Broadleaf weed management in lentil grown on different soil types in South Australia
Broadleaf weed management in lentil grown on different soil types in South Australia
Author: Navneet Aggarwal, Amanda Cook, Amy Keeley (South Australian Research and Development Institute, SARDI, University of Adelaide), Brianna Guidera (SARDI), Penny Roberts (SARDI, University of Adelaide, Mallee Sustainable Farming) | Date: 17 Jul 2024
Take home messages
- Reflex® applied alone incorporated by sowing (IBS), or in combination with metribuzin, showed higher stunting in GIA Metro compared to the IMI tolerant varieties PBA Highland XT and GIA Thunder, though the severity of herbicide damage was dependent on soil type, with alkaline sandy loam to clayey sand soils recording increased plant height reduction than near neutral loam/clay soils.
- Seasonal variation, including higher rainfall post-seeding, may have been a contributing factor in higher levels of crop damage at Hart in 2023.
- Reflex® provided control of wards weed, common sowthistle, wild turnip and Indian hedge mustard, however, it was ineffective for controlling medic. Including Group 5 herbicides applied as post-sowing pre-emergent (PSPE), and Group 2 and 12 herbicides as post-emergence at 5-6 crop-node stage (POST) improved broadleaf weed control compared to IBS herbicides only.
- Metribuzin applied POST in GIA Metro gave more flexibility and improved medic control compared to its post-sowing pre-emergent application.
- Sub-label rates of Group 5 herbicides were not as effective as the label rates for controlling broadleaf weeds. Furthermore, previous studies have found recurrent selection with exposure to reduced herbicides rates results in rapid evolution of herbicide resistance in weeds.
- GIA Metro was lower yielding compared to PBA Highland XT and GIA Thunder, where weeds were effectively controlled. However, this yield gap was reduced in the situations of unsatisfactory weed control in IMI lentils.
Why do the trial
With their potential for impressive economic returns, some pulse crops are becoming increasingly popular among South Australian (SA) growers. As a break crop, pulses can contribute to soil health through nitrogen fixation and can help to reduce the impact of carryover cereal diseases.
The adoption of new herbicide tolerant pulse crops, such as Group 2 Imidazolinone (IMI) tolerant lentil and faba bean, has helped growers to control broadleaf weeds more effectively in the pulse phase of their crop rotation. However, the availability of multiple IMI-tolerant varieties across cereals, pulses and canola has helped to create over-reliance on herbicides with this mode of action (MOA). This, in turn, has increased the prevalence and risk of IMI herbicide-resistant weeds developing. Accordingly, relying on IMI herbicides alone is not an effective long-term strategy for broadleaf weed management in pulses.
Growers in some SA regions, particularly the Yorke Peninsula and Eyre Peninsula, are expanding lentils into more acidic or highly alkaline sandy soils. The research work carried out in these regions (SAGIT TC121 and GRDC UOA2105-013RTX) highlighted that lentil crop safety from herbicide damage and effective weed control can be an even greater challenge on such soil types (Bruce et al. 2022). This research work was extended into highly alkaline soils at Tooligie, Kimba, Minnipa and Mudamuckla in the 2023 season to develop improved strategies for better weed control and herbicide resistance management of broadleaf weeds in lentil grown on the Upper Eyre Peninsula, (UOA2303-007RTX and UOA2105-013RTX). Additionally, a trial was established at Hart to represent lentil growing areas of the Mid-North region.
How it was done
The site details including soil type, varieties grown, and sowing and harvest dates of three research experiments are summarised in Tables 1 and 2. A pre-seeding spray of glyphosate (600 g ai/L) at 1200 mL/ha and Hammer® (carfentrazone 400 gai/L) at 30 mL/ha was applied to control existing weeds in the field. Lentil was sown at a depth of 4–5cm with a target plant density of 120 plants/m2 by using a no-till plot seeder fitted with knife-point tines and press wheels. Plots were 10m long and contained six crop rows spaced 22.5cm apart. Fertiliser rate was consistent with the local grower practice of 80kg/ha of monoammonium phosphate banded below the seed at sowing. The experiments were laid out in a randomised complete-block design with three replications. The solubility and adsorption coefficient values of the herbicides used as incorporated by sowing (IBS) or post-sowing pre-emergent (PSPE) in the study are summarised in Table 3. All herbicide rates used in the experiments are mentioned in terms of the commercial product (Tables 4–11). Not all herbicides used at these sites are registered for all the target weeds and were assessed for experimental purposes only, therefore, always read and follow product labels. Broadleaf weed pod/seed set was assessed near crop harvest from three randomly selected spots within a plot using a 50cm × 50cm quadrant. The statistical analysis was done with ANOVA, GENSTAT version 23.
Table 1: The range of soil pH (in H2O), organic carbon (OC) per cent and soil texture of the four Eyre-Peninsula (EP) and one Mid-North (MN) trial sites in 2023.
Location | pH H2O | OC % | Soil texture | |||
---|---|---|---|---|---|---|
0–10cm | 10–20cm | 0–10cm | 10–20cm | 0–10cm | 10–20cm | |
Minnipa (EP) | 8.8 | 8.9 | 0.98 | 0.70 | Sandy clay loam | Sandy clay loam |
Mudamuckla (EP) | 8.8 | 8.9 | 0.96 | 0.93 | Sandy loam | Clayey sand |
Kimba (EP) | 7.7 | 9.5* | 0.65 | 0.24* | Loam/clay | Clay |
Tooligie (EP) | 8.7 | 9.0* | 1.49 | 0.85* | Sandy clay loam | Sandy clay loam |
Hart (MN) | 8.3 | 8.5 | 1.77 | 1.00 | Clay loam | Clay loam |
*sample represented 10–30cm soil depth
Table 2: Target weed species, lentil variety, and sowing and harvest dates of the trial sites in 2023.
Location | Target weed species | Variety | Sowing date | Harvest date |
---|---|---|---|---|
Minnipa (EP) | Medics | GIA MetroP and PBA Highland XTP | 28 April 2023 | 16 October, 2023 |
Mudamuckla (EP) | Medics and wards weed | GIA MetroP and PBA Highland XTP | 27 April, 2023 | 30 October, 2023 |
Kimba (EP) | Common sowthistle and brassica weeds | GIA MetroP and GIA ThunderP | 10 May, 2023 | 2 November, 2023 |
Tooligie (EP) | Common sowthistle and brassica weeds | GIA MetroP and PBA Highland XTP | 23 May, 2023 | 23 November, 2023 |
Hart (MN) | Wild radish, common sowthistle and vetch | GIA MetroP and GIA ThunderP | 1 June, 2023 | 15 November, 2023 |
Table 3: Solubility and adsorption coefficient values of herbicides used in five trial sites in 2023.
Herbicide (Group) | Application timing in the experiments | Active ingredient | Solubility (mg/L @ 20°C) | Adsorption coefficient, Koc value | ||
---|---|---|---|---|---|---|
Diuron (5) | IBS*/PSPE** | 900g/kg diuron | 36 | Low solubility | 813 | Slightly mobile |
Metribuzin (5) | IBS/PSPE | 750g/kg metribuzin | 1165 | High solubility | 60 | Mobile |
Reflex® (14) | IBS | 240g/L fomesafen | 50 | Moderate solubility | 228 | Moderately mobile |
Terbyne Xtreme® (5) | IBS | 875g/kg terbuthylazine | 7 | Low solubility | 230 | Moderately mobile |
Terrain® (14) | IBS | 500g/kg flumioxazin | 0.8 | Low solubility | 889 | Slightly mobile |
*IBS: Incorporated by sowing, **PSPE: Post-sowing pre-emergence
Source: GRDC pre-emergents herbicide fact sheet.
Rainfall conditions
All the five experimental sites received lower than average growing season rainfall (GSR) (Figure 1). Minnipa site received 83% of the average GSR, while the corresponding values for Mudamuckla, Kimba, Tooligie and Hart were 50%, 56%, 40% and 76%, respectively. No substantial rainfall event occurred within the first two weeks after seeding at any of the Eyre Peninsula trial sites that could carry the risk of washing of pre-emergent herbicides applied either IBS or PSPE onto the crop rows. However, Hart (MN) trial site received 31mm rainfall within two weeks of sowing.
Figure 1. Average rainfall totals (mm) including long term average GSR, actual 2023 GSR, and rainfall two weeks post-sowing for five sites on the Upper Eyre Peninsula and Mid-North in 2023.
What happened
Crop safety
Crop damage in lentil was assessed using plant emergence counts, and visual assessments for chlorosis, necrosis and stunting. The level of crop damage in lentil from the use of Group 14 herbicides, Reflex® and Terrain®, and Group 5 herbicides, diuron and metribuzin varied across the different sites and is summarised below.
Plant establishment
There was no reduction in plant establishment observed from the application of any herbicide treatment compared with the untreated control at all the five experimental sites in 2023 (Tables 4, 6, 8, 9 and 11). Metribuzin applied as PSPE at 380g/ha in GIA MetroP proved safe, and the plant establishment. was similar to industry practices of using sub-label rates of Group 5 metribuzin at 120g/ha, Terbyne Xtreme at 430 g/ha and diuron at 200g/ha as IBS in IMI tolerant lentils. The only exception was at Hart, where emergence of GIA ThunderP sprayed with Reflex® 750mL/ha (IBS) followed by diuron 550g/ha (PSPE) was significantly reduced as compared to GIA MetroP sprayed with Reflex® 750mL/ha (IBS) followed by metribuzin 380g/ha (PSPE). Rainfall of 31mm received at this trial site within two weeks of sowing might have washed pre-emergent herbicides closer to the germinating seeds, resulting in lesser establishment of GIA ThunderP, whereas GIA MetroP escaped from this herbicide damage due to having metribuzin tolerance. Reduced emergence of IMI tolerant lentils sprayed with Reflex® (IBS) followed by diuron/metribuzin (PSPE) was also recorded at three trial sites in Yorke Peninsula in 2021 and 2022 that received 39mm, 52mm and 53mm of rainfall in the first two weeks after sowing (Bruce et al. 2022).
Reduction in plant biomass (stunting)
Plant stunting is recognised as a symptom of crop phytotoxicity from the application of Group 14 herbicides. Plant stunting visual scores at 12 weeks post-sowing were generally higher in GIA Metro than PBA Highland XT in the Reflex® and Reflex® + metribuzin treatments (Tables 4 and 6). These visual stunting symptoms in GIA Metro were present at the more alkaline sites of Minnipa and Mudamuckla within the first 12 weeks post-seeding, however, plant height measurements at 16 weeks post-seeding showed no reduction in plant height between the treated and untreated plots of GIA Metro, suggesting a level of plant recovery had occurred. Minnipa and Mudamuckla sites received 43mm and 28mm of rainfall, respectively, distributed over more than 20 days during a six-week period prior to the plant height measurements carried out in mid to late August. The resultant favourable growing conditions after this rainfall is thought to be responsible for plant recovery from the herbicide. At the Kimba site, with near-neutral soil pH, plant height measurements indicated no difference between treated and untreated plots of both GIA Metro and GIA Thunder. These results are consistent with previous findings of Bruce et al. (2022), where lentils grown on alkaline sandy soils recorded higher stunting from Group 14 herbicides compared to medium textured soils with near-neutral soil pH. Further, Reflex® (IBS) f.b. metribuzin (PSPE) recorded higher stunting in GIA Metro compared to GIA Thunder at the Hart trial site. The higher stunting recorded in GIA Metro at the Hart trial site compared to Kimba, though both sites had similar soil types, might be due to 31mm of rainfall received at Hart within the first two weeks after sowing that increased the risk of pre-emergent herbicides washing into the crop rows, against only 2mm of rainfall at Kimba in the same period (Figure 1).
Chlorosis and necrosis
Metribuzin applied post-sowing pre-emergent (PSPE) or post-emergent at 5–6 crop node stage (POST) did not cause chlorosis or necrosis in GIA Metro at 180 and 380g/ha (Tables 4 and 6). Furthermore, industry practice including a combination of Reflex® and metribuzin applied at the sub-label rate of 120g/ha (IBS) caused higher levels of chlorosis in PBA Highland XT compared to GIA Metro sprayed at highest label rate of 380g/ha. Reflex® at 500mL/ha (IBS) followed by Brodal® at 150mL/ha at 3–4 node growth stage in PBA Highland XT caused a higher level of chlorosis and necrosis than Reflex® at 500mL/ha (IBS) followed by Intercept® at 500mL/ha (POST) in PBA Highland XT, and Reflex® at 500mL/ha (IBS) followed by metribuzin at 380g/ha (POST) in GIA MetroP (Table 4).
Grain yield
The average lentil yields were low at Hart (average 1.57t/ha), very low at Tooligie (average 1.09t/ha), Minnipa (average 0.35t/ha) and Mudamuclka (average 0.17t/ha), but yields were high at Kimba (2.02t/ha) in 2023. Highly alkaline soils at Minnipa, Tooligie and Mudamuckla (Table 3), coupled with below average growing season rainfall (Figure 1), contributed to low yields. Overall, the yields of the GIA Metro averaged 19–72% lower in untreated plots than the best herbicide strategy. Similarly, PBA Highland XT and GIA Thunder yielded up to 35% and 15% lesser yields, respectively, in untreated plots than the best herbicide strategy in these varieties.
Reflex® at 500mL/ha (IBS) followed by Intercept® at 500mL/ha (POST) recorded the highest yield of PBA Highland XT at Minnipa (Table 5). It was 25% higher than GIA Metro sprayed with Reflex® at 500mL/ha (IBS) followed by metribuzin 380g/ha (POST), though both the treatments recorded similar level of weed control. NVT evaluation of GIA MetroP in SA, Victoria, Western Australia and New South Wales in 2021 and 2022 suggested it is 20 to 30% lower yielding than PBA Hurricane XT where weeds are controlled effectively and in the absence of herbicide damage (GIA Metro Fact sheet). However, there was no yield gap between two varieties in the absence of effective weed control in PBA Highland XT when relied either on Reflex® (IBS) alone, industry practices of Group 5 herbicides at sub-label rates applied alone as IBS or their combinations with Reflex®.
Further, GIA Thunder recorded up to 28% higher grain yield in the plots treated with Reflex® at 750mL/ha (IBS) followed by diuron 550g/ha (PSPE) followed by Intercept® at 750mL/ha (POST) compared to GIA MetroP sprayed with Reflex® at 750mL/ha (IBS) followed by metribuzin at 380g/ha (PSPE) at Kimba, though both the herbicide strategies recorded similar level of weed control (Table 8). However, this yield gap between two varieties was reduced up to 16% in the absence of effective weed control in GIA ThunderP while relying on Reflex® 500–750mL/ha (IBS) only. Similarly, GIA Thunder recorded up to 26% higher grain yield in the plots treated with Reflex® at 750mL/ha (IBS) followed by diuron 550g/ha (PSPE) followed by Intercept® at 750mL/ha (POST) compared to GIA Metro sprayed with metribuzin at 380g/ha (POST) at Hart, though both the herbicide strategies recorded similar level of weed control (Table 11).
Broadleaf weed control
Medics were the dominant broadleaf weed species at the Minnipa and Mudamuckla experimental sites. The Mudamuckla site also had additional background population of wards weed. Common sowthistle, and brassica weeds, including Indian hedge mustard and wild turnip, were the dominant broadleaf weed species at the Kimba site, and Tooligie had common sowthistle and Indian hedge mustard at the trial site. The seeds of wild radish susceptible to commonly used herbicides acquired from Plant Science Consulting, and cultivated vetch seeds (simulated tares) were broadcast in each plot before pre-emergent treatment application at Hart trial site.
The dose and timing of metribuzin application had a significant impact on its efficacy on medics. Metribuzin applied at 180g/ha either as PSPE or POST did not improve medic control compared to the unsprayed control in GIA Metro (Table 7). Further, metribuzin applied at 380g/ha (POST) was more effective in reducing medic pod set (28 pods/m2 compared to 225 pods/m2) when applied at the PSPE timing at Minnipa (Table 5). Similarly, POST application of metribuzin at 380g/ha (POST) reduced medic pod set by 92% compared to the PSPE application at Mudamuckla.
Group 14 herbicides Reflex® and Terrain applied IBS alone did not provide control of medics (Tables 5 and 7). A follow up application of metribuzin (POST) in GIA Metro, and Intercept® (POST) in PBA Highland XT was needed after Reflex® IBS to achieve some level of control of medic (7–27 pods/m2 at Minnipa, 5–9 pods/m2 at Mudamuckla). Off-label industry practices of using sub-lethal rates of Group 5 herbicides metribuzin (120g/ha), diuron (200g/ha), Terbyne Xtreme® (430 g/ha) IBS proved ineffective for medic control. Previous studies have revealed that recurrent selection with exposure to reduced rates of herbicides resulted in rapid evolution of herbicide resistance in some weeds and should be avoided (Neve and Powles 2005, Gressel 2011).
Reflex® (IBS) at 500–750mL/ha reduced plant numbers of wards weed to 1.5–2.5 plants/m2 compared to 27.5 plants/m2 in the unsprayed control plots (Table 7). A follow up application of metribuzin (POST) in GIA Metro, and Intercept® (POST) in PBA Highland XT provided control of wards weed plants that survived in intra-row spaces. Metribuzin on its own applied at both 180g/ha and 380g/ha, either PSPE or POST, proved effective for wards weeds control. Terrain did not prove effective for wards weed control (17.2 plants/m2).
Common sowthistle control improved with increased rates of Reflex® from 500ml/ha (17 pods/m2) to 1000mL/ha (2.7 pods/m2) as compared to unsprayed controls (130 pods/m2) at Kimba (Table 8). However, Reflex® at 500ml/ha, 750mL/ha and 1000mL/ha proved equally effective in controlling common sowthistle at Tooligie trial site (<7 pods/m2) that had lesser background population of this weed (79 pods/m2 in unsprayed control) (Table 10). Most of the surviving plants of common sowthistle in Reflex®-treated plots were found in the intra-row spaces, from where the applied herbicide was likely moved out by the seeding operation. Where Reflex® was applied IBS and followed by Group 5 herbicides metribuzin applied as PSPE/ POST, or diuron PSPE, the surviving weeds in the intra-row area were mostly controlled. Further, metribuzin at 380g/ha applied POST proved more effective in reducing common sowthistle pod set (0.3 pods/m2) compared to its PSPE application (27.6 pods/m2) (Table 8).
Reflex® applied IBS alone or in combinations with Group 5 herbicide metribuzin/diuron PSPE, plus a follow-up application of Group 2 herbicide Intercept® or Group 12 herbicide Brodal® post-emergent provided effective control of brassica weeds, such as Indian hedge mustard and wild turnip (<1 pod/m2), compared to unsprayed control plots (Tables 8 and 10).
What does this mean
Group 2 IMI herbicides will continue to be a valuable tool for broadleaf weed control in lentil for weeds that have not evolved resistance to this mode of action. The Group 14 herbicide Reflex® applied in combination with other registered Group 2, 5 and 12 herbicides has increased the options for broadleaf weed control in lentil. However, consideration should be given to the associated risks of crop damage when applied alone or with Group 5 herbicides, depending on the soil type and herbicide rates. Furthermore, results in these experiments showed the limitations of weed control with IBS applications of various chemistries compared to PSPE or POST applications where available.
New dual metribuzin and IMI tolerant lentil, GIA Metro, has provided new opportunities to control multiple broadleaf weeds, including improved medic control in lentil. Increased adoption of this variety will potentially help to reduce selection pressure and delay resistance build up to the IMI herbicides. Grain yield of GIA Metro is substantially lower than existing lentil varieties in the absence of weeds, or where weeds are controlled effectively without crop damage from Group 5 herbicides due to a fitness penalty associated with the metribuzin tolerance. GIA Metro is an option for lentil growers where weed competition and/or current herbicide options (for example, IMI-resistant broadleaf weeds) prohibit economical and sustainable lentil production. The strategic use of GIA Metro in some cropping rotations may assist in improved weed control in lentil and reduced weed seed bank burdens of Group 2 resistant weeds, allowing for a return to other lentil varieties in subsequent seasons. Growers must refer to the new permit for metribuzin use in GIA Metro in varying soil and weather conditions, as granted by the Australian Pesticides and Veterinary Medicines Authority (PER92810).
More research work is needed to understand the safest and most efficient way of controlling weeds in lentil in low rainfall areas, including the effective and judicious use of GIA Metro. More studies in low rainfall areas, with the growers’ preferences of not spending much, are required. Whether metribuzin POST could be a cost-effective strategy compared to other strategies with IBS and PSPE herbicides, needs further investigation. It will enable growers to make more informed and confident decisions about adopting these new tools for managing broadleaf weeds in lentil, especially in the regions where they have not been grown in the past.
Acknowledgements
The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, the authors would like to thank them for their continued support. The authors also thank the Hart Field site group, Long family at Tooligie, Cliff family at Kimba and Peter Kuhlmann at Mudamuckla. The help received from David Holmes at SARDI Port Lincoln, and the technical team members at SARDI Clare and Minnipa in the field is greatly appreciated. The authors also thank consultants and agronomists from the Eyre Peninsula region in conducting this research work.
References
Bruce J, Aggarwal N, Sherriff S, Trengove S, Roberts P (2022) Broadleaf weed control and crop safety in lentils. Eyre Peninsula Farming Systems summary 2022, pp 132-40.
GRDC pre-emergent herbicides fact sheet
GRDC UOA2105-013RTX. Development and extension to close the economic yield gap and maximise farming systems benefits from grain legume production in South Australia.
GRDC UOA2303-007RTX. NGN-Lentil check discussion groups to maximise profitability of lentil production in the Upper Eyre Peninsula.
Gressel J (2011) Low pesticide rates may hasten the evolution of resistance by increasing mutation frequencies. Pest Management Science 67(3), 253-257.
Neve P, Powles S (2005) Recurrent selection with reduced herbicide rates results in the rapid evolution of herbicide resistance in Lolium rigidum. Theoretical and Applied Genetics 110, 1154–1166.
SAGIT TC121. Improving crop safety and broadleaf weed control with herbicides in lentil.
Contact details
Navneet Aggarwal
Navneet.aggarwal@sa.gov.au
SARDI Clare Research Centre
70 Farrell Flat Road,
Clare-5453, SA.
Reference Tables
Table 4: Measures of crop phytotoxicity in two varieties of lentil to various herbicides and herbicide mixtures on alkaline sandy clay loam soils at Minnipa in 2023. Plant chlorosis score (1 = no chlorosis, 9 = plant death), necrosis score (1 = no necrosis, 9 = plant death), stunting score (1 = no stunting, 9 = plant death). Data labelled with the same letters within a column are not significantly different (P=<0.05).
Variety | Herbicide treatment (dose in terms of commercial product) | Emergence (plants/m2) | Chlorosis | Necrosis | Stunting | Plant height (cm) 16 WAS | |
---|---|---|---|---|---|---|---|
12 WAS** | |||||||
1 | GIA Metro | Metribuzin 380g/ha (POST)*** | 115 a | 1.0 b | 1.2 de | 1.5 cde | 13.4 c |
2 | Metribuzin 380g/ha (PSPE) | 105 a | 1.0 b | 1.0 e | 1.2 de | 13.5 c | |
3 | Reflex® 500mL/ha (IBS) | 107 a | 1.3 b | 1.5 bcd | 3.0 a | 13.0 c | |
4 | Reflex® 500mL/ha (IBS) f.b. Intercept® 500mL/ha (POST) | 99 a | 1.3 b | 1.3 cde | 2.8 a | 13.1 c | |
5 | Reflex® 500mL/ha (IBS) f.b. metribuzin 380g/ha (POST) | 99 a | 1.3 b | 1.7 bc | 2.7 ab | 12.9 c | |
6 | Reflex® 500mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) | 97 a | 1.3 b | 1.8 b | 3.3 a | 12.9 c | |
7 | Unsprayed control | 108 a | 1.0 cb | 1.0 e | 1.0 e | 13.8 bc | |
8 | PBA Highland XT | Reflex® 500mL/ha (IBS) | 117 a | 1.2 b | 1.2 de | 1.8 cd | 18.5 a |
9 | Reflex® 750mL/ha (IBS) | 90 a | 1.3 b | 1.5 bcd | 2.0 bc | 18.7 a | |
10 | Reflex® 500mL/ha (IBS) f.b. Brodal® 150mL/ha at 3–4 crop node stage | 110 a | 2.0 a | 3.5 a | 2.8 a | 15.4 b | |
11 | Reflex® 500mL/ha (IBS) f.b. Intercept® 500mL/ha (POST) | 80 a | 1.2 b | 1.3 cde | 2.0 bc | 18.5 a | |
12 | Reflex® 500mL/ha (IBS) + diuron 200g/ha (IBS)* | 97 a | 1.2 b | 1.5 bcd | 1.5 cde | 18.5 a | |
13 | Reflex® 500mL/ha (IBS) + diuron 200g/ha (IBS)* f.b. Intercept® 500mL/ha (POST) | 96 a | 1.2 b | 1.3 cde | 1.8 cd | 18.7 a | |
14 | Reflex® 500mL/ha (IBS) + metribuzin 120g/ha (IBS)* | 93 a | 1.8 b | 1.5 bcd | 2.0 bc | 17.1 a | |
15 | Terbyne Xtreme® 430g/ha (IBS)* | 97 a | 1.0 b | 1.2 de | 1.3 cde | 18.3 a | |
16 | Unsprayed control | 103 a | 1.0 b | 1.0 e | 1.3 cde | 18.3 a |
*Sub-label rate (industry practice), **Weeks after sowing
IBS: Incorporated by sowing, PSPE: Post-sowing pre-emergence, POST: Post-emergent at 5–6 crop node stage, f.b.: Followed by
***Metribuzin (POST) permitted only in GIA MetroP as per the permit PER92810 expiring on 31-12-2025.
Table 5: Efficacy of various herbicides and herbicide mixtures on medic density and pod set, and the associated grain yield of two lentil varieties on alkaline sandy clay loam soils at Minnipa in 2023. Data labelled with the same letters within a column are not significantly different (P=<0.05).
Variety | Herbicide treatment (dose in terms of commercial product) | Seed bearing medics/m2 | Medic pods/m2 | Yield (kg/ha) | |
---|---|---|---|---|---|
1 | GIA Metro | Metribuzin 380g/ha (POST)** | 6.3 efg | 28 d | 349 cde |
2 | Metribuzin 380g/ha (PSPE) | 31.4 ab | 225 bc | 286 def | |
3 | Reflex® 500mL/ha (IBS) | 13.7 cdef | 182 bc | 254 ef | |
4 | Reflex® 500mL/ha (IBS) f.b. Intercept® 500mL/ha (POST) | 4.4 gh | 26 d | 290 cdef | |
5 | Reflex® 500mL/ha (IBS) f.b. metribuzin 380g/ha (POST) | 0.8 hi | 7 de | 364 cde | |
6 | Reflex® 500mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) | 16.0 bcde | 125 c | 288 cdef | |
7 | Unsprayed control | 49.0 a | 433 a | 209 f | |
8 | PBA Highland XT | Reflex® 500mL/ha (IBS) | 22.1 bc | 188 bc | 367 cde |
9 | Reflex® 750mL/ha (IBS) | 18.5 bcd | 154 c | 369 bcde | |
10 | Reflex® 500mL/ha (IBS) f.b. Brodal® 150mL/ha at 3–4 crop node stage | 6.3 efg | 29 d | 357 cde | |
11 | Reflex® 500mL/ha (IBS) f.b. Intercept® 500mL/ha (POST) | 5.8 efgh | 27 d | 486 ab | |
12 | Reflex® 500mL/ha (IBS) + diuron 200g/ha (IBS)* | 25.0 bc | 196 bc | 394 abcd | |
13 | Reflex® 500mL/ha (IBS) + diuron 200g/ha (IBS)* f.b. Intercept® 500mL/ha (POST) | 5.3 fgh | 34 d | 496 a | |
14 | Reflex® 500mL/ha (IBS) + metribuzin 120g/ha (IBS)* | 9.0 defg | 139 c | 405 abc | |
15 | Terbyne Xtreme® 430g/ha (IBS)* | 25.0 bc | 161 c | 385 abcd | |
16 | Unsprayed control | 49.0 a | 296 ab | 315 cdef |
* Sub-label rate (industry practice)
IBS: Incorporated by sowing, PSPE: Post-sowing pre-emergence, POST: Post-emergent at 5–6 crop node stage, f.b.: Followed by
**Metribuzin (POST) permitted only in GIA MetroP as per the permit PER92810 expiring on 31-12-2025.
Table 6: Measures of crop phytotoxicity in two varieties of lentil to various herbicides and herbicide mixtures on alkaline sandy loam (0–10 cm) to clayey sand (10–20 cm) soil at Mudamuckla 2023. Plant chlorosis score (1 = no chlorosis, 9 = plant death), necrosis score (1 = no necrosis, 9 = plant death), stunting score (1 = no stunting, 9 = plant death). Data labelled with the same letters within a column are not significantly different (P=<0.05).
Variety | Herbicide treatment (dose in terms of commercial product) | Emergence (plants/m2) | Chlorosis on 20/7/23 | Necrosis | Stunting | Plant height 16 WAS* | |
---|---|---|---|---|---|---|---|
12 WAS** | |||||||
1 | GIA Metro | Metribuzin 180g/ha (POST)*** | 106 a | 1.0 d | 1.0 a | 1.3 b | 17.5 b |
2 | Metribuzin 180g/ha (PSPE) | 118 a | 1.0 d | 1.0 a | 1.3 b | 16.9 bc | |
3 | Metribuzin 380g/ha (POST) | 119 a | 1.2 cd | 1.0 a | 1.0 b | 17.2 bc | |
4 | Metribuzin 380g/ha (PSPE) | 113 a | 1.0 d | 1.0 a | 1.2 b | 17.9 b | |
5 | Reflex® 500mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) | 121 a | 1.0 d | 1.0 a | 2.3 a | 15.3 c | |
6 | Reflex® 500mL/ha (IBS) f.b. metribuzin 380g/ha (POST) | 121 a | 1.0 d | 1.0 a | 2.0 a | 16.1 bc | |
7 | Unsprayed control | 126 a | 1.0 d | 1.0 a | 1.2 b | 16.1 bc | |
8 | PBA Highland XT | Reflex® 500mL/ha (IBS) | 121 a | 1.2 cd | 1.0 a | 1.0 b | 24.1 a |
9 | Reflex® 750mL/ha (IBS) | 119 a | 1.3 bcd | 1.0 a | 1.2 b | 24.1 a | |
10 | Reflex® 500mL/ha (IBS) f.b. Intercept® 500mL/ha (POST) | 100 a | 1.5 abc | 1.2 a | 1.0 b | 24.9 a | |
11 | Terrain® 120g/ha (IBS) | 104 a | 1.8 a | 1.3 a | 1.0 b | 24.9 a | |
12 | Reflex® 500mL/ha (IBS) + metribuzin 120g/ha (IBS)* | 100 a | 1.7 ab | 1.2 a | 1.0 b | 24.0 a | |
13 | Reflex® 500mL/ha (IBS) + diuron 200g/ha (IBS)* | 112 a | 1.2 cd | 1.0 a | 1.2 b | 25.3 a | |
14 | Reflex® 500mL/ha (IBS) + diuron 200g/ha (IBS)* f.b. Intercept® 500mL/ha (POST) | 124 a | 1.0 d | 1.0 a | 1.0 b | 25.7 a | |
15 | Brodal® 80mL/ha (IBS)* + diuron 200g/ha (IBS)* f.b. Intercept® 500mL/ha (POST) | 105 a | 1.7 ab | 1.0 a | 1.0 b | 24.9 a | |
16 | Unsprayed control | 118 a | 1.3 bcd | 1.0 a | 1.0 b | 24.5 a |
* Sub-label rate (industry practice), **Weeks after sowing
IBS: Incorporated by sowing, PSPE: Post-sowing pre-emergence, POST: Post-emergent at 5–6 crop node stage, f.b.: Followed by
***Metribuzin (POST) permitted only in GIA MetroP as per the permit PER92810 expiring on 31-12-2025.
Table 7: Efficacy of herbicides on medic and wards weed density, and medic pod set on alkaline sandy loam (0–10 cm) to clayey sand (10–20 cm) soil at Mudamuckla in 2023. Data labelled with the same letters within a column are not significantly different (P=<0.05).
Variety | Herbicide treatment (dose in terms of commercial product) | Medic pods/plot | Wards weed/plot | Yield (kg/ha) | |
---|---|---|---|---|---|
1 | GIA Metro | Metribuzin 180g/ha (POST)** | 71.4 a | 0.1 de | 148 cde |
2 | Metribuzin 180g/ha (PSPE) | 97.8 a | 1.5 cd | 120 e | |
3 | Metribuzin 380g/ha (POST) | 7.8 bc | 0 e | 123 e | |
4 | Metribuzin 380g/ha (PSPE) | 98.2 a | 0.1 de | 150 cde | |
5 | Reflex® 500mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) | 77.1 a | 0 e | 136 de | |
6 | Reflex® 500mL/ha (IBS) f.b. metribuzin 380g/ha (POST) | 9.4 bc | 0 e | 131 de | |
7 | Unsprayed control | 85.2 a | 14.3 b | 122 e | |
8 | PBA Highland XT | Reflex® 500mL/ha (IBS) | 52.1 a | 1.5 cd | 202 ab |
9 | Reflex® 750mL/ha (IBS) | 67.1 a | 2.5 c | 201 ab | |
10 | Reflex® 500mL/ha (IBS) f.b. Intercept® 500mL/ha (POST) | 4.5 bc | 0 e | 216 ab | |
11 | Terrain® 120g/ha (IBS) | 81.5 a | 17.2 ab | 181 bcd | |
12 | Reflex® 500mL/ha (IBS) + metribuzin 120g/ha (IBS)* | 68.4 a | 1.3 cde | 194 abc | |
13 | Reflex® 500mL/ha (IBS) + diuron 200g/ha (IBS)* | 65.8 a | 2.7 c | 210 ab | |
14 | Reflex® 500mL/ha (IBS) + diuron 200g/ha (IBS)* f.b. Intercept® 500mL/ha (POST) | 0 c | 0 e | 243 a | |
15 | Brodal® 80mL/ha (IBS)* + diuron 200g/ha (IBS)* f.b. Intercept® 500mL/ha (POST) | 3.5 bc | 0 e | 212 ab | |
16 | Unsprayed control | 70.6 a | 27.5 a | 189 bc |
* Sub-label rate (industry practice)
IBS: Incorporated by sowing, PSPE: Post-sowing pre-emergence, POST: post-emergent at 5–6 crop node stage, f.b.: Followed by
**Metribuzin (POST) permitted only in GIA MetroP as per the permit PER92810 expiring on 31-12-2025.
Table 8: Crop growth and weed efficacy response to different herbicides on loamy clay (at 0–10 cm with near-neutral soil pH) to clayey soil (at 10–30 cm and alkaline reaction) at Kimba 2023.Data labelled with the same letters within a column are not significantly different (P=<0.05).
Variety | Herbicide treatment (dose in terms of commercial product) | Emergence (plants/m2) | Plant height (cm) 10 WAS** | Common sowthistle pods/m2 | Wild turnip pods/m2 | Indian hedge mustard pods/m2 | Yield (t/ha) | |
---|---|---|---|---|---|---|---|---|
1 | GIA Metro | Reflex® 750mL/ha (IBS) | 112 a | 10.5 cde | 6.3 cde | 0 c | 1.0 b | 1.76 c |
2 | Metribuzin 380g/ha(PSPE) | 104 a | 9.6 def | 27.6 b | 0.5 c | 0 b | 1.75 c | |
3 | Metribuzin 380g/ha (POST)*** | 105 a | 8.9 f | 0.3 def | 0 c | 0 b | 1.87 c | |
4 | Metribuzin 380g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 119 a | 9.3 ef | 7.3 cd | 0 c | 0 b | 1.64 c | |
5 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) | 108 a | 9.1 ef | 0.6 def | 0 c | 0 b | 1.94 c | |
6 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha(PSPE) + Brodal® 200mL/ha (POST) | 102 a | 9.0 ef | 0.6 def | 0 c | 0 b | 1.84 c | |
7 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 111 a | 9.9 def | 0.1 ef | 0 c | 0 b | 1.80 c | |
8 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha(POST) | 110 a | 8.7 f | 0 f | 0 c | 0 b | 1.87 c | |
9 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha(POST) + Intercept® 750mL/ha (POST) | 101 a | 9.9 def | 0 f | 0 c | 0 b | 1.92 c | |
10 | Unsprayed control | 119 a | 9.3ef | 124.3 a | 37.2 b | 11.8 a | 1.26 d | |
11 | GIA Thunder | Reflex® 500mL/ha (IBS) | 102 a | 11.9 abc | 26.8 b | 0.3 c | 0.9 b | 2.45 ab |
12 | Reflex® 750mL/ha (IBS) | 103 a | 12.3 ab | 17.0 bc | 0 c | 0 b | 2.32 b | |
13 | Reflex® 1000mL/ha (IBS) | 107 a | 12.9 a | 7.5 cd | 0 c | 0 b | 2.68 a | |
14 | Reflex® 750mL/ha (IBS) f.b. diuron 550g/ha (PSPE) f.b. Brodal® 200mL/ha (POST) | 108 a | 12.0 abc | 2.7 def | 0.6 c | 0 b | 2.69 a | |
15 | Reflex® 750mL/ha (IBS) f.b. diuron 550g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 98 a | 11.1 bcd | 0.1 ef | 0 c | 0 b | 2.66 a | |
16 | Unsprayed control | 104 a | 12.4 ab | 130.0 a | 57.8 a | 11.5 a | 2.30 b |
**Weeks after sowing,
IBS: Incorporated by sowing, PSPE: Post-sowing pre-emergence, POST: Post-emergent at 5–6 crop node stage, f.b.: Followed by
***Metribuzin (POST) permitted only in GIA MetroP as per the permit PER92810 expiring on 31-12-2025.
Table 9: Crop growth and yield in response to different herbicide strategies in lentil at Tooligie, 2023. Plant chlorosis score (1 = no chlorosis, 9 = plant death), necrosis score (1 = no necrosis, 9 = plant death).Data labelled with the same letters within a column are not significantly different (P = <0.05).
Herbicide treatment (dose in terms of commercial product) | Emergence /m2 | Chlorosis (10 WAS*) | Necrosis (10 WAS*) | Plant height (cm) 10 WAS* | Yield (t/ha) | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | GIA Metro | Reflex® 750mL/ha (IBS) | 130 a | 1.5 bcd | 1.5 bc | 8.7 bcdef | 1.10 abcd | ||||||
2 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) | 132 a | 1.5 bcd | 1.0 c | 8.2 def | 1.10 abcd | |||||||
3 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) f.b. Brodal® 200mL/ha (POST) | 118 a | 2.2 ab | 1.2 bc | 8.3 cdef | 0.85 e | |||||||
4 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 121 a | 1.8 abcd | 1.2 bc | 8.0 ef | 0.90 de | |||||||
5 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (POST)*** | 118 a | 2.5 a | 2.3 a | 8.0 ef | 0.99 cde | |||||||
6 | Unsprayed control | 127 a | 1.0 d | 1.0 c | 7.8 f | 0.87 e | |||||||
7 | PBA Highland XT | Reflex® 500mL/ha (IBS) | 104 a | 1.0 d | 1.0 c | 9.0 abcdef | 1.28 a | ||||||
8 | Reflex® 750mL/ha (IBS) | 123 a | 1.1 d | 1.0 c | 8.8 bcdef | 1.13 abc | |||||||
9 | Reflex® 1000mL/ha (IBS) | 125 a | 1.3 cd | 1.2 bc | 10.1 a | 1.11 abc | |||||||
10 | Reflex® 750mL/ha (IBS) + diuron 300**g/ha (IBS) | 129 a | 1.0 d | 1.0 c | 8.9 bcdef | 1.12 abc | |||||||
11 | Reflex® 750mL/ha (IBS) + diuron 300**g/ha (IBS) f.b. Intercept® 750mL/ha (POST) | 127 a | 1.5 bcd | 1.0 c | 9.6 ab | 1.11 abc | |||||||
12 | Reflex® 750mL/ha (IBS) f.b. diuron 550g/ha (PSPE) | 121 a | 1.0 d | 1.0 c | 9.5 abc | 1.22 ab | |||||||
13 | Reflex 750mL/ha (IBS) f.b. diuron 550g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 133 a | 1.2 cd | 1.0 c | 8.7 bcdef | 1.20 ab | |||||||
14 | Reflex® 750mL/ha (IBS) f.b. metribuzin 180g/ha (PSPE) | 131 a | 1.2 cd | 1.2 bc | 9.0 abcdef | 1.06 bcde | |||||||
15 | Reflex® 750mL/ha (IBS) f.b. metribuzin 180g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 124 a | 1.3 cd | 1.2 bc | 9.1 abcde | 1.10 abcd | |||||||
16 | Reflex® 750mL/ha (IBS) + Terbyne Xtreme® 860g/ha (IBS) | 131 a | 2.0 abc | 1.7 bc | 9.4 abcd | 1.10 abcd | |||||||
17 | Reflex® 750mL/ha (IBS) + Terbyne Xtreme® 860g/ha (IBS) f.b. Intercept® 750mL/ha (POST) | 116 a | 1.7 abcd | 1.2 bc | 9.1 abcde | 1.12 abc | |||||||
18 | Unsprayed control | 127 a | 1.0 d | 1.0 c | 9.2 abcde | 1.17 abc |
* Sub-label rate (industry practice), **Weeks after sowing
IBS: Incorporated by sowing, PSPE: Post-sowing pre-emergence, POST: Post-emergence at 5–6 crop node stage, f.b.: Followed by
***Metribuzin (POST) permitted only in GIA MetroP as per the permit PER92810 expiring on 31-12-2025.
Table 10: Weeds’ pod set in response to different herbicide strategies in lentil at Tooligie, 2023. Data labelled with the same letters within a column are not significantly different (P=<0.05).
Herbicide treatment (dose in terms of commercial product) | Common sowthistle pods/m2 | Indian hedge mustard pods/m2 | ||
---|---|---|---|---|
1 | GIA Metro | Reflex® 750mL/ha (IBS) | 0# c (0)** | 0# c (0)** |
2 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) | 0 c (0) | 0 c (0) | |
3 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) f.b. Brodal® 200mL/ha (POST) | 0 c (0) | 0 c (0) | |
4 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 0 c (0) | 0 c (0) | |
5 | Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (POST)*** | 0 c (0) | 0 c (0) | |
6 | Unsprayed control | 9.0 a (81) | 17.9 a (320) | |
7 | PBA Highland XT | Reflex® 500mL/ha (IBS) | 1.0 bc (1) | 1.0 c (1) |
8 | Reflex® 750mL/ha (IBS) | 0 c (0) | 0 c (0) | |
9 | Reflex® 1000mL/ha (IBS) | 2.6 bc (7) | 2.6 c (7) | |
10 | Reflex® 750mL/ha (IBS) + diuron 300*g/ha (IBS) | 3.3 b (11) | 3.3 c (11) | |
11 | Reflex® 750mL/ha (IBS) + diuron 300*g/ha (IBS) f.b. Intercept® 750mL/ha (POST) | 0 c (0) | 0 c (0) | |
12 | Reflex® 750mL/ha (IBS) f.b. diuron 550g/ha (PSPE) | 0 c (0) | 0 c (0) | |
13 | Reflex® 750mL/ha (IBS) f.b. diuron 550g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 1.8 bc (3) | 1.8 c (3) | |
14 | Reflex® 750mL/ha (IBS) f.b. metribuzin 180g/ha (PSPE) | 0 c (0) | 0 c (0) | |
15 | Reflex® 750mL/ha (IBS) f.b. metribuzin 180g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 0 c (0) | 0 c (0) | |
16 | Reflex® 750mL/ha (IBS) + Terbyne Xtreme® 860g/ha (IBS) | 0 c (0) | 3.4 c (12) | |
17 | Reflex® 750mL/ha (IBS) + Terbyne Xtreme® 860g/ha (IBS) f.b. Intercept® 750mL/ha (POST) | 0 c (0) | 0 c (0) | |
18 | Unsprayed control | 8.9 a (79) | 9.2 b (85) | |
Lsd 5% | 3.3 | 3.6 |
#Data after square-root transformation,
* Sub-label rate (industry practice), **Values in parentheses are original means
IBS: Incorporated by sowing, PSPE: Post-sowing pre-emergence, POS: Post-emergence at 5–6 crop node stage, f.b.: Followed by
***Metribuzin (POST) permitted only in GIA MetroP as per the permit PER92810 expiring on 31-12-2025.
Table 11: Weeds’ pod set and crop yield in response to different herbicide strategies in lentil at Hart, 2023. Plant chlorosis score (1 = no chlorosis, 9 = plant death), necrosis score (1 = no necrosis, 9 = plant death), stunting score (1 = no stunting, 9 = plant death). Data labelled with the same letters within a column are not significantly different (P=<0.05).
Crop/variety | Herbicide treatment (dose in terms of commercial product) | Crop Establishment plants/m2 4 WAS* | Chlorosis (10 WAS*) | Necrosis (10 WAS*) | Stunting (10 WAS*) | Vetch pods/m2 | Common sowthistle pods/m2 | Wild radish pods/m2 | Yield (t/ha) | ||
---|---|---|---|---|---|---|---|---|---|---|---|
Lentil (GIA Metro) | Metribuzin 380g/ha (POST)**** | 114 bc | 1.0 a | 1.0 a | 1.0 c | 5.9# c (35)*** | 0# b (0)*** | 0# b (0)*** | 1.89 b | ||
Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (POST) | 121 ab | 1.0 a | 1.0 a | 1.8 b | 7.0 c (49) | 0 b (0) | 0 b (0) | 1.73 b | |||
Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) | 128 a | 1.0 a | 1.0 a | 2.2 a | 15.1 b (228) | 0 b (0) | 0 b (0) | 1.05 c | |||
Reflex® 750mL/ha (IBS) f.b. metribuzin 380g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 116 ab | 1.0 a | 1.0 a | 2.3 a | 8.3 c (69) | 0 b (0) | 0 b (0) | 1.67 b | |||
Unsprayed control | 126 ab | 1.0 a | 1.0 a | 1.0 c | 19.9 a (396) | 4.2 a (18) | 30.4 a (924) | 0.52 d | |||
Lentil (GIA Thunder) | Reflex® 750mL/ha (IBS) f.b. diuron 550g/ha (PSPE) f.b. Intercept® 750mL/ha (POST) | 101 c | 1.0 a | 1.0 a | 1.0 c | 5.7 c (32) | 0 b (0) | 0 b (0) | 2.57 a | ||
Lsd 5% | 14 | NS | NS | 0.3 | 0.3 | 0.9 | 1.6 | 0.29 | |||
#Data after square-root transformation,
*Weeks after sowing,***Values in parentheses are original means
IBS: Incorporated by sowing, PSPE: Post-sowing pre-emergence, POST: Post-emergence at 5–6 crop node stage, f.b.: Followed by
****Metribuzin (POST) permitted only in GIA MetroP as per the permit PER92810 expiring on 31-12-2025.
GRDC Project Code: UOA2303-007RTX, UOA2105-013RTX,