It is a common observation that the seasons are not as predictable now as in the past. Particularly unpredictable is the ‘autumn break' which simply may or may not arrive. When it does come autumn rain generally brings joy and productivity especially if the weather remains warm but, unfortunately, there is a downside. Weed germination. Years of low rainfall have left much of Tasmania with bare soil on which there is a much greater risk of weed invasion. Weeds often seem to be the hardiest of plants, surviving bad times to prosper when the chance comes, leaving plenty of viable seed to move on wind, water, stock, muddy boots, tyres and machinery any of which can carry them off to new fields.
It is worth being alert to this because new weed incursions do happen. For example, northern Tasmania was until recently free of Serrated tussock (Nassella trichotoma). A roadside discovery two years ago found the first of this species seen here. It contained only a few plants which were eradicated and the site is inspected regularly to ensure further germinants do not get a foothold. Disturbingly though, a second site was found in the Northern Midlands at Cressy prior to Christmas. While bigger than the first, it still is a manageable incursion. Serrated tussock is a prime example of why weed vigilance is everybody's business. It is a plant that tolerates poor quality, very low nutrient sites, so native pastures and bush run country are particularly susceptible. Add to that the ability of Serrated tussock's seed panicle to move for many kilometres on the wind and suddenly much drought struck or overgrazed land is open to infestation. See here for more information on Serrated Tussock
Stock purchased from other regions, moved to and from agistment paddocks; hay and grain imported from elsewhere in Tasmania or the mainland for feeding out all give rise to potential new weeds on farm. Landholders need to be on the lookout for new plants. Places of particular importance are stockyards and feed out paddocks making sure that any new weeds brought in which do germinate are identified and eradicated. This is worth doing as seeds from many serious weeds can remain viable in the soil for some years.
Apart from new weeds, those we've had a little of but which have not become widespread, like Paterson's curse (Echium plantagineum), are also likely to receive the benefit of good autumn conditions. This could equally favour an increase in the range of current infestations or new introductions. Either way, as a small rosette the plant is most easily and cheaply killed, will have had least impact on pasture and is prevented from setting the next crop of seed. See here for more information on Paterson's Curse
Autumn rain provides a good opportunity to get on top of weeds such as Paterson's curse and many other species including thistles, capeweed, wild radish and wireweed.
DPIW's regional weed management officers can help landowners with the identification of any weeds that have turned up in feed and advise them of the best methods for eradication.
Your regional weed management officer can be contacted on 1300368 550.
Click here for general information on Tasmanian weeds