Some observations on weeds

A number of years ago I acquired my current property.  The block had been completely cleared and rivers of erosion ran down the hill.  Just about every weed was present in the pockets that would still support plant life.  In some parts nothing grew and great clouds of red dust appeared each summer.  After collecting every leaf in site (mainly eucalyptus being available) held down by wire netting, I was thrilled when the first flat weed appeared.  I noticed that the earthworm population appeared around these where organic matter had been trapped by the foliage.  On bare, disturbed soil, these tough plants are the first wave in returning natures balance.  If there is a patch of bare soil, something will want to grow there so it may as well be something you choose.  I can think of a number of weeds (some verbascums for instance) that flatly refuse to grow in cultivated areas.

Some plant emit chemicals that inhibit the growth of other plants around them (the more technical can supply the correct term), Shasta daises are one, I think the artemisias are another.  These can be a good initial planting in weedy areas.  Other plants, just by their vigor make wonderful weed suppressors.  Looking down on a thick planting of agapanthus, I cannot think of any weed including the veracious grasses and oxalis that has been able to come anywhere near them.

On pathways, we used fresh sawdust laid several inches thick in autumn so it will compact with the winter rains.  This probably has the same effect as vinegar.  It acidifies the soil to such an extent nothing grows or grows very weakly, that is apart from robbing the nitrogen while it slowing breaks down.  Lasts about 5 years before renewing.  Has the benefit of allowing water penetration and keeping soil temperatures and reflective heat down. Eucalyptus (which I gather you have a few) leaves make an excellent mulch in areas that will not be planted for a while, eg while waiting for a tree to get to some size.  The oil in these inhibits growth until it breaks down, takes about 4 years.  If you require the breakdown to be quicker, shred them.

Well after 10 years, I am left with two triffids, an oxalis that covers several acres here and couch.  Will certainly try the vinegar.  Once again, these are far less of a problem in areas that are heavily cultivated veggie patch and perennial boarders and cause most problems under roses, which requires the crawling around on knees bit.

Bye the way, any of the organic growers out there have a solution for a particularly veriliant aphid.  Only effects a standard pink honeysuckle and curls the leaves so my little vacuum cleaners (tiny birds which go up every stem each morning) and predators cannot get a look in.  Have tried cutting back, white oil, detergent all to no avail, they are there in there millions.  Any suggestions I will try.

Karen Roberts
Perth Hills
Western Australia
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