Fleabane- as seen along a roadside near you!

You can read about in a recent edition of the Weekly Times or see it for yourself- it appears to be everywhere! Fleabane is what it is called. There are three main species of fleabane (Conyza spp.) in Australia, namely tall fleabane, flax-leaf fleabane and Canadian fleabane- they are all considered weeds. Fleabanes are an erect annual herb; single stemmed and can reach 2m in height (tall fleabane, flax-leaf reaches 1m when mature). Stems and leaves are covered with fine hairs.  Leaves are grey green and narrow. Flowers are carried in branched heads with each cluster of tiny flowers being enclosed in a series of narrow green bracts.

Seeds are connected to a parachute of fine hairs and seeds only germinate/emerge from (or near) the soil surface. For this reason, the three closely related species are major weeds in minimal tillage cropping systems where the majority of seed remains in the soil surface. Tall fleabane is the more common fleabane in the Gippsland region found along roadsides, horticultural and non cropping areas.

Fleabane Fast Facts;

·         Tall fleabane is edible to native browsers such as wallabies but rarely eaten if other food is available

·         Crimson Rosellas have been reported eating the flowers of tall fleabane along with deer at the beginning of the flowering period

·         Fleabane is rated as having a medium high level impact on high value native vegetation communities in Victoria namely grassy woodlands and volcanic plain grasslands (DPI Weed Risk Assessment 2007). Dense stands of fleabane can smother native grassy vegetation.

·         Each plant can produce up to 110, 000 seeds of which up to 80% can be viable (Widderick and Wu, 2007)

·         Tall fleabane is the main weed of lemon orchards in Portugal (Economou et al, 2002)

·         Seeds don't possess dormancy, in other words they can germinate anytime throughout the year (whenever temperature and moisture requirements are met)

·         The depth of seed burial affects the seed survival of fleabane

o   When sown on the surface, 5% of the seed remains viable after 12 months

o   When buried at 50mm, 10% of the seed remains viable after 12 months

o   When buried at 100mm, 15% of the seed remains viable after 12 months

As seeds only germinate from (or near) the soil surface this is a true survival mechanism

 

Control

Tackling the problem will require a long term approach based on good agronomy and applying integrated weed management principles in order to prevent or retard fleabane resistance to herbicides i.e. use a variety of chemical and non-chemical tactics.

Given that the plant is an annual, producing thousands of seeds, a control program that prevents seed-set is vital. Crop rotations and planting configurations should be managed to maximise competition against fleabane.

Kate Williams 

Too much Blackberry Jam?

With blackberry infesting roughly 8.8 million hectares of temperate Australia, biological control remains the only viable management option for many infestations (CSIRO, 2011). In South Gippsland there is a great deal of community interest in leaf rust-fungus as a tool for controlling blackberry. Below are some of the frequent questions I'm asked about the biological control agent.

 

What is blackberry leaf rust-fungus?

A defoliating disease host specific to European blackberries approved for use in Australia.  The rust-fungus has fruiting bodies (spores) that damage leaves occasionally green stems, stalks, sepals and unripened fruit and is capable of causing severe defoliation in susceptible species given the right conditions.

 

What are the right/suitable conditions for the leaf rust-fungus to establish?

Light is one of the more important requirements, generally sites that have full sun and or very little shade are suitable.  Sites in open woodland, open creek lines and fence lines etc are preferable.  Shaded sites are typically not suitable.  Rainfall and temperature are the other important factors. Sites receiving an annual rainfall of 800mm or greater with an average maximum daily temperature of about 20°C for the month of January are more likely to be successful (Weeds CRC 2005).   

 

Is the blackberry leaf rust-fungus safe?

Rust spores are not toxic to humans and animals but may cause irritation to people sensitive to pollens and dusts. In such cases, it is recommended to wear safety equipment such as goggles, a respiratory mask and gloves when handling rust spores or infected foliage (CSIRO 2011). Strains of the blackberry leaf-rust fungus (Phragmidium violaceum) were thoroughly tested by the CSIRO before approval was obtained to release it in the environment. They were shown in host-specificity tests to be highly specific towards weedy European blackberries.

 

 

Sounds like a cheap & easy way to solve my blackberry problem! Where can I get some?

You may already have the leaf-rust on your property it's widely established in Australia including in South Gippsland; spores of the blackberry leaf-rust are spread by wind and can travel long distances in relatively short periods of time. Although it can be effective, the leaf-rust will not completely kill a blackberry plant. The leaf-rust relies upon its host to survive, its not going to eat itself out of house and home now is it? Also keep in mind that Biological control will not be effective across the range where blackberry infestations occur and therefore an integrated weed management approach will be necessary if effective control is what you're after.  If effective control is not viable given the size and location of the infestation and costs associated with control etc then the leaf-rust is particularly useful.

 

What if effective/thorough control is viable for me and my situation?

Then don't rely solely on the leaf-rust fungus, use a combination of control measures, (termed integrated control) at an on-going and landscape scale i.e. talk to your neighbours; have a year by year action plan based on resources at your disposal and, (to quote USA sports brand, Nike) Just Do It! True recovery of large areas of land for the production of pasture and the establishment of seedlings in plantation forests should only be expected following this. In areas reserved for conservation of native flora and fauna, control of blackberry infestations is a first step towards achieving an increase in species diversity. Reinvasion by weeds is a recurrent challenge therefore revegetation or pasture improvement strategies should be considered in tandem with any weed control program (CSIRO, 2011).

 

Kate Williams

South Gippsland Landcare Network

Run Rabbit Run!

A visible increase in rabbit (Oryctolagus cuniculus) numbers across south east Victoria has prompted Landcare groups along with the South Gippsland Community Weeds Taskforce to raise the issue.  As were all well aware, rabbits are nothing new to mainland Australia.  Since the late 18^th century they have hopped about the landscape digging warrens, decimating native vegetation, devouring pastures, sustaining fox populations and so on. Rabbits are that common these days that one doesn't bat an eyelid at the sight of bug's bunny peacefully nibbling grass on the roadside edge.

 Is it rabbits 'commonness' that has management efforts falling by the way side? Or is the effort to control rabbits by land managers undermined by the sheer magnitude of the problem? Or rather are we stepping back from the problem and depending on the release of a new biological control agent to save the day? The likely answer is yes to all of these factors.

It's a given that control programs cost money, as a result land managers often rely on once a year poisoning programs. Typically only on their own properties and when rabbit populations are high with no integration/follow up with other control methods. To achieve effective rabbit control effort must be continuous. Therefore it's not the effort that is undermining the result but rather the ineffective methods that are generally used. One needs to be able to; adopt and use integrated rabbit control, kill rabbits at a faster rate than they can replace themselves at all densities, ensure rabbit immigration into your control site is zero, monitor rabbits at low densities and take immediate action if the population increases and maintain a social environment with your neighbours and community that supports the goal of aiming for rabbit free.

The success of the myxomatosis virus released in 1952 was poignant, reportedly wiping out 99.8% of rabbits. However by the 1990's rabbits showed resistance to the virus and their numbers once again climbed back into the millions.  From 1996-1998 the Rabbit Calicivirus Disease (RCD) reduced rabbits by >50% in arid areas however once again, as with the myxo virus, numbers have bounced back.  If the history of biological control agents is anything to go by then we shouldn't depend on it to keep rabbit numbers under control, at least not in the long run.

If we stop tolerating the 'commonness' of rabbits and start to adequately control numbers we stand to win big time. A dairy farmer in Colac, Victoria (similar growing conditions to parts of South Gippsland) increased his milk production by 300% and doubled his fodder harvest over 5 years simply by tackling his rabbit problem. A sheep farmer in Colac, who also managed his rabbits effectively, increased his dry sheep equivalent from 1.75 to 7.75 over a 5 year period.

Whilst researching the topic of the impact on native vegetation from rabbits I came across this insightful quote; 'What's the difference between chainsaws, bulldozers and rabbits? Not much really. Though chainsaws and bulldozers are the preferred tool for clearing land, rabbits are just as effective. They eat tree seedlings so that when the mature trees die there are no young ones to replace them. The net effect is identical, only the time scale differs' (Pickard 1995, Managing Vertebrate Pests; Bureau of Resource Sciences and CSIRO).  Adequate control would give native vegetation a chance to regenerate and ultimately lend itself to providing habitat and food for native wildlife that was previously displaced by rabbits.

It's important to recognise that rabbits do impact us economically, socially and environmentally. We must not wait for the next biological control agent but rather act now to control their numbers using a variety of techniques, continuously and in coordination with our neighbours, (including public land managers) and local community. For further information on rabbit control visit the Department of Primary Industries (DPI) website at www.dpi.vic.gov.au or contact the South Gippsland Landcare Network Project Officer Kate Williams on 5662 5759 or email katew@wgcma.vic.gov.au. To record rabbit sightings in your area visit www.feralscan.org.au. Feral Scan is a citizen science website where you help map feral animals and the damage they cause.

Reference

Bloomfield, T., Paroz, G. Rabbits and Their Impact October 2010, LC0298 Department of Primary Industries, Attwood.

Photo caption: A single pair of rabbits (Oryctolagus cuniculus) can produce 30-40 young a year.

 

 Kate Williams, South Gippsland Landcare Network Project Officer

Wandering jew or trad (Tradescantia fluminensis, syn. T. albiflora) Environmental foe or Chicken delight?

The waterways in South Gippsland are well aquatinted with this weed from South America.  It loves nothing better than shady spot down by the river where it thrives on silty alluvial soils.  It's not a huge fan of being submerged in water but it does tolerate the occasional flood and will put up with being waterlogged ever now and again.

Wandering trad has hairless leaves which are glossy, slightly fleshy and dark green in colour. A distinctive feature of the plant is its stem-clasping leaves at the base. Flowers are white, about 1cm across displayed during spring and summer. Fruit is not formed on the plant in Australia therefore it does not spread by seed but rather by broken off sections of stem taking root.

As the name suggests, it wanders about and forms dense mats that smothers all native groundcover vegetation in its path. Subsequently preventing natural regeneration of trees and shrubs. Over time, (in a stream bank situation) this process causes eventual loss of native tree and shrub cover which can lead to erosion.  This makes wandering trad an unpopular addition to the natural environment in Australia. 

In terms of its control, there are several options (see below). Using a combination of these, (based on site specifics and resources at hand) is the best method.

Manual removal: small infestations can be dug out ensuring that all stem fragments are removed, (if not they will regrow) and disposed of appropriately. 

Solarisation: covering the plants with plastic sheeting for 6 weeks in the warmer months will weaken the plant (sunny situations only, this will not be effective in full shade). After removing the plastic any regrowth can be dug out or sprayed.

Herbicide: spraying with selective or non-selective herbicides, (using a surfactant) will work eventually but repeat treatments will be required. Herbicides registered in Victoria for use on wandering trad can be found on the APVMA website; www.apvma.gov.au.  

Alternative uses: Julie Cave, Blue Mountains City Council Bush Regeneration Team member has made some suggestions for the use of trad which include; turning the plant into liquid fertiliser or compost. Read more on this by visiting http://www.weedsbluemountains.org.au/index.php.

Whilst researching control methods for wandering trad I came across findings that suggest ducks and chickens love the stuff. Apparently Muscovies and chickens consume wandering trad readily with no ill effects (given that the plants have not been sprayed with herbicide). If someone works out how to drive a flock of ducks down to an infested gully for some crash grazing we might have another viable management tool. In a domestic situation, those with chooks (and wondering trad) may have themselves a cheap and useful solution to the problem.

For further information on the identification of wandering trad visit www.southgippslandweeds.com.au or contact Kate Williams, South Gippsland Landcare Project Officer on (03) 5662 5759 or email katew@wgcma.vic.gov.au. Information from this article taken from Wandering jew (Tradescantia fluminensis, sny. T. albiflora)  http://www.esc.nsw.gov.au/site/Weeds/Sheets/herbs/H%20Wandering%20jew.htm, Eurobodella Shire Council, NSW.

Kate