In article >,
Karen AKA Kajikit > wrote:


> If olives don't go feral how come the South Australian government has
> had to officially address the problem in the last few years? Just type
> 'feral olives' into google and up springs a forest of references to
> the Australian problem. Here's just one brief abstract that summarises
> it:
>
> Résumé / Abstract
> The olive (Olea europaea L.), imported into Australia and subsequently
> cultivated for economic purposes, has spread into native vegetation in
> several regions of southern temperate Australia. The impacts of olives
> going 'feral' have only recently been quantified. It is reported that
> native plant species diversity and canopy cover was 50% and 80% lower,
> respectively, in a native eucalypt woodland heavily invaded with feral
> olives. Consequently, feral olives are considered an environmental
> weed as well as being proclaimed a Pest Plant in South Australia. The
> 1990s has seen a resurgence in the olive industry. In response to the
> risk that new olive orchards will be foci for invasion into natural
> ecosystems currently free from feral olives, risk assessment and
> management guidelines were developed by the Animal and Plant Control
> Commission in conjunction with an Olives Advisory Group. Local
> governments and prospective growers can use the guidelines when
> assessing the suitability of a proposed olive orchard. However, if
> olives have escaped from orchards into native vegetation, then their
> removal is paramount. Unfortunately, feral olive control is a very
> costly and time consuming exercise, and requires careful planning
> before doing so. In severe cases of olive infestations, the removal of
> olives may lead to other problems in fragile ecosystems. It can cost
> up to A$15,000 per hectare to remove a dense infestation of feral
> olives, such as the one described in this paper.

I stand corrected. (And it was good that you added that corroborating
abstract.) My experience with olives is limited to California and
Croatia. Evidently you have much more efficient dispersal mechanisms
than we havehere. Rabbits? Platypusses? ;=} I would add that our
rainfall is only about 18 inches/year. We also have many old Eucalyptus
planting in this region and they are also not invasive. On the other
hand, we have had some pretty good rugby teams here at U.C.Davis
(although U.C.Berkeley it tops this year)

D.M.