Source: UNIVERSITY OF ARKANSAS submitted to
HIGH VALUE SPECIALTY CROP PEST MANAGEMENT
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0202362
Grant No.
(N/A)
Project No.
ARK02056
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2004
Project End Date
Sep 30, 2011
Grant Year
(N/A)
Project Director
Burgos, N.
Recipient Organization
UNIVERSITY OF ARKANSAS
(N/A)
FAYETTEVILLE,AR 72703
Performing Department
Crop, Soil & Environmental Sciences
Non Technical Summary
Low-acreage horticultural and ornamental crops are in demand by American consumers and are economically important for producers, but companies often fail to label herbicides for these important specialty crops. These studies will generate data to support herbicide registration efforts for a number of specialty crops in order to increase availability of herbicides needed for profitable production of these important crops.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2131199114010%
2131499114060%
2132199114030%
Goals / Objectives
1. To obtain the regulatory clearance of crop protection chemicals for high value specialty crops and minor uses on major crops with special emphasis on Reduced Risk chemicals. SPECIFIC Sub-Objectives in Arkansas for the High Value Specialty Crop Pest Management/IR-4 project are: A) to conduct efficacy studies on promising herbicides for specialty crops and ornamentals; and B) to evaluate carryover potential of herbicides on specialty crops. These studies contribute to the overall project goal of obtaining registration of herbicides for specialty crops.
Project Methods
Studies will be conducted to evaluate herbicide efficacy for controlling common weeds in vegetable and ornamental crops, including but not limited to table beets, watermelon, spinach and other greens (turnip, collard, mustard, and kale), Southern pea, and ornamental gourds. Crops will be planted in the field and will be grown under commercial production conditions. Herbicide efficacy will be evaluated by weed control and crop injury ratings, crop stand and vigor, and crop yield and quality. Herbicide carryover, important in rotations of many vegetable cropping systems, will be conducted to evaluate potentail residues left in the soil following herbicide use in a previous crop in the rotation. Persistence studies will be conducted in the field on cool-season vegetables, such as mustard, collard, cabbage, turnip, kale, and spinach, that are planted in the fall following the use of herbicides applied as late as July in summer crops and on warm-season vegetables, such as cucumber, cantaloupe, snapbeans, southern peas, summer squash, and sweet corn, that follow cool-season crops or other warm-season crops. Tomato and pepper may be studied if there is sufficient interest in these transplanted crops. For cool-season crops, herbicides will be applied to the soil at the labeled use rate and twice the labeled rate in July, and the crops will be planted in rows across the treated plots in August, September, October, and March. For warm-season crops, herbicides will be applied at the labeled use rate and twice the labeled rate in May. Crops will be planted in rows across the treated plots, initally in May and at monthly intervals through September. Extraneous vegetation will be removed from the plots. Crops will be rated for herbicide injury symptoms, compared to untreated plots, to establish effect of the herbicides and persistence of activity on the crops.

Progress 10/01/04 to 09/30/11

Outputs
OUTPUTS: Experiments conducted included: 1) the efficacy and crop safety of napropamide, linuron, and other herbicides applied pre-transplant (PreT), or in the row middles on basil; 2) tolerance of five brassica crops - cauliflower Imperial, Bok Choy Pak Choi Joi Choi, head cabbage Blue Lagoon, Chinese cabbage Cabbage Blues, and broccoli Premium Crop to pendimethalin and S-metolachlor applied post-transplant in the spring; 3) the efficacy and crop safety of pendimethalin and S-metolachlor applied pre-transplant and the same herbicides applied with either carfentrazone or flumioxazin in the row middles of Classic eggplant; 4) tolerance of succulent pea varieties: PLS 534, Gonzo, PLS 69, PLS 179, and PLS 134 to saflufenacil, clomazone, trifluralin, S-metolachlor, imazethapyr, and bentazon; 5) preplant (PPL) application of some standard and relatively new herbicides on greenbeans KSI 196; and 6) preplant and preemergence (PRE) herbicides on cowpea Early Scarlet. PARTICIPANTS: Researcher: Leopoldo E. Estorninos, Jr. Funding: IR-4; Allen Canning Co. TARGET AUDIENCES: Crop growers, extension personnel, agrichemical company representatives, researchers. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Basil. The high rate of napropamide (2.24 kg ai/ha), incorporated to soil prior to transplanting, is most effective in controlling the weed spectrum in this location for the whole season. This also produced the highest yield. This supported our first year recommendation of using napropamide at the high rate. Row-middle application would be effective only if coupled with a preplant application of a residual herbicide. To avoid weed shifts and weed resistance evolution, a program approach for weed control, involving herbicides with different modes of action need to be developed. For example, halosulfuron is a valuable treatment for nutsedge control, postemergence, but a pre-transplant herbicide is needed to control other weed species prior to the row-middle application of halosulfuron. Brassicas. Pendimethalin and S-metolachlor are safe on all brassicas tested. The herbicide treatments did not reduce brassica yields. Eggplant. Weed control in all plots at harvest was >90%, except for pendimethalin applied in the row middles at 1.12 kg/ha. The 2X rate of pendimethalin, applied in the row middle, was at par with the S-metolachlor and other herbicide treatments. Eggplant yield from the weed-free, nontreated plants was 22 mt/ha. Among treated plants, yield was highest with 2.24 kg/ha pendimethalin or 1.12 kg/ha S-metolachlor applied pre-transplant. Application of these herbicides alone or in combination with foliar herbicides in the row middles, reduced eggplant yield even though weed control was excellent. Succulent pea. The weed-free, nontreated plants produced 1,270 to 2,500 kg/ha fresh pods. PLS 534 and PLS 134 had the highest yields; however, these also were the most affected by herbicide treatments such that only imazethapyr PRE did not reduce the yield of PLS 534 and only bentazon fb quizalofop did not reduce the yield of PLS 134. Three herbicide treatments (clomazone, imazethapyr PRE, imazethapyr POST) did not reduce the yield of Gonzo. The yield of PLS 179 was reduced only by PRE application of saflufenacil and the preplant application of trifluralin. PLS 69 was tolerant to all herbicides tested. The best saflufenacil treatment is at 0.074 kg ai/ha, soil-incorporated. A high-yielding variety could compensate for yield loss from herbicide injury relative to a low-yielding variety. Imazethapyr POST is generally the safest herbicide treatment.

Publications

  • Estorninos, L.E., N.R. Burgos, E.A.L. Alcober, and T.M. Tseng. 2011. Efficacy of herbicides applied at different timings on greenbeans. SWSS Abstr. 64:135. Accessible at http://www.swss.ws/NewWebDesign/Proceedings/Archives


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Experiments conducted included the efficacy and crop safety of: 1) napropamide and other herbicides applied pre-transplant (PreT), or in the row middles on basil Caesar; 2) pendimethalin and S-metolachlor applied post-transplant on cabbage Cabbage Blues in the spring and fall, broccoli Premium Crop in the spring, and cauliflower Market Prize in the fall; 3) pendimethalin and other herbicides on eggplant Classic; 4) pendimethalin and S-metolachlor on green onion; 5) saflufenacil on succulent pea Lincoln; 6) preplant (PPL) application of some standard and relatively new herbicides on greenbeans KSI 196; and 7) preplant and preemergence (PRE) herbicides on cowpea Early Scarlet. Basil. Thirteen herbicide treatments were evaluated. Four of the herbicide treatments were napropamide at 1.12 (1X rate) and 2.24 kg ai/ha either pretransplant (PreT) soil-incorporated or at 3 wk after transplanting (WAT), in the row middles. Other herbicides tested were fomesafen, halosulfuron, linuron, S-metolachlor, pendimethalin, prometryn, pronamide, and oxyfluorfen. A handweeded check was included. Cabbage, spring and fall plantings; broccoli, spring planting; and cauliflower, fall planting. Pendimethalin (1.12 and 2.24 kg ai/ha) and S-metolachlor (0.71 and 1.41 kg ai/ha) were evaluated at post-transplant application. Eggplant. Pendimethalin was evaluated at 1.12 and 2.24 kg ai/ha one day before transplanting (Pre-T) or 3 wk after transplanting (WAT), in the row middles (RM). Other herbicides tested were S-metolachlor, S-metolachlor + carfentrazone, and S-metolachlor + flumioxazin in the row middles. Treatments were compared with a handweed check. The most dominant species in this test were barnyardgrass and Palmer amaranth. Green onion. Pendimethalin (1.12 and 2.24 kg ai/ha) and S-metolachlor (0.71 and 1.41 kg ai/ha) were evaluated. Dominant species were the same as in the eggplant test. Succulent pea. Ten herbicide treatments were evaluated relative to a handweeded check. Four of the treatments were saflufenacil at 0.008 and 0.012 kg ai/ha preplant incorporated (PPI) or preemergence (PRE). Other herbicides tested were clomazone, S-metolachlor, imazethapyr, bentazon, and quizalofop. Greenbeans. Fourteen herbicide treatments were evaluated including clomazone, S-metolachlor, fomesafen, flumioxazin, saflufenacil applied 1 wk PPL or PRE. This was conducted in the fall and spring. Cowpea. Fluthiacet-methyl and carfentrazone were tested on cowpea at PPL and PRE timings, along with other herbicides. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Crop growers, extension personnel, agrichemical company representatives, researchers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Basil. The high rate of napropamide had 100% weed control 8WAT. S-metolachlor controlled weeds 94% or better. Fomesafen, oxyfluorfen, pronamide and trifluralin had >90% general weed control of. Among the RM treatments, prometryn had >90% weed control. The check produced 11,455 kg/ha fresh biomass. Pre-T treatments fomesafen, the high rate of napropamide, oxyfluorfen, pronamide, S-metolachlor, and trifluralin. Prometryn POST-RM yielded similar to the check. Cabbage. In the spring, the high rate of pendimethalin and both rates of S-metolachlor caused 10% stunting, 3WAP. Stunting increased with time, up to 30% with 1.41 kg/ha S-metolachlor. S-metolachlor had 98-100% general weed control, but pendimethalin ctonrolled goosegrass and Palmer amaranth >80% 5WAP. In the fall, both rates of pendimethalin caused minimal stunting (6%) 3WAP. S- metolachlor consistently caused more stunting than pendimethalin. The check produced 13,700 kg/ha of head cabbage; only the high rate of pendimethalin produced an equivalent yield. Cauliflower. At 5WAP, pendimethalin caused 7-10% injury while S-metolachlor caused 10-17% injury at 0.71 to 1.41 kg/ha. The check produced 12,500 kg/ha of crop. The high rate of S-metolachlor reduced yield by 43%. The low rate of S-metolachlor and both rates of pendimethalin did not reduce yield. Eggplant. Control of Palmer amaranth, barnyardgrass, and other weeds was >90% with Pre-T S-metolachlor 8WAT. Carfentrazone and flumioxazin were not effective on emerged barnyardgrass. The check produced about 63,500 fruits/ha at 28,800 kg. S-metolachlor Pre-T, produced an equivalent amount of fruit (25,000 kg) and the 2X rate of pendimethalin Pre-T (19,800 kg). Green onion. The low rate of S-metolachlor had 95-96% control of barnyardgrass while the 1X rate of pendimethalin had 92% control at 3 and 5WAP. The 1X rate of pendimethalin had only 74% control of goosegrass at 3WAP. The low rate of S-metolachlor controlled goosegrass 95% up to 5WAP. The activity of 1.41 kg/ha S-metolachlor on Palmer amaranth remained as high as that of the 1X rate of pendimethalin (95% control) 5WAP. There was no noticeable injury on green onions. Succulent pea. General weed control from saflufenacil treatments ranged from 64-80%. Incorporating this herbicide resulted in 74-78% general weed control 5WAP. It was not effective on annual grasses, but controlled Palmer amaranth 95%, except with the low rate PRE. The best weed control was with clomazone and S-metolachlor at 97-100% 5WAP, comparable to that with imazethapyr PRE at 90% and trifluralin PPI at 93% weed control. The check produced about 2,600 kg/ha fresh pods. The succulent pea-labeled herbicides clomazone, imazethapyr, and S-metolachlor produced equivalent yields as the handweeded check at 2,240 to 3,367 kg/ha. The high rate of saflufenacil (0.074 kg ai/ha) reduced pod yield 64% when soil-incorporated and 40% when applied PRE. At the lower rate (0.049 kg ai/ha) saflufenacil produced similar pod yield as the check.

Publications

  • Burgos, N. R., V.K. Shivrain, E.A. Alcober, D. Motes, S. Eaton, T.M. Tseng, L. Martin. 2010. Canola Response to Residual Effects of Summer-applied Herbicides. WSSA Abstr. Vol. 50. Accessible at https://srm.conference-services.net/reports/
  • Estorninos, L. Jr., N.R. Burgos, D. Motes, E.A. Alcober, T.M. Tseng, P. Sapkota. 2010. Efficacy and crop safety of Spartan Charge on cowpea applied preplant or preemergence. WSSA Abstr. Vol. 50. Accessible at https://srm.conference-services.net/reports/
  • Estorninos, L.E.Jr., N.R. Burgos, V.K. Shivrain, E.A.L. Alcober, T.M. Tseng, P. Sapkota, and D.R. Motes. 2010. Efficacy and safety of herbicides applied preemergence and preplant on cowpea. SWSS Abstr. Vol. 63:169. Accessible at http://www.swss.ws/NewWebDesign/Proceedings/


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: In 2009, experiments covered weed control options for canola, cowpea, snapbeans, spinach, southern greens, and sweet sorghum. For canola: various residual herbicides applied in mid-May, mid-June, and mid-July were tested for potential carryover effect. Canola was planted in mid-September. Imazethapyr, imazamox, and the high rate of fomesafen (Reflex, 0.375 lb/A) were most injurious, reducing canola growth even when these herbicides were applied in mid-May. The safest herbicides for double cropping with canola include halosulfuron (0.046 lb/A), clomazone (0.375 lb/A), the low rate of fomesafen (0.1875 lb/A), flumioxazin, and the low rate of rimsulfuron (0.03 lb/A). These could be applied in mid-July without causing injury to canola planted in September. For cowpea: Sandea (halosulfuron, 0.024 & 0.048 lb/A), Reflex (fomesafen, 0.188 & 0.375 lb/A), Spartan (sulfentrazone, 0.188 & 0.375 lb/A), and Valor (flumioxazin, 0.188 & 0.375 lb/A) were tested at 12 d preplant (PPL) and preemergence (PRE) timings. This was a continuation of the 2008 experiment. Sandea was safe on cowpea regardless of rate and application timing. Reflex cannot be used PRE on cowpea, but can be used at least 12 days PPL. The labeled rate of Spartan (0.188) can cause minimal injury, PRE; no yield loss nor injury when applied PPL. Similarly, Spartan Charge (sulfentrazone + carfentrazone) applied PPL produced higher cowpea yields than the PRE application. Spartan Charge controlled Palmer amaranth, but the addition of glyphosate improved efficacy and consistency of weed control. Valor was not safe on cowpea. Aim (carfentrazone) and Cadet (fluthiacet) are relatively safe on cowpea, but hophornbeam copperleaf control was only 88%, which allows some regrowth. These herbicides would be useful components of cowpea weed control program. Hophornbeam copperleaf interference reduced cowpea yield up to 93%. The residual effects of imazethapyr (Pursuit), imazamox (Raptor), halosulfuron (Sandea), Spartan at two rates, clomazone (Command), Reflex at two rates, Valor at two rates, and rimsulfuron (Matrix) at two rates were evaluated. Herbicides were applied in mid-May, mid-June, and mid-July. In general, Pursuit, Spartan, and Reflex need longer crop rotation intervals. Leafy greens crops differed in tolerance to residual activity of various herbicides. In collard for example, Pursuit and Spartan had the highest carryover effect. The residual effect of Raptor and Sandea was gone 100 d after application, but caused about 30% and 20% injury, respectively, when collard was planted 74 d after application. The low rate of Reflex was safe to collard planted 100 d after application. The high rate of Reflex lasted more than 135 d after application. For spinach, Pursuit, Spartan and the high rate of Reflex showed the highest residual effect. Most herbicides showed significant carryover effect to spinach planted in mid-June. Valor had no residual effect on spinach. Kale and turnip greens also showed different tolerance patterns. For sweet sorghum, planting depth, herbicide options, varietal performance, planting dates, and sugar content were evaluated. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Information from this research is intended for vegetable growers, Extension Agents who can disseminate information to growers and organize grower trainings, private industry, and colleagues in academia. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Generated data and drafted a document to support the labeling of Spartan Charge on cowpea for Arkansas.

Publications

  • N.R. Burgos, V.K. Shivrain, E.A.L. Alcober, T.M. Tseng, D. Motes, S. Eaton, L. Martin, 2009. Spinach sensitivity to residual activity of summer-applied herbicides. T.E. Morelock International Spinach Conference, University of Arkansas, Fayetteville. Abstr. p.15.
  • Alcober, E.L., N.R. Burgos, V.K. Shivrain, D. Motes, M. Sales, and T. Tseng. 2009. Residual Effects of Herbicides in Summer Crops to Cool-Season Vegetables. Vol. 49. Accessible at http://wssa.net/Meetings/WSSAAbstracts/
  • Tseng, T., N.R. Burgos, E.L. Alcober, V.K. Shivrain, D. Motes, and T. Morelock. 2009. Tolerance of advanced cowpea (Vigna unguiculata) lines and cultivars to sulfentrazone herbicide. Vol. 49. Accessible at http://wssa.net/Meetings/WSSAAbstracts/ Alcober, E.A.L., N.R. Burgos, V.K. Shivrain, D. Motes, T.M. Tseng, and L.E. Estorninos. 2009. Residual effects of herbicides in summer crops to spinach and canola. Abstr. Arkansas Crop Prot. Asso. Res. Conf. 13:8.
  • P. Sapkota, N.R. Burgos, L. E. Estorninos, Jr., E.A. L. Alcober, and T.M. Tseng. 2009. Tolerance of sweet sorghum to metolachlor and mesotrione herbicides in non-irrigated conditions. Abstr. Arkansas Crop Prot. Asso. Res. Conf. 13:12.


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: This project aims to register additional herbicides for use on specialty crops where weed control is a major problem and options are limited or nonexistent. Specialty crops research in 2008 included weed control options for cowpea, spinach, southern greens, and sweet sorghum. For cowpea: Sandea (halosulfuron, 0.024 & 0.048 lb/A), Reflex (fomesafen, 0.188 & 0.375 lb/A), Spartan (0.188 & 0.375 lb/A), and Valor (flumioxazin, 0.188 & 0.375 lb/A) were tested at 12 d preplant (PPL) and preemergence (PRE) timings. This was a repeat of the 2007 experiment. Sandea was safe on cowpea regardless of rate and application timing. Reflex did not reduce cowpea yield when applied PPL. Reflex cannot be used PRE on cowpea. The recommend rate of Spartan for cowpea (0.188) can cause minimal injury at the PRE timing; no yield loss nor injury when applied PPL. Valor was not safe on cowpea regardless of rate and application timing. The residual effects of imazethapyr (Pursuit), imazamox (Raptor), halosulfuron (Sandea), Spartan at two rates, clomazone (Command), Reflex at two rates, Valor at two rates, and rimsulfuron (Matrix) at two rates were evaluated. Herbicides were applied at three timings, May 15, June 13, and July 15. For Collard, Pursuit had the most residual effect with 99% crop damage. The residual effect of Raptor and Sandea was gone 100 d after application, but caused about 30% and 20% injury, respectively, when collard was planted 74 d after application. It was safe to plant collard only after a low rate of Spartan was applied 135 d prior. Planting collard sooner than this caused unacceptable injury. Clomazone did not injure collard regardless of planting interval. The low rate of Reflex was safe to collard planted 100 d after application. The high rate of Reflex lasted more than 135 d after application. Valor had no residual effect on collard. Residual effect of Matrix was minimal. For kale, Pursuit caused 75% injury regardless of planting interval. The high rate of Spartan and Reflex also caused high level of injury to kale. The low rate of Spartan generally caused about 20% injury up to about 170 d from application. The low rate of Matrix did not cause any residual effects on kale, but the high rate did. Herbicides with the least residual effects on kale included Raptor, Sandea, Command, and Valor. For mustard, Pursuit caused 50 to 98% injury even when planted 168 d after herbicide application, which was the longest planting interval. Raptor caused about 50% injury to mustard when planted 74 d from application, but was safe to mustard planted at least 100 d after application. Sandea did not injure mustard planted 100 d after application. Reflex had the highest residual effect on mustard. Valor did not injure mustard at any rate and timing. For turnip, Pursuit and the high rate of Reflex caused the highest injury. Raptor, Sandea, Command, and Valor were safe to turnip at any of the planting intervals tested. For spinach, Pursuit, Spartan and the high rate of Reflex showed the highest residual effect. Most herbicides showed significant carryover effect to spinach planted 74 d after application. Valor had no residual effect on spinach. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The expected outcome are the expansion of some herbicide labels for use in minor crops and successful crop production with additional weed control options.

Publications

  • No publications reported this period


Progress 01/01/07 to 12/31/07

Outputs
This project aims to register additional herbicides for use on specialty crops where weed control is a major problem and options are limited or nonexistent. Specialty crops research in 2007 included weed control options for cowpea, spinach, southern greens, and sweet sorghum. For cowpea: Sandea (halosulfuron, 0.024 & 0.048 lb/A), Reflex (fomesafen, 0.188 & 0.375 lb/A), Spartan (0.188 & 0.375 lb/A), and Valor (flumioxazin, 0.188 & 0.375 lb/A) were tested at 12 d preplant (PPL) and preemergence (PRE) timings. Sandea was safe on cowpea regardless on rate and application timing. Reflex did not reduce cowpea yield when applied PPL, but caused less visual injury the low rate. Reflex cannot be used PRE on cowpea. The recommend rate of Spartan for cowpea (0.188) caused minimal injury at the PRE timing, no yield loss and no injury when applied PPL. The high rate of Spartan caused less injury PPL than PRE. Valor was not safe on cowpea regardless of rate and timing. There was varietal difference in cowpea tolerance to Spartan. Spinach was tolerant to several herbicides including Dual Magnum (metolachlor) and Outlook (dimethenamid) applied PRE or POST, Nortron (ethofumesate) PRE, Bolero (thiobencarb), Barricade (prodiamine), Far-Go (triallate), and ET 0.208 EC (pyraflufen-ethyl). Collards and kale were both tolerant to Dual Magnum applied PRE or POST. Outlook applied PRE was injurious to both crops, but both were tolerant to the POST application. Other treatments that both crops tolerated well were Bolero, Far-Go, and ET 0.208 EC. Command at 0.15 lb ai/A PRE caused less than 10% injury, but the 0.3 lb ai/A rate was more injurious, causingup to 19% bleaching. Collards were slightly more tolerant than kale to Barricade and the POST application of GoalTender; and kale was more tolerant to GoalTender PRE and to Prowl H20 applied PRE. Collard injury from GoalTender applied PRE dissipated by mid-April, and yield from those plots were among the highest in the experiment for both collards and kale. Mustard, and turnip were also tolerant to Dual Magnum, Outlook applied POST, and to Bolero, Barricade, Far-Go, and ET 0.208 EC applied PRE or POST. However, GoalTender PRE was much more injurious to these crops than to collards and kale, causing yield loss. For all greens and spinach, Everest and Prowl H20 applied PRE caused severe injury, and yield of most crops was reduced. Mustard, however, showed some tolerance to Everest applied POST. The tolerance of sweet sorghum to S-metolachlor (0 to 1.88 lb/A) and mesotrione (0 to 0.375 lb/A) was evaluated in a Taloka silt loam soil, pH 5.8 and 1.88% organic matter, under irrigated and nonirrigated conditions. The cultivar >Dale= was used. With irrigation, 40 d after application, up to 25% injury was observed from metolachlor treatments, with no rate effect. Mesotrione caused up to 30% injury, with higher injury at the high rate. Biomass yield was 56,000 to 57,000 lb/A with no effect from metolachor rate. High mesotrione rate produced less biomass than the low rate. Without irrigation, similar response as observed, except that biomass production was about 25% less than irrigated plots.

Impacts
Expansion of some herbicide labels for use in minor crops. Successful crop production with additional weed control options.

Publications

  • Burgos, N. R., L. P. Brandenberger, E. N. Stiers, V. K. Shivrain, D. R. Motes, L. Wells, S. Eaton, L. W. Martin, and T. E. Morelock. 2007. Tolerance of selected advanced cowpea (Vigna unguiculata L.) breeding lines to fomesafen. Weed Technol. 21: 863-868.


Progress 01/01/06 to 12/31/06

Outputs
The goal of this project is to register additional herbicides for use on specialty crops where weed control is a major problem and options are limited or nonexistent. Specialty crops research in 2006 includeed cowpea, spinach, southern greens, and sweet sorghum. Several herbicides were tested. Sandea (halosulfuron) is safe to use on cowpea when applied preemergence (PRE). Twenty advanced breeding lines were selected from preliminary tests and compared with the commercial standard, Early Scarlet. Fourteen advanced lines yielded better than Early Scarlet when treated with the commercial dose, 0.048 lb ai/A, of Sandea. The commercial rate of Sandea can be used early POST, but only on cultivars with higher tolerance to the herbicide. Other herbicides tested on cowpea included Ultra Blazer (acifluorfen), Reflex (fomesafen), Valor (flumioxazin), and Spartan (sulfentrazone). Spartan (sulfentrazone), applied preemergence, is generally safe on cowpea, but there is significant difference in tolerance between cultivars. The sensitive cultivars, i.e. Erect Set and AR blackeye#1 can incur about 30% yield loss from Spartan treatment. A reduced rate of 0.187 lb ai/A did not reduce yields of any cultivar. Spartan, at the commercial rate of 0.375 lb ai/A, provided 91 to 100% control of hophornbeam copperleaf with minimum injury on cowpea. This weed cannot be controlled by the currently labeled herbicides on cowpea. For spinach, several PRE herbicides were promising: thiobencarb, clomazone, dimethenamid, and prodiamine. Dimethenamid and fucarbazone were also safe when applied POST. The same PRE herbicides, including ethofumesate, as well as POST herbicides were also safe on collard and kale. Turnip was tolerant to the same herbicides, except clomazone. The only possible PRE herbicide for mustard is thiobencarb. However, mustard tolerates metolachlor, dimethenamid, flufenacet, prodiamine, and flucarbazone applied POST. The tolerance of sweet sorghum to S-metolachlor was evaluated in a Taloka silt loam soil, pH 5.8 and 1.88% organic matter. Two cultivars, Dale and Sugardrip, were treated with 1.0 to 1.9 lb ai/A metolachlor either preemergence or postemergence. Dale was taller and produced more biomass than Sugardrip. Despite some stand loss and stunting early in the season, fresh shoot biomass yield of sweet sorghum was not affected by metolachlor rate and timing of application. Averaged over herbicide treatments, Dale and Sugardrip produced 99.71 mt/ha and 66.7 mt/ha biomass, respectively. The nontreated checks produced 101 and 64 mt/ha biomass, respectively.

Impacts
Expansion of some herbicide labels for use in minor crops. Successful crop production with additional weed control options.

Publications

  • Burgos, N.R., L. Brandenberger, C. Thomas, L. Wells, V. Shivrain, D. Motes, S. Eaton, L. Martin, and T. Morelock. 2006. Cowpea tolerance to Sandea herbicide. Proceedings of the 2006 annual meeting of the Southern Region American Society of Horticultural Science. HortSci. 40:516.


Progress 01/01/05 to 12/31/05

Outputs
The project goal is to register herbicides for use on specialty crops where weed control is a major problem and options are limited or nonexistent. Specialty crops included cowpea, cucurbits, spinach, southern greens, sweet corn, and tomato. Several herbicides were tested. Sandea (halosulfuron) is safer to use on cowpea when applied preemergence (PRE) rather than postemergence (POST). Eight advanced breeding lines have higher tolerance to Sandea than the commercial standard, Early Scarlet. These lines can tolerate 2X rates of Sandea, PRE, which is commercially applied at 0.048 lb ai/A. The commercial rate of Sandea can be used early POST, but only on cultivars with higher tolerance to the herbicide. Early POST application (V2) of Sandea at 0.048 lb ai/A caused about 30% yield loss in Early Scarlet. Other herbicides tested on cowpea included Ultra Blazer (acifluorfen), Reflex (fomesafen), Valor (flumioxazin), and Spartan (sulfentrazone). Spartan, at the commercial rate of 0.375 lb ai/A, provided 91 to 100% control of hophornbeam copperleaf with minimum injury on cowpea. This weed cannot be controlled by the currently labeled herbicides on cowpea. For spinach, several PRE herbicides were promising: thiobencarb, clomazone, dimethenamid, and prodiamine. Dimethenamid and fucarbazone were also safe when applied POST. The same PRE herbicides, including ethofumesate, as well as POST herbicides were also safe on collard and kale. Turnip was tolerant to the same herbicides, except clomazone. The only possible PRE herbicide for mustard is thiobencarb. However, mustard tolerates metolachlor, dimethenamid, flufenacet, prodiamine, and flucarbazone applied POST. Targa (quizalofop) provided 100% control of seedling and rhizome johnsongrass as well as annual grasses without injury to cucurbits (cantaloupe, cucumber, summer squash, muskmelon) or transplanted tomato. A new POST herbicide from Valent, V-10142, provided excellent control (>90%) of Palmer amaranth and yellow nutsedge without causing injury on tomato. For sweet potato, flumioxazin pre-transplant followed by clomazone post-transplant provided >90% control of annual grasses, pitted and entireleaf morningglories, and Palmer amaranth with <20% foliar injury to the crop. Persistence studies of various herbicides were also conducted on cool-season and warm-season vegetable crops. For sweet corn, imazamox carried over for 2 months and sulfentrazone for 4 months after application. Sensitive cowpea cultivars can be injured by sulfentrazone applied 4 months prior. Of the herbicides tested, sulfentrazone was the most persistent, causing injury to other warm-season crops including snapbean, summer squash, muskmelon, cucumber, and transplanted tomato 4 months after herbicide application. Cool-season vegetable crops included cabbage, collard, kale, mustard green, spinach and turnip. All these crops were injured by imazethapyr and fomesafen applied three months before planting. Other herbicides tested did not cause injury to any cool-season crop in the same time frame, except for sulfentrazone which injured spinach planted three months after application.

Impacts
Expansion of some herbicide labels for use in minor crops. Crop tolerance and weed control levels are determined.

Publications

  • Burgos, N. R., C. M. Thomas, D. Motes, S. Eaton, L. Martin, and T. Morelock. 2005. Response of spring-planted spinach cultivars to Raptor. Proc. of the National Spinach Conf., Fayetteville, AR. p. 1.
  • Talbert, R. E., C. E. Thomas, and N. R. Burgos. 2006. Field evaluation of herbicides on vegetables and small fruits 2005. Arkansas Agric. Exp. Station Res. Ser. 47 pp. http://www.uark.edu/depts/agripub/Publications/researchseries.
  • Thomas, C. M., B. V. Ottis, N. R. Burgos, and R. E. Talbert. 2005. Biological persistence of herbicides used in rotation with vegetables. Proc. SWSS Annual Meeting. 58:146.
  • Thomas, C. M., R. E. Talbert, N. R. Burgos, and A. T. Ellis. 2005. Spinach: Herbicide obstacles and options. Proc. of the National Spinach Conf., Fayetteville, AR. p. 2.


Progress 01/01/04 to 12/30/04

Outputs
Studies continue in Arkansas, with support from the IR-4 program, to obtain data to support registration efforts for herbicides for minor-use crops, such as low-acreage horticultural and ornamental crops. Herbicide efficacy trials are being conducted in snap bean, southern pea, spinach, southern greens (turnip, collard, mustard, and kale), sweet sorghum, melons, grapes, and ornamental crops. In sweet sorghum, promising new herbicide uses include S-metolachlor PRE and dimethenamid-P PRE and early POST using herbicide-safened seed. Halosulfuron, clomazone, dimethenamid-P, flufenacet, and imazamox + bentazon are promising in snap bean. In southern pea, dimethenamid-P, flufenacet, clomazone, halosulfuron, imazamox, imazamox + bentazon, and sulfentrazone show promise. Only sulfentrazone controlled hophornbeam copperleaf. Sulfentrazone, flumioxazin, and thiazopyr controlled weeds in grapes. In warm-season vegetables, herbicides with little carryover potential were S-metolachlor, flufenacet, cloransulam, clopyralid, flumioxazin, imazamox, mesotrione, rimsulfuron, and halosulfuron. Sulfentrazone and prosulfuron had potential for carryover. In cool-season vegetables, clomazone, imazamox, and rimsulfuron had little carryover, and imazethapyr, fomesafen, sulfentrazone, and halosulfuron had high carryover potential. One of the recent endeavors has been the identification of breeding material and varieties of southern pea with tolerance to herbicides, especially acifluorfen, fomesafen, and bentazon. The Crop Protection Association (CPA) continues to function as the vehicle for information exchange among university researchers and extensionists, food processing companies, growers, and agricultural companies with interests in the region, including Allen Canning Company, Gerber Baby Foods, and Razorback Farms in Arkansas. Day-to-day interaction occurs with these field-management personnel on pest problems in production fields in the area. The CPA organization has developed a strong alliance with similar groups in other southern states and continues to hold meetings throughout the year, including a fall and summer teleconference format with personnel in Texas, Oklahoma, and Louisiana to discuss and prioritize IR-4 projects. These meetings allow joint planning for integrated pest management in important minor crops. The group will continue to involve entomologists, plant pathologists, and vegetable breeders to broaden the possibilities for integrated pest management. Experiments reported here provide information for safe, effective, and economical crop protection against weeds.

Impacts
Results from experiments help establish tolerance and weed control levels and provide support for registration of new herbicides in horticultural and ornamental crops. These crops are in demand by American consumers, and these research efforts will increase availability of herbicides needed for profitable production in important minor crops. Entities such as the Crop Protection Association allow a coordinated effort, with input from producers, consumers, and researchers, to accomplish these goals.

Publications

  • Thomas, C.M., Ottis, B.V., and Talbert, R.E. 2004. Herbicide carryover resulting in injury to vegetable crops. Abstr. Ark. Crop Protection Assoc. 8:6-7.