Environmental weeds: Trying for ivy control - and how many berries does it take to grow a bush?

During June-September, many berries have been cut off non-Australian bushy shrubs in this area, both in our garden and out in the native bushland and parkland where I help on the Landcare teams. So many bushes of privet, cotoneaster, briar rose, hawthorn, with so many hundreds of berries.

It made me think - why aren't there hundreds of seedlings of these shrubs springing up all over the place, having sprouted from the berries dropped by the bush and by birds?

Perhaps the reason is that a large proportion of berries are eaten and digested before the seeds in them can germinate. In her blog* in July this year, Rosemary (Mt Rogers Landcare Coordinator) writes that she watched silvereyes (small native birds) and mice eating cotoneaster berries. I've noted before that native parrots (crimson rosellas) and currawongs (native raven-type birds) almost queue up to eat the berries - for example, there were five currawongs one day, taking turns on the last bunches of privet in our garden! One can assume that some berries will be collected by insects such as ants - except that ants don't come out very much, if at all, in the cold winters we have here in Canberra.

Anyway, I've decided to do some tests. I've reserved bunches of privet berries and handfuls of cotoneaster berries from our own garden bushes, stored them on the back step in the normal weather, and today (11 September 2011) I've set them into shallow trenches, covered them with soil and watered them.

My idea is to see if seedlings emerge - in a mass, or just a few - and how long it takes. This is a very rough test, and if anything grows I intend to do a more scientific assessment next year.

Ivy is another pest plant that is rampaging - in a creeping sort of way - across the garden here. Like everyone else, I want to find a way to control it, so I've set up two tests so far. The first was simply to strip the growth off a gate post where it was so well established it had grown berries! The stripping took place in mid-winter, when the ivy was probably not growing fast. In the same few days, I also began the second test: thoroughly spraying the leaves of ground ivy with Roundup (proprietary herbicide) and then immediately (within a minute or two) covering the sprayed leaves with a thin layer of mulch.

The results of the stripping are encouraging. (They are a repeat of my experience in another garden where I just pulled the ivy out and off the side of the house, and also pulled out any regrowth later. Excellent control.) Only one stem of ivy remains on the gate post (it was inaccessible to my stripping in July-August), and it has a few new shoots on it now, as we move into spring.  Provided I hook that stem out soon somehow, I expect that growth to come under control easily.

The results of the spraying and covering are negative. The mulch has been breached in a few places by big ivy leaves, and where I pull the mulch back to look beneath it, there is healthy ivy waiting to burst through. However, grasses and other weeds that were sprayed along with the ivy are very dead.

The next test will be to apply two sprays: first a detergent solution, using the detergent from the kitchen for dishes, followed quickly afterwards with a spray of Roundup. It'll be important not to make the leaves too wet with the detergent. The detergent is supposed to break through the waxy coating on the leaves so the Roundup can penetrate into the plant tissue. But if the leaves get too wet the Roundup spray will probably just run off.

When attacking woody weeds in bushland, the Landcare teams work in pairs: one person clears around the stem of a weedy shrub, and then, when the other person with the Roundup bottle is ready, they cut the stem and 'dab' it with Roundup within seconds. That method works very well and should work for ivy - but imagine having to dab every small ivy stem! I've heard that for ground ivy you can run the mower over it and then spray (with a drop or two of detergent in the spray bottle). But again I think that needs to be a 2-person job, with one mowing and one spraying within seconds of the mower passing.

If ivy was coming into our garden through a fence or some similar barrier from a neighbour, where the fence acted as a sort of filter, it should be manageable to cut a small cluster of stems and spray them within seconds with Roundup (again with detergent added).

If successful, that could be a drawback to neighbourly relations. Roundup is supposed to kill the plant right down to the roots. So I might achieve the ivy-control I wanted but lose the friendship of my neighbour - assuming she liked to have ivy growing on her side of the fence. Tricky!

For the rest of the rampaging ivy here, I plan to pull it up and then watch for and pull out the regrowth. It should be a simple and effective way to get this weed under control this spring.

*www.mtrogerslandcare.blogspot.com

Environmental weeds: Merrily berrying!

“A berrying we will go; a burying we will go....”   Well, not the second kind of burying, actually.

It’s remarkably easy and quick to cut the berries off the woody environmental weeds that are flourishing in our garden and in local patches of bushland.

On Sunday, in a 2-hour ‘weeding bee’ on Mt Rogers*, 8 people snipped off enough berries on twigs to fill a box trailer (with cage), packed tight, to about 1 metre deep. Just using secateurs or loppers we completely harvested the red and purple berries on bushes of Cotoneaster (Cotoneaster species), Hawthorn (Crataegus monogyna), Briar rose (Rosa rubiginosa), and Privet (Ligustrum species). These woody shrubs, viciously prickly in the case of Hawthorn and Rose, have been taking over the hillside where we were working, shading out and crowding native shrubs and grasses.

There were signs that kangaroos have been roosting under one of the Privet/Hawthorn tangles, and again elsewhere under a dense Cotoneaster bush. But they can go on doing that — we only cut off the berries on Sunday; the main structure of the bushes is still there, though more open to let light through.

Autumn is the time when the berries are present and obvious, and easy to remove before the birds eat and spread them out everywhere to germinate in spring. Once spring comes, we will return to these bushes, cut the stems near the ground and dab them immediately (within 5 seconds) with weedicide. That is the best way to kill the roots, it seems, to get rid of the plants altogether.

After we’d all had a break for a cuppa and a welcome muffin, the trailer’s owner set off for the green-waste tip, taking the yield of our 16 person-hours of work.

Weeding bees once a month are a rewarding way to spend a couple of hours outdoors (especially if it’s not raining) giving oneself a glowing sense of goodness!!

In fact, I personally think that community working groups are an excellent way to tackle weed control, for species that don’t need to be sprayed in large areas (such as grasses). The more community members who join in, the more that can be done, of course. If the job were to be left entirely to government employees, it would be very costly to pay enough of them to control the woody weeds, because though easy work it’s labour-intensive.

*Mt Rogers, in the north-west part of Australian Capital Territory, is a mound 704 m above sea level (at the top), derived from volcanic activity 425 million years ago (or thereabouts). It is crowned by native bushland, and entirely ringed by suburban gardens, .and it offers fabulous views of New South Wales and Canberra. 

(Vehicles were only allowed onto this track for the working bee.)

Environmental weeds: Surely not in the garden?!

It’s autumn, and the bright red berries on the big evergreen Cotoneaster bushes in our garden are attracting the Crimson Rosellas and other birds, and adding highlights to the fencelines where green is the only other colour. The berries are beautiful! And a problem too!

Say the birds eat the berries and then pooh them out elsewhere, tomorrow or the next day (how long do birds keep food in their guts?), perhaps in native woodland or grassland. Then the seeds sprout and start to take over that patch. Plants that behave like that nowadays get listed as ‘environmental weeds’ — garden escapees, too active, too attractive (e.g. to birds), and altogether too competitive!

So we really need to control our garden Cotoneasters, or their berries (what a huge job!), for the good of the environment. And actually, having thought about it, I’ve just seen how, over time, we can rid ourselves of these plants without losing the benefits they give us now.

Hey, it’s not just our garden! We’re not the only people who have Cotoneaster or Privet, Ivy, Bamboo, Hawthorn, etc. Some gardens have Periwinkle and Honeysuckle and Broom and Gazanias as well! And that’s not the whole list by any means. Environmental weeds are in gardens in every state and territory of Australia. Until relatively recently, these competitors were the sorts of species you normally planted when you bought a house and land in a suburb or country town. The species that are ‘environmental weeds’ now weren’t seen as environmental weeds then. They were welcomed as being fast-growing, colourful and attractive to birds! Just the characteristics they’re now reviled for.

This is a challenge for environmental weed controllers. These plants are widespread in cultivation, and many gardeners want them for the roles they play in the garden. ‘And why not?’, one could ask. It’s only when they escape that they become a problem.

But what a problem! Two really invasive examples are Lantana, and Water Hyacinth. Fireweed, currently on the rampage, may also have ‘jumped the fence’ from a garden originally. And there are many many others.

Okay, back to our garden. We want privacy, beautiful and fragrant flowers, visiting birds, soil held in place by strong groundcovers, and so on. I reckon we must attack our own environmental weed species in stages, replacing one or two plants at a time with fast-growing alternatives such as wattles or bottlebrush! That strategy should spread both the cost and the need to find alternative screening options along the fencelines. Other plants will provide birds with food and cover till the alternatives are big. After all, ours is not the only garden in the area with berries!

You could ask ‘Why bother to control your environmental weed species if other people nearby don’t do the same thing?’. Well, others nearby probably are doing the same thing. The word seems to be spreading. Nurseries don’t sell these species any more, and the Nursery & Garden Industry of Australia has produced ‘Grow Me Instead’ booklets for every jurisdiction. Many people have visited the demonstration garden, at Floriade in Canberra each year, where local environmental weeds (in pots) are matched to replacement alternative species. And many people dump loads of environmental weeds during Canberra’s twice-yearly Weed-Swap weekends (March and October). (They are given a free native plant in exchange for their weeds!)

We’d better get to work on our attack Stage 1, while the soil’s still warm enough to plant replacements. And then there may be some time to get out to join the local Landcare groups’ weed working-bees that are helping clear environmental weeds from the native woodlands and grasslands. But that’s another story...

AM

Related links:

National ‘Grow Me Instead’ program: http://www.ngia.com.au/Category?Action=View&Category_id=151&Highlight=weeds (Nursery & Garden Industry of Australia)

Cotoneaster: http://www.weedsbluemountains.org.au/cotoneaster.asp

Fireweed: http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/profiles/fireweed#

Lantana: http://www.weeds.gov.au/publications/guidelines/wons/pubs/l-camara.pdf

Water hyacinth: http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/profiles/water-hyacinth#

Caption to photo: One of our Cotoneaster shrubs right now. These leaves are about 2 cm long. Other Cotoneasters in our garden have leaves 4-5 cm long, and their berries hang in bunches.