Weed control by heat or flaming typically uses flames to burn small weeds, directed away from desired crops. This research studied an enclosed flaming system for weed control before turfgrass establishment. Field research trials were conducted to explore the efficacy of a PL-8750 flame sanitizer at two application timings. Treatments included various application methods of PL-8750 flame sanitizer and common thermal and chemical weed control methods. Data were weed control relative to the control treatment. Species evaluated included carpetweed, Virginia buttonweed, spotted spurge, large crabgrass, goosegrass, old world diamond-flower, cocks-comb kyllinga, and yellow nutsedge. Turfgrass establishment was not successful in summer but was successful in fall. Fall-application timing trials resulted in > 60% tall fescue establishment at 6 wk after seeding (WAS) for all treatments. Summer-application timing trials resulted in unacceptable turfgrass establishment (≤ 18%) for all evaluated turfgrass species at 6 WAS. Broadleaf and grassy weeds were better controlled compared with sedge weeds. Overall, solarization; covered, emerged-weed flaming; and double applications of covered, emerged-weed flaming were the most successful treatments. Solarization controlled carpetweed, Virginia buttonweed, spotted spurge, large crabgrass, and goosegrass > 80% at 6 WAS. Weed control across thermal treatments were equal to or greater than the comparison chemical treatment (dazomet at 389 kg ha−1). Results indicate thermal weed control has potential for reducing weed populations before turfgrass establishment.

Methyl bromide is a common fumigant for effective weed control in polyethylene-mulched vegetable crops. However, the ban on methyl bromide in the United States has created a need to find a suitable alternative. This study investigated the herbicidal efficacy of phenyl isothiocyanate (ITC) as a methyl bromide alternative for weed control in polyethylene-mulched bell pepper during 2006 and 2007. Six rates of phenyl ITC (0, 15, 75, 150, 750, 1,500 kg ha−1) under low-density polyethylene (LDPE) or virtually impermeable film (VIF) mulch were tested against yellow nutsedge, Palmer amaranth, and large crabgrass. Additionally, a standard treatment of methyl bromide/chloropicrin (67 : 33%) at 390 kg ha−1 under LDPE mulch was included for comparison. VIF mulch provided no advantage over LDPE mulch in either improving weed control or marketable yield in bell pepper. Unacceptable pepper injury (≥ 60%) occurred at the highest phenyl ITC rate of 1,500 kg ha−1 at 2 WATP in both years, regardless of mulch type. Higher bell pepper injury was observed in 2006 (≥ 36%) than in 2007 (≤ 11%) at 750 kg ha−1 of phenyl ITC. The lower injury in 2007 could be attributed to aeration of beds 48 h prior to transplanting. Regardless of mulch type, phenyl ITC at 2,071 (± 197) and 1,655 (± 309) kg ha−1 was required to control yellow nutsedge, Palmer amaranth, and large crabgrass equivalent to methyl bromide in 2006 and 2007, respectively. Bell pepper marketable yield at all rates of phenyl ITC was lower than methyl bromide in 2006. In contrast, marketable yield in phenyl ITC at 750–kg ha−1 was equivalent to methyl bromide in 2007. It is concluded that phenyl ITC should be applied at least 4.2 times higher rate than methyl bromide for effective weed control, and bed aeration is required to minimize crop injury and yield loss. Additional research is needed to test phenyl ITC in combination with other weed control strategies to obtain effective weed control with acceptable crop safety.

Methyl bromide has been widely used as a broad-spectrum fumigant for weed control in polyethylene-mulched bell pepper. However, because of environmental hazards, the phase-out of methyl bromide requires development of alternative weed management strategies. Brassicaceae plants produce glucosinolates which are hydrolyzed to toxic isothiocyanates following tissue decomposition, and therefore can be used as a cultural strategy. Field experiments were conducted in 2007 and 2009 to study the influence of soil amendment (‘Seventop’ turnip cover crop vs. fallow) and the effect of initially planted yellow nutsedge tuber density (0, 50, and 100 tubers m−2) on the interference of yellow nutsedge in raised-bed polyethylene-mulched bell pepper. Total glucosinolate production by the turnip cover crop was 12,635 and 22,845 µmol m−2 in 2007 and 2009, respectively, and was mainly contributed by shoots. In general, soil amendment with the turnip cover crop was neither effective in reducing yellow nutsedge growth and tuber production nor in improving bell pepper growth and yield compared to fallow plots at any initial tuber density. Averaged over cover crops, increasing initial tuber density from 50 to 100 tubers m−2 increased yellow nutsedge shoot density, shoot dry weight, and tuber production ≥ 1.4 times. However, increased tuber density had minimal impact on yellow nutsedge height and canopy width. Compared to weed-free plots, interference of yellow nutsedge reduced bell pepper dry weight and marketable yield ≥ 42 and ≥ 47%, respectively. However, bell pepper dry weight and yield reduction from 50 and 100 tubers m−2 were not different. Light was the major resource for which yellow nutsedge competed with bell pepper. Yellow nutsedge shoots grown from initially planted 50 and 100 tubers m−2 caused up to 48 and 67% light interception in bell pepper, respectively. It is concluded that yellow nutsedge interference from initial densities of 50 and 100 tubers m−2 are equally effective in reducing bell pepper yield and that soil biofumigation with turnip is not a viable management option for yellow nutsedge at these densities.

Methyl bromide (MeBr), a widely used soil fumigant in tomato production, has been banned for ordinary agricultural uses. In the absence of MeBr, a viable alternative is imperative for weed control and prevention of economic loss in tomato production. A field study was conducted in the summers of 2010 and 2011 at Fayetteville, AR, to compare the efficacy and economics of herbicide programs consisting of pre-transplant followed by (fb) post-transplant herbicides in low-density polyethylene (LDPE) mulched tomato. Pre-transplant imazosulfuron at 0.112, 0.224, and 0.336 kg ai ha−1 and S-metolachlor at 1.6 kg ai ha−1 were fb a post-transplant mixture of trifloxysulfuron plus halosulfuron at 0.008 and 0.027 kg ai ha−1 at 4 wk after transplant (WATP). The standard MeBr treatment (2:1 mixture of MeBr plus chloropicrin at 390 kg ai ha−1), weed-free (hand weeding) control, and nontreated weedy check were used for comparison. Pre-transplant S-metolachlor fb post-transplant herbicides controlled Palmer amaranth ≥ 89%, large crabgrass ≥ 88%, and yellow nutsedge ≥ 90%, which was comparable to the control with MeBr. Tomato recovered the injury (≤ 19% at 6 WATP) from post-transplant herbicides in the later weeks. S-metolachlor–containing herbicide programs yielded marketable tomato fruit comparable to the yield with MeBr. Economic evaluation of the herbicide programs demonstrated a net return of $3,758.50 ha−1 from the S-metolachlor–containing herbicide program in LDPE-mulched tomato. Likewise, this herbicide program showed minimum loss of ≤ $671.61 ha−1 in net return relative to MeBr. In conclusion, a herbicide program consisting of pre-transplant S-metolachlor fb post-transplant trifloxysulfuron plus halosulfuron is a viable alternative to MeBr for weed control and marketable yield in LDPE-mulched tomato production.

Soil solarization has been proposed as an alternative to methyl bromide for controlling nutsedges. Little is known, however, about the relationship between soil solarization and nutsedge tuber viability. Combinations of elevated temperatures and durations of exposure were evaluated for their effect on purple nutsedge and yellow nutsedge tuber viability and new tuber production in growth chamber studies. Estimates of the duration of exposure at each temperature that reduced nutsedge growth parameters 50% (TT50) were supplied by log-logistic regression analysis. Nutsedge tuber viability was reduced when temperatures were ≥ 45 C. Relative to purple nutsedge, yellow nutsedge tuber viability had smaller TT50 values for 45, 50, and 55 C. Tuber viability TT50 at 60 C was similar for both nutsedges. The TT50 for production of new purple nutsedge tubers at 50 C was larger than that for yellow nutsedge. However, there were no differences between species in TT50 values for new tuber production at higher temperatures. With sufficient durations of exposure, both purple and yellow nutsedge tubers were killed at temperatures ≥ 50 C. However, application of these data to field situations in Georgia may be limited using present technology because the soil temperature cannot be raised to high enough levels for acceptable solarization effects.

Weeds persist and cause economic losses in agricultural systems because they exploit underused portions of that system. Reducing the effect of weeds on agroecosystems begins with minimizing the number of propagules (e.g., seeds and tubers) that are produced and returned to the soil. Purple nutsedge is a problematic weed around the globe, persisting between growing seasons as tubers in the soil. Halosulfuron is an effective herbicide for controlling purple nutsedge foliage and is used in corn and several vegetable crops. Studies were conducted to evaluate the effect of various rates of halosulfuron on purple nutsedge tuber production. Single, presprouted purple nutsedge tubers were transplanted into outdoor microplots and treated after 6 wk of growth with six rates of halosulfuron (7 to 208 g ai ha−1) POST with a nontreated control (NTC). All shoots that had emerged at the time of application were marked with plastic rings; this allowed for classification of tubers at exhumation of (1) tubers attached to shoots that had emerged by the time of application, (2) tubers attached to shoots that emerged after application, and (3) tubers without an aerial shoot during the study. Seven weeks after application, the tubers in the microplots were exhumed and tubers were classified, quantified, and their ability to sprout was evaluated. In the NTC, there were 530 total tubers, with a log-logistic regression model describing the tuber population with increasing halosulfuron rate. The rate of halosulfuron that reduced total tuber population 50% (I50) was 8 g ha−1. In the NTC, 200 tubers were attached to shoots that emerged following halosulfuron application, and this class of tubers had an I50 of 19 g ha−1. Viability of tubers with shoots that emerged following halosulfuron application was 28% at the 52 g ha−1 halosulfuron, suggesting the action of the herbicide may have rendered the tuber nonviable after new shoots were produced. The final classification of tubers was those that did not have an aerial shoot during the study. These were tubers in which apical dominance suppressed shoot development or were likely the most-recent tubers to develop. Of the three classes, the tubers without shoots were the most numerous in the NTC, with 294 tubers and an I50 of 1 g ha−1. Halosulfuron is an effective herbicide that not only controls purple nutsedge foliage but also reduces the number of new tubers produced and overall tuber viability. This could be an important component to reduce the long-term population density of the weed.

Fomesafen and imazosulfuron are two recently registered herbicides for use in Florida bell pepper. Field studies were conducted in 2012 and 2013 to evaluate PRE, POST-directed (POST-DIR), and PRE followed by (fb) POST-DIR control programs utilizing these new herbicides for nutsedge control in Florida bell pepper. PRE treatments included: S-metolachlor at 0.71 and 1.07 kg ai ha−1, fomesafen at 0.28 and 0.42 kg ai ha−1, S-metolachlor at 0.71 kg ha−1 + fomesafen 0.28 kg ha−1, and S-metolachlor at 1.07 kg ha−1 + fomesafen at 0.42 kg ha−1. POST-DIR treatments included imazosulfuron at 0.21 and 0.34 kg ai ha−1. PRE fb POST-DIR treatments included S-metolachlor at 0.71 or 1.07 kg ha−1 fb imazosulfuron at 0.21 kg ha−1 and fomesafen at 0.28 or 0.42 kg ha−1 fb imazosulfuron at 0.21 kg ha−1. Nutsedge control in both years at 28 d after planting was similar among all PRE treatments providing ≤ 60% control. The addition of imazosulfuron POST-DIR following S-metolachlor or fomesafen PRE provided greater control compared to S-metolachlor or fomesafen alone 14, 21, and 28 d after the POST-DIR application. Plots treated with S-metolachlor resulted in lower marketable weight and marketable fruit count compared to fomesafen in 2012; however, this was not observed in 2013. The results for these studies indicate the importance of a PRE fb POST-DIR herbicide for nutsedge control and that fomesafen or S-metolachlor PRE fb imazosulfuron POST-DIR provides growers with a viable tool capable of achieving season-long control of nutsedge in bell pepper.

Field experiments were conducted in 2006 and 2007 to evaluate the herbicidal activity of phenyl isothiocyanate (ITC) on yellow nutsedge, Palmer amaranth, and large crabgrass in tomato grown on two polyethylene-mulched types. Treatments included two mulch types (low density polyethylene [LDPE] mulch and virtually impermeable film [VIF] mulch) and phenyl ITC at 0, 15, 75, 150, 750, and 1,500 kg ha−1. A standard rate of methyl bromide/chloropicrin (67 : 33%) at 390 kg ha−1 under LDPE mulch was included for comparison. Regardless of mulch type, phenyl ITC at 1,452 (±133) and 1,719 (±426) kg ha−1 was required for broad-spectrum weed control equivalent to methyl bromide in 2006 and 2007, respectively. Tomato injury was ≥ 44% at the highest phenyl ITC rate of 1,500 kg ha−1 at 2 wk after transplanting (WATP) both years, irrespective of mulch type. Greater crop injury was observed from 750 kg ha−1 of phenyl ITC in 2006 (≥ 27%) than in 2007 (≤ 10%). The greater injury in 2006 was attributed to a higher phenyl ITC concentration because holes in the plastic mulch for transplanting were punched at the time of transplanting in 2006; whereas, in 2007 holes were punched 2 d before transplanting, allowing 2 d of aeration before transplanting. Tomato marketable yield at all rates of phenyl ITC was lower than with methyl bromide in 2006. However, in 2007, marketable yield in plots treated with phenyl ITC at 750 kg ha−1 was equivalent to methyl bromide. Overall, VIF mulch was no more effective than LDPE mulch at increasing weed control or improving the marketable yield of tomato either year.

Field trials were conducted in the spring of 2004 and the spring and summer of 2005 to evaluate cantaloupe tolerance to rimsulfuron and halosulfuron applied to cantaloupe at the two-leaf stage, five- to six-leaf stage, plants having 30- to 40-cm vines, and plants having up to 5-cm-diam melons. Additionally, control of eight weed species was evaluated in these trials in 2005. Cantaloupe plant injury from rimsulfuron differed among application timings and trials, but applications were generally more injurious when applied at the two early crop stages. Halosulfuron was less injurious to cantaloupe, but 31 and 14% injury occurred following the two-leaf and five- to six-leaf applications, respectively, in the second trial in 2005. In the first trial of 2005, number of marketable melons the first week of harvest was lower for all halosulfuron applications compared with the nontreated control (30 to 37% reduction). In the second trial of 2005, total number of marketable melons was comparable to the nontreated control for each of the halosulfuron treatments, except the five- to six-leaf and up to 5-cm-diam melon applications. Injury estimates were poor indicators of occurrence or absence of delays in crop earliness or number of marketable melons. Rimsulfuron was generally effective (≥ 80% control) in controlling seedling Texas panicum, large crabgrass, tall morningglory, pitted morningglory, and Palmer amaranth, but was ineffective against yellow and purple nutsedge and goosegrass. Halosulfuron was effective in controlling yellow and purple nutsedge, but was ineffective against Texas panicum, large crabgrass, goosegrass, pitted morningglory, tall morningglory, and Palmer amaranth.

Yellow nutsedge is a problematic weed in polyethylene-mulched tomato production. Soil fumigation with methyl bromide is the most effective method of controlling nutsedges, but because of ozone depletion, the phase-out of methyl bromide has complicated nutsedge control in polyethylene-mulched tomato and other vegetable crops. Plants belonging to the Brassicaceae family produce glucosinolates, which upon tissue decomposition generate biocidal isothiocyanates and therefore can be used as a biological alternative for yellow nutsedge control. Field experiments were conducted in 2007 and 2009 to study the influence of soil amendment with ‘Seventop’ turnip cover crop on the interference of yellow nutsedge planted at 0, 50, and 100 tubers m−2 in raised-bed polyethylene-mulched tomato production. There was no advantage of soil amendment with Seventop on reducing yellow nutsedge interference in polyethylene-mulched tomato. Regardless of soil amendment, increasing initial tuber density from 50 to 100 tubers m−2 increased yellow nutsedge shoot density, shoot dry weight, and tuber production at least 1.7, 1.6, and 1.6 times, respectively. As a result, tomato canopy width, shoot dry weight, and marketable yield decreased with increasing initial tuber densities. However, increased tuber density had minimal impact on tomato height. Relative to weed-free plots, interference of yellow nutsedge at 50 and 100 tubers m−2 reduced marketable yield of tomato up to 32 and 49%, respectively. Shading of the middle and lower portion of tomato plants by yellow nutsedge shoots could be the major factor for reducing tomato growth and yield in weedy plots. It is concluded that soil amendment with Seventop turnip is not a viable option for reducing yellow nutsedge interference at 50 and 100 tuber m−2 in polyethylene-mulched tomato.

In the absence of an effective alternative to methyl bromide (MeBr), weeds cause a significant economic loss in bell pepper production. A study was conducted to evaluate the efficacy and economics of PRE followed by (fb) POST-directed (POST-DIR) herbicide programs compared with MeBr for weed control in low-density polyethylene (LDPE) mulched bell pepper production. Imazosulfuron at 0.112, 0.224, and 0.336 kg ai ha−1 and S-metolachlor at 1.6 kg ai ha−1 were PRE-applied fb POST-DIR applied mixture of trifloxysulfuron + halosulfuron at 0.008 and 0.027 kg ai ha−1, respectively, at 4 wk after transplanting (WATP). The standard MeBr treatment (67 and 33% mixture of MeBr + chloropicrin) was applied at 390 kg ai ha−1. In addition, a weed-free (hand weeding) and a non-treated control were used for comparison. S-metolachlor-containing herbicide program controlled Palmer amaranth ≥ 90%, large crabgrass ≥ 78%, and yellow nutsedge ≥ 90%, which were comparable to MeBr. After POST-DIR herbicide application, bell pepper was injured ≥ 17% with the S-metolachlor-containing herbicide program at 6 WATP; however, the crop later recovered. Marketable bell pepper yield in plots treated with S-metolachlor (≥ 29.9 ton ha−1) was comparable to those treated with MeBr. Economic evaluation of the imazosulfuron herbicide programs demonstrated the loss of ≥ $7,300 ha−1. Conversely, the S-metolachlor-containing herbicide program was profitable with a net return of $9,912 ha−1. In addition, the S-metolachlor herbicide program generated a net profit of $173 ha−1 compared to the MeBr application. Therefore, PRE-applied S-metolachlor fb POST-DIR applied trifloxysulfuron + halosulfuron is a potential alternative to MeBr for weed management in LDPE-mulched bell pepper production given the weed spectrum evaluated in this study.

The phase-out of methyl bromide requires alternative nutsedge management options in vegetable systems. Options that target tuber production, the primary means of reproduction, will be most beneficial. A study was conducted to evaluate the response of purple nutsedge and yellow nutsedge foliar growth and tuber production to a range of glyphosate rates. Glyphosate was applied at six rates between 0.41 and 2.57 kg ae ha−1 to 5-wk-old nutsedge plants with multiple shoots. The rate of glyphosate needed to reduce growth 50% (I50) was similar for purple nutsedge foliar growth (0.58 kg ha−1) and tuber biomass (0.55 kg ha−1). In contrast, I50 for yellow nutsedge foliar growth was 0.73 kg ha−1, which was greater than the I50 for tuber biomass (0.41 kg ha−1). First-order tubers, those directly attached to the initial tuber, had an I50 of 0.70 and 0.44 kg ha−1 of glyphosate for purple nutsedge and yellow nutsedge tuber biomass, respectively. For all higher-order tubers, I50 values ranged from 0.29 to 0.60 and 0.14 to 0.30 kg ha−1 of glyphosate for purple nutsedge and yellow nutsedge tuber biomass, respectively. Glyphosate at 0.74 kg ha−1 prevented fourth-order purple nutsedge and third-order yellow nutsedge tuber production (terminal tubers for yellow nutsedge). Fifth- and sixth-order purple nutsedge tuber production was eliminated by the lowest tested rate of glyphosate (0.41 kg ha−1). Effective nutsedge management options will require consistent control between spring and autumn crops. Glyphosate is economical, poses no herbicide carryover issues to vegetables, and minimizes nutsedge tuber production; therefore, it is a suitable candidate to manage nutsedges.

Polyethylene mulch is an effective component of weed management in vegetable production. However, nutsedges are persistent and proliferate in these systems. Greenhouse studies evaluated the growth and tuber production of purple nutsedge and yellow nutsedge grown in pots covered with black-opaque polyethylene mulch, clear-colorless polyethylene mulch, or nonmulched. Single, presprouted nutsedge tubers were planted and growth evaluated over 16 wk. Relative to the nonmulched, yellow nutsedge shoot production was reduced 46 and 72% by black and clear mulch, respectively. The number of yellow nutsedge shoots that pierced and emerged through black and clear mulches was reduced 96% relative to emerged shoots in the nonmulched control. Yellow nutsedge in the nonmulched produced 366 tubers per initial tuber, whereas tuber production was reduced 49 to 51% in black and clear mulch. Growth of purple nutsedge shoots and tubers in black polyethylene mulch was similar to the nonmulched. Clear polyethylene reduced purple nutsedge tuber biomass relative to nonmulched, but clear mulch was similar to black mulch in nearly all measured variables. Without mulch, yellow nutsedge produced more shoots, shoot biomass, tubers, tuber biomass, and root biomass than purple nutsedge. However, growth of yellow nutsedge was hindered by polyethylene mulch, whereas differences in purple nutsedge growth among mulches could not be detected. The relative insensitivity of purple nutsedge and sensitivity of yellow nutsedge growth to the physical mulch barrier could lead to a shift in nutsedge species composition in mulched vegetable production.

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.

The continued phase-out of methyl bromide (MBr) challenges vegetable growers' abilities to control weeds in plasticulture production. Herbicides, such as EPTC (S-ethyl dipropylthiocarbamate), may be needed as part of a MBr alternative system. An experiment was conducted during the springs of 2008 and 2009 in Ty Ty, GA, to determine tomato, pepper, eggplant, and watermelon tolerance to EPTC applied under mulch. Treatments consisted of a factorial arrangement of four rates of EPTC (0, 2, 3, or 4 kg ai ha−1) and two plastic mulch types (low density polyethylene [LDPE] mulch or a high barrier mulch [HBM]). Each crop was planted 28 d after applying herbicides and laying mulch. EPTC, regardless of rate, applied under LDPE mulch did not impact plant growth, fruit number produced, or fruit weights for any crop. Conversely, pepper, tomato, and eggplant heights were reduced 65 to 72%, 30 to 75%, and 9 to 32%, respectively, by EPTC at 2 to 4 kg ai ha−1 when applied under HBM. Similar trends were observed for crop yield; fruit number and weight were reduced by 71 to 84% for pepper, 36 to 76% for tomato, and 7 to 15% for eggplant when EPTC was applied at 2 to 4 kg ai ha−1 as compared to the no EPTC HBM control. Watermelon stem lengths, fruit number, and fruit weights were not impacted by EPTC applied under HBM mulch. It appears as though HBMs reduce the loss of EPTC through volatilization, thereby increasing the dose present at time of planting. EPTC could be included as part of a MBr alternative system for tomato, pepper, eggplant, and watermelon when applied under LDPE mulch, and may also be applied at labeled rates with the HBM utilized in this experiment for watermelon.

Methyl bromide has been a key fumigant for broad-spectrum weed control in polyethylene-mulched bell pepper. However, the ozone-depleting nature of methyl bromide has led to its scheduled phaseout from U.S. agriculture. Thus, an effective alternative to methyl bromide is needed. Field trials were conducted in 2007 and 2009 to evaluate the crop response and weed control efficacy of allyl isothiocyanate (ITC) in polyethylene-mulched bell pepper. The experiment included various combinations of two mulch types (low density polyethylene [LDPE] and virtually impermeable film [VIF] mulch) and six rates of allyl isothiocyanate (0, 15, 75, 150, 750, 1,500 kg ha−1). Additionally, a standard treatment of methyl bromide/chloropicrin (67 : 33%) at 390 kg ha−1 under LDPE mulch was included for comparison. Bell pepper injury was < 3% in all treatments, except 11% injury at 1,500 kg ha−1 allyl isothiocyanate under VIF mulch at 2 wk after transplanting (WATP). VIF mulch did not provide additional weed control and marketable pepper yield over LDPE mulch. Allyl isothiocyanate at 932 (± 127) kg ha−1 controlled yellow nutsedge (90%), Palmer amaranth (97%), and large crabgrass (92%) through 6 WATP and maintained the marketable yield equivalent to methyl bromide treatment. This research demonstrates that allyl ITC under an LDPE mulch can serve as a potential alternative to methyl bromide for weed control in polyethylene-mulched bell pepper.

Integrated management programs are becoming increasingly necessary for nutsedge control in the absence of methyl bromide. In 2012, field studies were established and maintained for a period of 2 yr at two locations to evaluate the additive effect of fallow programs and preplant fumigants for nutsedge control in bell pepper. The study included eight fallow programs consisting of eight combinations of glyphosate (G) and cultivation (C), and two fumigants; 1,3-dichloropropene + chloropicrin, dimethyl-disulfide + chloropicrin, and a nontreated check. All fallow programs provided greater late-season control of nutsedge compared to the nontreated, with the greatest control of nutsedge observed with glyphosate fb (followed by) glyphosate (GG) and glyphosate fb cultivation fb glyphosate (GCG) fallow programs. Fumigation provided additional nutsedge control in single-input fallow programs. Increased marketable yield was observed in 2012 with the application of either fumigant compared to a nonfumigated control. Furthermore, increased marketable yield was observed with more intensive fallow programs in 2013. Nutsedge control in bell pepper was significantly increased when a fallow program was used in combination with other weed-management practices.

Nutsedge control is challenging in commercial vegetable production in the absence of methyl bromide, and therefore, an effective alternative is needed. This study investigated allyl isothiocyanate (ITC) as a methyl bromide alternative for purple nutsedge control under polyethylene-mulch. Greenhouse experiments were conducted to compare the retention of allyl ITC in treated soil (3,000 nmol g−1) under low-density polyethylene (LDPE) and virtually impermeable film (VIF) mulches. Field experiments were conducted to evaluate the effectiveness of allyl ITC (6 rates: 0, 15, 75, 150, 750, 1500 kg ai ha−1) under VIF mulch against purple nutsedge. Additionally, a standard treatment of methyl bromide+chloropicrin (67 : 33%) at 390 kg ai ha−1 under LDPE mulch was included for comparison. In the greenhouse experiment, the predicted half-life of allyl ITC under LDPE and VIF mulch was 0.15 and 0.59 d, respectively. In the field experiment, it was predicted that allyl ITC at 1,240 and 1,097 kg ha−1 under VIF mulch is required to control purple nutsedge shoot and tubers equivalent to methyl bromide + chloropicrin at 4 wk after treatment (WAT). It is concluded that allyl ITC under VIF mulch would need to be applied at 2.8 to 3.2 times the standard treatment of methyl bromide + chloropicrin under LDPE mulch for commercially acceptable purple nutsedge control.

Heating the ambient air of a whole, or a portion of a food-processing facility to 50 to 60°C and maintaining these elevated temperatures for 24 to 36 h, is an old technology, referred to as heat treatment. There is renewed interest in adopting heat treatments around the world as a viable insect control alternative to fumigation with methyl bromide. There is limited published information on responses of the Indian meal moth, Plodia interpunctella (Hübner), exposed to elevated temperatures typically used during heat treatments. Time-mortality relationships were determined for eggs, fifth-instars (wandering-phase larvae), pupae, and adults of P. interpunctella exposed to five constant temperatures between 44 and 52°C. Mortality of each stage increased with increasing temperature and exposure time. In general, fifth-instars were the most heat-tolerant stage at all temperatures tested. Exposure for a minimum of 34 min at 50°C was required to kill 99% of the fifth-instars. It is proposed that heat treatments aimed at controlling fifth-instars should be able to control all other stages of P. interpunctella.