Field studies were conducted near Crowley, LA in 2005 through 2007 to evaluate the effects of simulated herbicide drift on ‘Cocodrie' rice. Each application was made with the spray volume varying proportionally to herbicide dosage based on a constant spray volume of 234 L ha−1 and a glyphosate rate of 863 g ae ha−1. The 6.3%, 54–g ha−1, herbicide rate was applied at a spray volume of 15 L ha−1, and the 12.5%, 108–g ha−1, herbicide rate was applied at a spray volume of 29 L ha−1. Compared with the nontreated, glyphosate applied at one tiller, panicle differentiation (PD), and boot resulted in increased crop injury. The greatest injury was observed on rice treated at the one-tiller timing. Applications of glyphosate at one tiller, PD, and boot reduced plant height at harvest and primary and total crop yield. Rice treated at primary crop maturity was not affected by glyphosate applications.

Glyphosate-resistant Palmer amaranth has become a major threat to soybean production in the southern United States. Arkansas soybean producers rely heavily on glyphosate-resistant soybean; hence, an alternative solution for controlling resistant Palmer amaranth is needed. A field experiment was conducted at Marianna, AR, during 2009 and 2010 in which soybean production systems were tested in combination with deep tillage and no tillage to determine the impact on Palmer amaranth emergence. To establish a baseline population, 250,000 glyphosate-resistant Palmer amaranth seeds were placed in a 1-m2 area in the middle of each plot and incorporated in the soil, and emergence was evaluated five times during the season. Production systems of full-season soybean with a rye cover crop or soybean double-cropped with wheat, which had high amounts of plant residue on the soil surface reduced Palmer amaranth emergence more than systems without deep tillage and a cover crop or wheat. When used in combination with deep tillage, these systems reduced Palmer amaranth emergence by 98 and 97%, respectively, in 2009 and by 73 and 82%, respectively, in 2010. Deep tillage alone caused an 81% reduction in emergence averaged over both years. Soybean double-cropped with wheat used in combination with deep tillage provided a 95% reduction in Palmer amaranth emergence over the 2-yr period. This research shows that deep tillage in combination with soybean production systems that have high amounts of residue on the soil surface are alternative means for providing a high level of control of glyphosate-resistant Palmer amaranth and could lessen the dependence on chemical weed control.

The introduction of transgenic crops with resistance to 2,4-D will provide growers with new weed management options in soybean. Field and greenhouse experiments were conducted in 2010 and 2011 to determine the influence of weed height on compatibility of glufosinate and 2,4-D in resistant soybean. Results from these experiments indicate a significant increase in the rate of glufosinate or 2,4-D is needed when applied alone in order to achieve similar levels of weed control as lower rates of glufosinate and 2,4-D combinations. Mixtures of glufosinate and 2,4-D were more effective in controlling common waterhemp, Asiatic dayflower, and barnyardgrass than either herbicide alone, and with the magnitude of difference greater as the height of common waterhemp increased. Large crabgrass control decreased when glufosinate was applied with 2,4-D compared with glufosinate alone, with the magnitude of the reduction greater as weed height increased. Sequential application of glufosinate and 2,4-D eliminated the antagonism noted with tank mixtures. Soybean yields were also reduced by approximately 3% in response to 30 to 35–cm compared to 10 to 15–cm herbicide applications because of the combination of weed interference and reduced control. Overall, results from these experiments indicate that glufosinate plus 2,4-D combinations are likely to provide increased control of problematic weeds like Asiatic dayflower and common waterhemp while providing similar grass control as herbicide programs that contain glufosinate alone.

A 2-yr (2009 to 2010), no-till (direct-seeded) “follow-up” study was conducted at five western Canada sites to determine weed interference impacts and barley and canola yield recovery after 4 yr of variable crop inputs (seed, fertilizer, herbicide). During the initial period of the study (2005 to 2008), applying fertilizer in the absence of herbicides was often worse than applying no optimal inputs; in the former case, weed biomass levels were at the highest levels (2,788 to 4,294 kg ha−1), possibly due to better utilization of nutrients by the weeds than by the crops. After optimal inputs were restored (standard treatment), most barley and canola plots recovered to optimal yield levels after 1 yr. However, 4 yr with all optimal inputs but herbicides led to only 77% yield recovery for both crops. At most sites, when all inputs were restored for 2 yr, all plots yielded similarly to the standard treatment combination. Yield “recovery” occurred despite high weed biomass levels (> 4,000 kg ha−1) prior to the first recovery year and despite high wild oat seedbank levels (> 7,000 seeds m−2) at the end of the second recovery year. In relatively competitive narrow-row crops such as barley and canola, the negative effects of high soil weed seedbanks can be mitigated if growers facilitate healthy crop canopies with appropriate seed and fertilizer rates in combination with judicious herbicide applications to adequately manage recruited weeds.

Glyphosate-resistant (GR) weeds, especially GR Palmer amaranth, are very problematic for cotton growers in the Southeast and Midsouth regions of the United States. Glufosinate can control GR Palmer amaranth, and growers are transitioning to glufosinate-based systems. Palmer amaranth must be small for consistently effective control by glufosinate. Because this weed grows rapidly, growers are not always timely with applications. With widespread resistance to acetolactate synthase-inhibiting herbicides, growers have few herbicide options to mix with glufosinate to improve control of larger weeds. In a field study using a WideStrike® cotton cultivar, we evaluated fluometuron at 140 to 1,120 g ai ha−1 mixed with the ammonium salt of glufosinate at 485 g ae ha−1 for control of GR Palmer amaranth 13 and 26 cm tall. Standard PRE- and POST-directed herbicides were included in the systems. Glufosinate alone injured the WideStrike® cotton less than 10%. Fluometuron increased injury up to 25% but did not adversely affect yield. Glufosinate controlled 13-cm Palmer amaranth at least 90%, and there was no improvement in weed control nor a cotton yield response to fluometuron mixed with glufosinate. Palmer amaranth 26 cm tall was controlled only 59% by glufosinate. Fluometuron mixed with glufosinate increased control of the larger weeds up to 28% and there was a trend for greater yields. However, delaying applications until weeds were 26 cm reduced yield 22% relative to timely application. Our results suggest fluometuron mixed with glufosinate may be of some benefit when attempting to control large Palmer amaranth. However, mixing fluometuron with glufosinate is not a substitute for a timely glufosinate application.

Amaranthus control in cotton can be difficult with the loss of glyphosate efficacy, especially in conservation-tillage cropping systems. Research was conduction from 2006 to 2008 at EV Smith Research Center, Shorter, AL, to determine the level of glyphosate-susceptible Amaranthus control provided by four initial tillage and herbicide treatments, including 1) moldboard plowing followed by a single-pass disking and field cultivation plus pendimethalin at 1.2 kg ai ha−1 preplant incorporation (PPI), 2) two-pass disking followed by field cultivation plus pendimethalin at 1.2 kg ha−1 PPI, 3) no tillage including an application of pendimethalin at 1.2 kg ha−1 PRE, or 4) no tillage without pendimethalin in 2006. No further tillage practices or pendimethalin applications were utilized after study initiation. Initial tillage operations, including inversion with disking or disking twice, resulted in Amaranthus density of ≤ 4 plants m−2 and 47 to 82% control, whereas no-tillage treatments had ≥ 4 plants m−2 and 14 to 62% control. Subsequent applications of PRE herbicides included fluometuron at 1.68 kg ai ha−1 or prometryn at 1.12 kg ai ha−1 and provided 53 to 98% and 55 to 93% control, respectively, and reduced Amaranthus density compared to no PRE herbicide to < 2 plants m−2, regardless of tillage treatment. A POST application of glyphosate at 1.0 kg ae ha−1 improved control in conjunction with almost all treatments in each year. Results indicate that a one-time tillage operation followed by a return to reduced tillage may aid in the reduction of Amaranthus density when used with PRE-applied herbicides; however, this system will likely not provide adequate control when high population densities of glyphosate-resistant Amaranthus are present, thus highlighting the need for a highly efficacious POST herbicide system.

Field studies were conducted in Louisiana and Mississippi in 2009 and 2010 to evaluate coapplications of glyphosate, pyrithiobac, and residual herbicides on growth and yield of glyphosate-resistant cotton. Treatments were a factorial arrangement of glyphosate (0 and 860 g ae ha−1), pyrithiobac (0 and 470 g ai ha−1), and two residual herbicides (pendimethalin [1,120 g ai ha−1], S-metolachlor [1,070 g ai ha−1], and no residual herbicide). Cotton injury was greatest 3 d after treatment (DAT) and decreased at each evaluation interval until 28 DAT when pyrithiobac was coapplied with glyphosate. Cotton injury ranged from 4 to 17% through 14 DAT when pyrithiobac was applied alone (no residual herbicide) or with pendimethalin, but injury decreased to ≤ 3% after 14 DAT. Cotton injury 3 to 21 DAT following pyrithiobac plus S-metolachlor ranged from 4 to 31%, but S-metolachlor alone injured cotton 1 to 7%. When pyrithiobac was included, cotton injury following S-metolachlor was 3 to 15% greater than that following pendimethalin from 3 to 14 DAT. Pendimethalin did not reduce plant height at 21 or 42 DAT compared with treatments receiving no residual herbicide, but S-metolachlor reduced plant heights 5 and 4% at 21 and 42 DAT, respectively. Although cotton injury was severe in some cases and persisted until 21 DAT, the injury did not cause reductions in yield. This indicates the early-season cotton injury was transient, and cotton was able to recover from the injury with no observed differences in yield.

Methiozolin is a new isoxazoline herbicide being investigated for selective POST annual bluegrass control in creeping bentgrass putting greens. Glasshouse and field research was conducted from 2010 to 2012 in Tennessee and Texas to evaluate annual bluegrass control efficacy with methiozolin. Application placement experiments in the glasshouse illustrated that root absorption was required for POST annual bluegrass control with methiozolin at 1,000 g ai ha−1. Soil-plus-foliar and soil-only applications of methiozolin reduced annual bluegrass biomass greater than treatments applied foliar-only. Field experiments evaluated annual bluegrass control efficacy with two application rates (500 and 1,000 g ha−1) and six application regimes (October, November, December, October followed by [fb] November, November fb December, and October fb November fb December) on sand- and soil-based putting greens. Annual bluegrass control with methiozolin at 1,000 g ha−1 on sand-based greens ranged from 70 to 72% compared to 87 to 89% on soil-based greens. Treatment at 500 g ha−1 controlled annual bluegrass 57 to 64% on sand-based greens compared to 72 to 80% on soil-based greens. Most sequential methiozolin application regimes controlled annual bluegrass more than single applications. On sand-based greens, sequential application programs controlled annual bluegrass 70 to 79% compared to 85 to 92% on soil-based greens. Responses indicate that methiozolin is a root-absorbed herbicide with efficacy for selective control of annual bluegrass in both sand- and soil-based creeping bentgrass putting greens.

Aminocyclopyrachlor (AMCP) is a newly developed synthetic auxin herbicide for broadleaf weed control in turfgrass systems. AMCP has been observed to undergo rapid photodecomposition in shallow water when exposed to sunlight. Most herbicide applications on golf courses occur during the morning when dew is still present on the turfgrass canopy. These conditions could result in efficacy loss if photolysis occurred while AMCP is suspended in dew droplets. Research was conducted to determine the effect of ambient moisture on AMCP efficacy. AMCP (79 and 105 g ae ha−1), aminopyralid (280 g ae ha −1), and two AMCP granular formulations (84 g ha−1) were applied to dew-covered (WET) and dew-excluded (DRY) ‘Tifway' bermudagrass plots. Herbicide treatments applied to WET plots had greater visually rated bermudagrass injury than respective treatments applied to DRY plots at 7 and 21 d after treatment (DAT), with the exception of aminopyralid at 21 DAT. Normalized difference vegetative index on turfgrass quality complemented visual ratings, indicating greater turfgrass quality reductions when applied to WET vs. DRY plots. These results indicate that AMCP applications made to dew-covered turfgrass can increase herbicidal efficacy, and no significant losses due to photodegradation were observed.

With the loss of methyl bromide (MeBr) and high prices of alternatives, tomato growers are applying lower fumigant rates or adopting a reduced system. Without the broad-spectrum control provided by the complete fumigant system, a fallow weed program might be needed to avoid an increase in pest pressure with consecutive years of application of the reduced-fumigant system. Nutsedges are among the pests of interest due to their fast reproduction by underground structures and ability to spread and quickly infest a field. Field trials were conducted between February and December of 2011 in Balm, FL, to evaluate the impacts of fallow treatments, fumigants, and halosulfuron on nutsedge control. The trial design was a split–split plot with main, sub-, and subsubplots being fallow, fumigant, and herbicide treatment, respectively. Fallow treatments were spaced evenly throughout the fallow season and consisted of sequential combinations of cultivation (C) and/or glyphosate (G) applied at 2.24 kg ae ha−1; including: C, CC, G, GG, CG, GC, GCG, and NO (nontreated control). Fumigant treatments included a reduced-fumigant system of 1,3-dichloropropene plus chloropicrin 40:60 (1,3-D + pic) at 281 kg ha−1, a complete fumigant system of dimethyl disulfide plus chloropicrin 79:21 (DMDS + pic) at 545 kg ha−1, and no fumigant (NoFum). Herbicide treatments were either two POST applications of halosulfuron at 39 g ai ha−1 (Hal) or no halosulfuron (NoHal). In general, the fallow weed treatment GCG was the most effective in reducing nutsedge shoot emergence through the plastic mulch. When the reduced-fumigant system 1,3-D + pic was combined with GCG fallow treatment and halosulfuron (GCG:1,3-D + pic:Hal), no differences were found between this combination and the complete fumigant system DMDS + pic with halosulfuron and combined with CC, G, GG, CG, GC or GCG. This study shows the importance of adding a fallow weed program and halosulfuron to either a reduced or complete fumigation system to minimize the reproduction and growth of nutsedges.

Studies were conducted in 2010 and 2011 to determine the effect of herbicide-based Palmer amaranth management systems in ‘Covington' sweetpotato. Treatments consisted of three herbicide application times. Pretransplant applications were flumioxazin at 107 g ai ha−1, fomesafen at 280 g ai ha−1, flumioxazin at 70 g ha−1 plus pyroxasulfone at 89 g ai ha−1, or no herbicide. A second herbicide application was applied within 1 d after transplanting (DAP) and consisted of S-metolachlor at 800 g ai ha−1, clomazone at 630 g ai ha−1, or no herbicide. Two weeks after planting (WAP) plots received S-metolachlor at 800 g ha−1, metribuzin at 140 g ai ha−1, a tank mix of S-metolachlor at 800 g ha−1 plus metribuzin at 140 g ha−1, hand-weeding followed by (fb) S-metolachlor at 800 g ha−1, or no herbicide. Crop tolerance, Palmer amaranth control, and sweetpotato yield in systems containing fomesafen pretransplant were similar to flumioxazin-containing systems. Systems containing flumioxazin plus pyroxasulfone pretransplant resulted in increased crop stunting and decreased sweetpotato yield in 2010, compared with systems containing flumioxazin or fomesafen, but were similar to systems with flumioxazin or fomesafen in 2011. In 2010, systems containing S-metolachlor applied within 1 DAP resulted in increased sweetpotato injury, similar Palmer amaranth control, and reduced no. 1, jumbo, and total sweetpotato yield, compared with systems with clomazone. In 2011, systems containing clomazone were more injurious to sweetpotato than systems receiving S-metolachlor, but Palmer amaranth control and sweetpotato yield were similar. Systems containing metribuzin 2 WAP resulted in increased sweetpotato injury and Palmer amaranth control (in 2010) but similar no. 1 and total sweetpotato yields, compared with systems containing S-metolachlor at 2 WAP. Hand-weeding fb S-metolachlor provided greater Palmer amaranth control and no. 1 sweetpotato yield than did systems of S-metolachlor without a preceding hand-weeding event in 2010.

Field experiments were conducted in 2011 and 2012 in Belle Glade, FL to evaluate the response of sweet corn and weed control to pyroxasulfone on high-organic-matter soils in the Everglades Agricultural Area (EAA) of southern Florida with the use of dose-response curves. Pyroxasulfone was applied PRE at 31.25, 62.5, 125, 250, 500, and 1,000 g ai ha−1 on soil with 80% organic matter. Dose-response curves based on a three-parameter log-logistic model were used to determine pyroxasulfone rate required to provide 90% control (ED90) of spiny amaranth, common lambsquarters, and common purslane in sweet corn. The ED90 values for spiny amaranth, common lambsquarters, and common purslane control were 209, 215, and 194 g ha−1 of pyroxasulfone, respectively, at 21 d after treatment (DAT). At 42 DAT, the ED90 values for spiny amaranth, common lambsquarters, and common purslane control were 217, 271, and 234 g ha−1 of pyroxasulfone, respectively. Sweet corn yield increased with increasing rates of pyroxasulfone. An estimated 214 g ha−1 of pyroxasulfone was required to maintain sweet corn yield at 90% level of the weed-free yield. In addition, pyroxasulfone did not result in sweet corn injury. These results indicate that pyroxasulfone can provide effective weed control in sweet corn on high-organic-matter soils of the EAA.

Three experiments were conducted to evaluate early POST control of yellow woodsorrel using PRE-applied herbicides. In experiment 1, yellow woodsorrel was seeded at two dates in a commercial pine-bark substrate and grown until reaching either the cotyledon–one-leaf (C-1L) or two- to four-leaf (2-4L) growth stage. The herbicides isoxaben, indaziflam, and dimethenamid-p were applied at these growth stages. Two rates of isoxaben and indaziflam provided yellow woodsorrel control (≥ 80% reduction in fresh weight [FW]) when applied at the C-1L stage; however, once yellow woodsorrel reached the 2-4L stage, indaziflam was the only herbicide that provided effective control at both rates tested. Experiments 2 and 3 were similar to experiment 1, except two labeled rates of dithiopyr were also evaluated. In experiment 2, all herbicides evaluated provided ≥ 90% reduction in FW of yellow woodsorrel at the C-1L stage. Although no differences in FW were observed among any of the herbicide treatments when yellow woodsorrel were treated at the 2-4L stage, control ratings indicated that indaziflam provided the most effective yellow woodsorrel control. Experiment 3 results also indicated that isoxaben, indaziflam, and dithiopyr controlled yellow woodsorrel (≥ 95% reduction in FW) when treatments were applied at the C-1L stage, whereas dimethenamid-p reduced shoot FW 70%. When yellow woodsorrel was treated after reaching the 2-4L stage, indaziflam provided the greatest control of any herbicide evaluated.

Inputs, including herbicides, used in crop production may create negative environmental impacts. One solution to minimize these adverse effects is the adoption of integrated weed management (IWM) with the intention of reducing herbicide use. This study, conducted in 2010, estimates the willingness of farmers to pay for the adoption of more effective weed management methods. Results suggest that the willingness to pay (WTP) for IWM is greater than the WTP for other weed management methods, including chemical weed management and chemical and mechanical weed management. This study also identified a number of factors that influence the adoption of IWM on wheat farms in Iran using a multinomial logit model. Total annual income, area under irrigated wheat, wheat yield loss due to weeds, perennial nature of the weeds, and having awareness of weed resistance to herbicides had a positive effect on the adoption of IWM practices. However, having rain-fed (dryland) wheat cultivation and a larger number of plots on the farm had a negative influence on the choice of IWM.

Turfgrass weed scientists commonly use visual ratings (VR) to assign a numerical value to a turfgrass or weed response. These ratings lack quantifiable numerical values and are considered subjective. Alternatives to VR, including line intersect analysis (LIA) and digital image analysis (DIA), have been used to varying extents in turfgrass research. Alternatives can be expensive, labor intensive, and can require extensive calibration and increased time for data acquisition. Minimal research has been conducted evaluating rating methods used in turfgrass weed science. Trials were conducted in 2007 and 2008 to evaluate ratings methods used to quantify large crabgrass populations as influenced by tall fescue mowing height (2.5, 5.1, 7.6, and 10.2 cm). Percent large crabgrass cover was assessed utilizing VR, LIA, and DIA to determine if differences existed among evaluation methods. Pairwise comparisons, Pearson's correlation, and linear regression were performed to compare evaluations. All rating methods were significantly correlated to one another. Differences of large crabgrass cover estimates existed between LIA and DIA data at all mowing heights and between VR and DIA data at the 7.6 and 10.2 cm mowing heights in 2007. Authors believe that shadows produced by the turf canopy at higher (≥ 7.6 cm) mowing heights increased DIA estimates of large crabgrass cover. At trial initiation in 2007, researchers did not capture calibration images because the methodology to eliminate a shadow influence using a standard digital image had not been published. Additional DIA calibration in 2008 corrected for canopy shadows, and no differences were observed in large crabgrass cover between all evaluation methods indicated by nonsignificance pairwise comparisons and estimated regression parameters. These data indicate VR are no different than LIA or DIA in estimating large crabgrass cover as affected by tall fescue mowing height.

Early-season weed competition may cause substantial yield losses in onion. Oxyfluorfen and bromoxynil are POST herbicide options for weed control once onion has developed two leaves, which often takes 4 to 6 wk. Multiple applications of oxyfluorfen at 35 and 18 g ai ha−1 and bromoxynil at 35 and 18 g ae ha−1 with adjuvants were evaluated for onion safety and weed control under controlled greenhouse conditions. Oxyfluorfen at 35 g ha−1 plus organosilicone surfactant caused 42% onion injury at 12 d after three sequential applications. Onion treated with bromoxynil at 18 g ha−1 plus high surfactant oil concentrate had lower fresh weight (0.7 g) compared to methylated seed oil (MSO) (1.2 g) or petroleum oil concentrate (POC) (1.3 g) at the same bromoxynil rate. The addition of nonionic surfactant to bromoxynil, averaged across bromoxynil rates, provided 17 and 39% control of redroot pigweed and common lambsquarters, respectively. Redroot pigweed control with oxyfluorfen at 35 or 18 g ha−1 plus any tested adjuvant was excellent (≥ 93%). Results suggested the use of POC or MSO with either oxyfluorfen or bromoxynil for subsequent field trials because of similar common lambsquarters and redroot pigweed control and onion safety.

Crop interference and weed-competitive cultivars are a component of integrated weed management, but their use requires understanding the extent to which rice can interfere with weed growth and how weeds may respond to rice interference. Growth of blistering ammannia was studied in a screen house by growing it alone or with rice seeded in rows (20 cm) or broadcast at the rate of 25 and 75 kg ha−1. The growth of blistering ammannia was similar whether grown with rice seeding rates of 25 or 75 kg ha−1 or with broadcast or row-seeded rice, suggesting that the weed is a weak competitor if rice is planted uniformly. Rice interference greatly reduced the number of blistering ammannia leaves and leaf, stem, total shoot, and root biomass. However, the weed showed the ability to reduce the effects of rice interference by increasing leaf and stem biomass in the upper half of the plant, and increasing specific stem length. At 11 wk after planting, blistering ammannia had 71 to 80% leaf biomass in the upper half of the plant when grown with rice interference compared with only 29% when grown without rice interference. Despite such plasticity, blistering ammannia shoot and root biomass at final harvest decreased by 94 to 99% when grown with rice compared with its biomass without crop interference. These results suggest that blistering ammannia is a poor competitor and uniform rice density could be very effective in suppressing blistering ammannia in direct-seeded rice systems.

Potatoes are an important global food crop typically produced in high-input systems in temperate zones. Growers that have access to compost may use it to improve soil health and increase tuber yields, but compost may also increase weed competition by increasing early-season water availability and weed growth. A field study at the Michigan State University Montcalm Research farm in 2010 and 2011 investigated the impact of compost on weed competition in potato. Potatoes were grown in field plots with 0, 4,000, or 8,000 kg carbon (C) ha−1 of compost under weed-free conditions, and in competition with common lambsquarters, giant foxtail, and hairy nightshade. Compost did not increase biomass or seed production of any weed species. Giant foxtail and hairy nightshade at 5.3 plants per meter of row reduced potato yield by 20%; common lambsquarters reduced yield by 45%. The yield reduction by giant foxtail and hairy nightshade was due to a decrease in tuber bulking, whereas yield reductions from common lambsquarters were a result of lower tuber set and bulking. Potato yield increased 5 to 15% in compost compared to non-compost treatments; tuber specific gravity decreased by 0.3% in composted treatments. Across weed densities, elevated soil potassium levels in the 8,000 kg C ha−1 composted treatment may have increased potato yield and decreased tuber specific gravity.

A written survey administered to 3,500 Florida cattle producers in 2006 documented tropical soda apple as the most common pasture weed across the state of Florida. Over 80% of the survey respondents reported tropical soda apple on their ranches, and over 65% declared the plant to be a major problem for their cattle operation. On ranches that reported tropical soda apple infestations, the level of pastures infested with this weed ranged from a low of 4% in north Florida to a high of 12% in central Florida. The cattle producers' most common strategies to tropical soda apple were herbicide application and mowing. These strategies were used by 32% of respondents in north Florida, 75% in central Florida, and 76% in south Florida. On a statewide basis, 20% of cattle producers used herbicides alone, 7% used mowing alone, and 20% used both methods. Some cattle producers reduced the cattle stocking rate as a consequence of tropical soda apple infestations. This negative impact was reported by only 2% of cattle producers in north Florida, 6% in central Florida, and 7% in south Florida. With the use of the economic input/output model IMPLAN, tropical soda apple control costs resulted in economic losses throughout Florida of $15 million annually in 2006 to cattle producers and their supporting business sectors.

Students studying weed science would expand their knowledge by conducting targeted experiments on invasive weeds. Tamarix spp., some of the most problematic weeds known in the United States, have value for weed science education. Tamarix was used in an undergraduate laboratory course to demonstrate weed science principles for a minimal cost and with great potential for academic enhancement. The laboratory exercise was designed to teach weed science students about the difficulty associated with controlling invasive weeds even at a relatively young age in a region where plants have been detected but large-scale invasion has not occurred to emphasize the importance of early detection and rapid response. The successful execution of this exercise and the positive student response suggests that Tamarix and other weeds with similar reproductive capacities could be valuable additions to weed science curricula. Innovative approaches to teaching weed science facilitate greater learning of this complex subject by students from diverse backgrounds and academic disciplines.