Rust arises on the leaves as tiny reddish-brown lumps. Yellow splotches will appear on the tops of the leaves. Mint rust is caused by the rust fungus Puccinia methane, which causes dusty patches and pustules on leaves, as well as plant mortality or severe stunting. Mint infested with rust should not be ingested. The leaves eventually die and fall off, leading the plant to become barren. It is aided by overhead irrigation, which causes water to remain on plant leaves for long enough for fungus spores to develop. Due to high humidity around the plants, mints that are densely planted or that need to be thinned are at risk.
The difficulty with rust is that each of the bumps contains hundreds of tiny spores that burst and blow in the wind to other mint plants in the garden, necessitating their inspection as well. They grow inside the plant’s living tissues, extracting nutrients from the cells without destroying them. When these fallen leaves sprout in the late summer and early fall, darker patches often develop instead.
Mint rust can appear as white lumps on mint leaves in its early stages. They can’t live in an active condition on dead plant material, so they have to switch to a perennial host or create resting spores to go through the dormant season. Most people suggest pulling out all infected plants and replanting them in a different section of the area, or planting mint in vessels as an intercrop from now on because it is a fungal problem. Others recommend burning the patch to destroy rust spores, but this isn’t practical for many people because mint patches are commonly located near the home or in raised beds, and you don’t want to start a fire in either of these locations! Infected plants should be removed as quickly as possible, and healthy plants should be transplanted to a different garden bed, but they should be monitored for signs of rust infection.
