Golfdom, July 2017

FIGURE 4 Turf parasitic nematode life cycles Spring Population Density Summer Fall Nematode populations increase and decrease throughout the season Most turf parasitic nematode populations peak in the height of the summer or early fall However root knot nematodes peak in early spring and can only be controlled when the nematodes are present and countable in the soil Once they enter plant roots little can be done to manage them is heavier than the solution so separation is relatively easy However every lab uses different equipment for extraction and often uses slightly different techniques This can result in different nematode counts from different labs Consequently it may be difficult to compare thresholds from one lab to another If labs use substantially similar techniques nematode counts will be relatively close but never the same Superintendents frequently ask how to send a nematode sample for analysis The best answer Ask the lab Labs can determine nematode counts from a cup cutter plug of soil Unfortunately most damage thresholds are determined using composite samples so cup cuttersized soil plugs may be misleading If a superintendent suspects nematodes in turf decline a cup cutter soil plug from a damaged area is a good way to start but if theres an indication of a potential problem it needs a follow up with a composite sample Composite samples are averages across a green In this process the superintendent takes 20 to 30 cores from a green and combines them into a single composite sample A composite sample allows for a more consistent count and reduces the variability involved if a sample comes from a nematode hotspot Take composite sample cores only 2 THE FOUR TO WATCH FOR Stunt Lance Root knot inches to 3 inches deep Nematodes only survive where roots are present so core depths of deeper than 4 inches arent useful Obviously the depth of the core can change nematode counts by diluting dense populations of nematodes at the surfaces with empty soil deeper down Also composite samples should not be random Conduct the sampling systematically using either a grid or zig zag pattern Its important to sample for nematodes at the appropriate time of year The best time to look for most nematodes is spring through early summer However you can detect root knot nematodes only in the early spring while juveniles are present in the soil Figure 4 Once root knot nematodes migrate into roots they cannot be extracted with soil and cannot be controlled by chemical means Nematodes continue to be a serious issue for turfgrass managers and while southern regions tend to be the hardest hit high nematode populations also cause significant damage on northern golf courses Fortunately a new set of modern nematicides have been developed to help turfgrass managers deal with these intractable pests Nathaniel Mitkowski Ph D is a turfgrass pathologist at the University of Rhode Island You may reach him at mitkowski@ uri edu for more information Seven time winner of the national Folio Award for editorial excellence EDITORIAL ADVISORY BOARD Mike Bavier CGCS Ret Barrington Ill Conrad Broussard CGCS ST JAMES PLANTATION Southport N C Julio Diaz PUNTACANA BEACH AND GOLF CLUB Punta Cana Dominican Republic Damon Di Giorgio PLAYA GRANDE GOLF COURSE Rio San Juan Dominican Republic Chris Erickson DEL MAR COUNTRY CLUB San Diego Calif David Hay CGCS MISSION HILLS COUNTRY CLUB Rancho Mirage Calif Bill Irving WOLF CREEK GOLF CLUB Olathe Kan Rees Jones REES JONES INC Montclair N J Tim Kreger EXECUTIVE DIRECTOR CAROLINAS GCSA Tom Lively CGCS TPC SAN ANTONIO San Antonio Texas Tom Marzolf FAZIO GOLF COURSE DESIGNERS Hendersonville N C Roger Meier VALHALLA GOLF CLUB Louisville Ky Tyler Otero NORTH JERSEY CC Wayne N J Jeff Plotts TPC SAWGRASS Ponte Vedra Beach Fla Jackson Reiswig CORAL CREEK CLUB Placida Fla Steve Sarro PINEHURST COUNTRY CLUB Denver Colo Alex Stuedemann TPC DEERE RUN Silvis Ill Andy Wilson BETHPAGE STATE PARK GOLF COURSE Farmingdale N Y July 2017 Golfdom 35 Golfdom com