Holly (Ilex aquifolium); a Naughty not Nice bush invader

With its glossy dark green leaves and scarlet red berries its no wonder European culture has long associated holly with Christmas time. Native to Europe, holly was introduced to Australia for ornamental use (Muyt 2001) and has now become a familiar foe in areas with cool, moist climates- including southern Victoria and Tasmania among other places.

 

Holly prefers fertile, deep, friable, moist and well drained soils- like those found within the Strzelecki Ranges. Plants are typically dormant in cooler areas over winter however they may continue to grow during mild winters and in warmer locations. Small white flowers are produced in late spring to early summer with red fruit developing over autumn- winter on female plants. On any given plant, some leaves have sharp triangular spines along the leaf edge while others are spineless.

 

The plant is of primary concern due to its impact on recreation and native vegetation. Holly forms dense thickets, (if left uncontrolled) restricting access to people and vehicles in remote areas or along poorly maintained tracks. The berries and leaves of holly are toxic to people, especially children. Reported symptoms include nausea, vomiting, diarrhoea, collapsing and unconsciousness (the fruit is not considered fatal) (Sheperd 2004). In a damp or wet forest environment, those areas once occupied by tall native shrubs will become dominated by holly creating a poor shrub layer. In turn impacting upon the lower layers of vegetation i.e. herbs and ground cover plants and preventing natural regeneration. Another feature which puts this plant on the naughty not nice list is that it provides a food source and shelter for pest animals. The berries are to some extent eaten by foxes (Garcia, Martines & Obeso 2007) as well as browsed by goats and deer (Obeso 1997).

 

To control holly seedlings and plants less than 1 metre tall can be dug out. Tops are prone to break away when pulled so if roots remain they should be dug out. All removed material should be disposed of appropriately, Larger plants can be controlled using the cut and paint or drill and fill methods. If using herbicide, treat the plant in spring- early summer when the plants are actively growing. Priority for initial treatment should be given to fruit-bearing female plants. For further information on the identification or control of holly please contact Kate Williams, South Gippsland Landcare Network Project Officer on (03) 5662 5759 or email katew@wgcma.vic.gov.au.

 

Kate

Become aware of Coastal weeds over Christmas/New Year

What do Bluebell Creeper, Dolichos Pea and Polygala all have in common? They are low maintenance plants for the garden? This is true however beyond the garden these plants are considered a threat to coastal spots including areas frequently visited over the Christmas/New Year break.

The threat posed by bluebell creeper and dolichos pea is caused by there tendency to spread and form dense matts that smother native groundcover plants and shrubs. Whilst polygala doesn't smother vegetation, (as the others do) it does dominate the understory of coastal woodland. Left uncontrolled, these processes of smothering and dominating can, among other things, simplify vegetation communities making them less equipped to support a range of native fauna i.e. less flora diversity= less fauna diversity.

On the way to or from your local beach spot over summer take the time to see if you can spot either of these plants, (or all three if you're really lucky!) Common areas to look include; next to walking paths through bush on or near sand, the edges of bush in coastal areas or roadsides. What to look for; bluebell creeper as the name suggests, is a shrubby evergreen climber with blue flowers from September to February. Come late summer to autumn the plant would have developed oval fleshy berries. Dolichos pea is a perennial vine with pale mauve to purple pea like flowers from September to January. The type of polygala species commonly found in coastal areas is Polygala myrtifolia, an erect to spreading shrub growing to 3m high. Like the flowers of dolichos pea, the flowers of polygala resemble a pea and are purple to mauve also flowering from spring to summer.

In terms of control, permission should be sought from the land manager before any weed control is undertaken. Should you identify any of these plants over summer, I encourage you to be proactive by working with other locals/visitors or as individuals to seek permission and bring about control to reduce further spread. In a garden situation, there are numerous plants that look similar and can be planted as a great alternative. The south east Victorian coastline is truly special, (hence the vast number of holiday makers come Christmas!) and therefore well worth protecting from weed invasion.

For

further information on identification and control of bluebell creeper, dolichos pea or polygala please visit www.southgippslandweeds.com.au or contact Kate Williams, South Gippsland Landcare Project Officer on (03) 5613 5973 or email katew@wgcma.vic.gov.au. Please note; the plants described above are environmental weeds and not listed as noxious under the Catchment and Land Protection Act 1994.

Broom species

Driving the roads of Victoria during this time of the year, be it at high speeds or a slow Sunday drive, it's hard to ignore the patches of yellow on roadside margins. It's a tell tale sign that spring is here when the daisy shaped flowers of cape weed and pea shaped flowers of broom species are in full bloom.

Whilst cape weed and broom are both in action at the moment, its broom that I will touch on for the purposes of this article not cape weed. The main reason being is that the optimum time to control species of broom is now and in the coming months prior to seed set in late spring to early summer.

Broom is an evergreen plant that can dominate native shrub vegetation growing 3 meters high and wide. There are three species of broom found in the region, Cape Broom (Genista monspessulana), English Broom (Cytisus scoparius) and Flax-Leaf Broom (Genista linifolia). All of the three species of broom are listed as noxious and regionally controlled within West Gippsland.

A common scenario for broom invasion occurs with the plant starting out in disturbed areas i.e. the edge of bushland or next to a water course. Over time, (if left uncontrolled) the infestation will expand into less disturbed areas i.e. within the bushland itself. It's for this very nature of invasion that broom constitutes a fire hazard. For example in roadside areas adjacent to bushland, (where fires are most likely to start) broom can form a flammable understory at the edge of a forest and spread into bushland.

Aside from being a fire hazard, species of broom are a concern to native vegetation given their ability to dominate native vegetation and severely impact regeneration of overstory plants including eucalypts and wattles for example. In addition, the seeds are highly poisonous potentially causing injury to fauna. In terms of its impact on agriculture, broom species are considered a low risk. The plant would not develop in cultivated situations and can easily be controlled by mechanical means.

For the above mentioned reasons, the opportunity to control the plants should be seised this spring. The community are working to keep weeds such as broom under control-your assistance in controlling broom on land under your control will help this effort. Small plants can be hand pulled if the soil is soft enough, larger plants can be slashed prior to flowering and any regrowth should be foliar-sprayed with the appropriate registered chemical.

Soursob

Oxalis pes-caprae

　

Found in range of locations from gardens to roadsides, the noxious weed Oxalis pes-caprae or soursob is a concern primarily in pastures and amongst indigenous vegetation. It is distinguished by three heart-shaped leaflets with or without stalks that fold in dull days or at night. Flowers are bright yellow in colour and open in sunlight and close at night. There are masses of underground bulbs which are spread by water, birds, in dumped garden waste and during cultivation (not to be confused with native varieties of oxalis which have no bulbs).

Although primarily a weed affecting cultivated areas, soursob in pastures has the potential to replace almost all desirable plants from the time of autumn rains to well into the spring reducing carrying capacity. Stock will selectively graze more palatable species than the soursob with its high oxalate content. Soursob has severe impacts on indigenous ground-flora with dense infestations eradicating smaller plants.

In terms of its control, soursob would have to one of the most, (if not the most!) difficult weeds to eradicate. Control is made problematic for two main reasons; firstly it is the vigorous network of underground bulbs that render hand weeding or mechanical removal ineffective. Secondly it is the irritating life cycle of the plant that limits effective herbicide use to a one week window at the bulb exhaustion stage. A one week window that could open at any time between May and July. Suffice to say soursob is a weed that takes several years to control. Another suggested method of control involves using a combination of light exclusion and raking however this would be suited to a garden situation. Cultivation and grazing are generally ineffective means of control.

The optimum time for herbicide control may have come and gone for 2010 but the weed is no more apparent than now. Take the time to check your priority areas of land. Soursob is one to keep in the back of your mind, as spring and summer pass you'll be well prepared to strike with vengeance come autumn next year. Information on how to determine the bulb exhaustion stage will be provided as part of weed talk next year (prior to the optimum control time). If you would like further information on soursob please contact Kate Williams, Project Officer with the South Gippsland Landcare on (03) 5613 5973 or email katew@wgcma.vic.gov.au