In colder parts of the country where turf goes completely dormant, nematodes will typically follow suit since their food source has shut down. Nematodes will then overwinter as eggs and wait until warm weather returns to hatch and do their thing. Unfortunately, in the transition zone and farther south it can be a different story, and overseeding changes things dramatically. When nematodes find a fresh food source and temperatures remain warm enough, they can stay active and even double in numbers over the winter.
Since the advent of ultradwarf bermudagrasses, the number of courses that overseed putting greens has reduced dramatically, but it is still done in some cases – particularly by those without ultradwarf greens. In addition, many courses still overseed areas like tees, fairways and even rough to provide better color and playability in winter.
With overseeding, it is not uncommon to have weak bermudagrass in the spring after transition. Perhaps you have already experienced transition issues from overseeding? Maybe it occurs regularly in the same locations? Those would be the areas to test for nematodes. Testing prior to overseeding will give you time to treat if counts come back high, thus preventing nematodes from reaching catastrophic numbers over the winter. If you haven’t tested for nematodes yet, there is still time. Spring nematicide applications have also proven effective at improving the transition back to warm-season turf when nematode pressure is high.
If your nematode testing or control strategies missed the mark this winter don’t worry, at least you have plenty of time to develop a plan before the next overseed. Also, keep an eye out for the next issue of the USGA Green Section Record, where we’ll have a comprehensive article on nematode control strategies.
Southeast Region Agronomists:
Chris Hartwiger, director, Agronomy – chartwiger@usga.org
Jordan Booth, Ph.D., director, USGA Course Consulting Service – jbooth@usga.org
John Rowland, Ph.D., agronomist – jrowland@usga.org