Reserve’s red blush a worrying sign

THOSE residents who live near or enjoy the bushland adjacent to the south-eastern end of Fred Campbell Drive will have noticed the explosion this year of the distinctive Mickey Mouse Plant (Ochna serrulata).

Last year there seemed to be barely more than a smattering of these bright red-tipped bushes with their green berries that turn black as they mature.

The trouble is that our birdlife just loves those berries. They dutifully eat and spread their seeds when they poop elsewhere ... so now the bushland that stretches out eastwards towards Bridgeman Downs is riddled with Ochna growing up to 3-4m in height and, in places, quite densely clumped.

The really bad news is that it’s not at all easy to eradicate, according to experts.

(You can read lots about Ochna serrulata online, thanks to the Brisbane Rainforest Action and Information Network.)

Pine Rivers Shire Council has contracted a specialist weed control firm, Technigro, to treat a portion of the Dawn Road Reserve’s Ochna infestation, primarily along each side of the new fire trails.

PRSC’s supevisor, natural areas, Kat Smith said the council is starting its weed-control program along the fire trails and then working its way further in over time.

One initial benefit of this will be weed management along the fire breaks to improve access and reduce fuel load.

Technigro’s technical officer, natural areas and mosquito division, Steve Milner toured the trails earlier this week as two technicians from his company began what could be four weeks or more of work treating the infestation to the council’s specifications.

Initially Technigro's task is limited to treating the fire trails themselves and a 10m buffer on either side.

“Over the coming weeks, we’ll be treating the Ochna with a combination of diesel and the herbicide called Starane 200, which we will mostly apply as a stem spray as part of a technique known as basal barking,” Mr Milner explained.

“Sometimes we will need to use the cut-and -swab method instead. We will also do a follow-up foliar spray to kill off any stragglers.’’

He said the addition of diesel to the herbicide helped the plants draw in the treatment to their circulation systems more efficiently.

“Because we use diesel, residents may notice a ‘fuel’ smell initially,’’ Mr Milner explained, “but the diesel itself evaporates pretty quickly and poses no danger at all.’’

He gave a reassurance that the treatment would not cause harm to surrounding plants, nor would it wash off and into the creek.

However, the Technigro team did say the mixture is likely to take three or four weeks before it begins to affect the particularly hardy Mickey Mouse Plants that have been treated. The initial symptoms will be discolouration and wilting of the leaves.

Ironically, because the plants are now flowering and producing fruit, the effects of the treatment may take a little longer to appear.

Nevertheless, Mr Milner said, treatment is best done while the plants are growing in the warmer spring/summer months rather than during their dormant periods in the cooler weather. For example, the same treatment applied in the winter months could take up to six months to take effect.

Any unripe seeds will still be drawing nutrients from the main body of the plant, so they will be affected if the plant is treated.

However, Mr Milner confirmed any ripe (black) seed still on treated plants will no longer be accessing nutrients from the plants so, while the herbicide will not pose any threat to birdlife who might eat the ripe berries, the seeds inside the berries will still be viable – i.e., able to reproduce new plants wherever they fall or are deposited.

What is especially worrying for those of us interested in the Dawn Road Reserve, is that local, interstate and international horticultural experts agree Ochna is terribly invasive.

The Technigro team members treating the Dawn Road Reserve described Ochna as a “very tough, aggressive, persistent, adaptable pest that will out-compete native vegetation for space, water, light nutrients and its seeds will even germinate in deep shade”.

Take a walk down the fire trail that heads due east from the end of Fred Campbell Drive and you can see for yourself just how fast and far this pest has spread. It has even out-done the lantana!

For Steve Milner, who has more than 20 years of weed-management experience, and his technicians, this particular infestation of Ochna serrulata is the worst they have ever seen.

It seems our weather conditions this year have been perfect for the Mickey Mouse Plant.

Trina McL

(Thanks to Steve Milner for the use of close-up images of Ochna serrulata).