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Expanding the capability of misting herbicide

application for woody weeds in the rangelands

2017 – 2019

Project Report – Bellyache Bush Trial Desert Channels Queensland Inc.

A project funded by the Australian Government through the Department of Agriculture and Water Resources and delivered by Desert Channels Queensland with the support of the Queensland Government and landholders in the region.

May 2019

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Table of Contents

List of Figures .............................................................................................................................. III

List of Tables ...............................................................................................................................IV

1. Introduction ......................................................................................................................... 5

1.1. Background ................................................................................................................. 5

1.2. Location of Trials .......................................................................................................... 6

2. Trial Methodology ............................................................................................................... 7

2.1. Selection of trail sites ................................................................................................... 7

2.2. Chemical selection ....................................................................................................... 8

2.3. Technique .................................................................................................................... 8

2.4. Weather conditions ................................................................................................... 12

3. Results ............................................................................................................................... 13

4. Recommendations ............................................................................................................. 16

Appendix ................................................................................................................................... 17

Appendix A- Trial site photographs after misting operations ................................................... 17

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List of Figures

Figure 1: Bellyache bush infestation on grassland(left) and riparian area (right) .................................. 5

Figure 2: Location map of trial sites in Coalbrook and Bromvil property ............................................... 7

Figure 3: Misting site index map for Bellyache Bush .............................................................................. 9

Figure 4: Monitoring site near Coalbrook, Cambridge Creek ................................................................. 9

Figure 5: Mister used in the trial process ............................................................................................. 10

Figure 6: Misting Bellyache Bush in Bromvil trial site ........................................................................... 11

Figure 7: Bellyache Bushes under tree crown cover. ............................................................................ 12

Figure 8: Chemical infested area with 100% efficacy rate .................................................................... 13

Figure 9: Lots of fallen dead leaves and dead stem of Bellyache Bush after Chemical Control ........... 14

Figure 10: Bellyache Bush after misting operation in trial sites ........................................................... 17

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List of Tables

Table 1: Misting Site Index for Coalbrook and Bromvil property ........................................................... 8

Table 2: Weather condition recorded during misting of Bellyache Bush ............................................. 12

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1. Introduction

1.1. Background The Australian Government, through the Department of Agriculture and Water Resources provided $334,400 in funding to Desert Channels Queensland for the project “Expanding the capability of misting herbicide application for woody weeds in the rangelands”. The purpose of the project was to develop the expanded use of misters for herbicide application to control woody weeds in the rangelands, with a focus on Prickly Acacia, Rubber Vine and Bellyache Bush. This report focuses on the Bellyache Bush trial area.

Bellyache Bush (Jatropha gossypiifolia) is a Weed of National Significance. It is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. Bellyache bush has impacts on pastoral and conservation areas of north eastern Australia. Its main impact on pastoralism is the loss of grazing country. It also increases the costs of mustering and fencing. It is generally acknowledged that the shallow root system and canopy cover of bellyache bush precludes growth of other plants, often outcompeting native vegetation and reducing pasture growth. Dense infestations may occur on river flats and other areas of good loamy soil. Bellyache bush has taken over extensive sections of river frontage in several locations, reducing biodiversity and increasing mustering costs. The fruits of bellyache bush are poisonous to humans and animals. The toxic substance is a toxalbumin which, when eaten, leads to symptoms of gastroenteritis and the eventual death of some animals. There have been many stock deaths reported due to bellyache bush poisoning, mainly in times of severe drought.

Figure 1: Bellyache bush infestation on grassland(left) and riparian area (right)

Bellyache bush is a squat, thick-stemmed shrub 2.5−4 m tall developing from a short, single-stemmed plant with three or four young leaves sprouting from the top. Young leaves are deeply divided into three rounded lobes, and are purple coloured and sticky. Older leaves are bright green, about 10 cm in diameter, and may have up to five lobes, the edges covered in coarse, dark brown hairs. The flowers are small, red with yellow centres, and found in small clusters throughout the upper part of the plant. Seed pods are smooth and oval, about the size of a cherry and 12 mm across; they contain three to four seeds about 8 mm long. Castor oil plant is similar but usually taller than bellyache bush. The leaves are larger and clearly different, with more lobes (seven to nine) which are much more pointed. Flowers and fruit are on an obvious spike near the top of the plant. Fruit are covered with soft spines and are 2.5 cm across, much larger than those on bellyache bush.

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Bellyache bush flowers throughout the year when moisture is adequate. The seeds germinate during October to December. The weed is spread by different agents in different ways. Fruit eating birds, rain water, livestock and machinery used by humans can help in spreading weed in other areas. A native of tropical America, bellyache bush was sometimes grown as a garden plant. It has escaped and become naturalised in various areas of Australia. Bellyache Bush has a widespread but scattered distribution throughout Australia. It is most common in the northern parts of Queensland, the Northern Territory and Western Australia, but is also present in central and south-eastern Queensland and in other parts of the Northern Territory. The most extensive infestations in Queensland exist within the Burdekin River catchment, where it extends from north of Charters Towers to the Burdekin river mouth and back along many of its tributaries, including the catchments of the Bowen, Suttor, Bogie and Belyando Rivers. Smaller populations are also present in the Banana, Broadsound, Bourke, Cook, Dauringa, Emerald, Peak Downs, Flinders, Fitzroy, Jericho and Whitsunday shires. In the Northern Territory, Bellyache Bush occurs in the Darwin, Katherine, Middle Point, Batchelor, Willeroo, Mataranka and Daly Waters regions. Large infestations also occur to the south-west of Katherine, on Tipperary Station and on Channel Island. Populations in Western Australia are mainly located in the eastern part of the Kimberley region. It is usually common along riverbanks and roadsides areas. As bellyache bush has been a major threat to native plant, animal species and endangered plant communities, it is necessary to control the weed to encourage the regeneration of native plants.

1.2. Location of Trials To undertake the trials, riparian areas were selected for the misting of prickly acacia. In a natural or well managed state, riparian areas are important for many reasons. They can support diverse vegetation, help maintain bank stability, and increase ecological and economic productivity. These conditions support cleaner water, reduce disease and pests, and retain important nutrients and soil. These areas are also colonised first by this weed species and, due to increased available moisture, reach maximum density and produce the greatest amount of seed. Riparian areas are vulnerable and easily degraded. As weeds can flourish at high rates in riparian areas due to suitable growth environment, it can cause significant damage to the riparian area. The importance of managing riparian land well is increasingly being recognised, and protection, rehabilitation and restoration work is being undertaken across the catchments. While, landowners have legal rights and responsibilities for managing riparian areas, a lack of time plus dependence on control techniques that require high labour inputs and expense, means control in these areas is not being undertaken. The cost of controlling the weed infestation and the requirement for regular follow up after initial control has been a significant problem. Two properties were selected for these trials, one on the north of Richmond and the other on the north of Muttaburra in western Queensland where conditions and weed infestations allowed multiple sites to be selected over a range of densities and age profiles.

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2. Trial Methodology

2.1. Selection of trail sites The trial areas were selected because of the following reasons:

dense riparian infestation of the weeds.

distribution of weeds along the length of the creek allowing replication of the selected chemicals trials.

distribution of weeds across the creek lines to test penetration of the selected chemicals

accessible to different age profiles of Bellyache Bush to test efficacy Moreover, selected areas were also easy to access as they were located beside the main road. The properties Bromvil and Coalbrook were selected for bellyache bush trials. Coalbrook had one trial site which was located on north side of Cambridge Creek of Woolgar locality. Similarly, Bromvil had one trial site which was located on the east of Hughenden-Muttaburra Road.

Figure 2: Location map of trial sites in Coalbrook and Bromvil property

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2.2. Chemical selection A detailed trail design was developed in conjunction with Biosecurity Queensland (Charters Towers Tropical Weed Research Centre). As per the designed trial, Brushoff (metsulfuron methyl) or Starane (fluroxypyr) were proposed to treat bellyache bush where Starane Advanced was used to treat Bellyache Bush on Coalbrook property and combination of Brushoff and Stinger was used for Bromvil property. The chemical rates used for Starane Advanced used was 2.8 litres per 400 litres water. Similarly, the rate used for combination of Brushoff and Stinger was 40 grams Brushoff per 100 litres water and 60 grams Stinger per 100 litres water.

2.3. Technique The following trial design was implemented to evaluate the chemical control technique at chosen sites.

I. The test area of Coalbrook and Bromvil property had 200 m segment of trial site.

Table 1: Misting Site Index for Coalbrook and Bromvil property

Property Time and date Chemicals used

Coalbrook Morning, 31/08/18 Starane Advanced

Bromvil Mid-day, 09/04/19 Brushoff and Stinger

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Figure 3: Misting site index map for Bellyache Bush

II. Monitoring sites establishment

Two transect sites were established on 30th November, 2018. A steel fence peg was place on north side of Cambridge Creek to mark the monitoring sites. Photos of the misting area near the peg were captured using a mobile device via Fulcrum application. Additional information like trial condition and trial details were also recorded on the app. These sites however provided limited point information and could not provide the data about the changes in effectiveness through the range of conditions encountered over the section.

Figure 4: Monitoring site near Coalbrook, Cambridge Creek

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III. Chemical treatment

Misting with the evaluated rates of chemical was used to treat the weed present at each site. A mister mounted on the trailer was used for spraying the chemical into weeds. The mister has a sprayer and a chemical tank on the side and was modified for spraying desired rate of chemical. The mister was modified and fitted to a heavy-duty trailer and pulled by a Yamaha Rhino also modified for the experiment. Combined they allowed access at all sites, maintained required Workplace Health and safety requirements and allowed the mister to stay on the surveyed line despite significant changes in topography.

Figure 5: Mister used in the trial process

The misting process occurred on 30th November 2018 at Coalbrook site and on 8th April 2019 at Bromvil site. In accordance with the trial design, and to test the effectiveness of chemical, trial sites were treated morning using the chemical. The vehicle pulling the mister was fitted with a GPS, from there buffers were marked so that the effectiveness of the chemical could be measured as distance from the mister increased. The weather conditions (humidity, wind speed and temperature) were recorded during misting operation.

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Figure 6: Misting Bellyache Bush in Bromvil trial site

IV. Ground Monitoring of trial sites

Bellyache bushes were mostly found grown under the crown cover of native trees (as in figure 7) in the trial sites which made it difficult to detect them using the drone imagery. Therefore, site visit was conducted to monitor the effectiveness of the chemical on the shrubs after three months of misting operation in February 2019 as well as post wet season in May 2019 for Coalbrook property. Similarly, Bromvil site was monitored on first week of June 2019. However, the acquisition of drone imagery was done to identify the affected area for visual interpretation. Furthermore, the trial sites were visually monitored and individual plants were identified on the ground to support the visual interpretation of drone imagery for the evaluation of the progress. Photographs (in Appendix A) were taken around the misting trial sites during monitoring period.

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Figure 7: Bellyache Bushes under tree crown cover.

V. Evaluation of chemical efficacy

The assessment of the efficacy of the chemical used was done based on the visual monitoring of the site, comparing transect point photographs and identification of the individual plants treated in the trial area.

2.4. Weather conditions The information recorded regarding the weather condition during misting operations were humidity, temperature and wind speed. The weather condition recorded of trial sites during misting of the Bellyache Bush are tabulated below:

Table 2: Weather condition recorded during misting of Bellyache Bush

Locality

Conditions

Wind speed (m/s)

Temperature (deg. C)

Humidity (%)

Coalbrook 1.7 26.3 55.8

Bromvil 1.5 30 30

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3. Results There were two trial sites; one on Coalbrook property and the other on Bromvil property, which were used to conduct the test on Bellyache Bush. Primarily the project has tested the effectiveness of the chemicals used to treat the Bellyache Bush. However, it has also tested the effectiveness of the technique in response to changes in density and distance from the mister. The technique has been success for the Bellyache Bush but there are some variations which is theorised to be due to the site issues. To test the hypothesis the mister path was logged and plotted and the location of plants in the trial site was identified. The sites were paired to test chemical efficacy with chemical application to test efficacy with variations in density and distance from mister. The site in Coalbrook property was treated between 6:00 am to 6:30 am and Bromvil site was treated between 11:30 am to 12:00 pm. The chemicals used to treat each site are listed in Table 1. Both the sites have areas of both dense and light infestation over the misting area. Mostly the area under the tree crown cover were heavily infested whereas the outlier bellyache bush has lightly infested the open area. The area within 40 m of mister line have sufficient chemical infestation as a result of which 100 % of bellyache bush weed were affected in the area (figure 8). The effect of the chemical was indicated by lots of fallen dead leaves and the dead stem of the weed plants (in figure 9) in the trial sites. Bellyache bush present within the area beyond 40 m of mister line remained unaffected due to lack of chemical infestation in the area. It means the efficacy of chemicals are unaffected by the density of the plants but distance from the misting track impacted on the chemical efficacy.

Figure 8: Chemical infested area with 100% efficacy rate

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Figure 9: Lots of fallen dead leaves and dead stem of Bellyache Bush after Chemical Control

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4. Recommendations

I. The operational decision tree is updated to reflect results above to achieve a primary control:

a) This technique is effective for small to fully grown plants b) Is effective from light to heavy densities of plants c) Time of day restrictions can be removed where the control technique is directed

against distance from mister line d) Weather restrictions be updated to include low humidity days where the

temperature is below 30 degrees Celsius

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Appendix Appendix A- Trial site photographs after misting operations

The below figure shows the pictures after the misting operations from the misting trial sites in trial area of Coalbrook and Bromvil property. The dead leaves and stem of the weed plants can depict the effect of chemicals.

Figure 10: Bellyache Bush after misting operation in trial sites

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