Weed Spotter newsletter issue 18 - November 2016

Garden centre fined for selling a State prohibited weed

A garden centre in south east Melbourne has been fined a total of $4500 for selling the noxious weed horsetail (Equisetum spp) at its Braeside nursery. The Moorabbin Magistrates' Court was told that in October last year the nursery had eight of the plants on display for sale. Prosecutor Tanyth Young said the store manager and a company director had admitted to stocking the plants for most of 2015.

The magistrate fined the company $1500 on each of three counts of offering to sell, display and possess a noxious weed. Agriculture Victoria's Biosecurity Manager for the South East, Peter Kennedy, said it was an important result given the risk that horsetails pose to Victoria's agricultural industries and environment. 'Horsetails are among the world's worst agricultural weeds due to their invasive capabilities,' he said. 'They contain chemicals that are toxic to livestock and have the potential to become persistent weeds of wetlands and other low-lying areas in southern Australia.'

Green stems of a horsetail weed

Volunteer effort hits an all-time high in the fight to eradicate hawkweed from Falls Creek

The Falls Creek Hawkweed Eradication Program has once again succeeded in detecting and treating infestations of hawkweeds (Hieracium spp) in the Victorian high country. This season 104 volunteers, the highest number of volunteers ever, joined in the search for hawkweeds. The volunteers ranged in age from 15 to 81 years old, with some coming from as far as New South Wales, South Australia, Queensland, New Zealand and even China.

Open countryside with volunteers looking for hawkweed

A total of 117 ha was surveyed by volunteers, contractors and Parks Victoria staff. Volunteers surveyed about 48 per cent of this area and contributed 65 per cent of total search hours. There were 28 new infestations found and 22 of these (79 per cent) were found by volunteers. In total volunteers donated 2,906 hours to the program. While much of this time was spent surveying, volunteers helped with a range of tasks including:

organising teams
GPS tracking
flagging infestations
rope marshalling
time keeping
entering data
taking photos
supervising and leading teams.

The eradication of hawkweeds from Victoria's high country is dependent on a consistent search effort each season, to locate and treat these invasive plants. Volunteers make a substantial contribution to this and their involvement is greatly appreciated by Parks Victoria and Agriculture Victoria. If you would like to volunteer your time to this exciting project in the 2016 to 2017 season, you can email hawkweed@parks.vic.gov.au. The email box is monitored from October and the program runs in December and January.

Time to look out for camel thorn

Now is the time to start looking out for camel thorn (Alhagi maurorum) as emergence of new shoots can start as early as October, particularly on lands under irrigation. Camel thorn normally grows best in areas where it can access additional water during the growing season so look out on:

field borders
roadsides
alongside waterways
drainage lines
irrigated land.

Infestation of camel thorn, spiny weed with small pink flowers

Camel thorn is a rigid, multi-branched, spiny shrub commonly 25 to 60cm tall, but can grow up to 1.5m.

In Victoria vegetative reproduction by rhizomes, or re-sprouting root fragments, is the primary factor in localised spread. Its biology and ecological characteristics make it a hard weed to control, particularly once it has established. Early detection and rapid response to prevent establishment is critical to the camel thorn eradication program in Victoria.

Invasive water weed detected in Nillumbik

A large infestation of the State prohibited weed water hyacinth (Eichhornia crassipes) has been treated on a property in Nillumbik Shire, after it was discovered by an eagle-eyed Weed Spotter who recognised the distinctive plant in photos on a real estate website. The infestation was discovered close to the Yarra River, and if undetected could have spread into the river, creating environmental damage and negatively impacting fishing and other water activities.

Green shiny leaves and purple flowers of water hyacinth

Agriculture Victoria Biosecurity Officers removed 377 water hyacinth plants from a pond on the property during June, with several thousand more plants subsequently detected and removed from a second location on the property.

Water hyacinth originates from Brazil and is extremely invasive. It can form dense mats across waterways, rendering them unusable for transport and recreation. Infestations of water hyacinth can also kill aquatic life by preventing light from penetrating the water and by reducing oxygen levels. Water hyacinth is one of the world's worst aquatic weeds and poses a serious risk to our waterways.

Heavy rains: Welcome, but ideal for alligator weed dispersal

While the recent heavy rains across the state are welcome, the downside of this is that the increased waterway flows and flooding are ideal for alligator weed (Alternanthera philoxeroides) dispersal. New alligator weed plants can readily grow from fragments dispersed from parent infestations, to produce new infestations downstream.

A large infestation of alligator weed growing over a waterway

Alligator weed thrives both on land and in water, and it has an extensive and long-lived root system, making it a challenging State prohibited weed to control. The leaves are bright green and spear shaped, growing in opposite pairs along a hollow stem. Flowers are papery and ball shaped, silvery-white and grow on individual stalks. Roots grow from joints in the stem.