Mechanical and Biological Weed Control E16
Dunn, G.1 ; Penfold, C.2
1) Four Leaf Farms, Tarlee, South Australia 5411; 2) University of Adelaide, Roseworthy Campus, South Australia 5371
|Weed control accounts for some $400 million, or
80% of pesticide used by Australian farmers each year. It also remains the major
impediment to the wider adoption of organic farming in this country and possibly globally.
Two non-conventional weed control alternatives are now being investigated, which could
provide farmers with additional tools to compliment other management strategies required
for successful weed control. Preliminary outcomes of trials in progress are provided
1. Mechanical control, using either the rotary hoe weeder (Yetter) from the USA or a harrow comb weeder (Lely and Hatzenbichler) from Austria. These have been trialled pre and post sowing and post crop emergent in pea, faba bean, canola and wheat crops. The rotary hoe weeder was of no benefit in this environment. Conversely, the harrow comb weeder has achieved very effective control under optimal conditions. For this to occur, the crop must either be secure from damage prior to emergence or significantly better anchored than the weeds post emergent. Obtraining such conditions simultaneously with a dry soil surface crust is the main constraint to weed control with these machines.
2. Biological control, using sheep as the weed control agent, in crops which they find unpalatable. Research to date has shown chick peas (Cicer arietinum), faba beans (Vicia faba), narbon beans (Vicia narbonensis), coriander (Coriandrum sativum), and mustard (Brassica juncea) to be unpalatable. Weeds including wild oats (Avena sativa), annual ryegrass (Lolium rigidum) and wireweed (Polygonum aviculare) were grazed in preference to the above species, with little trampling damage. Grazing at light stocking rates during the early stages of crop growth has the potential to suppress weed competition for moisture, nutrients and light, enabling the crop to outgrow the weeds. Later grazing may also reduce the seed set by established weeds.