1 Mechanical digestion is evident, where one can see the breaking down of large food particles into smaller ones after being ground by the teeth. 2  While the chemical changes that take place happen within the body and are not visible.
Using a pre-emergent herbicide around your property could stop these territorial plants from overtaking your home's most valued green space. Pre-emergent herbicide is a type of weed killer that prevents weed seeds from sprouting. Unlike normal herbicide, it is meant to stop weeds from growing in the first place by spraying or spreading a chemical onto the soil so that weeds have difficulty placing down their roots.
Preen is a pre-emergent weed prevention product. It prevents weed seeds from germinating instead of killing existing mature weeds. Preen works on a wide variety of annual weeds, but it won't have an effect on perennial weeds because they already have established roots.