Basic analysis includes identification of most plant pathogenic fungi and bacteria as well as cultural and physiological conditions that are apparent and may be responsible for plant problems. Basic analysis usually includes a microscopic examination of tissue but may also include culturing where needed to isolate a potential pathogen from symptomatic tissue.
An ELISA test is an Enzyme-Linked ImmunoSorbent Assay used to detect a specific organism. In the Clinic, these tests may be used to detect highly specific organisms such as Pantoae stewartii, the causal agent of Stewart’s Wilt of corn. Other Immunostrips tests are designed to detect an organism only at the genus level as there are many species that are common pathogens on many hosts. Phytophthora spp. is one such test that is available. An ELISA test can take several hours, but analysis may take days to perform if tissue preparation is time consuming. This test is preferred where a larger sample volume needs to be processed. Tests we typically have in stock include:
Bacteria: Xylella fastidiosa—causal agent of bacterial leaf scorch;
Oomycetes: Phytophthora spp.
Pantoae stewartia testing and analysis for other specific pathogens can also be performed but fees may be higher, and we require prior notification if testing is desired.
Immunostrip tests are lateral flow devices that use the same antibodies as an ELISA test. These are typically designed for very specific pathogens such as Hosta Virus X (HVX) but some tests are less specific and only detect an organism at the genus level such as Phytophthora spp. this test may be particularly useful for a small number of samples or where a rapid diagnosis is desired. Tests we typically have in stock include the following:
Viruses: Cucumber Mosaic (CMV), Impatiens Necrotic Spot (INSV), Tobacco Mosaic (TMV), and Tomato Spotted Wilt (TSWV).
Bacteria: Xanthomonas hortorum pv. pelargonii (Xhp), and Ralstonia solanacearum (Rs);
Oomycetes: Phytophthora spp.
Additional tests that may be available if requested in advance include the viruses: Hosta Virus X (HVX), Pepper Mild Mottle (PepMV), Squash Mosaic (SqMV), Zucchini Yellow Mosaic (ZYMV), Potato Virus X (PVX), Potato Virus Y (PVY), and the bacterial pathogen Clavibacter michiganensis subsp. michiganensis.
DNA Extraction is done to prepare plant tissue or isolates of fungi or bacteria for further analysis using PCR or Sequencing. DNA extracted elsewhere can be submitted for PCR or sequncing of specific organisms.
PCR stands for Polymerase Chain Reaction, and this method is used to amplify specific strands of DNA of organisms that may be used to identify either groups of organisms such as Phytophthora or very specific organisms such as Phytophthora ramorum, the causal agent of Ramorum Blight or Sudden Oak Death. PCR can also be used to identify an unknown organism by sequencing.
In addition to P. ramorum, the Clinic currently offers PCR testing for the pathogens causing oak wilt and alfalfa brown root rot.
Sequencing is a method used to analyze a product from PCR to identify a specific organism based on a portion of the genome of the organism. Fragments of the genome are compared to those of known organisms, and depending on the size and quality of the fragment used and available sequences of known organisms for comparison, sequencing may be used to identify an organism to the genus, species, or subspecies level.
Nematode extraction is performed using either a pie plate (5-day) or sugar flotation (1 day) method is used to obtain nematodes from a 100 gram soil sub-sample. The pie plate method is used for more quantitative analysis. The sugar flotation method may be more useful in determining if specific nematodes are present including cyst nematodes or very large nematodes such as Xiphinema. There are other forms of nematode analysis for specific nematodes that may incur a different fee. This may include analysis of plant tissue for garlic bloat, pinewood, or burrowing nematodes.
Soil Testing or Nutritional Analysis:
For soil analysis or nutritional analysis, please submit the sample directly to the Cornell Nutrient Analysis Lab.
If you suspect insect damage, please submit the sample directly to the Insect Diagnostic Lab.