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1996, No. 5
Some Observations on Spring, 1996 Amenity Turf "Stemminess"
Several turf managers have called to report amenity turf with poor mowing quality and a yellow-brown appearance.
In many situations, this relates to the extremely stemmy nature of turfgrasses this spring, especially in tall and fine-leaf fescues and perennial ryegrasses.
In cool season turfgrass, flowering is normally induced during the cool, short days of autumn and winter, while the production of flowering stems (culms) occurs in the late spring or early summer.
Often, these flowering stems do not mow cleanly, leaving shredded ends.
Moreover, the leaves attached to these stems turn brown and wither as the culm decomposes.
The shredded stems and drying leaves give the affected turf a yellow-brown appearance.
As the turf evolves this summer, these stems will decompose and cease being an aesthetic problem.
At present, be sure your mower blades are sharp, and, if possible, mow when the turf is dry.
Broadleaf Weeds in Turf
Populations of several broadleaf weed species seem to be more prevalent this spring than in recent springs.
Various species of speedwells (Veronica spp.) got a foothold last fall in areas where turf was damaged.
As cool season annuals, these weeds will commonly die as temperatures rise this summer.
For future information, attempt to develop a dense, healthy turf that can compete with the speedwells, and other cool and warm season annual weed species.
Populations of the cool season perennial weeds, white clover (Trifolium repens), broadleaf plantain (Plantago major or P. rugelli), and ground ivy (Glechoma hederacea), also seem to be on the increase this spring.
These species are favored by the recent cool, wet weather.
Postemergence broadleaf herbicides are often applied to successfully control these weeds (see 1996 Turf Tips #4 for herbicide recommendations).
Also remember that autumn can be a particularly good time to control both cool season annual AND cool season perennial broadleaf weeds using postemergence herbicides.
Turf Pathology Report
Drs. Hank Wilkinson and Randy Kane report outbreaks of several diseases.
In northern Illinois, cool weather pythium and pink snow mold have appeared primarily on creeping bentgrasses.
Also in the northern portions of Illinois, some leaf blight problems have appeared on bent and amenity turfgrasses.
In central Illinois, red thread can currently be found on some fine-leaf fescues.
These problems are related to the cool, wet spring weather and should become less of a concern as weather turns warmer and drier.
Also, the presence of red thread is often associated with low nitrogen fertility.
Hank also points out that the excessive precipitation has probably reduced overall turf root development.
He recommends that turf managers use management practices that enhance root development such as reducing thatch, traffic, and soil compaction; avoiding excessive nitrogen fertilization; and enhancing drainage in turf areas that are routinely troubled by heavy soils and excessive moisture retention.
Annual White Grubs
Several callers have reported finding annual white grubs in turf areas this spring.
Generally, spring treatment of annual white grubs is not recommended by U. of I. entomologists for several reasons.
First, at this stage in their life cycle, these grubs are difficult to effectively control.
Second, there generally needs to be large populations of annual white grubs to warrant control (8-12 grubs/ft.2).
Finally, in spring, the turf will generally outgrow the damage caused by the feeding of a few annual white grubs.
(TOM VOIGT)
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