Virus Symptoms showing in Oklahoma

Marla is "a mite concerned" about the health of some wheat plots!

Y'all remember my last blog about inoculating wheat plants with wheat streak mosaic virus (WSMV)? Well, we recently took the ratings from this screening test. Rating diseases is done visually by assessing the symptoms and damage caused by the pathogen. In the case of WSMV, this means giving each plant a score on a scale from 0 to 5, where 0 is no disease symptoms and 5 is basically crispy, toasted leaves.

Another option for rating virus infection is doing an ELISA test to actually measure the amount of virus present in a sample. ELISA is an acronym – it stands for Enzyme Linked ImmunoSorbent Assay and is a wet chemistry procedure that uses isolated antibodies to quantify the amount of antigens present in the plant. The procedure is carried out in a microtiter test plate. The final step of an ELISA test is a color change reaction. The more yellow the test plate turns, the more virus antigen is present. The test plate is read and a computer can relate the depth of color to a number representing the "titer" of the sample. The deeper the yellow, the higher the titer count will be, due to a larger virus infection.

OSU trial site at Kildare, OK: Yellowing and leaf rolling caused by wheat streak mosaic virus and wheat curl mites

Dean and I also visited Kildare, Oklahoma recently to take a look at the Oklahoma State University wheat variety trial. The trial was showing major symptoms of WSMV. We brought a few plants back and a quick look under the microscope revealed the tiny critters causing all the trouble: wheat curl mites.

Wheat Curl Mite: Close-up and on a leaf surface.

Until next time,