Integrated Pest Management



Thatch (Ryan Davis, Utah State University Extension)



Thatch is living and dead turfgrass stems, stolons and rhizomes that occur just above the soil level. Thatch development can be caused by vigorously growing/high lignin-producing turf cultivars, over-fertilization, frequent and short-duration irrigation, compacted/layered soils, heavy, wet soils, or fungicides and insecticides that limit microorganism or earthworm function. Thatch over 1⁄2-inch in depth can be detrimental to a lawn, creating harborage for fungal pathogens and arthropods, reducing cold, heat, and drought tolerance and preventing penetration of pesticides and fertilizers.


To manage thatch, apply fertilizer based on turf needs, select low-thatch turf cultivars, promote deep rooting by watering deeply and infrequently, minimize the use of turf fungicides and insecticides, physically/mechanically remove thatch, top-dress turf with a compatible soil or organic material and core aerate in the fall or spring when grass is actively growing.