Die-back of twigs and even some large areas in trees is probably due to the lack of soil moisture. These trees received good rainfall last year, but now as soil water depletes, they are unable to take up enough water to meet their demands. Even after our recent rain, deep watering may be necessary. A disease of landscape trees and scrubs that may deserve more notice is caused by the wood rot fungus Inonotus rickii. The cankers contain chlamydospores, long lived spores that can infect numerous hosts.
Initial infections are more likely at wound sites.
Disease may not be noticed until plants are in decline, and no curative treatments are practiced. In Arizona, Inonotus rickii has been described on pyracantha, Circidium, Parkinsonia, elderberry, grape and box-elder, but its potential host range is probably much larger. We have found the sexual stage of Sphaerotheca fuliginea, cucurbit powdery mildew, in the greenhouse on cantaloupe inoculated with spores from infested melon fields in central Arizona. This gives the versatility of the fungus for survival and resistance development here another perspective. Also, increased acreage and extended growing season of melons and watermelons means more acreage to scout and more inoculum potential for powdery mildew.