Rust is a common name for a group of fungi. Rust looks the same on many types of plants, but actually each plant is attacked by a different fungus specific for that plant. Rust first appears as small pustules on the underside of the leaves. The color is generally orange-yellow. Some species of rust fungi are not a typical rust color and have purple or brown pustules instead. In any case, the plant looks as if it has a bad case of measles.
How to make soda spray for rust 2 tablespoons baking soda 1 gallon water 6 tablespoons vegetable oil 2 tablespoons kelp extract Mix ingredients together and spray solution on rust-covered areas. Repeat as necessary.
Rust can spread fairly quickly and the infected plants can become stunted or die. Quick action should be taken when rust is spotted.
Remove all infected parts and discard properly. Keep away fallen leaves from around healthy plants. If you overhead-water, do it in the morning and give the plants a chance to dry out during the day. Dust with sulfur to prevent some rust infections but sulfur can acidify the soil, so check the soil's pH before applying. Plant new ornamentals with plenty of room to allow good air circulation.
Beneficial insects are attracted to your garden by coreopsis, feverfew, and sweet alyssum.