Evaluation of a rapid diagnostic field test kit for identification of Phytophthora species, including P. ramorum and P. kernoviae at the point of inspection

Abstract

Plant health regulations to prevent the introduction and spread of Phytophthora ramorum and P. kernoviae require rapid, cost effective diagnostic methods for screening large numbers of plant samples at the time of inspection. Current on-site techniques require expensive equipment, considerable expertise and are not suited for plant health inspectors. Therefore, an extensive evaluation of a commercially available lateral flow device (LFD) for Phytophthora species was performed involving four separate trials and 634 samples. The assay proved simple to use, provided results in a few minutes and on every occasion a control line reacted positively confirming the validity of the test. LFD results were compared with those from testing a parallel sample, using laboratory methods (isolation and real-time PCR). The diagnostic sensitivity of the LFD (87·6%) compared favourably with the standard laboratory methods although the diagnostic specificity was not as stringent (82·9%). There were a small number ( n = 28) of false negatives, but for statutory purposes where all positive samples must be identified to species level by laboratory testing, overall efficiency was 95·6% as compared with visual assessment of symptoms of between 20-30% for P. ramorum and P. kernoviae . This work demonstrates the value of the LFD for diagnosing Phytophthora species at the time of inspection and as a useful primary screen for selecting samples for laboratory testing to determine the species identification.

Pathogenicity of Phytophthora pluvialis to Pinus radiata and its relation with red needle cast disease in New Zealand

“…To complement direct isolation, a range of diagnostic techniques have been employed in the diagnosis of the disease from field material. These include visual examination for the presence of the characteristic needle symptoms, microscopic examination of sporangia on the needles and the use of a serological test kit capable of indicating the presence of Phytophthora species to genus level (Lane et al 2007). Use of the kits resulted in a significant increase in the number of Phytophthora-positive results, as recovery by isolation does not always occur.…”

Management of plant health risks associated with processing of plant-based wastes: A review

“…Serological methods (Lane et al, 2007) are used for pre-screening infected plant material for Phytophthora spp. but are not specific enough for species identification.…”

Probing biomolecular interaction forces using an anharmonic acoustic technique for selective detection of bacterial spores

“…Labelled antibody-based tests, such as dip-stick method (Dewey et al 1989) and lateral flow devices (LFD) (Lane et al 2007), are relatively fast and easy-to-use but provide only qualitative or semi-quantitative data at limited sensitivity (Skottrup et al 2008). Immunosensors based on platforms such as surface plasmon resonance (SPR) (Hoa et al 2007), quartz crystal microbalance (QCM) (Cooper and Singleton 2007) and cantilever-based sensors (Waggoner and Craighead 2007), provide rapid and easy detection with high sensitivity and quantification wherein the binding of receptors (immobilized on the immunosensor surface) with pathogens via pathogen-specific surface epitopes results in a direct measurable signal without the requirement for labels.…”