Loeppky, H.A.

English

University of Saskatchewan Research Archive

Why Lontrel Shouldn't Be Used In Mustard Crops H.A. Loeppky Agriculture Canada, Research Station, Melfort, Saskatchewan INTRODUCTION Current low grain prices have forced producers to look for alternative crops. Brown, oriental, and yellow mustard are drought tolerant, short season crops well adapted to the Brown and Dark Brown soils, areas where cropping options tend to be more limited. Mustard seed is currently produced primarily for the condiment market, although the future holds promise of oilseed quality mustard. Good weed control is essential to prevent yield reductions and reduced market value of the seed due to contamination by weed seeds. At present, the only broad-leaved weed herbicides registered for use in mustard, trifluralin and ethalfluralin, must be applied before seeding and incorporated into the soil. This practice destroys crop residues, dries the seedbed and leaves the soil prone to erosion. Lontrel and Muster, two postemergence herbicides, have proven to be safe and effective in canola whether applied individually or as a tankmix (Blackshaw 1989, Swanton and Chandler 1989). Seven of the fifteen most abundant weeds in Saskatchewan mustard fields are controlled by these two herbicides, including stinkweed, wild buckwheat, Canada thistle and perennial sowthistle (Douglas and Thomas 1986). Muster has shown promise for controlling wild mustard in tame mustard {Blackshaw and Derksen 1992), but little is known about domestic mustard tolerance of Lontrel, either alone or with Muster. Research was conducted at Lethbridge, Alberta and Indian Head, Saskatchewan to determine the effects of dose and time of application of Lontrel, alone or mixed with Muster, on seed yield and quality of brown, yellow and oriental mustard. MATERIALS AND METHODS Two field studies were conducted at Lethbridge Research Station, Lethbridge, Alberta and at Indian Head Experimental Farm, Indian Head, Saskatchewan in 1989 and 1990. The soil at Lethbridge was a Dark Brown Chernozem of sandy loam texture: 57% sand, 17% silt, 26% clay, pH 8.0 and 2.0% organic matter. At Indian Head, the soil was a Black Chernozem of silty clay texture: 4% sand, 24% silt, 72% clay, pH 7.6 and 4% organic matter. The tests were fertilized according to soil test recommendations. Ethalfluralin was applied overall at 1.1 kg ha·1 and incorporated as recommended to a depth of 1 0 em to control grassy and broad-leaved weeds. In early May, yellow mustard, cv. 'Kirby'; oriental mustard, cv. 'Cutlass'; and brown mustard, cv. 'Common' were seeded on fallowed land at 8 to 10 kg ha·1 to a depth of 3 em with 15-23 em row spacing. Furadan {0.27 kg ha-1) was applied with the seed to control flea beetles. In the first experiment, Lontrel was applied at 0.10, 0.15, 0.20, 0.30 and 0.60 kg a.i. ha·1 at the 4- or 1 0-leaf stage of mustard. It is currently registered for weed control in canota at o~ 15 - 0.30 kg a.i. ha·1, applied at the 3-to 6- leaf stage of the crop. The 4- and 1 0-leaf stages were chosen to represent the recommended stage, and a late application Oust before canopy closure), respectively. A randomized complete block design was used. The other, a factorial experiment, was conducted with Lontrel applied at 0, 0.1 0, 0.20, and 0.30 kg a.i. ha·1 and 166 Muster at 0, 0.01, 0.02 and 0.03 kg a.i. ha·1• Muster is currently registered for weed control in canota at rates of 0.015- 0.023 kg a.i. ha·1 • Herbicides were applied when the mustard was in the 4- to ·6-leaf stage. A randomized complete block design was used. Agral 90 was included at 0.25% v/v in all Muster treatments. Hand-weeded controls were included in both experiments. All treatments were applied with a C02 - pressurized sprayer delivering 110 and 170 L ha·1 at Indian Head and Lethbridge, respectively. Mustard cultivars were sown perpendicular to the herbicide plots in 2m parallel strips forming a split block design. Experiments had four replicates. Subplot sizes were 2 by 7 mat Lethbridge and 2 by 6 mat Indian Head. Visual crop tolerance ratings were taken in mid-July. These ratings were based on a scale of 0-9, where 9 = no injury and 0 = complete kill. According to this scale the maximum injury rating for commercial acceptance is 7. Mustard cultivars were harvested by cutting a 1 m2 area by hand at Lethbridge and by combining a 2.4 m2 area with a small plot combine at Indian Head. Thousand seed weights were calculated at Lethbridge in 1989 and 1990 and at Indian Head in 1989. Nuclear magnetic resonance (NMR) was used to determine oil content of the seed. SAS was used for all data analysis. RESULTS AND DISCUSSION Below normal precipitation occurred at both locations in 1989. At Lethbridge, test plots were irrigated with 50 mm of water at seeding time to aid in establishment. As a result, the relative yield of the three types of mustard was similar in both years. At Indian Head, where plots were not irrigated, yellow mustard seed yield was less than brown or oriental mustard in 1989. However, in 1990 when precipitation was 115% of normal, yellow mustard out yielded both brown and oriental mustard. The B. juncea types, brown and oriental are known to b~ particularly drought tolerant. Brown and oriental mustard oil content was generally higher in 1989 than in 1990, while yellow mustard oil content was generally lower in 1989 than in 1990. The change in oil content from one year to the next differed in magnitude between locations. This explains the site-year by variety interactions (Table 1 ). Although there were differences in response related to location and year in both experiments, there was a general linear decline in yield and oil content of all three mustards as Lontrel rate increased (Tables 2-4). The rate of decline in yellow mustard yield and oil as Lontrel rate increased was less than that of the brown and oriental indicating that the B. hirta species is less sensitive than B. juncea. A reduction in oil content alone is not necessarily undesirable, since low oil content is desirable in the condiment mustards, but yield reductions are not acceptable. · Very little injury was visible in either experiment when injury ratings were taken in July however, at maturity, seed pods appeared shorter. Application of 0.15 kg a.i.ha·1 of Lontrel {the lowest rate registered for weed control in canota) resulted in an increase in thousand seed weight of 2% in brown, oriental, and yellow mustard (data not presented). When mixed with Muster, this rate of Lontrel resulted in a 13% increase in brown mustard thousand seed weight, 9% increase in oriental thousand seed weight and 6% increase in yellow thousand seed weight. Brown mustard tended to be the most affected when application was made at the 1 0 leaf rather than the 4 leaf stage, oriental mustard was intermediate and yellow mustard was the least affected by time of application (Tables 2-4). According to single degree of freedom contrasts, brown mustard yield reductions were significantly greater when clopyralid was applied at the 1 0 leaf rather than the 167 4 leaf stage at Indian Head in 1990 and Lethbridge in 1989. As well, oriental mustard yield was significantly lower when clopyralid was applied at the later growth stage in both years at Indian Head. Significant differences between leaf stage in yellow mustard occurred only at Indian Head in 1990. Yellow mustard oil content was significantly affected by growth stage at time of application in 3 of 4 site-years. According to oil content estimates, howe~ver, the difference in oil content was less than 1% when Lontrel was applied at the 10 leaf rather than the 4 leaf stage. Tolerance to Muster, in general, was greatest in brown mustard, intermediate in oriental and poorest in yellow mustard. This confirms an earlier report by Blackshaw and Derksen (1992). As was the case in their work, tolerance was influenced by site-year, however, the reason for this is unknown. Mustard yield, oil content and thousand seed weight were affected by Lontrel application regardless of whether or not it was applied with Muster. In general, however, the addition of Muster resulted in greater yield and oil content reductions. Mixtures of these two herbicides have been reported to act synergistically in controlling redroot pigweed and common lamb's-quarters, without increasing canola injury (Blackshaw 1989). SUMMARY Mustard species displayed differences in the tolerance to Lontrel and mixtures of Lontrel with Muster. However, in this study, crop tolerance was never acceptable. Yellow mustard was the most tolerant with yield reductions of 9% and 8%, respectively, when Lontrel was applied at 0.15 kg a.i. ha·1 alone or with Muster. This same rate applied to oriental mustard resulted in average yield reductions of 22 and 35%, alone or with Muster, respectively. In brown mustard, average yield reductions were 20 and 30%, respectively, when Lontrel was applied at 0.15 kg a.i. ha·1 alone or with Muster. Although Lontrel and Lontrel +Muster provide good weed control in canola, these products cannot be used safely in mustard. ACKNOWLEDGMENTS The author wishes to thank Dr. Bob Blackshaw (Lethbridge Research Station) for his collaboration, and Steve Kopp, Karl Schiffer, Sherry Gore and G; Epp for their technical assistance. REFERENCES Blackshaw, R.E. 1989. Synergistic mixes of DPX-A7881 and clopyralid in canola (Brassica napus). Weed Tech. 3: 690;.695. Blackshaw, R.E. and Derksen, D.A. 1992. Response of cultivated mustard species to DPX-A7881. Can. J. Plant Sci. 72: 203-207. Douglas, D.W. and Thomas, A.G. ·1986. Weed Survey of Saskatchewan Mustard, Lentil and Dry Pe'a- Crops 1985. Weed Survey Series Publication 86-2. pp. 157. Available from: Agriculture Canada, Regina. Swanton, C.J. and Chandler, K. 1989. Control of wild mustard in canola with postemergence herbicides. Can. J. Plant Sci. 69: 889-896. 168 Table 1. Analysis of variance of mustard yield and oil content response to Lontrel applied alone at the 4 or 10 leaf stage, or with Muster at the 4-6 leaf stage. Lontrel at two different leaf stages: Lontrel with Muster: Source of Variance df Yield Oil Content Source of Variance df Yield Oil Content P>F P>F P>F P>F Siteyear (S) 3 .0009 .0901 Siteyear (S) 3 .0111 .9207 Cultivar (V) 2 .0004 .0001 Cultivar (V) 2 .0098 .0251 S*V 6 .0013 .0138 S*V 6 .0001 .0001 1-' .0910 Muster 3 .0007 .1438 0'\ Leaf Stage (LF) 1 .0198 1..0 Rate (A) 4 .0001 .0002 Lontrel (L) 3 .0001 .0017 LS*R 4 .8712 .1418 Muster*L 9 .1934 .5203 S*LS 3 .5935 .3528 S*Muster 9 .8693 .6660 S*R 12 .0327 .0220 S*L 9 .0035 .0039 S*LS*R 12 .0691 .4545 S*Muster*L 27 .1453 .0401 V*LS 2 .7063 .3137 V*Muster 6 .1426 .2414 V*R 8 .0013 .0262 V*L 6 .0001 .0057 V*LS*R 8 .0145 .8233 V*Muster*L 18 .9386 .9333 S*V*LS 6 .0687 .2476 S*V*Muster 18 .0152 .8058 S*V*R 24 .0806 .2305 S*V*L 18 .0011 .0001 S*V*LS*R 24 .7975 .8058 S*V*Muster*L 54 .3728 .2288 Table 2. Brown mustard yield and oil content response to Lontrel alone at the 4 or 10 leaf stage or with ethametsulfuron (Muster) at the 4-6 leaf stage. I. Lontrel applied at the 4 leaf stage Yield Yield Oil content Oil content response ~ reductionz response ~ reductionz Indian Head 1989 y=135-.21x **Y .8634 15% y=30. 72-.01 X ** .8749 3.3% 1990 Y= 93-.10x NS .8029 11% y=29.50-.002x NS .3687 0.6% Lethbridge 1989 y=175-.23x NS .9013 13% y=32.0-.01 X ** .9426 3.1% 1990 y=212-.28x ** . 8487 13% . y=32.2-.01 X ** .7816 3.1% ..... II. Lontrel applied at the 1 0 leaf stage -...) 0 Indian Head 1989 y= 94-.11x ** .5720 12% y=29.7-.007x ** .6667 2.4% 1990 y= 73-.11x ** .7731 15% y=29.6-.004x NS .5316 1.4% Lethbridge 1989 y=134-.19x ** .8487 14% y=29.8-.009x •• w .8770 3.0% 1990 y=205-.27x ** .8693 13% y=31.4-.009x * .8449 2.1% Ill. Lontrel with Muster Indian Head 1989 y=171-.37x ** .9883 22% y=32.65-.02x ** .9888 6.1% 1990 y= 87-.15x ** .8359 17% y=31.18-.004x NS .9151 1.3% Lethbridge 1989 y=221-.47x ** .9853 21% y=33.09-.02x ** .9447 6.3% 1990 y=233-.43x ** .8803 19% y=32.09-.017x · ** .8668 5.3% zPotential yield or oil content reduction per 0.1 kg a.i. ha·1• YBased on single degree of freedom 'Contrasts for linear response to increasing clopyralid rates: **, * and NS are significant at the 1% and 5% levels and not significant, respectively. wSignificant EMM*C interaction. Table 3. Oriental mustard yield and oil content response to Lontrel alone at the 4 or 10 leaf stage or with ethametsulfuron (Muster) at the 4-6 leaf stage. I. Lontrel applied at the 4 leaf stage Yield Yield Oil content Oil content response ~ reductionz . response ~ reductionz Indian Head 1989 y=142·.25x **Y .8199 18% y=32.4-.009x ** .7881 2.8% 1990 y=118-.15x * .5153 13% y=31.7-.002x NS .3631 0.6% Lethbridge 1989 y=190-.29x ** .9871 15% y=34.9-.01x ** .8572 2.9% 1990 y=289-.37x ** .8824 13% y=34.0-.007x ** .7820 2.1% ...... II . Lontrel applied at the 1 0 leaf stage -...J ...... Indian Head 1989 y= 94-.15x ** .8878 16% y=30.9-.005x ** .8533 1.6% 1990 y= 92-.14x ** .8533 15% y=31.6-.001x NS .2838 0.3% Lethbridge 1989 y=166·.23x ** .8758 14% y=35.0-.01x '** .9710 2.9% 1990 y=267·.34x ** .9120 13°/o y=33.8· .007x ** .7737 2.7% Ill. Lontrel with Muster Indian Head 1989 y=172-.51x ** .9528 30% y=34.5-.02x ** .9406 5.8% 1990 y=143-.27x ** .9904 19% y=33.4· .002x NS .4545 0.6% Lethbridge 1989 y=220-.45x ** .9154 21% y=36.3-.023x •• w .9499 6.3% 1990 y=291-.67x **w .9782 23% y=34.7-.017x ** .9239 4.9% zPotential yield or oil content reduction per 0.1 kg a.i. ha·1• YBased on single degree of freedom contrasts for linear response to increasing clopyralid rates: **, * and NS are significant at the 1% and 5% levels and not significant, respectively. wSignificant EMM*C interaction. Table 4. Yellow mustard yield and oil content response to Lontrel alone at the 4 or 10 leaf stage or with ethametsulfuron (Muster) at the 4-6 leaf stage. I. Lontrel applied at the 4 leaf stage Yield Yield Oil content Oil content response (! reductionz response (! reductionz Indian Head 1989 y=171-.10x NSY .9882 6% y=25.5-.004x **Y .8327 1.6% 1990 y=228-.08x ** ·.9382 4% y=24.9-.003x NS .5806 1.2% Lethbridge 1989 y=228 .... 12x NS .5893 5% y=25.7-.001x ** .9649 2.3% 1990 y=352-.23x ** .8320 7% y=28.7-.006x NS .8460 2.1% 1-' II. Lontrel applied at the .1 0 leaf stage ....J Indian Head 1989 y=167-.12x ** .9851 7% y=24.8-.005x ** .9552 2.0% N 1990 y=214-.155x ** .9292 7% y=24.1-.0008x NS .2190 0.3% Lethbridge 1989 y=239-'.16x NS .7771 7% y=24.5-.006x ** .8606 2.4% 1990 y=336-.214x NS .9126 6% y=27 .8-.006x * .7127 2.2% Ill. Lontrel with Muster Indian Head 1989 y=150-.075x **w .8714 5% y=25.8-.004x ** .9818 1.6% 1990 y=170-.083x * .4504 5% y=26.4-.0007x NS .3630 0.3% Lethbridge 1989 y=303-.183x ** .9998 6% y=25.9-.006x ** .9963 2.3% . 1990 y=310-.185x NS .8061 6% y=26.8-.006x ** .9799 2.2% zPotential yield or oil content reduction per 0.1 kg a.i. ha·1• YBased on single degree of freedom contrasts for linear response to increasing clopyralid rates: **, * and NS are significant at the 1% and 5% levels and not significant, respectively. wSignificant EMM*C interaction. 

Why Lontrel shouldn't be used in mustard crops

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Why Lontrel shouldn't be used in mustard crops

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