Weed seed viability is an important parameter to assess the efficacy of soil disinfestation methods like fumigation and steam. In field experiments, seed samples are commonly placed in permeable bags and buried at several depths in soil before the application of soil disinfestation treatments. The seed samples are recovered several days to weeks after treatment and then seed viability is determined in the laboratory. The process of sample installation and recovery is time consuming and may expose personnel to hazardous conditions such as heat or fumigants. Described is a custom soil probe system, developed to simplify installation and recovery of weed seeds from soil. Each soil probe is capable of holding weed seed samples at three different depths up to 30 cm. The following hypothesis was tested: viability of weed seeds is similarly affected by soil disinfestation treatments whether the seeds were contained in the soil probe system or seed bag assays. Two different soil disinfestation trials were conducted: (1) a repeated micro-plot study (USDA Salinas, 1 m-2), using steam as a soil disinfestation treatment and (2) a field study in a commercial strawberry field with 1,3-dicloropropene plus chloropicrin (Pic-Clor 60) as soil disinfestation method. In both studies, seed viability of burning nettle, common knotweed, and common purslane (tetrazolium assay) and germination rates of yellow nutsedge tubers were assessed. Results indicate that the soil probe system can be used as an alternative to the seed bag assay to assess weed control efficacy of described soil disinfestation methods.

Field studies were conducted at the Pontotoc Ridge-Flatwoods Branch Experiment Station in Pontotoc, MS in 2015 and 2016 to determine the influence of lay-by metribuzin application on weed control and sweetpotato crop response. With the exception of weedy and hand-weeded checks, all plots received flumioxazin at 107 gaiha−1 pre-transplanting followed by (fb) clomazone at 1,120 gaiha−1 immediately after transplanting. Lay-by treatments consisted of S-metolachlor (800 gaiha−1), metribuzin (210 or 315 gaiha−1), metribuzin (210 gha−1) plus napropamide (1,120 gaiha−1), and metribuzin (210 gha−1) plus S-metolachlor (800 gha−1). At 4 weeks after transplanting, sweetpotato crop injury was 3 to 15%, but was transient and not evident after 6 (2015) to 8 weeks after transplanting (2016). Season-long weed control was excellent (≥98%) for all herbicide treatments used in the study. Hand-weeded check plots yielded 4,600; 18,350; 28,770; and 1,520 kgha−1 of jumbo, No. 1, marketable, and cull grades, respectively. Jumbo, No. 1, and marketable yields from all herbicide-containing treatments in the study were greater than the weedy check and similar to the hand-weeded check. For all treatments, the portion of yield graded as cull was similar to the hand-weeded check. Canner yield response differed between years. In general, canner yield was greater in 2016 (8,460 to 10,670 kgha−1) than 2015 (1,570 to 3,570 kgha−1). In both years, canner yield in all treatments was similar to the hand-weeded check with one exception: in 2015 sweetpotato receiving metribuzin plus napropamide yielded more canners (3,570 kgha−1) than the hand-weeded check (2,300 kgha−1).

Studies under Florida conditions for susceptibility of pasture weed species to the new herbicide, aminocyclopyrachlor (ACP), are essential. Sensitivity of weed species was dependent upon the species and environment. Whitehead broom was not susceptible to ACP. Dogfennel control was consistently above 85% 1 yr after treatment with ACP at 140 g ha−1 and all ACP premixes. Milkpea was initially sensitive to all ACP treatments, but regrowth was evident in all treatments after 1 yr at one location. All ACP treatments resulted in 100% control of tropical soda apple 1 yr after treatment at one location, but less than 50% control at a second location. Herbicide applications with ACP, when labeled, will likely provide good to excellent control (80 to 100%) of several weed species.

A study was conducted to refine herbicide rates for sequential applications of sulfometuron methyl over newly planted Eucalyptus benthamii seedlings in the Coastal Plain of the southeastern United States. Container-grown, 6-wk-old seedlings were planted in July 2011 on a nonbedded agricultural site in Quincy, FL and on a bedded forestry site in Wing, AL. Treatments included a single sulfometuron application at 13, 26, 39, or 52 g ha−1, 2 wk after planting; sequential applications at the same rates, 2 and 8 wk after planting; and a nontreated check. All sulfometuron treatments provided effective control of all vegetation groups at both sites, with the exception of 13 g ha−1 for forbs in Quincy. Sparse weed cover in Wing was eliminated by any sulfometuron treatment. In Quincy, two applications provided better weed control than a single one, resulting in more bare ground and less grass and vines. Bare ground increased with increasing sulfometuron rate from 0 to 26 g ha−1. The 26 g ha−1 rate resulted in 95 and 88% bare ground 6 and 12 wk after the first application, respectively, compared to 62 and 51%, respectively for the nontreated check. All sulfometuron treatments had a small positive effect on Eucalyptus seedling growth at the Quincy site, resulting in greater stem diameter (6.0 to 6.7 mm) than the nontreated check (5.0 mm), despite slight foliar necrosis. At the Wing site, in addition to slight foliar necrosis, sulfometuron decreased final seedling survival, height, and stem diameter (48 to 68%, 77.8 to 81.6 cm, and 8.7 to 9.2 mm, respectively), compared to the nontreated check (99%, 88.3 cm and 11.2 mm, respectively). Two sulfometuron applications at 13 to 26 g ha−1 provided selective weed control at both sites, but further refinement is needed for various Eucalyptus genotypes, soil, and vegetation types.

Scientists, above all others, approach public policy believing it to be scientifically rational—as it has been portrayed by the Good Government Movement, the League of Women Voters, and Mark Twain. Today, the problem is that public policy does not appear rational to scientists. While there is great opportunity for scientific input, neither the policy process nor the most influential policy input is necessarily scientifically rational. To understand the relationship of science to policy, one has to look at how the public views science today, the style of policy, the style of science, and how the policy process may have been captured by “irrational” interests. Only then can a realistic marriage be made between science and policy.

During routine use of fluazifop-P-butyl for grass control, county extension agents in Georgia observed control of bristly starbur in grower fields. Experiments to characterize the activity of fluazifop-P-butyl on bristly starbur were conducted under greenhouse conditions in Gainesville, FL, during 2001 and 2002. Fluazifop-P-butyl activity was characterized as a function of herbicide rate and time after application. Commercially available fluazifop-P-butyl was compared to technical fluazifop-P-butyl as a function of herbicide rate and bristly starbur height. Finally, injury to bristly starbur was evaluated when clethodim, diclofop, fluazifop-P-butyl, haloxyfop, quizalofop-p, and sethoxydim were applied at two growth stages. Fluazifop-P-butyl caused >90% injury to bristly starbur with all other post graminicides displaying <8% injury. Nonlinear regression revealed a sigmoidal response of bristly starbur injury to fluazifop-P-butyl. Estimates for 50 and 90% bristly starbur injury (I50 and I90) were 0.07 and 0.14 kg ai/ha, respectively. There was no difference in activity of technical and commercial fluazifop-P-butyl formulations. There was a differential response of bristly starbur to fluazifop-P-butyl over time as a function of plant height at the time of treatment. However, 14 days after treatment (DAT) all treatments displayed >89% injury. Bristly starbur response to fluazifop-P-butyl was similar to injury associated with contact-type herbicides.

Little lovegrass, an annual species native to Europe, was not listed in the floras that describe the plants of Idaho and Washington. Twelve collections were made between 1984 and 1992 from four Idaho counties and six Washington counties. Those records extended the range of this species 450 to 1000 km northwest of populations reported in the literature. Approximately 600 km separated the furthest of the new collection sites, indicating widespread naturalization in those states. Eight of the collections were from roadsides, suggesting that human transport technology had a substantial influence on this plant's dispersal.

Ten herbicides were evaluated for poison-hemlock control in established alfalfa in Utah. Hexazinone, metribuzin, and terbacil controlled poison-hemlock 90% or more but diuron and pronamide did not. Either glyphosate or 2,4-D applied in May at 1.1 kg ae ha-1 controlled poison-hemlock 97 to 98% compared to 60 to 75% with 2,4-DB at that rate. Dicamba and bromoxynil did not control poison-hemlock.

Because of its dissipated appearance and enormous profusion on waysides and in vacant lots during northern California winters, mallow (Malva spp.) is one of the last uncultivated herbs I would have considered eating. My mistake. Several species of weedy Malva have been used interchangeably for food, tea, and medicine for thousands of years–among them little mallow (Malva parviflora L. ♯3 MALPA), common mallow (M. neglecta Wallr. ♯ MALNE), round-leaf mallow (M. rotundifolia L.), and high mallow (M. sylvestris L. ♯ MALSI).

Coapplication of herbicides and insecticides affords growers an opportunity to control multiple pests with one application given that efficacy is not compromised. Trifloxysulfuron was applied at 5.3 g ai/ha both alone and in combination with the insecticides acephate (370 g ai/ha), oxamyl (370 g ai/ha), lambda-cyhalothrin (34 g ai/ha), acetamiprid (45 g ai/ha), thiamethoxam (45 g ai/ha), endosulfan (379 g ai/ha), indoxacarb (123 g ai/ha), emamectin benzoate (11 g ai/ha), methoxyfenozide (67 g ai/ha), spinosad (75 g ai/ha), and pyridalyl (112 g ai/ha) to determine the effects of coapplication on control of some of the more common and/or troublesome broadleaf weeds infesting cotton. In addition, the insecticides acephate, oxamyl, lambda-cyhalothrin, thiamethoxam, and endosulfan, at the rates listed above, were applied either alone or in combination with trifloxysulfuron at 7.9 g/ha to assess the effects of coapplication on thrips control. Control of hemp sesbania (insecticides oxamyl and lambda-cyhalothrin), sicklepod (insecticides methoxyfenozide and pyridalyl), redroot pigweed (insecticides thiamethoxam, methoxyfenozide, spinosad, and pyridalyl), and smooth pigweed, Palmer amaranth, and common lambsquarters (all insecticides) with trifloxysulfuron may be reduced when coapplied with the indicated insecticides for each species. Control of pitted, tall, ivyleaf, and entireleaf morningglory with trifloxysulfuron was not affected by the insecticides evaluated. Coapplication of trifloxysulfuron with the insecticides evaluated also resulted in no negative effects on thrips control.

Seven field experiments were conducted in Oklahoma to compare efficacy and wheat response to currently registered cheat suppression or control herbicide treatments. Chlorsulfuron + metsulfuron premix (5:1 w/w) at 26 g ai/ha applied PRE controlled cheat 20 to 61%, increased wheat grain yields at two of seven locations, and decreased dockage due to cheat at five of seven locations. Chlorsulfuron + metsulfuron at 21 g/ha tank-mixed with metribuzin at 210 g/ha, applied early fall POST, controlled cheat 36 to 98% and increased wheat yield at four of seven locations. Metribuzin applied POST in the fall at 420 g/ha controlled cheat 56 to 98% and increased wheat yields at five of seven locations. Both POST treatments decreased dockage at all locations.

Trifluralin is used for weed control in wheat but may reduce vegetative growth and yield. Postemergence (POST) herbicides may cause additional plant stress to trifluralin-stressed wheat. Field studies at Groton, SD in 1991 and 1992 and at Highmore, SD in 1992 evaluated the effects of 2,4-D-amine, difenzoquat, metsulfuron, and a combination of fenoxaprop-ethyl + 2,4-D-ester + MCPA-ester on hard red spring wheat cultivars ‘2375,’ ‘Prospect,’ and ‘Butte 86’ seeded in areas treated with preplant incorporated trifluralin either in the spring before seeding (0.56 kg ai/ha) or the previous year (1.12 or 2.24 kg ai/ha). Trifluralin applied alone in the spring, and followed by some POST herbicides, reduced shoot dry weight and grain yield. Trifluralin reduced the yield of Prospect the most and the yield of 2375 the least. Yields of trifluralin-treated wheat were reduced 23% by metsulfuron and 14% by fenoxaprop-ethyl + 2,4-D + MCPA compared to yields of wheat treated with only the respective POST herbicide. Yields were not reduced with any trifluralin-POST herbicide combination when trifluralin was applied a year prior to seeding wheat.

In 1753, Carolus Linnaeus described tansy ragwort, Senecio jacobaea, in Species Plantarum. This species is a member of the largest genus of the sunflower family (Asteraceae), which encompasses 1300 genera and 21 000 species worldwide. Taxa in the genus Senecio L. range from herbs to shrubs and occur globally. Comparatively few senecios are of economic importance and many of them are weeds, among them tansy ragwort, which can infest pastures, crowding out more desirable forage and poisoning grazing livestock.

Access to detailed descriptions of the effects of applying specific rates of herbicides to crops and weeds in various growth stages is hampered by the format in which the relevant information is stored. Compared to traditional formats of journal articles and herbicide registration labels, computer database systems could easily cross-reference data from large numbers of experiments and answer specific questions concerning herbicide performance under particular conditions. Availability of this type of information could have far-reaching consequences for herbicide users, consultants, researchers, and regulators. A preliminary format for storing weed control information in IBM-PC compatible computers was developed, including procedures to enter data and retrieve information. Weed control efficacy or crop injury data for all rates of a herbicide or tank-mixture applied at a specific growth stage in a single test are used to generate dose/response equations by means of regression analysis routines. The best fitting of these equations is then used to estimate herbicide rates that would provide ten categories of control, ranging from a “no observable effect level” (NOEL) up to complete control. Rates are estimated only for those categories either within or bordering the range of the observed data, the remaining categories are empty. The estimated rates are stored in the database, along with the original data and other qualifying information. Access to information is organized around searches for a single herbicide, plant species, or pair of species. Search output is presented in a tabular format listing species, growth stage, herbicide name, and herbicide rates for the ten categories: NOEL, 10, 30, 50, 70, 83, 90, 95, 98, and 100% control or injury.

Current plant bioassays included in the guidelines for testing pesticides do not include the measurement of reproduction endpoints. A bioassay, based on reduction of flowering of cress was developed to detect soil residues of hexazinone and simazine at levels of 0.02 and 0.10 ppm, respectively. The endpoint used in the described bioassay is the percentage of plant viability that implies that the tested plants have reached the flowering stage. It was found that sensitivity of cress is lower in soils containing higher organic matter.

Shattercane accessions were collected from 33 corn fields previously treated with nicosulfuron or primisulfuron. In a greenhouse study, we found no resistance to primisulfuron among the accessions. However, 15% of the accessions were more tolerant to primisulfuron than the most susceptible accessions. Shattercane survival among the 33 accessions ranged from 0 to 39% at 40 g ai/ha. While most accessions emerged uniformly, 26% of the accessions had 5 to 38% emergence after primisulfuron treatment. Delayed emergence could facilitate herbicide avoidance.

The influence of ammonium sulfate on the activity of sethoxydim on wild oats and barley was examined under field conditions in 1989 and 1990. A chlorophyll assay, together with plant height and dry weight determinations, was used to quantify the visual ratings for sethoxydim activity. Ammonium sulfate enhanced the activity of 75 and 150 g ai ha-1 sethoxydim in 1989. In 1990, ammonium sulfate increased the activity of the lower rate of sethoxydim only. Of the three quantitative assays, chlorophyll concentration alone differentiated the more rapid development of injury symptoms with added ammonium sulfate that was observed in the visual ratings. The chlorophyll assay was not better than the visual rating assessment, however, and appears to offer no advantages that would justify the time required.