TOP PADDOCK Newsletter 32 December 2003

Editor: Karen Richardson Department of Business Industry & Resource Development GPO Box 3000, Darwin NT 0801 Phone (08) 8999 2133 ISSN: 1320-727X

Harvesting Floodplain Grass Seed with the airboat was terminated early because the water was too low and the depth variable, which Introduction made controlling the speed of the airboat difficult. There has been considerable interest in the Added to this was the danger of having to jump out of potential use of native floodplain grasses for the airboat into crocodile infested water to push the revegetation following control of Mimosa pigra. airboat through shallow areas and potential injuries For this to be practical, a ready supply of seed is from hitting submerged objects, including tree trunks. required, and methods needed to be developed for the harvest, cleaning, testing and storage seed The low pure seed yields obtained (Table1) show of the main floodplain grasses. wild harvesting of these species is not an economical proposition. A National Heritage Trust (NHT) Bushcare funded co-operative project between Agriculture, Weeds Table 1: Pure Seed yields from floodplain grasses Branch and Greening Australia staff was with a brush harvester. conducted during 2002 and 2003 to investigate commercial harvesting of floodplain grass seed. Grass Harvester Pure Seed Mode Yield (g/hour) Method: Hymenachne Tractor 1.3 A brush harvester was constructed to fit onto the Weeds Branch airboat to harvest seed of Hymenachne Airboat 0.8 Hymenachne acutigluma, Leersia hexandra and Pseudoraphis spinescens in standing water. Pseudoraphis Tractor 3.6 These grasses produce their seed mostly during the wet season when the stands are generally The Hymenachne seed yield from the airboat harvest accessible only by boat or airboat. was similar to that obtained in May 2000 with a cutter bar and catcher on the front of the airboat. Most of the “seed” caught is empty spikelets, and blows off after drying, during cleaning.

The problems with the harvest are the poorly synchronised seed set of these grasses and the high arthropod pressure on the developing seeds. A Hymenachne inflorescence viewed under a microscope reveals a community of small mites, bugs, leaf hoppers, thrips and caterpillars.

The quality of the seed harvested was poor for the Pseudoraphis, but good for the Hymenachne.

The Brush Harvester Table 2: Germination of seed harvested.

Grass Harvester Germin- Fresh Mode ation % ungerm- The construction of the brush harvester took inated % longer than anticipated as "new" ideas were needed to reduce the weight of the unit and to Hymenachne Tractor 38 16 account for the lack of control over harvest speed, Hymenachne Airboat 60 0 ie the speed of the airboat. Pseudoraphis Tractor 1 10 A frame was also constructed to allow the brush harvester to be used in shallow water by towing The low harvest rate would make the cost of seed with a small tractor or quad bike. prohibitive for end users. There is a need for these grasses to be grown as seed crops away from the As the floodplains dried out earlier than floodplains where the seed production may be anticipated in 2002 because of the low rainfall wet synchronized by controlling watering cutting and season in the Top End, the brush harvester could fertility. This situation would also remove the grasses not be tested on the floodplains until the 2003 dry from the arthropod pressure on developing season. inflorescences.

The brush harvester was successfully tested at Arthur Cameron Middle Point on Marrakai Station towed by a Principal Agronomist Kubota tractor on Pseudoraphis on 20 May 2003, and on Hymenachne on 27 May 2003. To Be or Not to Be a Weed – that On 28 May, the floodplain brush harvester was successfully tested on Hymenachne when is the Question! Potential mounted on an airboat. The harvesting period Weediness of Bt Cotton in potentially disperse, and were categorised as waterway, cattle habitat, native bush and roadside. Northern Australia Three seed types; black seed, fuzzy seed and seed cotton were hand-planted within each of these Cotton in Northern Australia habitats in the 1999-2000 wet season (summer) to As southern Australia contemplates one of the simulate cottonseed dispersal. Additional sites were most severe droughts in history, the wet season in established in the initial dry season (DS, winter), plus northern Australia announces its progression with a second series of sites in the second year. Plant spectacular thunderstorms, lightning displays, and numbers and fruit production were recorded over a increasing cyclone watch warnings. Although the two-year period to quantify germination, survivorship, 2002-03 wet season was below average in a fecundity (boll production) and seedling recruitment number of regions, localised persistent lows as contributors to weediness. contributed to abundant refill of major river systems. 500 mm fell within 1 week at some Regular counts of plants at each site were used to stations in the Roper River catchment. This area calculate population growth, which was equated to is an example of the attractive land and water invasiveness, considered a major determinant of resources that has renewed interest in cotton weediness. A value greater than one indicates the production in northern Australia. However, this population is increasing and may become invasive of region also has existing stakeholders with an that habitat, where a value less than one indicates active interest in the allocation of natural the population is decreasing. resources; it is a mecca for fishermen, contains productive pastoral lands, and provides for traditional Aboriginal landholders. Environmental concerns over the allocation of land and water resources for irrigated agriculture, of which cotton is a major contender, are continually being raised by stakeholder groups. Researchers within the Australian Cotton CRC at Katherine, Kununurra and Broome are committed to addressing these concerns through evaluating viable and environmentally responsible cotton production systems.

Weediness as a concern Northern Australia commercial cotton production systems would be based on genetically modified Bt cotton. This technology would be the foundation of IPM systems, which would effectively minimise pesticide use, but raised environmental concerns about the ecological effects of the transgene. One such concern was potential weediness, and whether the addition of the Bt gene would give an ecological advantage over conventional cotton in tropical areas. G.hirsutum evolved in tropical and sub-tropical areas, and isolated naturalised populations exist in northern Australia.

So, the question was “Could the Bt gene enhance the ability for improved cultivars to become naturalised, or alter the ability of existing naturalised populations to persist?” The Office of the Gene Technology Regulator (OGTR) and Environment Australia (EA), requested that these weediness risks be evaluated prior to commercial release of Bt cotton in northern Australia.

Answering the question A project commenced in 1999 to evaluate the potential for increased weediness of Bt cotton. This was done by comparing the growth and development of conventional and Bt cotton (containing combinations of CrylAc, Cry2Aa and Cry2Ab genes) in a range of habitats at Katherine (Kath), Kununurra (Knx) and Broome (Bme). These were habitats into which cotton could

3 Invasiveness was calculated for each of the two initial years of the project to allow populations to reach a more stable threshold in the second year after the initial establishment year, where seedling mortality was high.

The main body of the project was concluded at the end of 2001 with preliminary results included in a submission by Monsanto to OGTR in mid- 2002 for commercial release of Bollgard II in northern Australia. The response from OGTR was contained in the document DIR012/2002 (see www.ogtr.gov.au/rtf/ir/dir012finalrarmp.rtf ) where specific regulation continued to be required for ° releases north of latitude 20 south until further The Kununurra Drain and Broome cattle yard information on weediness could be provided. sites were conducive to establishment of cotton volunteers, but there was no increase Final Report in invasiveness for transgenic cotton The final report for the initial two years of the compared to conventional cotton. weediness project was published in November 2002, and made publicly available for perusal by environmental, scientific and regulatory bodies (http://www.cotton.crc.org.au/Assets/PDFFiles/TB 3051.pdf or DBIRD Publications Section). The Field Code Changed main findings presented in the report for the original 13 sites sown in the first year include:

 Within each site, seedtype was the main Formatted: Bullets and factor influencing germination. Seedcotton Numbering had the lowest germination rate, attributed to higher moisture requirement for imbibition, and also emergence difficulties from the lint. This has important implications for invasiveness. Seedling recruitment from established volunteer plants would be from seedcotton only, so the number of plants establishing for subsequent generations would be relatively small.  There were highly significant differences between sites for all the attributes measured.

 Poor establishment, growth and development Formatted: Bullets and occurred at all the native bush and roadside Numbering habitats. It is unlikely that cotton will be invasive of undisturbed natural habitats.

 Five sites had no plants remaining, and the Formatted: Bullets and remaining six sites had less than 3% of plants Numbering surviving from the original number of seeds sown.

 Only two sites, (both disturbed by human Formatted: Bullets and actions), an irrigation drain at Kununurra and a Numbering cattle yard at Broome had greater than 50% of plots with surviving plants, corresponding to less than 15% of plants surviving from the original number of seeds sown. These were the only sites from which plants produced viable open bolls and subsequently recruited some seedlings.

 Mean values for invasiveness were not greater Formatted: Bullets and than one for any genotype at any site, although Numbering Seedtype was the dominant factor affecting some individual plots in some habitats produced germination within each site. Seedcotton had values greater than one. This indicates that the lowest germination of the three seedtypes. cotton populations, independent of genotype, will not be invasive weeds of non-agricultural habitats.

4 experimentally quantified, it was concluded that the addition of the Bt gene was unlikely to enhance the weediness of these naturalised populations. This was supported by a number of aspects including;

 The possibility for gene flow from Bt cotton to these populations is effectively zero due to their geographic isolation from suitable production areas. Any populations which may overlap with production areas could be easily eradicated.

 Indications that Bt susceptible insects are not a Formatted: Bullets and significant constraint to the growth of existing Numbering cotton populations and that fire, water availability and soil fertility are greater determinants of establishment of cotton populations.

 No evidence that existing naturalised populations Formatted: Bullets and are invasive of their current habitats, to which Numbering they have adapted. The Roper River catchment is an area potentially suitable for commercial  Experimental evidence from the multi-site study, production in northern Australia. It also which indicated that the Bt gene did not enhance contains populations of naturalised cotton the ability of improved cultivars to become a as shown here on the banks of the Roper weed. River. The answer Monitoring of naturalised cotton populations None of our results indicated that the addition of the There are approximately 60 recorded populations Bt gene would enhance the rate of population growth, of naturalised cotton in the NT. A number of or invasiveness of cotton in northern environments. these were monitored to provide supplementary We concluded that the commercial release of Bt information on whether the Bt gene may modify cotton in northern Australia posed no greater hazard the ability of these populations to persist. The than conventional cotton. majority of populations occur as isolated patches in littoral, coastal or floodplain fringe habitats. Figure 1 illustrates the known locations of naturalised cotton in the NT, in association with potential suitable cotton growing areas. Although the effect of insect herbivory was not

Figure 1. Feral (naturalised) cotton populations in the NT. Shaded areas represent potential growing regions in the NT. 5 Discussion Do you have a Grapevine? While we believe our two-year study clearly indicates that cotton is unlikely to survive and National Grapevine Leaf Rust Eradication establish in most habitats, we continue to monitor Program our experimental populations at two sites for an extended period. Measurements are continuing at A new plant disease that only affects Grapevines was the Broome Cattle Yard and Kununurra Drain detected in Darwin in July 2001. This disease is sites, with data indicating that the populations are caused by the fungus Phakopsora euvitis and is continuing to decline. The extension of population common throughout South East Asia. At this stage monitoring at these habitats with the greatest risk the disease has only been identified in urban Darwin, of cotton volunteer establishment will better Palmerston and a few vines in the rural area. represent population dynamics of a perennial plant and provide greater scientific rigor in the A DBIRD team is carrying out an eradication estimation of invasiveness over time. This program. So far 640 vines have been identified from updated information will be included in a survey of 38,000 properties. Over 50% of these subsequent submissions to OGTR for commercial vines were positive for the disease and these vines release of Bt cotton in northern Australia. were removed. Re-testing of the residual vines is now under way. Cotton development in northern Australia continues to be an emotive issue, with considerable interest from local communities, pastoralists and fishing bodies on the possible environmental impacts of such an industry. Establishment of a commercial cotton industry based on Bt genotypes may lead to incidences of volunteer cotton plants in specific niches. However there is no indication that the likelihood of this occurrence would be increased due to the addition of Bt genes as compared to an industry based on conventional cotton. Therefore it is a volunteer management issue rather than a gene regulatory issue. Bt cotton would form an integral component in the development of an environmentally sustainable industry based on responsible utilisation of the land and water resources of northern Australia. A healthy grapevine

This article appeared in The Australian Cottongrower Magazine - April/May 2003 edition, p26-30 Rowena Eastick Cotton Agronomist

PASTORAL VET SERVICES

Business moved from Kununurra to Darwin. Continuing to provide vet and consulting services to the NT and Kimberley region.

 Pregnancy testing  Cattle spaying  TB testing  Horse and dog medicine and surgery An infected grapevine  Cattle nutrition advice More testing of rural and remote vines is required so  Bull testing if you have a grapevine please call the hotline on  Rangeland monitoring 1800 001 565 and help protect Australia’s $4.4 Billion  Vet supplies a year wine and grape industries.

Matt Bolam BVSc Quarantine requirements are in place to protect the Phone: 8985 6355 NT $20 million table grape industry at Ti Tree. Mobile: 0408 920088 Email: [email protected] Graham Schultz Address: PO Box 1251 Operations Manager Nightcliff NT 0814 NGLREP

6 Searching for the Calligrapha beetle that feeds on the weed Sida

Has anyone seen any calligrapha this year?

Calligrapha eggs

The Weeds Branch (Department of Infrastructure Planning and Environment) are trying to get hold of the beetle. We want to build up numbers of the insect as early this wet season as possible.

The biological control agent, Calligrapha has been released on the weed Sida since 1989. It has become widely established but its numbers Calligrapha larvae fluctuate over seasons and over years. It is essential that calligrapha finds green sida over the A late wet season and long dry do not help its dry season to survive. The beetle becomes survival and they need people to move them around difficult to find over the dry season as the weed to help spread and increase their population. But its dies back, surviving on whatever green sida it can numbers can build up quickly and if they are put into find. Calligrapha finds refuge in areas where sida a sida infestation early enough they are very can source water such as creeks, water troughs, damaging. leaking taps. The Weeds Branch are hoping to get hold of the beetle early this wet season and if anyone has seen the calligrapha beetle could they please contact the Weeds Branch on 89 992266 or email: [email protected]

Sida Plant – close up

Sida Plant

7 Buying Seed – are you getting The Germination test shows what is expected to grow in the field, eg: Germination 40%, Hard 35%, what you are paying for? Abnormal 5% Total 80% Dead seed 20%

With the large variety of Seed Certificates For explanations on these and other tests contact: available on the Australian market, information on Albert Simonato a Certificate can be confusing and sometimes Senior Seed Analyst hard to find. NT Seed Laboratory Phone 8999 2236 The Northern Territory Seed Laboratory staff can help with this information and explaining any terminology that is hard to understand. Listed Seed Quality below is some of the information to look for BEFORE buying seed. Seed quality is often taken for granted or overlooked when buying seed. However, the higher cost of a 1. Before buying seed ask the supplier for a good seed line is generally worth the expense if current Seed Certificate, This can be faxed examined on a cost/benefit basis. through. Low quality seed can lead to establishment failure 2. Check that the testing was done by a especially under marginal planting conditions. Re- recognised Seed Laboratory. planting operations and lost planting opportunities are 3. Check the date on the Certificate to see when costly and are irrecoverable losses to farm profits. the test was completed, A current Certificate Good quality seed: should be less than 6 months old, preferably . increases the chance of uniform germination only 2-3 months old. . reduces the risk of crop or pasture establishment 4. Check that the seed named on the Certificate failure is what you want/need. 5. Check what sort of tests were done on the The quality value of seed is determined by assessing seed. purity (ie, freedom from inert matter and weed seeds) and germination. This is called "pure live seed" or 6. Check if any other seed contaminants in the PLS and this is a yardstick of quality when buying purity are listed as Declared or Prohibited seed. The table below shows the importance of seed under the Northern Territory legislation. pasture seed quality. Different planting rates of each seed line are needed to sow 70 'live' seeds/m2. When the seed arrives check that the Lot Number on the Certificate you have been sent matches the Line A: Good quality; priced at a reasonable figure. Lot Number on the bags. If not ask for another Certificate for the different lot number, if one isn’t Line B: Average quality seed line with a reduced price. sent, send the seed to the Northern Territory Seed Line C: "Cheap line"; germination and purity both low. Laboratory for testing ( the tests required are generally BULK SEARCH, PURITY, and Table1. Determining the cost of lesser quality seed. GERMINATION ) or return the seed back to the supplier. Line Price Quality Pure Planting Cost (purity x live rate* of live Information, the tests above will tell you are ; germination) seed kg/ha seed % $/kg . Bulk search- what other seed is in the sample A 10.00 80 x 40 100 32 2 20.00 if any ,including weeds –( number/kg.) B 6.50 70 x 20 100 14 4.5 29.50 . Purity – how much pure seed, inert matter, C 4.00 60 x 10 100 6 10.5 42.00 other seed if in the sample in (%) . Germination – Germination – how much will * to give equivalent planting rate of live seeds germinate (%) The 'cheap' line of seed (ie: line C) is clearly the more Hard – Dormant – Legumes (%) expensive purchase. Very high seeding rates of the Fresh – Dormant – Grasses (%) lower quality seed line are required to achieve the Dead – Dead (%) same result as the expensive 'value for money' seed line. Some Certificates will have Viability Test results instead of Germination Test results on the seed Albert Simonato The difference between the two types of test is; Senior Seed Analyst The viability test will show the percentage of NT Seed Laboratory Viable seed and Dead seed in a sample eg: Live seed 80%, Dead seed 20%

8 The Australian Rangeland Society 13th Biennial Conference

Staff in the

5-8 July 2004 DBIRD

It doesn't get better than this! An Australian Agriculture Rangeland Society Conference held right in the very heart of Australia. Our theme, “Living in the Section Outback” will examine the topics of risk management, indigenous land management, biodiversity monitoring, business systems and wish you and multiple use. We will explore how isolated people, with a wide variety of values and needs, create your family a opportunities within the environment of Australia's rangelands. very safe and Attention land managers and students: heavily discounted registrations available Happy Christmas

For a draft program and to register your interest go to: and New Year! www.austrangesoc.com.au/conferences.asp or contact:

Sarah Nicolson, Intercomm Event Coordination 22 Edmund Ave, Unley, SA 5061 Ph: (08) 8357 3378 Email: [email protected]

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