graminoids, forbs, and leafy spurge was estimated during the middle and the end of each grazing season. Cattle used 20 and 2% of the herbage in the zero and low density infestations, respectively, by mid-season. Moderate and high density infestations were avoided until the milky latex in leafy spurge disappeared in early fall, and herbage availability in zero and low density infestations declined. Herbage use in moderate and high density infestations increased to an average of 46% by the end of the grazing season compared to 61% in zero and low density infestations. An annual herbage loss of at least 35% occurred in pasture infested with 50% density or more of leafy spurge.

Safflower (Carthamus tinctorius L. ‘Hartman’) in the rosette growth stage or early bolting stage tolerated thiameturon {3-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] amino] sulfonyl]-2-thiophenecarboxylic acid} at 5, 10, and 15 g ai/ha. Safflower also tolerated chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} at 18 g/ha if safflower was taller than 15 cm at time of application. The fresh weight of above-ground biomass of common sunflower (Helianthus annuus L. #3 HELAN), treated at two plant sizes with thiameturon, was reduced more than 88%. Soil activity of thiameturon also reduced the seedling vigor of common sunflower, but thiameturon in soil was not as lethal to common sunflower as were foliar applications.

The effect of various growth regulators on seedling field bindweed (Convolvulus arvensis L. # CONAR) growth and control with herbicides was evaluated. Fourteen growth regulators were applied at 0.38 to 380 g/ha 7 days before herbicide application in greenhouse, growth chamber and field studies. Field bindweed seedlings pretreated with growth regulators were more effectively controlled by herbicides compared to those not pretreated in greenhouse evaluations. Abscisic acid [[R-(Z,E)]-(+)-5-(1-hydroxy-2,6-6-trimethyl-4-oxo-2-cyclohexane-1-yl)-3-methyl-2,4-pentadicenoic acid] (ABA), ancymidol [a-cyclopropyl-a-(p-methoxyphenyl)-5-pyrimidine methanol], cycloheximide {3-[2-(3,5-dimethyl-2-oxocylohexyl)-2-hydroxyethyl]glutarimide}, ethylenediamine tetraacetic acid [N,N′-1,2-ethanediyl-bis-(N-(carboxymethyl) glycine] (EDTA), and 1-naphthaleneacetic acid (NAA) increased field bindweed stem length. Ancymidol and gibberellic acid [ent-3α,10,13-trihydroxy-20-norgibberell-1,16-diene-7,19-dioc acid 19,10-lactone] (GA) increased root weight, and GA increased root length. Cycloheximide, ethephon [(2-chloroethyl)phosphonic acid] and MH (1,2-dihydro-3,6-pyridazinedione) decreased field bindweed root weight. Ancymidol, GA and IAA (indole-3-acetic acid) increased the number of shoots per plant of seedling field bindweed. Dicamba (3,6-dichloro-2-methoxybenzoic acid) efficacy was enhanced following field bindweed preconditioning with ethephon and IAA. Ancymidol and cycloheximide applied as pretreatments increased glyphosate [N-(phosphonomethyl)glycine] activity on seedling field bindweed. Ancymidol and IAA pretreatment improved field bindweed control with triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}. Herbicide-growth regulator combination treatments that increased field bindweed control in greenhouse and growth chamber studies did not increase top growth control in the field.

The objective of this paper is to discuss ways to improve training of weed scientists for research, including student backgrounds, appreciation for total production systems, economics, computer science and technology, reassessment of technical subject matter areas, and practical experience.

A rotary wiper was developed to apply herbicides selectively to weeds beneath horticultural crops such as fruit trees and ornamentals. Herbicide is delivered internally through a circular pipe manifold imbedded in a rotary polyurethane foam disk, thus avoiding herbicide drift. A free-wheeling bumper wheel, larger than the wiper disk, is mounted just above the disk causing it to move around a tree trunk or shrub on contact. The rotary wiper effectively applied herbicides to weeds within the row of fruit trees.

The objective of this study was to determine the effectiveness of tebuthiuron {N-[5-(1,1-dimethylethyl)- 1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} to treat brush-infested arid rangeland under field-scale conditions. A 130-ha tract in southern New Mexico dominated by creosotebush [Larrea tridentata (Sesse & Moc. ex DC.) Coville #3 LARTR) was treated with pelleted tebuthiuron at 0.4 kg ai/ha. After the fourth season following treatment, control of creosotebush, honey mesquite (Prosopis glandulosa Torr. #PRCJG), and tarbush (Flourensia cernua DC. # FLOCE) was 87, 48, and 100%, respectively. Total shrub density was reduced from 4440 plants/ha to 570 plants/ha. Grass basal area increased from 1.1 to 3.4%. The treatment did not affect forbs greatly. Total herbaceous above-ground biomass production in the fourth season after treatment was 860 kg/ha compared to 140 kg/ha on an adjacent untreated area. Perennial grass production was nearly 11-fold greater on the treated area than on the untreated area.

Plantain, which weary toilers dig from their lawns, hoe from their gardens, or cultivate from their fields was brought to the United States to serve man. Originally considered a valuable medicinal herb and an edible green, it was grown in monastery gardens and was cultivated in botanic gardens. It still is raised as a crop for bird feed.

Two conventional greenhouses were modified into a containment facility for the study of foreign noxious weed species that could be dangerous to North American agriculture. The facility was designed for research on the biology, ecology, and weed control technology of foreign noxious weeds, without the escape of propagules. Two growth chambers and a germinator are located within the containment facility for evaluations under controlled environmental conditions. A standard operating procedure is followed to preclude the escape of weed seeds or propagules while minimizing restrictions to research. The facilities are locked and located in a secure fenced area to reduce the probability of accidental or intentional damage. Procedures for emergencies have been designed to facilitate aid without compromising the containment security. Knowledge concerning weeds that have the potential to threaten North American agriculture will be gained from research performed within this facility.

Field days on diagnosis of plant problems were conducted by Extension specialists at Michigan State University. The objective was to expose participants to a variety of plant growth problems. Techniques were developed to simulate crop injury from herbicide and fertilizer misapplication and environmental stress. Twenty demonstration plots each were established for corn (Zea mays L.) and soybeans [Glycine max (L.) Merr.]. A specific problem was demonstrated in each plot. Two field days were held in 1985. One field day was conducted for agribusiness personnel and the other for Extension field staff. Promotion of the field days was a cooperative effort among Michigan Cooperative Extension Service, Michigan Pesticide Association, and Michigan Plant Food Council. Resource people conducting tours of the plots and leading discussions of the problems included a weed scientist, a soil fertility specialist, and a crop production agronomist. An evaluation survey indicated that this event was useful in furthering the understanding of plant growth problems. Based on the survey responses, future plant problem diagnosis field days are being planned in Michigan.

Effects of 0.1 M ammonium sulfate, 0.1 M potassium phosphate, and 7 g/ha of the isopropylamine salt of imazapyr {(+)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-pyridinecarboxylic acid} were evaluated on the phytotoxicity of the ammonium salt of imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} and the ammonium salt of imazethapyr {(+)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid} applied postemergence to pitted morningglory (Ipomoea lacunosa L. #3 IPOLA). While each of these salts and imazapyr applied alone had no effect, combining them with imazaquin or imazethapyr significantly increased control of pitted morningglory.

A survey showed weed scientists agree that basic agronomy, crop production and plant-oriented courses are essential in weed science education. Although there was no consensus on the structure of a core curriculum or even on whether one was needed, they agreed that curricula must be constructed to fit student interests, goals, and abilities.

After 25 yr in research and teaching, I moved into administration about 2 yr ago. Thus I shall discuss with you the image of weed science as a recent outsider, which I consider myself. From this perspective, I want to point out both the positive and negative aspects of our weed science image. In other words, what are our strengths and weaknesses? Can we build on our strengths and overcome our weaknesses?

Since the late 1970s, the reason(s) for the performance of certain pesticides to fail after several years of continuous use has been studied. These pesticides include representatives from the herbicide, insecticide, and fungicide groups, encompassing several classes of chemistry–carbamates, carbamothioates (thiocarbamates), and organophosphates.

Although not all graduate students will teach in the classroom, all will use teaching skills in some aspects of their work. Graduate students can participate in activities that will prove useful in later teaching situations. They can prepare audio-visual materials or design and conduct experiments and demonstrations in the laboratory. Carefully selected and well-prepared graduate students can give lecture or laboratory presentations; however, care must be taken not to detract from the quality and continuity of the course from the standpoint of students who are enrolled for credit (and are paying for the course).