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Nematodes:
A CHALLENGE TO MANAGE IN SOUTHERN TURFGRASSES By Dr. Bruce Martin, Professor Emeritus – Clemson University Adapted from: Bruce Martin. 2016. Nematodes in southern turf grasses. Golfdom 73 (5)
Al ab ama Tu rf Tim es > >> Wint er 2021
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ematodes are an understudied category of pests in turfgrasses, even though the tiny ‘roundworms’ are among the most abundant of animals on Earth. Nematodes inhabit many habitats and niches, and include free-living forms, truly aquatic species, and the parasites. The parasitic nematodes can be pests of invertebrate animals, such as insects as well as vertebrate animals, including humans. They began to be recognized as significant pests in the South after World War II when interest in golf accompanied the vibrant economy. Florida was the first state to report nematode injury in bermudagrass turf (Christie, et al 1954). Since that time over 60 years ago, locations throughout the United States reported on nematodes associated with damaged turf. Initial reports were usually surveys of the genera and species of nematodes associated with various turfgrasses, and included familiar nematodes such as Belonolaimus longicaudatus (sting), Hoplolaimus galeatus (lance), Trichodorus and Paratrichodorus spp. (stubby root), and others such as Helicotylenchus (spiral), Criconemella (ring), Criconemoides (sheathoid), Hemicycliophora (sheath), Tylenchorrhynchus (stunt), Meloidogyne (root-knot) and Hypsoperine (false root- knot nematode). Surveys are still important, with the understanding that identification now utilizes traditional and modern molecular identification tools. For example, a survey was conducted in North and South Carolina golf courses (Zeng et al. 2012) which revealed 24 nematode species belonging to 19 genera and 11 families. Helicotylenchus dihystera, Mesocriconema xenoplax (a ‘ring’ nematode), Hoplolaimus galeatus, Tylenchorhynchus claytoni (a ‘stunt’ nematode), Belonolaimus longicaudatus, Meloidogyne graminis and Paratrichodorus minor were the most prevalent and abundant species in golf course turfgrasses in both states. Twelve species were new records of plant parasitic nematodes in turfgrasses in both NC and SC. Further work, such as the development of molecular tools to quickly identify species 16
of root-knot (Ye, et al, 2015), will lead to a better understanding of these particular pests and their impact on golf course turfgrasses and turfgrass in general. These reports and the experiences of plant scientists and turfgrass managers confirm the role of nematodes as significant but often overlooked pests in turf. As soilborne pests, nematodes are ‘out of sight’ and all too frequently ‘out of mind’. These pests are root parasites and their effects on turf can mimic other causes of weak turf, which likely leads to uncertainty in diagnosing their true nature as primary pathogens. Sometimes nematodes are never recognized as the true cause of a problem. In most state labs, the primary plant problem diagnostic lab is not coupled with nematode identification services. Nematode identification and enumeration require different techniques and experiences than those typically employed in diagnostic labs for fungal pathogens. This means that the diagnostician should also be trained in nematology and be familiar with the symptoms they can induce and have an appreciation of the potential contribution of nematodes as pests. In any case, clients of nematode identification labs should develop a relationship with the service and provide as thorough information as possible to aid the labs in making the right diagnosis. This is especially important in the Southern states where nematodes are recognized and known to be important. Because of the warming climate, nematodes are increasingly recognized in other states in cool season grasses where heat and drought stress are more common in summer months. Alabama turfgrass managers are very fortunate to have a nematology lab in their state. Located at Auburn University, the Alabama Cooperative Extension System operates a Plant Diagnostic Lab that includes the services of nematode testing providing identification and numbers of each type per sample. The nematology lab performs soil nematode analysis for $10 per sample. Your local ACES office can provide the test kit boxes and forms for such tests.
