Noxious Weeds On The Increase

February 14, 2000 The Southern Weekly Magazine

A mild winter and good spring rainfall have resulted in the prolific growth of noxious weeds this season.

Local government, which works closely with landowners, leads the fight against the threat of noxious weeds. We talk to one such council, Wagga City Council, to see what they are doing about this serious problem.

This season has been an incredibly busy one for Wagga City Council's Noxious Weeds Inspector Bob Thurling and his staff at the Wagga city council. Mr Thurling said that due to the mild winter and good spring rainfall there is a larger than normal presence of noxious weeds in the area this season. These favourable conditions have resulted in a growth spurt of many weeds.

Weeds that have flourished this summer include Blackberry, St John's Won, Bathurst Buns, St Barnaby's Thistle, Scotch/Illyrian Thistles, Paterson's Curse, Spiny Burrgrass, Golden Dodder, Silverleaf Nightshade, Buffalo Bun, Devil's Claw, Galvanised Burr, Tree of Heaven, Johnson Grass and Blue Heliotrope.

Noxious weed control is enforced by Wagga City Council, taking control of weeds on its roadsides and property. The Wagga council also inspects weed infestations on private property and issue notices. The maximum penalty for failing to comply with a notice is now $11,000.

Authorities are also able to charge landowners for the cost of follow-up inspections that are required after the issue of notices or for the cost of eradicating noxious weeds where the landholder has failed to comply with a notice.

Public authorities (e.g. government departments, statutory bodies) must control noxious weeds on land under their control, to the extent necessary to prevent weeds from spreading to other land.

Noxious weeds are categorised according to the action required for their control. Mr Thurling said this takes into consideration the extent of the weed, available control methods and the threat of further spread or damage. The category for each weed may vary for each Local Control Authority.

The Noxious Weeds Department covers a vast area of 4866 square kilometres. 'There are 2570 rural holdings, 2350 kilometres of roads and 2300 kilometres of creeks and river banks to monitor," Mr Thurling said. Mr Thurling said that Golden Dodder is now germinating at a very fast rate due to the rise in the river and the amount of broadleaf plants along the banks.

"Golden Dodder is a W1 category (Notifiable. A weed, which is of limited distribution but which poses a severe threat to agriculture, the environment, or the community. The presence of the weed on land must be .notified to the local control authority and the weed must be fully and continually suppressed) and a major threat to farming and market gardens and is distributed through crops," Mr Thurling said.

St John's Wort (classified as W2 - a weed that poses a threat to agriculture, the environment or the community and has the potential to spread to other areas. The weed must be fully and continually suppressed and destroyed) has also experienced rapid growth.

"This has been an excellent season for St John's Wort, the mild winter leading to early germination and the frequent rainfall giving rise to further germinations each time it rains," Mr Thurling said. "These different stages of germination slow down the control program but council staff will cover all council roads at least twice this season," he added.

The spread of Scotch/Illyrian Thistles is also of great concern to the council. "Many farms have had excellent germination on thistles this season mainly due to the ideal conditions - mild winter and good early summer rains. There are large amounts of seedlings appearing in areas where they have not been seen for many years," he added.

The council's inspectors continue to inspect the natural gas pipeline for any outbreaks of Pathenium Weed.

"We are also keeping an eye on the cropping industry because of the numbers of harvesters that come into this area from Queensland where Pathenium Weed is a major problem," Mr Thurling said.

Silverleaf Nightshade is also of major concern to the council because it is spreading from farm to farm because of cultivation and seeding.

The council also has a significant problem with Paterson's Curse. "Council staff spend a huge amount of time on the control of Paterson's Curse on roads and council land," Mr Thurling said. "Paterson's Curse is spreading throughout Australia at an alarming rate. Cost of control is expensive and due to the rise in costs and lower prices for produce in the fanning community less is being spent on efforts to control this plant," he said.

Like several other weeds it is trying to control, the Wagga council has an extensive biological control program on Paterson's Curse. "All agents that have been released at nursery sites have established with larvae being found in most sites. "This control method is very slow. It takes up to 10 years for the insect numbers to build up at each site to see any reduction in plant numbers taking place," Mr Thurling explained. All biological nursery sites must be fenced off so that stock cannot graze therefore damaging plants and insects -eggs and larvae. The agents used are Leaf Mining Moth, Crown Boring Weevil, the Flea Beetle, the Stem Boring Beetle and The Pollen Beetle.

If you have any queries or problems with noxious weeds contact Bob Thurling or Steve Martin, Noxious Weeds Inspectors on 02 6926 9486.