Sulfonylureas represent one of the largest herbicide groups that have been widely used since 1980s. Their continuous use has resulted in development of sulfonylurea resistance in weeds. The aim of this research was to investigate options to manage putative sulfonylurea-resistant chickweed in barley stands and to evaluate the effect of chickweed and its management on barley yield. A field experiment was arranged as a randomized complete block design and included 14 herbicide treatments applied at two different times. Tribenuron-methyl (sulfonylurea) affected minimal control of chickweed. A bromoxynil-ioxynil (photosystem II inhibitor) mix did not control chickweed efficiently. However, nearly total control was achieved with fluroxypyr, mecoprop, and their mixtures (synthetic auxins and photosystem II inhibitors). Chickweed had no effect on barley yield whether controlled or uncontrolled. Therefore, further evaluation of the chickweed management threshold would be needed. It seems that even in the boreal region, typified by a cold climate, limited solar radiation, a very short growing season, and relatively low-intensity cropping systems, unilateral use of sulfonylureas might lead to herbicide resistance. Although resistant weed populations can be controlled with herbicides of groups other than the sulfonylureas, this represents an increasing problem when planning weed management, especially when including sulfonylurea-resistant crops. 1. Introduction Acetolactate synthase (ALS) inhibitors were commercialized in 1982, chlorsulfuron being one of the first active ingredients used. They quickly spread around the world and, due to their selectivity, low application rate, and broad-spectrum effectiveness, in many cases came to represent a key component of weed management [1]. Sulfonylureas belong to the group of ALS inhibitors. Widespread reliance solely on sulfonylureas has led to a situation where by 1998 large numbers of weed species were reported to be resistant to sulfonylureas [2]. Sulfonylurea-resistant weed species currently number over 100 [1]. The first reported sulfonylurea-resistant weed, prickly lettuce (Lactuca serriola L.), in 1987 was resistant to chlorsulfuron [3]. This was followed in 1988 by a common chickweed [Stellaria media (L.) Vill.] population in Canada [4]. In the northern temperate region (Norway and Sweden) ALS-resistant chickweed has been reported from Sweden in 1995 and Norway in 2002 (www.weedscience.com) but not in the northern boreal region (e.g., Finland). Sulfonylurea resistance derives mainly from a single-point mutation in
References
[1]
S. B. Powles and Q. Yu, “Evolution in action: plants resistant to herbicides,” Annual Review of Plant Biology, vol. 61, pp. 317–347, 2010.
[2]
P. J. Tranel and T. R. Wright, “Resistance of weeds to ALS-inhibiting herbicides: what have we learned?” Weed Science, vol. 50, no. 6, pp. 700–712, 2002.
[3]
C. A. Mallory-Smith, D. C. Thill, and M. J. Dial, “Identification of sulfonylurea herbicide-resistant prickly lettuce (Lactuca serriola),” Weed Technology, vol. 4, pp. 163–168, 1990.
[4]
J. T. O'Donovan, G. M. Jeffers, D. Maurice, and M. P. Sharma, “Investigation of a chlorsulfuron-resistant chickweed population,” Canadian Journal of Plant Science, vol. 74, no. 4, pp. 693–697, 1994.
[5]
P. Kudsk, S. K. Mathiassen, and J. C. Cotterman, “Sulfonylurea resistance in Stellaria media [L.] Vill,” Weed Research, vol. 35, no. 1, pp. 19–24, 1995.
[6]
H. J. Beckie and X. Reboud, “Selecting for weed resistance: herbicide rotation and mixture,” Weed Technology, vol. 23, no. 3, pp. 363–370, 2009.
[7]
J. K. Norsworthy, S. M. Ward, D. R. Shaw et al., “Reducing the risks of herbicide resistance: best management practices and recommendations,” Weed Science, vol. 60, pp. 31–62, 2012.
[8]
W. K. Vencill, R. L. Nichols, T. M. Webster et al., “Herbicide resistance: toward an understanding of resistance development and the impact of herbicide-resistant crops,” Weed Science, vol. 60, pp. 2–30, 2012.
[9]
L. G. Holm, The Worlds' Worst Weeds: Distribution and Biology, University Press of Hawaii, Honolulu, Hawaii, USA, 1977.
[10]
H. Fogelfors, “The competition between barley and five weed species as influenced by MCPA treatment,” Swedish Journal of Agricultural Research, vol. 7, no. 3, pp. 147–151, 1977.
[11]
H. H. Mann and T. W. Barnes, “The competition between barley and certain weeds under controlled conditions IV. Competition with Stellaria media,” Annals of Applied Biology, vol. 37, pp. 139–148, 1950.
[12]
P. J. W. Lutman, P. Bowerman, G. M. Palmer, and G. P. Whytock, “Prediction of competition between oilseed rape and Stellaria media,” Weed Research, vol. 40, no. 3, pp. 255–269, 2000.
[13]
L. H？met-Ahti, “The boreal zone and its biotic subdivision,” Fennia, vol. 159, pp. 69–75, 1981.
[14]
U. Meier, Ed., Growth Stages of Mono-and Dicotyledonous Plants: BBCH Monograph, Federal Biological Research Centre for Agriculture and Forestry, 2001, http://www.jki.bund.de/fileadmin/dam_uploads/_veroeff/bbch/BBCH-Skala_englisch.pdf.
[15]
R. Marshall, R. Hull, and S. R. Moss, “Target site resistance to ALS inhibiting herbicides in Papaver rhoeas and Stellaria media biotypes from the UK,” Weed Research, vol. 50, no. 6, pp. 621–630, 2010.
[16]
P. Kudsk and S. K. Mathiassen, “Herbicid resistens—status,” DJF Rapport, vol. 99, pp. 127–139, 2004.
[17]
J. F. Cahill Jr., “Lack of relationship between below-ground competition and allocation to roots in 10 grassland species,” Journal of Ecology, vol. 91, no. 4, pp. 532–540, 2003.
[18]
P. J. Kramer and J. S. Boyer, Relations of Plants and Soils, Academic Press, San Diego, Calif, USA, 1995.
[19]
A. H. Fitter, “Effects of nutrient supply and competition from other species on root growth of Lolium perenne in soil,” Plant and Soil, vol. 45, no. 1, pp. 177–189, 1976.
[20]
P. Hamouz, K. Hamouzová, J. Holec, and L. Ty？er, “Impact of site-specific weed management on herbicide savings and winter wheat yield,” Plant, Soil and Environment, vol. 59, pp. 101–107, 2013.
[21]
J. Salonen and L. R. Ervi？, “Efficacy of chemical weed control in spring cereals in Finland,” Weed Research, vol. 28, no. 4, pp. 231–235, 1988.
[22]
E. Stasinskis, “Effect of preceding crop, soil tillage and herbicide application on weed and winter wheat yield,” Agronomy Research, vol. 7, pp. 103–112, 2009.
[23]
A. Légère, F. C. Stevenson, D. L. Benoit, and N. Samson, “Seedbank-plant relationships for 19 weed taxa in spring barley-red clover cropping systems,” Weed Science, vol. 53, no. 5, pp. 640–650, 2005.
