Balance and Callisto Performance
- Isoxaflutole vs. Mesotrione: the battle of the bleachers. D. D. Lingenfelter, W. S. Curran, and K. Handwerk. Proc. NEWSS 56:24.
- 1998 Isoxaflutole (Balance) Performance in Northeastern U.S. University Field Trials. E. L. Werner, W. S. Curran, F. J. Himmelstein, R. J. Durgy, J. M. Jemison, P. C. Bhowmik, and D. P. Veilleux, 1999. Proc. NEWSS (in press).
- Balance Performance in Penn State Field Trials - A Three Year Summary. E. L. Werner and W. S. Curran, 1998. Proc. NEWSS 52:115.
Isoxaflutole vs. Mesotrione: the battle of the bleachers. D.D. Lingenfelter, W.S. Curran, and K. Handwerk. Proc. NEWSS 56:24.
Isoxaflutole and mesotrione (proposed common name) are relatively new pigment inhibiting herbicides that are labeled for use in field corn (Zea mays). Each of these herbicides controls susceptible species by inhibiting the 4-HPPD enzyme, despite being from different chemical families. Isoxaflutole, an isoxazole, is strictly a preemergence herbicide, while mesotrione, a callistemone, can be applied either pre or postemergence. Field research has been conducted at Penn State University since 1995 with isoxaflutole and since 1999 with mesotrione.
Field studies were conducted using typical, replicated, small-plot research techniques under various tillage and environmental conditions. Isoxaflutole was usually applied from 0.047 to 0.094 lb ai/A, while mesotrione was applied at 0.094 and 0.187 lb ai/A, POST and PRE, respectively. Lower mesotrione PRE use rates (0.047 to 0.094 lb ai/A) were included in 2001. Both herbicides were applied PRE alone and in combinations with atrazine and/or chloro- or oxyacetamide herbicides. Mesotrione was also evaluated POST, alone and in combination with atrazine and other herbicides. Necessary adjuvants were included in the POST spray mixture. Visual control ratings were taken periodically throughout the growing season.
Isoxaflutole and mesotrione applied alone PRE, provided excellent control (±95%) of common lambsquarters (Chenopodium album) and velvetleaf (Abutilon theophrasti). Pigweed species (Amaranthus hybridus and A. retroflexus) control improved at the higher use rates compared to lower rates with both herbicides (increasing from 87 to 95%). Control of common ragweed (Ambrosia artemisiifolia) with isoxaflutole increased from 81 to 93%, as rate increased, while mesotrione, at either rate, provided only 82% control. Mesotrione was better than isoxaflutole on the control of several polygonum species, including Pennsylvania smartweed (Polygonum pensylvanicum), wild buckwheat (Polygonum convolvulus), and prostrate knotweed (Polygonum aviculare), as well as, on dandelion (Taraxacum officinale). Mesotrione applied POST provided >90% control of common lambsquarters, velvetleaf, and smooth pigweed. Common ragweed and wild buckwheat averaged 88% control, but control improved with the addition of 0.25 to 0.75 lb ai/A atrazine.
Isoxaflutole provided 80 to 91% control of giant foxtail (Setaria faberi), yellow foxtail (Setaria glauca) and fall panicum (Panicum dichotomiflorum) across all rates, while mesotrione had minimal effect on these grass species. On average, mesotrione provided better yellow nutsedge (Cyperus esculentus) control (84%) as compared to isoxaflutole (67%).
In summary, both isoxaflutole and mesotrione provide effective control of many common annual broadleaves found in Pennsylvania and Northeast cropping systems. However, since both have weaknesses on certain weed species, tank-mixing with atrazine and/or pre-grass herbicides usually will be necessary to improve and broaden their weed control spectrum. Selection will mainly depend on weed spectrum, cost, and use restrictions. More research is still needed to better identify appropriate rates for mesotrione use in corn.
1998 Isoxaflutole (Balance) Performance in Northeastern U.S. University Field Trials. E. L. Werner, W. S. Curran, F. J. Himmelstein, R. J. Durgy, J. M. Jemison, P. C. Bhowmik, and D. P. Veilleux, 1999. Proc. NEWSS (in press).
Isoxaflutole (Balance) is a newly registered preemergence corn herbicide from Rhone-Poulence Ag Company that is effective for controlling some grassy and many broadleaf weed species. Balance has not yet received registration in the northeast, but research continues to optimize use rates for varying soil type. In 1998, four northeastern universities conducted similar trials that examined varying rates of Balance in combination with other herbicides. The Pennsylvania State University (PA), University of Massachusetts (MA), University of Connecticut (CT) and University of Maine (ME) completed these protocols. Upon analysis it was determined that the textural class of the soils where the studies were conducted were either silty clay or silt loam. Balance, Harness and Atrazine were applied in combinations at varying rates to small field plots and treatments were replicated three times. Weed species common to all locations included, common lambsquarters, giant or yellow foxtail, common ragweed and pigweed. Weed control and crop injury were assessed throughout the season by a visual rating system.
Crop injury was evident only at the ME location. Early season ratings at this site indicated 13 to 64 % corn injury. This rating reflected percent bleaching and although the bleaching was severe, the crop recovered and end of season silage yields showed no significant difference. Crop injury at this site was probably due to herbicide movement to the crop seed zone caused by 3 inches of rainfall received three days after herbicide application. End of season ratings at the PA, ME and MA locations indicated excellent (90–100 %) control of lambsquarters, pigweed and ragweed regardless of Balance rate. Balance + Harness combinations offered good to excellent (85–100 %) foxtail control at the ME and MA locations. Foxtail control in PA was poor to good (77–90 %); this lack of control was probably due to the excessive rainfall (> 3 inches in one week) immediately following herbicide application and loss of residual activity. Foxtail control improved as the rate of Harness was increased from 0.6 to 0.9 lb ai/A for all locations.
Balance herbicide is an excellent product for controlling troublesome weeds such as common lambsquarters. Research needs to continue to examine the injury potential of Balance on certain soils or under different environmental conditions before this product is widely used in the northeast. However, Balance should be a good compliment for managing weeds in the northeast.
Balance Performance in Penn State Field Trials - A Three Year Summary. E. L. Werner and W. S. Curran, 1998. Proc. NEWSS 52:115.
Isoxoflutole (Balance) is a new corn herbicide developed by Rhone-Poulenc. The primary mode of action for isoxoflutole is pigment inhibition. Applied preemergence isoxoflutole controls numerous broadleaf weeds and suppresses annual grasses. The use rate of isoxoflutole ranges from 0.024 lb ai/acre for sandy soils to 0.188 lb for soils high in organic matter. The use rate for central Pennsylvania silt loam soils ranges from 0.071 to 0.094 lb ai/acre.
During the 1995, 96, and 97 growing seasons isoxoflutole was examined in Penn State herbicide efficacy trials. Small plot experiments were established in both central and Southeastern Pennsylvania with isoxoflutole being applied at increasing rates alone and in combination with various grass compounds and/or atrazine. Herbicides were applied with a pressurized CO2 backpack sprayer to plots measuring 10 by 25 ft. Visual assessments of corn injury and weed control were obtained early, mid, and late season using a 0 to 100% scale with 0 = no control and 100 = complete control.
End of season giant foxtail control ratings indicate a definite rate response for all three growing seasons. However control ratings varied depending on growing season conditions. Where moisture was not limited early in the season as in the 1995 and 1996 growing seasons, giant foxtail control ranged from 82 % for the 0.071 lb ai/acre rate to 94 % for the 0.094 lb rate. Where moisture was limited early in the season as it was for the 1997 growing season, control of giant foxtail dropped to 57% for the 0.071 lb rate to 72% for the 0.094 lb rate. The addition of a chloroacetamide herbicide with isoxoflutole greatly improved giant foxtail control in all cases.
There was no significant rate response for the control of common lambsquarters or velvetleaf for all three growing seasons. Isoxoflutole alone gave good to excellent control of common lambsquarters and velvetleaf all three seasons providing 90% or better control. The addition of a chloroacetamide herbicide increased control of common lambsquarters up to 97%, and the addition of atrazine improved velvetleaf control. Atrazine did not improve common lambsquarters control due to the presence of triazine resistance.
Corn injury has been an on-going concern when using isoxoflutole, however crop phytotoxicity has not been apparent in Penn State weed trials even at twice the normal use rate. PSU research has not examined the effect that other stress factors (e.g. compaction, corn rootworm, etc.) may have on isoxoflutole injury to corn, therefore growers will be urged to use caution during isoxoflutole’s inaugural year. In summary with the addition of a chloroacetamide herbicide, isoxoflutole will be a useful tool for Pennsylvania corn producers. Use rates may have to be fine tuned to provide maximum weed control benefit and minimal potential for crop injury.