I actually work in a bushcrew and spend many long hours spraying out weeds around native plants.

With herbicides in general it is a matter of dosage as to whether or not the plant will be killed or even made signicantly ill. With Roundup in particular you really have to get close to 100% coverage before it will have a significant effect. Even then with mature trees and shrubs they would be more than likely to bounce back eventually from the thousands of dormant buds.

So you can safely hit a small proportion of mature trees and shrubs in attempts to kill the weeds growing under them. It will kill the leaves and green stems hit by the spray but it is highly unlikely that the whole plant will die, unless it was previously stressed perhaps. If you don't like the look of a few burned branches then just prune them off before or after spraying.

Where you have to be careful is with smaller herbs and lilies etc where there is much less biomass and therefore often much less coverage with Roundup is required to kill the plant. Aim to hit no part of them and have a spray bottle handy if you accidently do so.

As Roundup is particularly efective on grasses and other monocotyledons that don't have bulbs or tubers. So plants, like Dianellas, are particularly sensitive while bulbine lilies and chocolate lilies will come back.

You can protect small sensitive plants with milk cartons, soft drink bottles or tree guards and then spray the weeds liberally between them. Any weeds that are to close will have to be hand removed, cut & painted or herbicide will have to applied to the leaves with a paint brush.

I work in a bush-regeneration crew too, however it is very rare that we do any spraying, this is more to do with the type of plants we are targeting and the approach to the work that we have, than any real aversion to spraying (we use the cut and swab method mostly). I think the advice that you need to get nearly 100% coverage to kill a native plant is somewhat flawed, I would be surprised if any bush-crew has actually tested this theory, because it would involve a very high level of carelessness. There are many native plants known to have a very low tolerance for Glyphosate (Roundup), in fact I would suggest it is one of the worst chemicals for off target damage. Greg, you are right to point out the variables involved, but I would simply say that the more careful you can be with spraying the better, certainly aim for good coverage of the target weed, but there is very little reason why you should need to hit a non-target at all, particularly in a domestic situation where you have all the time in the world to be careful. The suggestion to spray liberally is open to interpretation, it is actually quite difficult to spray as low as the per hectare rate that is indicated on the label of Glyphosate products and the majority of people outside of agriculture are spraying at rates more than double the recommended.
Artie, in reference to your question regarding long-term poisoning of the soil, I have a very careful approach to the use of chemicals, but when I bought my house I had a similar kikuyu problem and I resorted to the use of glyphosate, it was a once off, and I planned to plant out the areas and mulch heavily, so I knew I would not be using chemicals year in year out. When you say you have problem along the fenceline, if this is an area where you want absolutely nothing growing you may be looking at the long-term use of chemicals, which could be harmful to your soil. If you dont want a weed problem, you will need to plant something else to offer some competition to the weeds, maybe a low-growing ground cover. Nature hates a void and if you don't plant something, then more than likely a weed will find its way there.

Good Luck, mudlark

Hi Greg and Mudlark,

Thank you both for well-thought out, lengthy answers to my post - fantastic stuff.

I took great care to avoid spraying *any* of the native foliage when I sprayed the weeds yesterday, but I guess I'll really only find out in the coming week whether there was any 'collateral damage'. My previous experience (front fence) was initially positive, but I have lost plants in that area for no apparent reason, so I may have counted my chickens a little early.

Re the long term use of herbicides, it either that or take my neighbours to court. They dont seem to mind having grass of a metre or more along their side fence, and this naturally extends through the wire into my yard. I'm sure I'm not the only one who is envious whenever I see photos of gardens where the boundaries are 2 metre high brick or stone walls - talk about bliss !

Back to reality - I'll try to keep the spraying to a minimum, and try your suggestions re groundcovers, although I would have preferred my shrubs to have reached 2 metres before I bought in the ground forces :)

Hi Artie,

"gardens where the boundaries are 2 metre high brick or stone walls - talk about bliss !"

I know how you feel - if only I could afford that too!

You might also consider trenching the boundary and placing a plastic root barrier. I believe kikuyu roots can get reasonably deep. Also, what about placing a concrete strip at your boundary, say 200 mm wide over the top of the root barrier. That could at least place any kikuyu runners in plain view so that they would be more easily dealt with, by a spade if you don't like using a whippersnipper. (I don't have one of those either - I must be a reactionary because it seems just about every gardener in Australia has one - we're very "edge conscious".)

Cheers,
Frank

On the rare occassion that we use weed & feed or similar, we have a huge piece of board/cardboard and hold it up against the tree/shrub to protect it. You may also be able to use this method along the fenceline - rest the board on the ground against the fence, lean it inwards a bit towards yourself and lean over it to spray along the fenceline. This should protect your plants and blast the neighbours weeds.
We have used copper logs 1/2 sunk into the ground to help (a bit) keep back neighbour's grass.

Thanks Amelie. For all my fantasies of 2m high brick walls around my boundary, I know that grass seeds travel, so I cant place all the blame on my neighbours. Replacing every blade of grass with groundcovers or paving/crushed stone paths will be a long and expensive process, but thats my ultimate aim. One of the ironies of buying a house is that you can finally get stuck into a garden of your own, the irony being that your bank balance is usually several thousand dollars short of the figure needed for the required hard landscaping. C'est la Vie :)

Just thought I'd err on the side of caution and mention that in some states, South Australia being one of them, there are chemical trespass laws making it illegal to cause any intentional or unintentional 'drift' onto neigbouring properties. These laws are designed to protect us from agricultural pesticides but I believe they apply across the board.
*end of disclaimer* - *winks*

cheers, mudlark

I used Roundup for 20 yrs. in no till farming, and find it a marvellous product, provided all the precautions (as outlined by others in previous posts) are observed. In retirement I still use it for weed control around my Aust. plants, and along fencelines to keep the neighbours weeds out.
It is in my opinion the best option to kill weeds without all the effort of digging them out.
However observe all the label recommendations. In the event that there is overspray on desirable plants, if you douse them with water within a few minutes of the 'accident' you will not harm your garden plants.

Mudlark don't assume from that post that I am careless when spraying, nothing could be further from the truth. If it is possible and practical with the mature trees and shrubs then I will either prune the lower branches off or push them out of the way to allow me to spray the weeds underneath. Obviously with smaller and more sensitive plants we will hand weed around them.

In garden beds we also do not worry to much if we hit even a large number of Solanum seedlings in order to get the Gallium among them. We see Solanum seedlings popping up every where so the ones we kill will soon be replaced but the Gallium is a nightmare if it is let go.

It all has to be balanced with the limitations of running a business, limited time and limited funding for each job.

However there is little doubt in my mind that a 30 foot high gum tree or a 3 metre wide Boobialla will not be significantly effected if I hit one small branch. If they can survive a raging bush fires that takes out all the foliage then they can survive a minute does of Roundup.

I would also point out to artview that you can safely spray trunks and branches with Roundup as long as they are not green.

Do what you think you should do artview, prune the branches of your natives out of the way, tie them up out of the way, push them out of the way, pull the kikuyu runners (without breaking them) away from the foliage, protect the foliage of your natives with plastic bottles or bags or just put up with a bit of burned foliage BUT make sure you spray every last bit of the Kikuyu otherwise it will soon be back.

Hi Greg, My comments regarding carelessness related not to the whether or not a eucalypt would die if you were to "hit one small branch", but to the following from your contribution above, which I beleive is bad advice, especially on an internet forum:

"With Roundup in particular you really have to get close to 100% coverage before it will have a significant effect."

This is simply not true, there are too many variables involved and it would have been quite remiss of me not to address it, particularly as we work in a similar industry. Your comments suggest that I was probably right when I wrote that no bush regeneration crew would have tested this theory....it flies in the face of what the conservation industry is trying to do; firstly in terms of protecting native vegetation and secondly in preventing the unnecessary wastage of chemicals, and thirdly in addressing the broader environmental burden of carrying a greater chemical load than is neccessary...even a chemical like glyphosate which has, in the past, had the myth of being a non-residual, low-toxic, quick-fix heavily promoted.

Respectfully, mudlark

Hitting the odd small branch has little bearing on greater chemical loads. If it comes to that we would all be hand weeding exclusively but that it just not practical is it. Perhaps one day we will be spraying out biological control agents rather than herbicides.

You were right in hind site, perhaps "With Roundup in particular you really have to get close to 100% coverage before it will have a significant effect." was a bit too general. But it is certainly the case with Kikuyu and Couch and I have learned that from first hand experience.

No doubt smaller coverage will do significant damage to a native shrub and none of us want that. However again my experience thus far tells me it is unlikely to kill them out right even if you did hit 100% of them. Have hit some weedy shrubs and broadleaf weeds with roundup and it has had little or no effect on them.

Something like Garlon is far more potent and you have to be a lot more careful. But even then I have hit a small amount of mature shrubs unintentionally or unavoidably, been back later and seen that it has not had any lasting effect.

And any way this whole thing is about planted garden beds and not sensitive remnant sites. If there is any doubt or if it is practical then I always remove the branches in question anyway.