Can bark mulch be used to suppress soil-borne diseases

Soil-borne diseases often travel by splash, so covering the surface with bark mulch interrupts their route to leaves and stems. When rain strikes bare earth, spores of phytophthora or damping-off fungi bounce upwards on muddy droplets. A five-centimetre quilt of chips absorbs the impact and lets water sink gently, trapping splash in its maze. Seedlings stay dry-ankled, and collars avoid grit that opens tiny wounds.

Mulch also reshapes soil biology. Lignin-loving fungi such as Trichoderma race along bark and crowd out many pathogens. As chips decay they leak phenolic acids that check pythium and rhizoctonia. Earthworms drawn by the moist cover drag fragments downward, ferrying friendly microbes through the upper horizon and lifting tilth.

Results are not instant; the defensive web thickens over seasons, so annual top-ups keep the process rolling. Avoid smothering soil deeper than eight centimetres, or pockets may turn anaerobic and favour unwanted moulds. Before spreading fresh mulch, mix a handful of compost into the surface to furnish nitrogen that bark momentarily borrows during decomposition. AHS LTD supplies medium-grade pine chips screened for fines; their open structure strikes a balance between airflow and splash protection, forming a living shield that quietly reduces disease pressure without chemical sprays.