A field trial was undertaken at Kinnabulla (VIC) in 2019 to investigate combinations of sowing time, seed rate and herbicide treatments to control brome grass in barley. Spartacus CL barley was used in this trial to enable the use of Intervix® for post-emergence control of brome grass. In 2019, the trial site received 181 mm rainfall during the growing season (April-October), which was 23% lower than the long-term average for the site. However in December 2018, the site received a heavy downpour of 199 mm, which created good growing conditions for barley crop grown in 2019. In this trial, barley seeding rate did not have a significant effect on either yield (P=0.213), brome panicles/m2 at maturity (P=0.889) or brome seed set/m2 (P=0.409). This lack of effect of crop seed rate on the number of brome panicles and seed set could be related to the high plant available water during the crop and weed life-cycle or due to Spartacus being a less competitive barley cultivar due to its erect architecture. Time of sowing had a significant effect on brome panicles/m2 at maturity and brome seed set/m2. TOS 2 had a lower brome panicle density at maturity than TOS 1 across all herbicide strategies, which was most likely due to low pre-sowing weed kill in TOS 1 as brome grass had not yet germinated. However, brome population that had germinated after the opening rains was killed by glyphosate application prior to seeding barley in TOS 2. As the numbers of panicles were lower in TOS 2, brome seed set was also reduced in TOS2 relative to TOS 1. Herbicide strategy had a significant effect on barley grain yield. As the herbicides reduced the impact of brome on barley, its yield increased from 3.24 t/ha in the knockdown treatment (NIL), to 3.72 t/ha in the pre-emergent herbicides only and to 3.96 t/ha when the pre-emergent herbicides were followed by post-emergent Intervix. Somewhat surprisingly, TOS 2 produced higher yields than TOS 1 across all the treatments, with the greatest difference being 0.46 t/ha in the Nil herbicide treatments. However, the yield difference between the two times of sowing decreased when more effective herbicides were used (0.08t/ha difference between TOS 1 and 2 in pre-emergent only and 0.04t/ha difference when pre-emergent herbicides followed by Intervix). Higher barley grain yield in the later sown crop is most likely due to a significantly greater weed density in barley in TOS 1 than in TOS 2, as large numbers of early germinating brome plants were controlled with glyphosate knockdown in TOS 2. TOS 1 also experienced a mild frost during flowering, resulting in patchy frost damage. Furthermore, May 23 (TOS 2) sowing date still falls within the optimum sowing window for Spartacus, which is an early maturity variety, and TOS 1 on April 29 was earlier than optimum for this variety.

A field trial was undertaken in 2019 to investigate combinations of faba bean sowing time, seed rate and herbicide treatments to control annual ryegrass. ARG plant density was significantly influenced by the time of sowing (P<0.001), herbicide treatment (P<0.001) and the interaction between the time of sowing and herbicide (P=0.012). The 3 week delay in seeding faba beans had no impact on ARG plant density, as shown by the similar ARG density in the simazine + trifluralin treatment. However, POST clethodim and butroxydim had much greater efficacy in the 2nd time of sowing (TOS 2) than in the TOS 1. The same trend was evident in ARG seed set when crop seeding was delayed. In the Simazine + Trifluralin (IBS) treatment there was only an 8% reduction in ARG seed production when seeding was delayed. However, Simazine + Trifluralin (IBS) fb Clethodim had a 62% reduction in ARG seed production in TOS 2 than in TOS 1. ARG seed production was also strongly influenced by faba bean seed rate (P<0.001). The high faba bean seed rate had 43% less ARG seed set compared to the low faba bean seed rate. This result indicates that faba beans can be highly competitive with ARG at the high seed rate. Faba bean grain yield was significantly influenced by crop seed rate (P<0.001), with the high seed rate yielding 14% and 30% higher than the medium and low seed rates, respectively. Herbicide treatment had a significant effect on faba bean grain yield. When POST clethodim was applied after the Simazine + Trifluralin IBS (1.55 t/ha), faba bean grain yield improved by 43% to 2.211 t/ha. Crop yield responses to herbicides treatments were consistent with their efficacy on ARG, which highlights the sensitivity of faba bean grain yield to weed competition. This study has shown that at high plant density, faba beans can provide a significant suppression of ARG. However, faba beans were very intolerant to weeds as shown by the large yield losses. Higher seed rates, are important to both increase competitiveness of faba beans in suppressing ARG, and to also maintain grain yield. However, fungal disease management would need to be monitored and managed effectively.

A field trial was undertaken at Washpool in 2019 to investigate combinations of wheat sowing time, seed rate and herbicide treatments to control annual ryegrass. The average seedbank of annual ryegrass (ARG) at the site was 2249 ± 284 seeds/m2. There was no evidence at this site of any reduction in ryegrass infestation in wheat by delaying sowing by three weeks between TOS 1 (77plants/m2) and TOS (74plants/m2). This result suggests the Washpool ARG population likely has a high level of seed dormancy, reducing the rate of ryegrass germination after the opening rainfall events. Herbicide treatment had a significant influence on ARG plant density (P<0.001). Boxer gold and Sakura + Avadex reduced ARG plant density by 45% and 73% from the untreated control (125 ARG plants/m2). Wheat was much more competitive against ARG when it was sown early. This was made evident by the large increase in ARG seed production when seeding was delayed. When averaged across all other treatments TOS 1 produced 1634 ARG seeds/m2, which was 73% lower than 5974 ARG seeds/m2 produced in TOS 2 (P=0.013). Wheat seed rate had a significant influence on ARG seed production (P=0.005), with the high wheat seed rate supressing ARG seed production by 37% when compared to the lowest wheat seed rate (100 seeds/m2). Wheat grain yield at this site was significantly influenced by the time of sowing (P=0.001), seed rate (P=0.001), herbicide treatments (P=0.001), and the interaction between the time of sowing and herbicides (P=0.011). Wheat was much more tolerant to ryegrass competition when sown early (TOS 1) as shown by the small increase in grain yield in herbicide treated plots. In contrast, there was a significant increase in wheat grain yield in herbicide treatments in TOS 2. The results of this study clearly show that delayed sowing of wheat allows for greater seed set by ryegrass and is also associated with a large yield penalty.

Wheat plant density was significantly affected by the planting arrangement (P=0.027) and the herbicide treatment (P<0.001). The Ribbon seeder system had the highest wheat density (196 plants/m2) as compared to the knife-point system (180 plants/m2) and the Zero row spacing (177 plants/m2). Wheat plant density in the inter-row space in the Zero row spacing treatment was reduced by Treflan + Avadex and Boxer Gold. Annual ryegrass plant density was only affected by the herbicide treatments (P<0.001). Pre-emergent herbicide activity was much lower than expected (24-29% efficacy) and is likely to be due to extremely dry soil conditions at the site (decile 1 growing season). Similarly, the reduction in ryegrass spike density by the herbicides relative to the untreated control was low and ranged from 6 to 24%. There was no significant reduction in ryegrass seed production by the herbicide treatment, which was surprising because Sakura and Boxer Gold did reduce ryegrass spike density. Ryegrass was able to produce 18-20,000 seeds/m2 in different herbicide treatments, which highlights the poor efficacy of pre-emergent herbicide in dry conditions. Herbicide treatments had a significant effect on wheat grain yield with Sakura producing the highest yield (2.31 t/ha), closely followed by Boxer Gold (2.13 t/ha). Sakura and Boxer Gold treatments increased wheat grain yield by 29% and 19% compared to the untreated control, respectively.  These results show that ryegrass was quite competitive against wheat under the dry conditions experienced in 2018. The treatment of Sakura ($40/ha) increased wheat yield by 0.5 t/ha compared to the untreated control, which would have improved the gross margin by $150/ha.

Wheat plant density was significantly affected by the planting arrangement (P=0.012). The Ribbon seeder system had the highest wheat density (171 plants/m2) as compared to the knife-point system (156 plants/m2) and the Zero row spacing (151 plants/m2). The establishment of wheat plants in the inter-row space in the Zero row spacing treatment was strongly influenced by the pre-emergent herbicide treatment (P=0.002). Trifluralin, Avadex or Boxer Gold were higher risk pre-emergent herbicides for wheat establishment, whereas Sakura appears much safer where wheat seed is placed on the soil surface in the Zero row spacing system. Annual ryegrass (ARG) plant density was not significantly affected by the planting arrangement (P=0.513) or pre-emergent herbicide treatments (P=0.13). ARG spike density was not significantly influenced by wheat planting arrangement (P=0.185). Herbicide treatment did have a significant influence on ARG spike density (P=0.023) and ARG seed production (P=0.003). The best performing herbicide treatment of Sakura + Avadex still produced 16824 ARG seeds/m2. While this is 51% lower than the Treflan + Avadex, it will replenish the soil seedbank to a highly problematic level for the future. Wheat grain yield was significantly affected by the planting arrangement (P=0.034) and the herbicide treatments (P=0.004). Even though the differences in wheat yield were small <10% for planting arrangement and <14% for herbicide treatments, they were statistically significant.

The herbicide treatment had a significant effect on ARG density (P<0.001) in this field trial at Minnipa. Favourable rain events in June were highly suitable for the activity of both pre-emergent herbicides investigated in this trial. Averaged across the row spacing and SBU treatments, Boxer Gold and Sakura + Avadex reduced ARG plant density by 88% and 90%, respectively. The density of ARG spikes was significantly influenced by the herbicide treatment.  Boxer Gold reduced ARG spike density by 74% compared to the untreated control, whereas Sakura + Avadex caused 85% reduction in ARG spike density. The density of ARG spikes in Sakura + Avadex were significantly lower than in the Boxer Gold treatment. ARG seed production was also significantly affected by the herbicide treatment (P<0.001) but not by wheat row spacing (P=0.272) or seed boot design (P=0.994). ARG produced 5740 seeds/m2 in the untreated control, which was reduced by 74% by Boxer Gold and 86% by the mixture of Sakura + Avadex. Presence of ARG at 190 plants/m2 in the untreated control, reduced wheat grain yield by 11% compared to Boxer Gold or 8% compared to Sakura + Avadex. However, it was still profitable to control ARG with effective herbicide treatments. Based on cash grain price of Australian Premium Wheat (APW) of $400/t in 2018, Boxer Gold would be expected to increase the gross margin by $68/ha as compared $12/ha increase for Sakura + Avadex.

A field trial was undertaken at Mallala in 2019 to investigate combinations of wheat sowing time, seed rate and herbicide treatments to control brome grass. The average seedbank of brome grass at this site was 2877 ± 406 seeds/m2. The two week delay in sowing reduced average in-crop brome density from 567 plants/m2 to 352 plants/m2 (38%). Even though the reduction in brome density at Mallala was significant, it was a much lower reduction than that observed in the trial at Riverton (82% reduction). This difference in brome grass density with delayed sowing at these two sites highlights the large differences in seed dormancy between the populations of this weed species. Brome grass panicle density was significantly affected by wheat seed rate (P=0.039), and herbicide treatment (P<0.001) but not by the time of sowing (P=0.152). Increasing seed rate of wheat suppressed brome grass growth and reduced its panicle density. As wheat density increased from 100 seeds/m2 (low) to the highest seed rate (200 seeds/m2 – high) brome panicle density was reduced by 39%. These results support previous findings that higher crop density can be an important part of an integrated weed management program. Wheat grain yield increased consistently with the increase in seed rate or crop density. This trend correlates well with the improved suppression of brome grass panicle density observed in the trial. Not only did higher wheat density achieve superior weed suppression, it also provided a significant increase in grain yield. Herbicide treatments also had a highly significant effect on brome grass panicle density. However, there was no interaction herbicides and TOS or seed rate. This indicates that herbicides performed similarly in both times of sowing and the three seed rates. Sakura + Avadex significantly reduced panicle density as compared to Treflan + Avadex and Intercept (Clearfield technology) was used after pre-emergent Treflan + Avadex, it prevented brome plants from producing panicles (3 panicles/m2). Herbicide treatments had a large and significant effect on grain yield of wheat at Mallala (Figure 5). This is not surprising considering the high weed density present at the site and high competitive ability of brome grass. The treatment of Treflan + Avadex produced only 1.11 t/ha, which was significantly lower than the more expensive pre-emergent herbicide mixture of Sakura + Avadex (1.81 t/ha). However, when Intercept post-emergence herbicide was used, wheat yield increased further to 2.63 t/ha. In this trial, integration of Clearfield technology with pre-emergent herbicides not only prevented brome grass seed set as shown but the panicle density, it also delivered the highest grain yields.

A field trial was undertaken at Riverton in 2019 to investigate combinations of wheat sowing time, seed rate and herbicide treatments to control brome grass. The average seedbank of brome grass at the site was 1863 ± 303 seeds/m2. Brome grass at this site was effectively controlled (>80%) by delaying sowing by 2 weeks, with treatment effects from herbicide and wheat seed rate treatment only being significant in the early sown plots, where brome grass density was high. These results clearly indicate that brome grass population present at this site has very low seed dormancy and germinates readily after the season opening rains and can be effectively controlled with a knockdown herbicide. Wheat grain yield results reflected the level of brome grass control with herbicide and wheat seed rate treatments improving yields significantly as brome suppression improved. These treatments did not have a significant effect on yield when sowing was delayed because brome was effectively controlled by the knockdown herbicides. In the early sown crop when brome grass was controlled effectively with Intercept®, the 2 week delay in sowing caused a 9% reduction in wheat yield.

A field trial was undertaken at Minnipa in 2019 to investigate combinations of barley sowing time, seed rate and herbicide treatments to control annual ryegrass. The average seedbank of annual ryegrass (ARG) at the site was 4168 ± 411 seeds/m2. ARG plant density was significantly influenced by the time of sowing (P<0.001), herbicide treatment (P<0.001) and the interaction between the time of sowing and herbicide (P<0.001). There was a large impact of the 3 week delay in seeding barley on ARG plant density. This was particularly evident in the untreated control in which ARG density decreased from 676 plants/m2 in TOS 1 to 379 plants/m2 in TOS 2. This large reduction in ARG density due to delayed sowing is most likely related to rainfall events in early May, which would have caused weed emergence. Pre-emergence herbicides had higher efficacy in TOS 2 where the density of ARG plants had been reduced by the delay in seeding. This trend held through the season in the untreated control in which ARG spike density decreased from 306 spikes/m2 in TOS 1 to 199 spikes/m2 in TOS 2. In the trifluralin treatment, ARG produced 5078 seeds/m2 in TOS 2 as compared to 9192 seeds/m2 in TOS 1, a 45% reduction in ARG seed production. Unlike wheat in 2018, barley grain yield at Minnipa was not significantly influenced by the time of sowing (P=0.644). However, seed rate (P<0.001), herbicide treatment (P<0.001) and had a significant effect on barley grain yield. As stated earlier, there were large benefits of delayed sowing on weed control. In barley a three week delay did not significantly reduce grain yield as it had in the previous year in wheat. Lower yield penalty in barley from delayed sowing may be related to its earlier maturity than wheat.

Barley grain yield as significantly influenced by the time of sowing (P=0.025), seed rate (P<0.001) and the herbicide treatment (P<0.001). The delay of 4 weeks between the two sowing dates caused 22% (0.69 t/ha) reduction in grain yield or 25 kg/ha/day. Averaged over the two sowing dates and three seed rates, Boxer Gold treatment (2.996 t/ha) produced significantly greater barley grain yield than Treflan (2.634 t/ha) and the control (2.648 t/ha). Barley sown early (TOS 1) at high seed rate and sprayed with Boxer Gold produced 3.6 t/ha grain yield as compared to later sown crop (TOS 2) at low seed rate but treated with the same herbicide which produced 2.4 t/ha.

General application of Sakura + Avadex over the whole trial site provided good control of ARG. As a result, follow-up application of Boxer Gold @ 1.5 L/ha or 2 L/ha at GS 11 (1-leaf stage) did not significantly reduce ARG plant density.  Post-emergence application of Boxer Gold at 1.5 or 2 L/ha after pre-emergence Sakura + Avadex extended the period of weed control, which reduced spike density of ARG (P=0.02). At both sowing times, increase in wheat plant density from 100 to 200 plants/m2 reduced ARG spike density by 44%. Delayed sowing at this site reduced the competitive ability of wheat against ARG. Averaged across the seed rates and herbicide treatments, ARG produced 234 spikes/m2 in TOS 2 as compared to 75 spikes/m2 in TOS 1 (68% reduction in TOS 1). Additional post-emergence application of Boxer Gold significantly increased wheat grain yield (P=0.008) compared to the baseline treatment of Sakura + Avadex. Wheat yield increased by 9% or 0.4 t/ha with the additional post-emergence treatment of Boxer Gold as compared to Sakura + Avadex treatment alone. Wheat grain yield was also significantly affected by wheat seed rate (P<0.001). Wheat grain yield increased from 4.6 t/ha at the density of 100 plants/m2 to the maximum of 5.48 t/ha at the seed rate of 200 plants/m2. This yield gain of 0.9 t/ha clearly indicates that early sowing, wheat density of 200 plants/m2 and effective use of herbicides can have a large influence on the profitability of wheat in the HRZ.

Wheat grain yield at Minnipa was significantly influenced by the time of sowing (P=0.002), seed rate (P<0.001), herbicide treatment (P<0.001) and the interaction between the time of sowing and herbicide treatments (P<0.001). Averaged across the seed rates and herbicide treatments, wheat produced grain yield of 1.67 t/ha in TOS 1 as compared to 1.06 t/ha in TOS 2. There were large benefits of delayed sowing on weed control. However, these benefits came at a significant cost in wheat grain yield.

The trial site at Mallala was infested with a large seedbank of group A resistant brome grass, which made weed control in canola very difficult. Furthermore, the trial site experienced drought like conditions for most of the growing season which reduced the efficacy of atrazine. Even though the two-week delay in sowing reduced brome grass density from 927 plants/m2 in TOS 1 to 704 plants/m2 in TOS 2 (25%), this difference was not statistically significant.  However, the herbicide treatments (P=0.005) and the interaction between sowing date and herbicides (P=0.006) had a significant effect on brome grass plant density. Herbicide performance at the site was negatively affected by dry conditions and group A resistance in brome grass. As a result, even the best treatment combinations had more than 300 panicles/m2, which could lead to a large seed set in brome grass. When averaged across the sowing time, seed rate and herbicides, HyTTec Trophy produced 38% higher grain yield than Bonito. This difference in variety performance is consistent with superior crop establishment in HyTTec Trophy than Bonito. As a result of herbicide resistance in brome grass, yield increase in the Verdict treatment compared to the control (atrazine POST) was non-significant. However, use of clethodim increased yield by 61% compared to the control, which was statistically significant.

Barley plant density was significantly influenced by the time of sowing (P=0.025) and crop seed rate (P=0.002).  Averaged across the seed rates and herbicide treatments, the first time of sowing (TOS 1) had barley density of 125 plants/m2 compared to 82 plants/m2 in TOS 2, which was related to dry soil conditions after sowing in TOS 2. Brome grass plant density was significantly affected by the time of sowing (P=0.018) and the herbicide treatments (P<0.001).  The 4-week delay in sowing between TOS 1 and TOS 2, allowed greater emergence of brome grass seedlings before the sowing of the TOS 2.  Consequently, barley sown at TOS 2 had 48% lower brome grass infestation (107.9 plants/m2) than in TOS 1 (207 plants/m2). As expected, herbicide treatments had a significant (P<0.001) effect on brome grass density. When averaged across the sowing time and seed rates, the treatment of Treflan + Avadex was only moderately effective and reduced brome grass density by 36% (173 plants/m2) relative to the untreated control (271 plants/m2). In contrast, the same pre-emergent treatment (Treflan + Avadex) followed by Intervix reduced brome grass density by 90% (28 plants/m2). When averaged across seed rates and herbicide treatments, the time of sowing barley had a significant effect on its grain yield (P=0.011). TOS 1 produced 940 kg/ha greater barley grain yield than TOS 2. The post-emergence application of Intervix to the crop treated with Treflan + Avadex further increased barley grain yield by 872 kg/ha. These results are consistent with the trends in brome grass density and panicle production. The untreated control plots produced 40% lower grain yield than the Intervix treatment, which completely controlled brome grass. These results highlight the strong competitive ability of brome grass in cereals.

The average seedbank of ARG at the site was 3932 ± 270 seeds/m2. ARG plant density was significantly influenced by the time of sowing (P<0.001), herbicide treatment (P<0.001) and the interaction between the time of sowing and herbicide (P<0.001). The delay in seeding from TOS 1 to TOS 2 (16 weeks) caused a large reduction in ARG plant density. This was particularly evident in the untreated control in which ARG density decreased from 825 plants/m2 in TOS 1 to 31 plants/m2 in TOS 2 (96% reduction). This large reduction in ARG density due to delayed sowing is most likely related to an effective knockdown herbicide treatment after most ARG had emerged before TOS 2. Herbicide treatments reduced ARG plant density significantly in TOS 1, however herbicide effect on ARG plant density in TOS 2 was non-significant, possibly due to a much lower ARG density. While the delay in sowing significantly reduced ARG plant density (P<0.001), it did not significantly reduce ARG seed spikes (P=0.495). This result indicates that despite low ARG plant numbers in TOS 2, faba beans failed to compete effectively with ARG and suppress its growth. As a result, even at a relatively low density ARG was able to produce a large amount of seed for future infestations. Faba bean grain yield at Frances was significantly influenced by the time of sowing (P=0.033), seed rate (P<0.003), and herbicide treatment (P<0.001). Averaged across the seed rates and herbicide treatments, faba beans produced grain yield of 1.34 t/ha in TOS 1 as compared to 1.81 t/ha in TOS 2. Superior faba bean grain yield in TOS 2 In 2018 at Frances is most likely due to the reduction in ARG plant density.

A field trial was undertaken at Frances in 2019 to investigate combinations of barley sowing time, seed rate and herbicide treatments to control annual ryegrass. The average seedbank of annual ryegrass (ARG) at the site was quite low (472 ± 143 seeds/m2), which was reflected in low plant density at the site. ARG plant density was significantly influenced by the time of sowing (P=0.037), and herbicide treatment (P=0.009). There was a 37% reduction in ARG plant density between TOS 1 (20 plants/m2) and TOS 2 (13 plants/m2). Herbicide treatment had a significant effect on ARG plant density, with Boxer Gold showing lower efficacy on ARG than Treflan and Boxer Gold + Treflan. Unlike ARG plant density, ARG spike density was not influenced by time of sowing (P=0.171). ARG spike density was significantly influenced by barley seed rate (P=0.016), herbicide treatment (P=0.01) and the interaction between TOS and herbicide treatment (P=0.019). ARG spike density was 34% and 40% lower in medium and high seed rates respectively when compared to the low seed rate. These results suggest an improvement in ARG suppression from increasing barley competiveness with increased seed rate. Barley grain yield at the site averaged 6.6 t/ha. Herbicide treatment had a small (4-6%), but significant effect (P=0.009) on grain yield with Boxer Gold < Treflan ≤ Boxer Gold + Treflan for barley yield.

Herbicide strategy 1 (HS1), which was based on atrazine pre-sowing followed by clethodim (Select) post-emergence reduced ryegrass plant density relative to the untreated control by 57%. However, use of propyzamide pre-sowing, followed by atrazine and Select + Factor (HS 2) increased ryegrass control to 77%. Canola variety had a significant effect on ryegrass spike density (P=0.002). When averaged across the sowing dates and herbicide strategies, ryegrass growing in HyTTec Trophy produced 52 spikes/m2 as compared to 78 spikes/m2 in Bonito (33% reduction). HyTTec Trophy is a new hybrid triazine tolerant variety from Nuseed, which is known for high early vigour. Herbicide strategies also had a significant effect on ryegrass spike density (P<0.001). Ryegrass grown without any selective herbicide treatment (control – HS3) produced 128 spikes/m2 as compared to 40 spikes/m2 in HS1 and 29 spikes/m2 in HS2. This works out to 69% reduction in HS1 relative to the control and 78% reduction in HS2. Herbicide strategies had the largest effect on canola yield (P<0.001). HS1 and 2 produced canola yield of around 0.8 t/ha, which was almost 50% greater than the yield obtained in the control.

The herbicide treatment had a significant effect on annual ryegrass (ARG) plant density (P<0.001) in this field trial at Minnipa. Favourable rain events in May were highly suitable for the activity of both pre-emergent herbicides investigated in this trial. Averaged across the row spacing and seed boot treatments, Trifluralin and Boxer Gold reduced ARG plant density by 20% and 90%, respectively. The density of ARG spikes was significantly influenced by the row spacing (P<0.001), seed boot treatment (P=0.027), and the herbicide treatment (P<0.001). The 25cm row spacing had 20% lower ARG spike density than the 37.5cm row spacing treatment. The splitter seed boot treatment had 12% lower ARG spike density than the narrow seed boot treatment. Trifluralin only reduced ARG spike density by 20% compared to the untreated control, whereas Boxer Gold caused a 73% reduction in ARG spike density. ARG seed production was also significantly affected by the row spacing (P=0.003), seed boot (P=0.01), and the herbicide treatment (P<0.001). The normal (25 cm) row spacing set 38% less seed than the wide row spacing. The splitter seed boot treatment also had 32% lower ARG seed set compared to the narrow seed boot. ARG produced 4792 seeds/m2 in the untreated control, which was reduced by 11% by Trifluralin and 69% by Boxer Gold. Presence of ARG at 262 plants/m2 in the untreated control, reduced barley grain yield by 8% compared to Trifluralin or 16% compared to Boxer Gold. However, it was still profitable to control ARG with effective herbicide treatments. Based on cash grain price of Feed Barley of $250/t in 2019, Trifluralin would be expected to increase the gross margin by $32/ha as compared $71/ha increase for Boxer Gold.