PATHWAYS TO WATER QUALITY IMPROVEMENTS IN THE MYRTLE CREEK SUB-CATCHMENT 2020/2021 WET SEASON - SITE 2

NUTRIENT AND PESTICIDE APPLICATION DETAILS

SITE DETAILS Fertiliser + imidacloprid application date: 21 October 2020 Herbicide application date: 17 November 2020 BLOCK SIZE: All treatments were applied with the Queensland Government Department 5.75 ha of Agriculture and Fisheries Dual Herbicide Sprayer.

SAMPLED AREA: Treatment 1 0.388 ha • Inter row: Basta @ 2L/ha (220g/ha glyphosinate ammonia) • Row: Bobcat i-MAXX @ 3.2L/ha (180g/ha hexazinone and 36g/ha imazapic) ROW SPACING: and Spray.Seed 250 @ 1.2L/ha (162g/ha paraquat + 138g/ha diquat).

1.8 m Treatment 2 • Inter row: Basta @ 1L/ha (110g/ha glyphosinate ammonia) and Spray.Seed 250 VARIETY: @ 0.8L/ha (59.4g/ha paraquat & 50.6g/ha diquat) A Q242 • Row: Bobcat i-MAXX @ 3.2L/ha (180 gha hexazinone and 36g/ha imazapic) and Spray.Seed 250 @ 1.2L/ha (162g/ha paraquat + 138g/ha diquat). CROP CLASS: 6R Treatment 3 • Inter row: Spray.Seed 250 @ 1.5L/ha (111.4g/ha paraquat and 94.9g/ha diquat)

HISTORICAL ANNUAL YIELD: • Row: Bobcat i-MAXX @ 3.2L/ha (180g/ha hexazinone and 36g/ha imazapic) and Spray.Seed 250 @ 1.2L/ha (162g/ha paraquat + 138g/ha diquat). 90 tph

Treatment 4 SOIL TYPE: • Inter row: Roundup 540 @ 2L/ha (1080g/ha glyphosate) Crystal Brook (cracking clay) • Row: Bobcat i-MAXX @ 3.2L/ha (180g/ha hexazinone and 36g/ha imazapic) and Spray.Seed 250 @ 1.2L/ha (162g/ha paraquat + 138g/ha diquat). LOCATION IN SUB-CATCHMENT: Foxdale Treatment 5 • Inter row: Basta @ 2L/ha (220g/ha glyphosinate ammonia) and Spray.Seed 250 @ 1.5L/ha (111.4g/ha paraquat & 94.9g/ha diquat) and Bobcat i-MAXX @ 1.16L/ha (145g/ha hexazinone + 29g/ha imazapic) • Row: Bobcat i-MAXX @ 3.2L/ha (180g/ha hexazinone & 36g/ha imazapic) and Spray.Seed 250 @ 1.2L/ha (162g/ha paraquat + 138g/ha diquat).

Treatment 6 • Inter row: control - no herbicide applied. • Row: control - no herbicide applied. FERTILISER APPLICATION: TESTED FOR:

• CB51851 @ 390kg/ha • Dissolved Inorganic Nitrogen (DIN) – Total nutrient applied: • Filterable Reactive Phosphorus (FRP) N – 113.1kg/ha P – 0kg/ha • Imidacloprid K – 70.2kg/ha • Hexazinone S – 0kg/ha • Imazapic • Glyphosate • Glufosinate Ammonium • Paraquat • Diquat

RUNOFF EVENT DATA

DAYS FROM LAST FERTILISER + DAYS FROM LAST HERBICIDE EVENT DATES IMIDACLOPRID APPLICATION APPLICATION

1* 20–21 November 2020 33 3

2* 9–10 December 2020 55 22

3 25 December 2020 71 38

4 6 January 2021 83 50

5 7-8 January 2021 84 51

6 10 January 2021 85 53

7 11 January 2021 4 54

* Events 1 and 2 were generated by flood irrigation

RAINFALL

120

100

80

60 RAIN (MM) 40

20

0

1/10/2020 8/10/2020 5/11/2020 3/12/2020 7/01/2021 15/10/2020 22/10/2020 29/10/2020 12/11/2020 19/11/2020 26/11/2020 10/12/2020 17/12/2020 24/12/2020 31/12/2020

DATE

Figure 1 Rainfall data measured at Wandarra weather station.

PATHWAYS TO WATER QUALITY IMPROVEMENTS IN THE MYRTLE CREEK SUB-CATCHMENT RESULTS NOTE: Nutrient and pesticide loads are estimates only. Freshwater ecotoxicity thresholds cannot be applied to paddock scale monitoring. Freshwater aquatic ecosystem species protection values are referenced only for discussion. P concentrations are indicative and actual concentrations are likely to be slightly higher.

DIN (Dissolved Inorganic Nitrogen)

0.45 0.6% 0.4 0.35 0.5% 0.3 0.4% 0.25 0.2 0.3%

0.15 0.2% 0.1 0.1% 0.05 DIN CONCENTRATION (PPM) CONCENTRATION DIN 0 0 1 2 3 4 5 6 7 1 2 3 4 5 6 7 TOTAL % OF APPLIED DIN LOST IN RUN-OFF EVENT # EVENT #

Average 2021 Event Target Average Figure 2 DIN concentration in run-off (ppm). The Mackay Whitsunday Water Figure 3 percentage of applied nitrogen lost as DIN in run-off. Quality Plan’s, DIN water quality in event current conditions is 0.429 ppm and 2021 event target is 0.300 ppm, both for the Myrtle Creek. Provided for discussion only.

FRP (Filterable Reactive Phosphorus)

0.4 1000 0.35 900 0.3 800 0.25 700 600 0.2 500 0.15 400 0.1 300 200 0.05 FRP CONCENTRATION (PPM) CONCENTRATION FRP 100 0 FRP LOST IN RUN-OFF (G/HA) 0 1 2 3 4 5 6 7 1 2 3 4 5 6 7 TOTAL EVENT # EVENT #

Average 2021 Event Target Average

Figure 4 FRP concentration in run-off (ppm). The Mackay Whitsunday Water Figure 5 FRP lost in run-off (ppm). There was no phosphorous applied, Quality Plan’s FRP water quality in event current conditions is 0.200 ppm therefore percentage of phosphorous lost cannot be calculated. and 2021 event target is 0.193 ppm, both for the Myrtle Creek. Provided for discussion only.

IMIDACLOPRID

0.8% 1.2 0.7% 1.0 0.6% 0.8 0.5%

0.6 0.4% 0.3% 0.4 0.2% 0.2 0.1% 0 0 1 2 3 4 5 6 7 1 2 3 4 5 6 7 TOTAL

IMIDACLOPRID CONCENTRATION (PPB) CONCENTRATION IMIDACLOPRID EVENT # EVENT #

Average 95% FGV Average % OF APPLIED IMIDACLOPRID LOST IN RUN-OFF

Figure 6 Imidacloprid concentration in run-off (ppb). Freshwater guideline Figure 7 percentage of applied imidacloprid lost in run-off. value (FGV) is the aquatic ecosystem protection guideline value at the 95% species protection level and is applicable only to freshwater systems. Imidacloprid value is 0.11 ppb. Provided here for discussion only.

2020/2021 WET SEASON – SITE 2 HEXAZINONE

35 18% 30 16% 25 14% 12% 20 10% 15 8% 10 6% 4% 5 2% 0 0

HEXAZINONE CONCENTRATION (PPB) HEXAZINONE CONCENTRATION 1 2 3 4 5 6 7 1 2 3 4 5 6 7 TOTAL EVENT # EVENT #

Treatment 1 Treatment 5 Treatment 6 95% FGV Treatment 1 Treatment 5

RUN-OFF IN HEXAZINONE LOST APPLIED OF %

Figure 8 Hexazinone concentration in run-off (ppb). Freshwater guideline Figure 9 percentage of applied hexazinone lost in run-off. value (FGV) is the aquatic ecosystem protection guideline value at the 95% species protection level and is applicable only to freshwater systems. Hexazinone value is 1.1 ppb. Provided here for discussion only.

IMAZAPIC

5.0 10% 4.5 9% 4.0 8% 3.5 7% 3.0 6% 2.5 5% 2.0 4% 1.5 3% 1.0 2% 0.5 1% 0.0 0% IMAZAPIC CONCENTRATION (PPB) IMAZAPIC CONCENTRATION 1 2 3 4 5 6 7 1 2 3 4 5 6 7 TOTAL EVENT # EVENT # % OF APPLIED IMAZAPIC LIST IN RUN-OFF Treatment 1 Treatment 5 Treatment 6 95% FGV Treatment 1 Treatment 5 Treatment 6

Figure 10 Imazapic concentration in run-off (ppb). Freshwater guideline Figure 11 percentage of applied imazapic lost in run-off. value (FGV) is the aquatic ecosystem protection guideline value at the 95% species protection level and is applicable only to freshwater systems. Imazapic value is 0.41 ppb. Provided here for discussion only.

GLYPHOSATE

8 4.5% 7 4.0% 6 3.5% 3.0% 5 2.5% 4 2.0% 3 1.5% 2 1.0% 0.5% 1 0.0%

GLYPHOSATE CONCENTRATION (PPB) CONCENTRATION GLYPHOSATE 0 1 2 3 4 5 6 7 TOTAL 1 2 3 4 5 6 7 EVENT # EVENT # % OF APPLIED GLYPHOSATE LIST IN RUN-OFF Treatment 4 Treatment 4 Treatment 6

Figure 12 Glyphosate concentration in run-off (ppb). Freshwater guideline Figure 13 percentage of applied glyphosate lost in run-off. value (FGV) is the aquatic ecosystem protection guideline value at the 95% species protection level and is applicable only to freshwater systems. Glyphosate value is 1200 ppb. Provided here for discussion only.

PATHWAYS TO WATER QUALITY IMPROVEMENTS IN THE MYRTLE CREEK SUB-CATCHMENT GLUFOSINATE AMMONIUM

0.38 0.720% 0.37 0.715%

0.36 0.710% 0.35 0.705% 0.34 0.700% 0.33 0.32 0.695% 0.31 0.690% 1 2 3 4 5 6 7 1 2 3 4 5 6 7 GLUFOSINATE CONCENTRATION (PPB) CONCENTRATION GLUFOSINATE EVENT # % OF GLUFOSINATE LOST IN RUN-OFF EVENT #

Treatment 1 Treatment 2 Treatment 5 Treatment 6 Treatment 1 Treatment 2

Figure 14 Glufosinate ammonium concentration in run-off (ppb). Figure 15 percentage of applied glufosinate ammonium lost in run-off.

IRRIGATION WATER TEST One grab sample was taken during the first flood irrigation event, straight from the cup. The test showed the following levels of chemical: • Glyphosate = 1 ppb • Imidacloprid = 0.9 ppb • Diuron = 0.3 ppb • Glufosinate ammonium, paraquat, diquat, hexazinone, imazapic, atrazine were all undetected.

DISCUSSION

Please note that all concentrations are estimates only. Hexazinone and imazapic graphs show that Treatment 5 This is not a replicated research trial. Due to equipment (highest application of Bobcat i-MAXX) has the highest limitations, water samples were unable to be collected for concentrations in run-off compared to Treatment 1 the entire events. This may result in actual concentrations (example treatment without Bobcat i-MAXX applied being higher or lower than the estimates provided. All to the interrow), and the control treatment (lowest flow data used to calculate percentage of chemicals lost losses). Previous research shows losses of 13% of many in run-off are based on one sampler due to equipment applied herbicides if run-off occurs after 48 hours or error. The information is provided as a guide for so (this excludes pendimethalin and flumioxazin which comparison between treatments at this site only. have significantly lower losses (see The Herbicide Risk Matrix)). This suggests that APPLICATION RATE is the This trial aimed to compare different chemical options major influence on losses. Losses for hexazinone and using the Dual Herbicide Sprayer (DHS). The DHS allows imazapic are roughly in line with this research. However, knockdown chemicals such as glyphosate and Basta imidacloprid losses were far smaller than 13%, this (glufosinate ammonium) to be used in the interrow, whilst indicates a positive outcome for imidacloprid at this site. different products can be applied to the cane row at the same time, for example Bobcat i-MAXX (hexazinone and The results show that significant reductions in pre- imazapic). emergent herbicides can be achieved with the DHS. Weed counts, cane growth measurements and yield No paraquat or diquat was detected in any sample from measurements will also be compared between any treatment. Very small detections of glufosinate treatments. These will be shared once available. ammonium (Basta) were detected in the first irrigation event on some treatments. Small detections of DIN losses at this site only exceeded the Mackay glyphosate were detected in the glyphosate treatment Whitsunday Water Quality Plan’s DIN 2021 Event Target in (Treatment 4). However, glyphosate was also detected one event. FRP losses do not exceed the FRP 2021 Event in the control treatment (Treatment 6 - no glyphosate target significantly. It is expected that paddock scale applied). It is likely that the glyphosate detected entered run-off would be of higher concentration than in-creek the control treatment through irrigation water and concentrations due to scale and dilution. Whilst paddock possibly small residual amount from applications in scale run-off cannot be directly compared, this indicates a previous years. Analysis of irrigation water did detect positive result. glyphosate, see graphs.

2020/2021 WET SEASON – SITE 2 REFERENCES/FURTHER INFORMATION The Herbicide Risk Matrix - Attachment 1 Runoff Loads Compared to Application Rate. Fillols, E. 2018. Mackay Whitsunday Water Quality Improvement Plan 2014-2021. Folkers, A., Rhode, K., Delaney, K. & Flett, I. 2014.

FOR FURTHER INFORMATION PLEASE CONTACT Brad Pfeffer E [email protected] M 0419 175 815

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