Sustainable Gardening. Soils ain’t Soils Part 18.

Welcome to our latest gardening articles written by a passionate horticulturist for our equally passionate local gardening community living on Bribie Island and surrounding districts. Last issue we touched base on the difficulties of eradicating Nut grass, “Cyperus rotundus”, in our lawns and gardens and the difficulties encountered when trying to control an infestation growing in an established garden bed situation. Also touched base on how the Nut grass herbicide: (Sempra)Tm, when applied and diluted at the recommended dose rate, is absorbed and translocated into the nuts (referred to as tubers) in the soil and subsequently destroys these underground storage organs and therefore any re-emergence should not occur. I should mention though, that the whole process from the initial application of this herbicide to the death of the plant can take 3 weeks or more. The leaf blades slowly go yellow and wilt and as the poison translocates its way through the root system and subsequently to the tubers, the plant finally collapses. Unlike Glyphosate, the major ingredient in the herbicide (Round-up) Tm, which kills most weeds but not always the underground tubers. These herbicides are indiscriminate in their mode of action and not practical in turf situations due to the possibility of non-target collateral damage to the surrounding turf, unless the weeds are hand painted with a wicking wand of course.
Now its official, summer has arrived and so has the afternoon thunderstorms, which delivered plenty of rainfall recently which had a tremendous influence on spurring on the growth rate of most plants, lawns and weeds accordingly. Most lawns that I inspected last month had multiple weed species thriving and subsequently, immediate control measures were put in place to control the outbreak. I am very much a sustainable gardener and I try and reduce my reliance on chemicals in the landscape as much as possible but if you have Nut grass, Mullumbimby couch, Oxalis, Bindi or Paspalum creeping through your favourite sward of green, then when these weeds become rampant, flower or set seed, the problem quickly gets out of hand and as a result we become more reliant on herbicides unfortunately and any eradication programs can be tiresome, laborious and expensive and they need to initiated with military like precision, in a programmed maintenance plan.
Now, the weed, Creeping Oxalis, “Oxalis corniculata” (a little trifoliate, clover type weed with dainty little yellow flowers) and also the dreaded Flick weed, “Cardamine hirsute” which both produce a thin sensitive seed capsule that explodes on contact with any weight bearing droplets of moisture or when coming in to contact with our hands or feet or disturbed by animals, hence the common name of the weed being (flick weed), which as a result catapults miniscule little seeds up to 3 metres away from the mother plant, which can make control measures almost impossible and subsequently ‘due vigilance’, is needed when initiating a control strategy for these diabolical weeds. If you have had to use multiple herbicides, insecticides or fungicides on your lawn and garden as of late, it would be a great time to add some organic matter, beneficial microbe brews, (worm or seaweed), light dressings of composted manures to re-establish and feed your soil microorganisms and increase the overall fertility of your sward of green. These natural microbes and composted materials can be added now and will benefit your sward immensely, your soil and lawn will slowly become more resilient and more robust as time goes by. Try using a mulcher mower to recycle the clippings back into your lawn once you have controlled the flowering weed and seed heads, to help assist in building up the soil carbon which also feeds the soil microflora and in turn feeds your turf and plants too. I like to use well composted manures that have been processed and refined to reduce the threat of introducing further weed seeds possibly contained in the manure. So that’s your microbial lot this month and stay tuned for next issue of Soils ain’t Soils, until then- Happy gardening indeed!
By Mick O’Brien. Dip.Hort(MAIH) RH- 101