Preventing fungal disease on rose bushes

Experiencing a summer of high temperatures, fires, smoke, ash and Santa Ana winds, residents look forward to having some relief.

The weather has moderated slightly, and along with the change comes cooler nights with more moisture collecting on leaves. This moisture with the daily accumulation of ash and small dust particles provides a great environment for mildew, rust and black spot on roses.

Black spot is the most common and important disease of roses found everywhere roses are grown. The disease does not kill the plant outright but, over time, the loss of leaves can weaken the plant making...