Rust and Mildew on Landscape Plants

Rust and Mildew on Landscape Plants

July 28, 2017

With the wet and humid summer we have had so far we have seen many fungal diseases affecting trees and shrubs. Two of the most prevalent have been mildews and rust.

RUST:   It’s easy to spot rust on a trowel or garden tool. It’s that reddish orange flaky stuff that forms when metal reacts with moisture and oxygen. Rust is a disease that also harms our landscape plants. It even affects vegetable plants and your lawn. First signs of rust are tiny orange to rusty brown spots and specks on leaves.   If untreated the spots turn into a bumpy looking spot and eventually will break open and release tiny spores that spread by wind and watering. Rust is usually not fatal, but can cause plants to experience stunted growth. Also dead branches and premature leaf drop can happen as well. Lawns can take on a little reddish coloration and you may see some orange- red dust as you mow.   Rust loves damp conditions. Don’t overwater plants and if you water overhead with sprinklers do it early in the day so foliage can dry before nightfall as this will help prevent rust. You can also control rust with a Copper fungicide, dust or Neem Oil.

MILDEW: Mildews are easily spotted by the white powdery appearance on the upper surfaces of leaves. One of the most common that we see in our area is Powderly Mildew. Plants that are subject to daily irrigation are the most prone to get powdery mildew as excessive moisture and humidity contributes to its development.   Landscapes that promote good light and aeration tend to discourage powdery mildew. There are some plants such as roses that seem to get this disease no matter what. For the most part fungicides can be applied to prevent or control mildews. Bonide Fung-Onil works well for this.

Listen to me every Friday at 11:50am as I talk live with Terry Henne on the Farm Show on 790am WSGW

Get out and enjoy the beautiful weather this weekend!