Golf Course Management

JUL 2017

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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07.17 GOLF COURSE MANAGEMENT 67 demnify from Bayer, and Nimitz Pro G from Quali-Pro. These three nematicides along with several others released since 2010 pro - vide multiple weapons in the arsenal against nematodes. However, for many, the question remains: Do these new nematicides work as well as Nemacur? To answer this, we need to review a little about Nemacur, the types of nematodes that damage turf, and preliminary research data on the effectiveness of these new nematicides. We will then evaluate the prop - erties of Divanem, Indemnify and Nimitz Pro G, and their relative efficacy on the four nematode genera that are currently the most problematic on golf course turf in the United States: sting, lance, root-knot and Pacific shoot-gall nematodes. The active ingredient in Nemacur was fe - namiphos, an organophosphate pesticide that affects the nervous system. Because all nema - todes have similar nervous systems, they were all impacted by Nemacur. Further, fenami - phos has both contact and systemic activity and, therefore, is effective on nematodes in soil and, to some degree, inside roots. Nema - cur was a very versatile treatment; it worked well against all turfgrass nematodes (10). The new nematicides can work just as well as Nemacur — and in some cases better — but not across the board on all the different species of nematodes. Major turf nematodes Sting nematodes Sting nematodes (Belonolaimus and Ibipora species) are strict ectoparasites. They feed on plant roots while remaining in the soil. All the life stages of sting nematode (eggs, juveniles and adults) reside in the soil. Consequently, they can be killed by either contact nemati - cides through direct exposure, or by systemic nematicides that they ingest while feeding. University of Florida research has shown that during cooler months (fall through spring in Florida), these nematodes are generally active in the top 4 inches (10 cm) of the soil profile. However, during the hot summer months, sting nematodes move deeper in the soil, and many will be 6 inches (15 cm) or deeper at that time (5). For best control of sting nematode, a nematicide needs to move through the thatch and into the soil underneath. Lance nematodes Lance nematodes (Hoplolaimus species) are migratory endoparasites, meaning that they move into, move out of, and burrow within roots. At any given time, some lance nema - todes will be in the soil, and others will be inside of roots (8). Systemic nematicides are more effective on this type of nematode. Con - tact nematicides can be very effective on the lance nematodes in the soil, but those inside roots will be unaffected until they exit the root. Therefore, to effectively control lance nematode, a nematicide's contact active ingre - dient needs either to stay in the soil for a long time or to be applied frequently so that nema - todes leaving roots get exposed to it over time. Root-knot nematodes Root-knot nematodes (Meloidogyne spe - cies) are sedentary endoparasites. They enter a root, move to the central cylinder where they establish a feeding site, and remain there for the rest of their life. Eggs are deposited into an egg mass either inside the root or at the root surface. The second-stage juvenile hatches from the egg and enters a root near its root tip. The root-knot nematode is thus potentially exposed to contact nematicides for only a short part of its life cycle. Systemic nematicides work best on these nematodes because they may affect all the life stages of the nematode within the root. Contact ne - maticides only impact root-knot nematodes if eggs are exposed at the root surface, or during the short period the juveniles are outside the root. Research at the University of Florida has found that the most common root-knot nem - atode species on turf in that state (Meloidogyne graminis) proliferates in roots growing in the thatch and upper 1.5 inches (3.8 cm) of soil (5). Therefore, a contact nematicide will be A bermudagrass green in Florida infested by sting nematode in spring. The center area was treated with Indemnify the previous fall, and the areas to the left and right were not treated.

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