Ask the Master Gardeners
Q: Has the gardening community made any advancement to manage Japanese stiltgrass without destroying the lawn? In the past I destroyed the sections of lawn containing Japanese stiltgrass using Roundup, and reseeded in the fall to again re-establish a beautiful lawn. In the early spring and again in late spring I apply a pre-emergent herbicide only to have the Japanese stiltgrass return.
A: Japanese stiltgrass is a warm season annual grass that differs from crabgrass in that it grows as vigorously in shade as in full sun. Japanese stiltgrass begins its growth cycle earlier than crabgrass in spring, by as much as two to four weeks, depending on seasonal temperatures.
(Poughkeepsie Journal file photo)
This grass is adapted to a wide variety of habitats, moist or dry. It will quickly fill in disturbed areas or bare spots in the lawn, and easily moves into wooded areas where it crowds out understory plants.
Each plant may produce from 100 to 1,000 seeds (viable for at least five years) before it dies in fall. Seed is easily carried to new areas by heavy rain and human activity; Japanese stiltgrass is widely distributed throughout the Hudson Valley.
The best defense against Japanese stiltgrass and other weeds in the lawn is a vigorous turf with minimal bare spots where weed germination can occur. Cultural factors that affect turf health include adequate sun, soil quality, including neutral soil pH, judicious timing and application of seed, fertilizer and pest management.
That said, Japanese stiltgrass is still a relatively new turf weed in the Hudson Valley. As yet, management practices for turf situations regarding this pest are still developing.
Stay tuned for further information, and feel free to contact your local Cornell Cooperative Extension office with any lawn-care or gardening questions.
— Amy Albam, senior horticulture/diagnostic lab educator, Cornell Cooperative Extension of Rockland