How do weeds spread?
Environmental weeds via seed, fruit or cuttings can be dispersed in many ways: • Natural mechanisms including wind, stormwater, birds, ants, animals and humans (with seed attached to faeces, fur, feathers, shoes and clothes). • Artificial mechanisms such as vehicles, gardening equipment, dumping of garden waste or moving contaminated soil or mulch. • Garden Escapees. • Vegetative cultivation where weeds have runners, bulbs and tubers.
Storm water runs off surfaces such as roads, car parks, houses and garages, driveways and industrial areas. Storm water can carry seeds and plant fragments kilometres away from the source and often into bushland areas and waterways. Plant fragments and seeds remain viable through this process and once settled, can grow into new plants. It is not only plant material that carries in the storm water but pollutants as well, which increase the nutrient levels of our natural areas. Weeds often thrive on areas where the soil has high nutrient levels.
A Weeds are spread in many different ways depending on the type of plant. Once the means by which a weed has spread is identified preventative measures can be taken. Some of the more common methods of weed spread and possible preventative measures are described below: 1. Bulk Seed and Certified Seed Weed seeds are often found in seed purchased for sowing pastures or crops. Seed may be certified or uncertified and both may contain contaminating weed seeds. Noxious weeds cannot be legally sold for sowing. Certified seed is produced under the strict supervision of the Academy of Grain to ensure that the seed is true to type as described on the label. Certification does not guarantee that the seed is weed-free but does guarantee that the seed lot has been officially sampled and tested in an accredited seed testing laboratory and is free of noxious weeds. Uncertified seed can be produced by anyone, and is produced without official supervision.
There are actually no such things as weeds. When a farmer plants certain seeds which he hopes will produce a valuable crop, he calls any other plant which grows up in his field and interferes with his crop a weed. Basically, though, weeds are plants that do harm. Some are poisonous to cattle and horses. Others injure crops by robbing them of sunlight, soil, minerals and water. Others act as parasites, or serve as hosts to insects or plant diseases that cause harm. Weeds are spread by various means. Some are carried from place to place in fodder, in dust, in rubbish and in manure. But most weeds that cause so much trouble do not spread because of mans carelessness. They have their own devices for spreading their seeds.
