Sampling and Extraction of Plant Parasitic Nematodes

The study of nematodes requires availability of nematode specimens and their population densities in plants and soil. This can be achieved using adequate sampling schemes and extraction methods. In this chapter, the most common and suitable sampling and extraction procedures and equipment are described. These include the use of Baermann's funnels, Cobb's decanting and sieving, floating methods such as the Oostenbrink method and Fenwick can, elutriators such as Seinhorst methods, centrifugation methods including that of Coolen, and mechanical and enzymatic maceration. The combination of different methods for cleaning the nematode suspensions is described, such as Cobb's sieving with Baermann's funnels or centrifugation, and for cysts combining Seinhorst's elutriator or Fenwick can with the alcohol methods. Methods for extraction of eggs and/or juveniles of cyst and egg mass forming nematodes, to be used as inoculum or to ascertain egg viability, are also described. Only little information is also noted on the use of molecular tools to identify and quantify nematode populations in soil and roots.

Mist chamber extraction for improved diagnosis of Meloidogyne spp. from golf course bermudagrass

Meloidogyne spp. are among the most damaging plant-parasitic nematodes to golf course bermudagrass in the southern United States. Diagnostic samples processed by centrifugal flotation often recovered only low numbers of vermiform Meloidogyne spp. life stages (J2 and males) from soil, while roots were found to be heavily infested by sedentary life stages. Therefore, the University of Florida Nematode Assay Lab (NAL) evaluated mist extraction from turf plugs as a method for diagnosis of Meloidogyne spp. from golf course bermudagrass. Soil and turf plugs were obtained from 596 golf course bermudagrass small plots from multiple locations and cultivars over several years, and vermiform Meloidogyne spp. extracted from 100 cm³ of soil by centrifugal flotation and by mist chamber extraction from four 3.8-cm-diam. turf plugs were compared. Additionally, both extraction methods were performed on 431 golf course bermudagrass diagnostic samples received by the NAL from Florida, 36 golf course bermudagrass diagnostic samples from Texas, and 34 golf course bentgrass/bluegrass samples from California. In the small plots, and the bermudagrass samples from Florida and Texas, mist extraction had higher detection and recovery rates of vermiform Meloidogyne spp. than did centrifugal flotation. However, centrifugal flotation had higher detection and recovery rates than mist extraction from bentgrass/bluegrass samples from California. Mist extraction from turf plugs is superior to centrifugal flotation from soil for diagnosis of Meloidogyne spp. on golf course bermudagrass, but not on golf course bentgrass and bluegrass.