Cladonia sandstedei forms cushion-shaped lichens that colonize open environments and is distributed throughout the Caribbean and the south-eastern United States. It co-occurs in parts of its range with C. subtenuis, a morphologically similar taxon that is distinguished from the former by the presence of usnic acid. Preliminary phylogenetic analysis with the RPB2 and TEF-1α loci revealed that these taxa were closely related, but relationships were inconsistent among markers. Here, we combined phylogenetic and population genomic analyses based on RADseq data to clarify the evolutionary relationships and phylogeography of these taxa. Both approaches indicate that the taxa cannot be separated based on secondary metabolites, as previously proposed, but instead form a complex composed of several lineages, largely unrelated to chemistry but with a strong geographical structure in their genetic variation. Continental populations formerly separated under the names C. sandstedei and C. subtenuis were closely related to each other. A similar pattern was observed in the Jamaican counterparts of these taxa, suggesting homoplasy of secondary chemistry. Discriminant Analysis of Principal Components (DAPC) hinted at potential conspecificity between populations in Cuba and Puerto Rico on one hand, and between Jamaica and the continental US on the other; however, phylogenetic analysis and other population-level analyses (PCA and fineRADstructure) suggested that both insular and continental populations were more likely to be reproductively isolated from each other. Based on this, we propose to recognize only one species for the entire complex, under the older name C. sandstedei, with the four spatially structured clades as subspecies: C. sandstedei subsp. sandstedei (restricted to Jamaica) and C. sandstedei subsp. subtenuis comb. nov. (restricted to continental North America) exhibit several chemosyndromes variably containing usnic acid and/or atranorin. The two additional subspecies described here as new, C. sandstedei subsp. cubana and C. sandstedei subsp. landroniana, exhibit the atranorin chemosyndrome and are restricted to Cuba and Puerto Rico, respectively. Our work reaffirms the power of combining RADseq-based phylogenetics and population genetics to disentangle taxonomic and evolutionary histories in poorly understood, closely related and phenotypically similar lichen-forming fungal species.

Potato is the third most important staple food crop globally following rice and wheat. In the United States, potato is grown on approximately 410,000 ha with a farm-gate value of US$1,032 million. In Canada, potato is grown on approximately 134,000 ha with a farm-gate value of US$235 million. The objective of this manuscript, compiled by the Weed Science Society of America Weed Loss Committee, was to estimate potato yield loss caused by weed interference. Potato yield data from weedy and weed-free plots (or plots with >95% weed control) was obtained from researchers working on weed management in potato in the United States and Canada or from published manuscripts from 2000 to 2018. Potato yield loss from weed interference was 12% to 61% when no weed management tactics were implemented. The average yield loss for all states/provinces (where data was obtained) due to weed interference was 44%. Weed interference would cause a farm-gate loss of approximately US$465 million and US$61 in the United States and Canada, respectively, if weeds are not controlled. These results indicate that weed management is critical for successful potato production, and that an ongoing need for research exists on weed management in this crop.

Field studies were conducted from 2005 to 2009 in Idaho and Oregon to 1) evaluate the competitive effect of volunteer potato on sugar beet yield (volunteer potato competition experiment), and 2) determine the optimum timing of volunteer potato removal from glyphosate-tolerant sugar beet fields using glyphosate (volunteer potato removal timing experiment). The volunteer potato competition experiment consisted of eight potato densities, including the untreated check: 0, 6,741, 10,092, 13,455, 16,818, 20,184, 26,910, and 40,365 tubers ha−1. The volunteer potato removal experiment consisted of 10 removal timings (including the untreated check) ranging from the 10-cm rosette stage to mid-tuber bulking. There was a linear decrease in sugar beet root and sucrose yield as volunteer potato density increased (P < 0.001) such that with every volunteer potato tuber per square meter, sugar beet root yield decreased by 15% and sucrose yield decreased by 14%. At the highest volunteer potato density (40,365 tubers ha−1), sugar beet root yield was 29,600 kg ha−1 (compared to 73,600 kg ha−1 for the untreated), representing a 60% reduction in sugar beet root yield. In the removal timing study, a one-time application of glyphosate at the 10-cm rosette, hooking, and tuber initiation stages provided 74% to 98% reduction in volunteer potato tuber biomass. Delaying volunteer potato removal beyond the tuber initiation stage reduced sugar beet root and sucrose yield (12% to 20%), resulting in an economic loss of $104 to $161 per hectare. The best potato removal timing that optimizes the trade-off between improved control and potential for sugar beet yield reductions is before or at the tuber initiation stage.

The objective of this WSSA Weed Loss Committee report is to provide quantitative data on the potential yield loss in sugar beet due to weed interference from the major sugar beet growing areas of the United States and Canada. Researchers and extension specialists who conducted research on weed control in sugar beet in the United States and Canada provided quantitative data on sugar beet yield loss due to weed interference in their regions. Specifically, data were requested from weed control studies in sugar beet from up to 10 individual studies per calendar year over a 15-yr period between 2002 and 2017. Data collected indicated that if weeds are left uncontrolled under optimal agronomic practices, growers in Idaho, Michigan, Minnesota, Montana, Nebraska, North Dakota, Ontario, Oregon, and Wyoming would potentially lose an average of 79%, 61%, 66%, 68%, 63%, 75%, 83%, 78%, and 77% of the sugar beet yield. The corresponding monetary loss would be approximately US$234, US$122, US$369, US$43, US$40, US$211, US$12, US$14, and US$32 million, respectively. The average yield loss due to weed interference for the primary sugar beet growing areas of North America was estimated to be 70%. Thus, if weeds are not controlled, growers in the United States would lose approximately 22.4 million tonnes of sugar beet yield valued at approximately US$1.25 billion, and growers in Canada would lose approximately 0.5 million tonnes of sugar beet yield valued at approximately US$25 million. The high return on investment in weed management highlights the importance of continued weed science research for sustaining high crop yield and profitability of sugar beet production in North America.

Based on an extensive survey of French primary sources and a discussion of the recent literature on fiscal policy in France and Europe during Louis XIV's wars, this article revisits the rationale behind the first experiment with paper money undertaken by finance minister Michel Chamillart, comparing it to other belligerents’ strategies, in particular England's, to adjust their monetary regime to the challenges of funding long wars of attrition. The article shows how concerns about economic activity, coinage and the need to finance the war deficit led to a series of debasements of the French currency, the establishment of a bank in the form of a Caisse des emprunts and the introduction of mint bills, which became legal tender and caused the first experience of fiat money inflation in history. Whereas Chamillart's personal shortcomings have been recently suggested as the cause of Louis XIV's humbling in the War of the Spanish Succession, I argue on the contrary that the introduction of paper money in 1704 was key to the capacity of France to sustain its military effort, but that a succession of military defeats against a more powerful coalition led to inflation. I also argue that the introduction of paper money saved the Caisse des emprunts and its bonds which helped sustain the war effort up until the peace. By situating the use of paper money within the broader question of the exercise of power in the absolute monarchy, this article examines the formation of fiscal policy, paying attention to the ways in which government sought advice from experts. It concludes by calling for further studies on policy- and decision-making under Louis XIV.

Glyphosate-resistant (GR) kochia is an increasing management concern in major cropping systems of the northwestern US. In 2014, we investigated four putative GR kochia accessions (designated as ALA, VAL, WIL, DB) collected from sugar beet fields in eastern Oregon and southwestern Idaho to characterize the level of evolved glyphosate resistance and determine the relationship between the 5-enol-pyruvylshikimate-3-phospate synthase (EPSPS) gene copy number and level of glyphosate resistance. The EPSPS gene copy number was used as a molecular marker to detect GR kochia in subsequent surveys in 2015 and 2016. Based on LD50 values from a whole-plant dose-response study, the four putative GR kochia populations were 2.0- to 9.6-fold more resistant to glyphosate than the glyphosate-susceptible (GS) accession. In an in vivo leaf-disk shikimate assay, leaf disks of GS kochia plants treated with 100-μM glyphosate accumulated 2.4- to 4.0-fold higher amounts of shikimate than the GR plants. The four GR accessions had 2.7 to 9.1 relative EPSPS gene copies compared with the GS accession (<1 EPSPS gene copies), and there was a linear relationship between EPSPS gene copy number and glyphosate resistance level (LD50 values). The 2015 and 2016 GR kochia survey results indicated that about half of the collected populations from sugar beet fields in eastern Oregon had developed resistance to glyphosate whereas only one population from the Idaho collection was confirmed glyphosate resistant. This is the first confirmation of GR kochia in sugar beet fields in eastern Oregon and southwestern Idaho. Diversified weed control programs will be required to prevent further development and spread of GR kochia in sugar beet-based rotations in this region.

A field study was established in southern Iowa in 1994 to study seasonal and long-term weed population dynamics on land being brought back into production after 8 yr as part of the conservation reserve program (CRP). The study was a split-plot design with four replications; two tillage regimes, two crop rotations, and three herbicide application methods were used. Even though the tillage regime did not influence individual weed population density throughout the study, the no-till (NT) regime had more weeds compared to conventional tillage (CT). However, when weeds were grouped into categories, tillage influenced broadleaf weeds in 1994 and 1996 and total weeds in 1995. Plots under the NT regime had an average of 46 broadleaf weeds m−2 compared to 27 in CT in 1994, with Amaranthus rudis Sauer (common waterhemp) being the most prevalent. NT had a total of 186 weeds m−2 compared to 125 m−2 weeds in CT in 1995; however, in 1996, CT plots had 184 weeds m−2 compared to 121 m−2 in the NT regime. Except for broadleaf weeds in 1994, crop rotation did not influence the number of weeds, and herbicide application methods had the greatest effect on weed populations. Overall, weed populations were greater in 1997, 1996, and 1995 than in 1994 for all herbicide application methods. The no-herbicide treatment had the highest number of weeds throughout the study. The total number of weeds in band and broadcast treatments averaged 41 and 26 m−2 in 1994; 96 and 24 m−2 in 1995; 96 and 12 m−2 in 1996; and 109 and 95 m−2 in 1997. The use of broadcast herbicides in NT should be recommended for land coming out of CRP. Regardless of the herbicide application method or crop rotation, CT plots had better yields for both Zea mays L. (corn) and Glycine max L. (soybean). Glycine max had a better stand compared to Z. mays in the first year, indicating that a rotation starting with G. max might be preferred in the land coming out of CRP.

The influence of tillage, crop rotation, and weed management regimes on the weed seedbank in land previously under the conservation reserve program (CRP) for 8 yr was determined from 1994 through 1997. The study was a split-plot design with four replications, two tillage systems, two crop rotations, and three weed management treatments. Eleven weed species were recorded in 1994 and 1995, and 13 in 1996 and 1997. The weed seedbank was dominated by broadleaf species. In 1994, the first year after CRP, the seed population density in the top 15 cm of the soil profile was 51,480 seeds m−2, of which 60 and 20% were pigweed and common lambsquarters. The population density of pigweed seeds in the seedbank increased over time and reached 51,670 seeds m−2 in 1996. In contrast, the seed population density for foxtail species was only 417 seeds m−2 in 1994, but it increased to 7,820 seeds m−2 in 1997. The large increase in foxtail species seed population density in the 4-yr period was mainly in the no-herbicide weed management treatment. The weed seedbank was reduced similarly by band and broadcast herbicide treatments. Tillage and crop rotation did not influence the weed seedbank or Shannon's diversity index, nor did they interact with the weed management treatments in any of the years. The weed seedbank population density varied with the years and time of soil sampling. Weed seed population densities tended to be greater in the fall but declined significantly by time of the spring sampling. The no-herbicide treatment had a more diverse weed seedbank compared with band and broadcast herbicide weed management treatments. An average of one grass and three broadleaf weed species were identified in the three weed management treatments. Band and broadcast herbicide treatments reduced the weed seedbank population density but did not affect the number of broadleaf weed species observed.

Weed management in green onion continues to be a challenge for vegetable growers in Ohio. Field experiments were conducted from 2005 to 2009 to evaluate oxyfluorfen efficacy on common purslane and prostrate pigweed and green onion tolerance when applied POST at 0, 30, 70, 105, and 290 g ai ha−1 approximately 3 wk after planting. No crop injury was observed from any of the herbicide rates, except in 2009 when 209 g ha−1 oxyfluorfen resulted in 10% injury at 7 d after treatment. The transient injury did not reduce green onion yield. Green onion yield ranged from 1.8 to 2.2 kg plot−1 in 2006 and 1.3 to 1.5 kg plot−1 in 2009. In 2007 yield increased linearly from 1.9 to 3.0 kg plot−1 with oxyfluorfen rates of 0 to 105 g ha−1. Common purslane control increased as the rate of oxyfluorfen increased. Application of oxyfluorfen at 70 to 105 g ha−1 provided the best control of common purslane, ranging from 61 to 95% across the years. Similar control results were observed for prostrate pigweed. Prostrate pigweed control with 70 to 105 g ha−1 ranged from 40 to 93% from 2005 to 2009. These results suggest that green onion tolerates oxyfluorfen rates of 70 to 105 g ha−1, and these rates provide common purslane and prostrate pigweed control that growers would find acceptable. Registration of the water-based formulation of oxyfluorfen would provide growers an opportunity to control weeds and reduce the need for hand labor.

Teff is a warm-season C4 annual grass crop grown for forage and food grain that has recently increased in production in parts of the United States. Hay from teff is well suited for livestock, especially horses. The objective of this study was to evaluate teff and weed response to selected herbicides in field studies conducted at the Malheur Experiment Station, Ontario, OR in 2009 and 2010. Herbicides were applied POST when teff was at the four-leaf stage. Broadleaf weed control at 21 d after treatment was greater than 91% across herbicide treatments. Only the premix of 2.5 g ai ha−1 florasulam + 99 g ae ha−1 fluroxypyr + 15 g ai ha−1 pyroxsulam provided acceptable control of barnyardgrass. Due primarily to barnyardgrass competition, teff treated with a premix of 2.5 g ha−1 florasulam + 99 g ha−1 fluroxypyr + 15 g ha−1 pyroxsulam produced 7,200 kg ha−1 of teff hay compared with 4,800 kg ha−1 of teff hay for 2,4-D and dicamba and 4,200 kg ha−1 teff hay when no herbicides were used. Teff grain production was greater with 2.5 g ha−1 florasulam + 99 g ha−1 fluroxypyr + 15 g ha−1 pyroxsulam compared with any of the other treatments. The use of a premix of florasulam + fluroxypyr + pyroxsulam would improve broadleaf and grass weed control in ‘Tiffany' and ‘Dessie' teff varieties, improve hay and grain yield, and reduce production costs.

Field studies were conducted in 2011 at the Malheur Experiment Station, Ontario, OR and Prosser, WA to evaluate the effect of simulated glyphosate drift on direct-seeded dry bulb onion. Glyphosate was applied at 8.6, 25.8, 86, 290, 434, and 860 g ae ha−1 when onion plants were at the flag-, two-, four-, and six-leaf stages. Onion foliar injury was directly related to the glyphosate dose and varied with application timing. Foliar injury at 7 d after treatment (DAT) ranged from 0 to 12% for glyphosate ≤ 25.8 g ha−1. Foliar injury increased at 21 DAT when glyphosate was applied ≥ 25.8 g ha−1 to plants at the flag- and four-leaf stage, and ranged from 24 to 99%. The 50%-injury glyphosate dose at 21 DAT was lowest when onion was treated at the four-leaf and flag stages and was estimated to be 76.8 and 81 g ha−1, respectively. Onion injury severity increased when glyphosate was applied at ≥ 86 g ha−1 and eventually resulted in plant death at 860 g ha−1. Foliar injury was inversely correlated to U.S. no. 1 onion yield. Onions displayed sensitivity to very low glyphosate doses especially at the four-leaf stage. Shikimic acid accumulation increased with the increase in glyphosate dose and was positively correlated with foliar injury and negatively correlated with plant height and onion yield.

Yellow nutsedge is an important weed problem in furrow-irrigated fields in the Treasure Valley of eastern Oregon and southwestern Idaho. Field studies were conducted in 2008 and 2009 to evaluate the effect of PPI S-metolachlor or EPTC followed by POST halosulfuron and dicamba plus glyphosate or glyphosate alone on foliar yellow nutsedge control and tuber production in corn. Corn plant height at 8 and 24 d after treatment (DAT) was reduced 20 and 17%, respectively, in POST herbicides alone compared with PPI plus POST herbicide treatments. Yellow nutsedge control at 8 DAT averaged 78% for treatments that included PPI application of EPTC or S-metolachlor 1,600 g ai ha−1 followed by halosulfuron plus dicamba (35 plus 155 g ha−1 or 70 plus 310 g ha−1) plus glyphosate 785 g ha−1 compared with POST treatments alone (49%). The control at 24 DAT was 84% for treatments that contained halosulfuron plus dicamba compared with 73% for POST glyphosate alone. Yellow nutsedge tubers were reduced 56 to 68% among treatments at the end of 2008. Tuber reduction in 2009 was greater with treatments that included PPI herbicides followed by sequential halosulfuron plus dicamba (35 plus 155 g ha−1) plus glyphosate compared with glyphosate alone. Corn yield reflected the level of yellow nutsedge control and early-season weed interference. Treatments that included PPI herbicides had an average yield of 8.2 T ha−1 compared with 6.6 T ha−1 with sequential glyphosate alone. There was a correlation between percent foliar control and the number of yellow nutsedge tubers produced at the end of each year. Application of PPI herbicides followed by POST halosulfuron plus dicamba (35 plus 155 g ha−1 or 70 plus 155 g ha−1) plus glyphosate improved yellow nutsedge control, reduced early corn–weed competition, and produced the highest corn yield under furrow-irrigated conditions.

Field experiments were conducted in 2001 and 2002 at two sites in Ohio to characterize the effect of isoxaflutole herbicide applied the previous year to field corn on processing tomato, bell pepper, cabbage, snapbean, and cucumber. Isoxaflutole was applied preemergence to field corn in 2001 at 0, 53, 70, 105, and 210 g ai/ha. There were no rotational crop cultivar by herbicide rate interactions at either site. Generally, there was a higher level of visible injury on crops at the Fremont site. Isoxaflutole residues at either site did not affect processing tomato yield. Bell pepper yield was reduced 33% when rotated into 210 g ai/ha rate plots only at Fremont. Snapbean marketable yield was reduced by isoxaflutole carryover from 70 and 210 g ai/ha rates resulting in 0.39 and 0.0 t/ha at Fremont. Similarly, isoxaflutole soil residues from 105 and 210 g ai/ha resulted in 14 and 24% visible injury on cucumber but did not reduce marketable yield. Site differences in soil characteristics and precipitation in the application year may have contributed to observed differences in crop response.

Field studies were conducted in 2010 in Ontario, OR, to evaluate the response of direct-seeded dry bulb onion, sugar beet, and pinto beans to imazosulfuron soil residues 12 mo after application to control weeds in potato. The studies were organized as randomized complete block designs with three replications each. Imazosulfuron was applied alone PRE at 224 and 450 g ai ha−1, sequentially at 224 g ha−1 PRE and POST, or in tank mixture with S-metolachlor 1,060 g ha−1. Very few onion plants emerged in plots previously treated with imazosulfuron at 224 g ha−1, regardless of timing. Emerged onion plants were severely injured and never matured. No onions emerged from residues of imazosulfuron applied at 450 g ha−1. A few sugar beet plants emerged from 224 g ha−1 but were severely stunted and never grew beyond the first set of leaves. There was no sugar beet emergence from imazosulfuron sequential applications, regardless of the rate and application timing. However, imazosulfuron residues did not affect pinto beans, which emerged and produced marketable yield, similar to grower standard and nontreated plots. The results suggest sensitivity of direct-seeded dry bulb onion and sugar beet, but not pinto beans, to imazosulfuron residues 12 mo after application.

A field study was conducted at Vezaiciai branch of the Lithuanian Institute of Agriculture from 1998 to 2000 to determine weed emergence dynamics in potato and to estimate the effect of different intervals of weed crop competition on potato tuber yield if regular interrow cultivation was applied. Treatments varying in intervals of weed-free conditions and competition were laid out in a randomized complete block design with six replications. The greatest emergence of annual broadleaf such as common lambsquarters and other weeds (62 to 86% of the season total) in the crop was observed in the period from potato planting until flowering. Emergence of winter annuals such as field violet and scentless mayweed was greatest in the period from the 20-cm potato plant height until harvesting. The 20-cm potato height was the most important stage affecting potato yield loss due to weed competition. Potato yield losses due to weed competition were minimized when weeds were removed before the potatoes reached 20 cm or kept clean from this point forward. The results indicated that the critical weed-free period, when weed competition was detrimental to yield, started from planting and lasted until 25 d after flowering.

A weed emergence prediction model, WeedCast, was used as a decision aid to schedule potato cultivation with and without herbicides at Wooster, OH, USA; Charlottetown, PE, Canada; and Fargo, ND, USA, from 2001 to 2003. Studies were laid out in a split-plot design with herbicides (±) forming the main plots and cultivation timing as subplots. Cultivation was done at 15, 30, or 60% of predicted weed emergence. Subplots were either left unsprayed or treated with metolachlor + metribuzin at 1.68 + 0.5 kg ai ha−1 and only cultivated at predetermined timing. Cultivation timing was based on predicted emergence of common lambsquarters at Wooster and Charlottetown, whereas eastern black nightshade was the indicator weed at Fargo. Weed control for the different cultivation timings varied among sites and years and was consistently better in plots where herbicides were followed by cultivation. Cultivation alone resulted in poor weed control and significantly reduced potato tuber yield compared with those in plots where weed control also included herbicides. Use of herbicides followed by cultivation and hilling increased tuber yield by 4.6, 4.3, and 8.7 t ha−1, when cultivations were done at 15, 30, and 60% of predicted weed emergence, respectively, and 12.2 t ha−1 for hilled-only plots. The average potato yield increase at Charlottetown was 9.7, 5.9, 6.9, and 7.4 t ha−1 for hilled-only plots and for hilled after cultivations at 15, 30, and 60% of predicted weed emergence with herbicides, respectively. There was no apparent pattern for treatment effects at Fargo, and the potato tuber yields were greatly reduced mainly because of excessive precipitation during potato establishment. Use of WeedCast as a decision-aid tool could be an asset in determining when to do the first and subsequent cultivations. It may work best for growers who use cultivations in potato to remove weeds that were not controlled by herbicides.

Knowledge of environmental factors influencing demography of weed species will improve understanding of current and future weed invasions. The objective of this study was to quantify regional-scale variation in vital rates of giant ragweed and common sunflower. To accomplish this objective, a common field experiment was conducted across seven sites between 2006 and 2008 throughout the north central U.S. maize belt. Demographic parameters of both weed species were measured in intra- and interspecific competitive environments, and environmental data were collected within site-years. Site was the strongest predictor of belowground vital rates (summer and winter seed survival and seedling recruitment), indicating sensitivity to local abiotic conditions. However, biotic factors influenced aboveground vital rates (seedling survival and fecundity). Partial least squares regression (PLSR) indicated that demography of both species was most strongly influenced by thermal time and precipitation. The first PLSR components, both characterized by thermal time, explained 63.2% and 77.0% of variation in the demography of giant ragweed and common sunflower, respectively; the second PLSR components, both characterized by precipitation, explained 18.3% and 8.5% of variation, respectively. The influence of temperature and precipitation is important in understanding the population dynamics and potential distribution of these species in response to climate change.

Field studies were conducted in 2008 in Ontario, OR and Paterson, WA to determine the effect of simulated glyphosate drift on ‘Ranger Russet’ potato, including visual injury, shikimic acid accumulation, and tuber yield. Glyphosate was applied at 8.5, 54, 107, 215, and 423 g ae ha−1; which corresponds to 0.01, 0.064, 0.126, 0.254, and 0.5 of the lowest recommended (846 g ha−1) single application dose for glyphosate-resistant corn and sugar beet. Glyphosate was applied when potato plants were at 10-cm height, stolon hooking, tuber initiation, or bulking stage. The greatest visual foliar injury was observed when glyphosate was applied at a dose of 54 g ha−1 or greater and potato plants were at the hooking stage. The lowest foliar injury was observed when glyphosate was applied to potato plants at the bulking stage. The I50 glyphosate dose at 42 d after treatment (DAT) was estimated to be 167 g ha−1 for potatoes sprayed at the hooking stage. The corresponding glyphosate dose to result in 50% injury for potatoes sprayed at tuber initiation, 10-cm height, and bulking stages were 129%, 338%, and 438%, respectively, greater than hooking stage. The U.S. No.1 potato yield was inversely related to vine injury and shikimic acid accumulation. Shikimic acid accumulation increased when glyphosate was applied at 107 g ha−1 or greater. U.S. No.1 potato yield was reduced by 46% and 84% relative to the untreated control (55 and 76 T/ha) when glyphosate was applied at 107 g ha−1 to plants in the hooking stage at Ontario and Paterson, respectively. Tuber yields at both sites were lowest when glyphosate was applied at hooking and tuber initiation stages.

Field studies were conducted in 2007 and 2008 near Nyssa, OR, and Pasco and Paterson, WA to evaluate yellow nutsedge and broadleaf weed control and potato tolerance to imazosulfuron. No injury symptoms from imazosulfuron were evident on potato at Nyssa, whereas in Washington, imazosulfuron caused some chlorosis of potato foliage ranging from 6 to 15% and < 4% at 6 and 15 d after POST application, respectively. Sequential applications of imazosulfuron controlled yellow nutsedge better than a single PRE application. Sequential applications of imazosulfuron or imazosulfuron in combination with s-metolachlor controlled yellow nutsedge > 92 and 89% at 21 and 42 d after POST applications, respectively. Imazosulfuron controlled ≥ 98% of common lambsquarters and 100% of pigweed species. Imazosulfuron provided season-long control of common mallow at Nyssa. However, imazosulfuron failed to control Russian thistle at Paterson, and only partially controlled hairy nightshade. Yield of U.S. no. 1 potato at Nyssa ranged from 44 to 54 T ha−1 and 42 to 52 T ha−1 for imazosulfuron PRE and imazosulfuron sequential treatments in 2007 and 2008, respectively. U.S. no. 1 potato yield following imazosulfuron PRE and sequential treatments at Pasco ranged from 49 to 57 T ha−1 in 2007, and at Paterson from 36 to 54 T ha−1 in 2008. Lower yields in 2008 were attributed to poor control of hairy nightshade. Imazosulfuron has potential to become a valuable tool for yellow nutsedge management in potato. Studies are needed to evaluate the soil persistence for imazosulfuron in order to determine safety to crops grown in rotation with potato.