June 24, 1994
On Austrian pine, the damage caused by these two diseases is worse than it has been for at least a decade. Injury to ponderosa pine is also severe, but this species is less common in the Iowa landscape. Paula Flynn did a brief article on these and other conifer diseases in the May 4, 1994 issue.
Black rot is a bacterial disease that affects crucifers (vegetables in the cabbage family). The pathogen, Xanthomonas campestris pv. campestris, is particularly damaging to cabbage and cauliflower, but turnip, rutabaga, collard, and kohlrabi are also susceptible. Broccoli is somewhat resistant, and radish is usually highly resistant. Wet conditions favor pathogen growth and spread
Now is the time to begin watching for the tell-tale orangish discoloration of turfgrass characteristic of feeding damage by the greenbug aphid. A small amount of damage has been observed here in Ames.
Several aphid species appear to be in greater-than-average abundance so far this summer. This includes the leafcurl ash aphid, a minor annoyance that cause the leaves on the ends of green ash twigs to tightly coil into a gnarled mess, the pine bark aphid discussed 3 weeks ago, and two or more species of aphids on maple foliage.
Roses are among the most popular and versatile plants grown in flower gardens. Roses offer a large assortment of growth habits, sizes, and shapes as well as a variety of leaf and flower colors. The American Rose Society, with nearly 20,000 members, has surveyed its members to determine their favorite cultivars. Some of their favorites include:
The previous issue of the Horticulture and Home Pest News contained a list of perennials that perform well in partial to heavy shade. A number of trees and shrubs can also be successfully grown in partial shade.
Trees and Shrubs Adapted to Partial Shade