Four biotypes (pathotypes) of the citrus nematode, Tylenchulus semipenetrans, occurring in California, U.S.A. were differentiated on the basis of differences of infectivity on 'Homosassa' sweet orange, 'Troyer' citrange, 'Pomeroy' and 'Rubidoux' Poncirus trifoliata, 'Thompson Seedless' grape, and 'Manzanillo' olive. A method for differentiating biotypes of T. semipenetrans is described. Field o...

Pasteuria penetrans Sayre & Starr parasitizes several nematode species and is considered a promising biocontrol agent of the root-knot nematode, Meloidogyne spp. (1,7). Numerous plant-parasitic nematodes, including Tylenchulus semipenetrans, however, are seldom if ever infected by this biocontrol agent (3). Tylenchulus semipenetrans Cobb is the most economically important and widespread nematod...

Greenhouse studies have shown that when rough lemon (Citrus limon) seedlings infected with TyIenchulus semipenetrans were transplanted into soil infested with Glomus mosseae, the mycorrhizal fungus infection increased seedling growth compared to nonntycorrhizal seedlings. Tylenchulus semipenetrans significantly suppressed seedling growth below that of mycorrhizal seedlings. Histological observa...

The presence of two biotypes of the citrus nematode (Tylenchulus semipenetrans) in Italian citrus and olive orchards has been confirmed by comparing host specificity. Host reaction to California biotypes C1 and C3 and to three populations from Arizona, Texas, and Florida indicates that of these five United States biotypes, all except C3 consistently fit biotype C1. These findings, and the resul...

Investigations were undertaken to determine the suitability of sucrose and magnesium sulphate solutions and a silica colloidal suspension with centrifugation for extracting Tylenchulus semipenetrans from citrus roots. The efficiency of incubation, sodium hypochlorite, centrifugation, and maceration methods was also compared. Numbers of females recovered by centrifugation with colloidal silica w...

Of the many nematode species that parasitize citrus, Tylenchulus semipenetrans is the most important on a worldwide basis. Management of the citrus nematode remains problematic as no one tactic gives adequate control of the nematode. An overall management strategy must include such components as site selection, use of non-infected nursery stock, use of at lease one post-plant nematode control t...

A Tylenchulus sp. found in a Georgia peach orchard parasitized peach roots in the greenhouse. Citrus roots were not parasitized, indicating that the nematode was not the citrus nematode. Morphologically similar populations were found in one peach orchard in Alabama, two orchards in Arkansas, and one in South Carolina. Males were present in the Alabama populations and one of the Arkansas populat...

In a survey of antagonists of nematodes in 27 citrus groves, each with a history of Tylenchulus semipenetrans infestation, and 17 noncitrus habitats in Florida, approximately 24 species of microbial antagonists capable of attacking vermiform stages of Radopholus citrophilus were recovered. Eleven of these microbes and a species of Pasteuria also were observed attacking vermiform stages of T. se...

Tylenchulus semipenetrans is an important and widespread plant-parasitic nematode of citrus worldwide and can cause citrus slow decline disease leading to significant reduction in tree growth and yield. Rapid and accurate detection of T. semipenetrans in soil is important for the disease forecasting and management. In this study, a loop-mediated isothermal amplification (LAMP) assay was develop...