GR Volunteer Corn Control with mixture of Clethodim and Dicamba
Vitor M. Anunciato
2020-11-19
Interactions of Clethodim and Dicamba on Glyphosate-resistant Volunteer Corn Control
Vitor Muller Anunciato, Gabrielle de Castro Macedo, Daniel Araujo Doretto, Jeff A. Golus, Caio A. Carbonari, Greg R. Kruger
Introduction
Glyphosate Resistant Volunteer Corn (GRVC) is a common weed in soybean fields (Tao B. et al. 2007).
Can reduce soybean yield through competition, cause problems with harvest, host insects and diseases, and contaminate soybean seeds at the harvest. (Marquardt, P. T., & Johnson, W. G. 2013).
Clethodim (WSSA Group 1) used in grass control in postemergence applications. However, antagonistic interactions have been reported when applied in tank-mixtures with synthetic auxins (WSSA Group 4). (Blackshaw et al. 2006; Harre et al. 2020).
Clethodim and dicamba mixture are utilized to increase the spectrum of weeds control. (Underwood, M. G. et al. 2016).
Objectives
- To evaluate the effects of clethodim and dicamba tank-mixture on GRVC control at different heights, with and without the use of non-ionic surfactant (NIS).
Hyphotesis
Non-ionic surfactant (NIS) will increase the control of GRVC when treated with the mixture of clethodim and dicamba.
As the plant height increase will decrease the control of GRVC when treated with the mixture of clethodim and dicamba.
Study desing
Field planted at Dryland Farm, North Platte - NE, University of Nebraska-Lincoln/WCREEC, in 2019 and 2020.
- 62,500 seeds/ha (25,000 seeds/acre).
Plants heights: 30 cm (12 in), 60 cm (24 in) and 90 cm (72 in).
Those fields study was conducted in randomized complete block design in a factorial treatment arrangement with 4 replications and 2 experimental runs.
- Split in plots with 3 x 10 m (10 x 30 ft each).
Statistical analysis
Biomass data were subjected to ANOVA test and means were separated using Fisher’s LSD test with post-hoc Tukey test at α = 0.05.
Colby’s Equation was used to determine the type of interaction occurred Colby, S. R. (1967). And the difference between the estimated and obseverd control values was compared by studentized t test α = 0.1.
E = (X+Y) - (X*Y)/100X and Y are the effects of the herbicides applied alone (expressed as percent‐of‐control).
The Observed control for the herbicide mixture is then compared to the E = expected control.
- If p value > 0.1
- Obs greater Exp = SYNERGISM
- Obs less Exp = ANTAGONISTIC
- If p value ≥ 0.1
- ADDITIVE
- If p value > 0.1
Preceptation
- Systemic herbicides as clethodim and dicamba are highly affected by the climate, the difference of precipitation between the field studies conduction could be derived from the difference of precipitation.(Adkins, S. W. et al 1998; Zhou, J. et al 2007)
Discussion
- If the control of GRVC is realized earlier it has the best response hitting 80% in the lowest dose and 96% in the highest dose (136 g ai/ha) when the plants are sprayed with 30cm of height. On the other hand, when the plants had 90 cm the maximum control achieved was 58%. Those results agree with Costa et al 2014 they highlighted the importance of completing the management in the transgenic volunteer corn plant development early stages.
Conclusion
The mixture tends to be antagonistic independent of the presence or absence of the NIS.
The antagonistic effect is the predominant interaction, independent of the tested dose of clethodim it cants present a different interaction with dicamba. But even with the antagonic effect the mixture of 136 g ai/ha of clethodim with 560 g ae/ha of dicamba presents satisfactory control ±85% when the plants are treated at 30 cm
- Results showed that cutting the rate of clethodim is not a good strategy for management of GRVC and timeliness is critical for the success of this tool in the field, because GRVC is not a conventional weed.
References
Tao, B., Zhou, J., Messersmith, C. G., & Nalewaja, J. D. (2007). Efficacy of glyphosate plus bentazon or quizalofop on glyphosate-resistant canola or corn. Weed Technology, 21(1), 97-101.
Marquardt, P. T., & Johnson, W. G. (2013). Influence of clethodim application timing on control of volunteer corn in soybean. Weed Technology, 27(4), 645-648.
Blackshaw, R. E., Harker, K. N., Clayton, G. W., & O'Donovan, J. T. (2006). Broadleaf herbicide effects on clethodim and quizalofop-P efficacy on volunteer wheat (Triticum aestivum). Weed technology, 20(1), 221-226.
Underwood, M. G., Soltani, N., Hooker, D. C., Robinson, D. E., Vink, J. P., Swanton, C. J., & Sikkema, P. H. (2016). The addition of dicamba to POST applications of quizalofop-p-ethyl or clethodim antagonizes volunteer glyphosate-resistant corn control in dicamba-resistant soybean. Weed Technology, 639-647.
Harre, N. T., Young, J. M., & Young, B. G. (2020). Influence of 2, 4-D, dicamba, and glyphosate on clethodim efficacy of volunteer glyphosate-resistant corn. Weed Technology, 34(3), 394-401.
References
Colby, S. R. (1967). Calculating synergistic and antagonistic responses of herbicide combinations. Weeds, 15(1), 20-22.
Adkins, S. W., Tanpipat, S., Swarbrick, J. T., & Boersma, M. (1998). Influence of environmental factors on glyphosate efficacy when applied to Avena fatua or Urochloa panicoides. Weed Research (Oxford), 38(2), 129-138.
Zhou, J., Tao, B., Messersmith, C. G., & Nalewaja, J. D. (2007). Glyphosate efficacy on velvetleaf (Abutilon theophrasti) is affected by stress. Weed science, 55(3), 240-244.
Costa, N. V., Zobiole, L. H. S., Scariot, C. A., Pereira, G. R., & Moratelli, G. (2014). Glyphosate tolerant volunteer corn control at two development stages. Planta Daninha, 32(4), 675-682.