May 2, 2007
Samples with the following problems have come into the Plant Disease Clinic recently:
Hostas with dead centers
Rhizosphaera needle cast on spruce
They're back! This is the year the periodical cicadas (a.k.a., periodical "locust" and 17-year cicada) will reappear above ground in a small portion of east-central Iowa. After living as nymphs underground since 1990, this is the year they transform to noisy, winged adults to emerge in June for a brief moment in the sun. Then they will disappear back in the ground where they will stay until 2024. Amazing.
Trees provide many environmental and psychological benefits. However, trees and turfgrass are not very compatible. Large trees cast considerable shade. Trees also compete with the turfgrass for water and nutrients. As a result, most turfgrasses have a difficult time growing in the vicinity of large shade trees.
The Plant Disease Clinic received a sample this week of a 10-year-old Gold Standard hosta that was dead in the center of the clump. The client was concerned that the hosta appeared to be dying from the inside out over the past few years, and had not shown much growth in recent years.
This is a fairly common problem on some varieties of hosta. A dead center is not an indication of disease in this case. The hosta puts on most of its new growth on the outside of the clump each year, and over several years the old, dead growth from past years accumulates in the center.