Treating orange rust

Q. What is this orange stuff on my blackberry plant’s leaves? How do I treat it?

John from Berlin Center

A. Brambles are all the shrubs in the Rubus genus. You think of them as all types of raspberries and blackberries. All brambles, with the exception of red raspberries, get a terrible disease called orange rust.

Orange rust is first noticed as yellow pustules on the underside of leaves of brambles. Many homeowners do not turn the leaves over when the plant shows the first signs. Thus, they will most likely notice small leaves with yellow edges in the spring of the next season.

The disease is terrible due to the systemic infection. Once the plant has this disease, it goes throughout the plant’s systems. Then, it survives the winter within the host plant.

There is no treatment. There is no cure. There are only methods used to control the disease and prevent the disease from infecting more brambles. Our recommendations, including details from plant pathologist, Mike Ellis, are:

Purchase only plants that are disease-free, certified nursery stock. Plant in a different area and inspect the plant several times before moving into your bramble patch.

When diseased plants first appear in early spring, dig out the plants and roots. Destroy them before pustules form, break open, and discharge the orange masses of spores. If plants are not removed, these spores will spread the disease to healthy plants through the air.

Remove all wild brambles from within and around the planting site. If there are woods nearby, you have wild brambles.

Maintain good air circulation in the planting by pruning out and destroying old fruited canes immediately after harvest, thinning out healthy canes within the row, and keeping the planting free of weeds.

To learn more about the disease, go to: http://go.osu.edu/orangerust.

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County.