Wednesday, April 30, 2008

Rust on Agastache

Another good smelling herb sample! Agastache sp. (pronounced ah gas TAH kee) is a perennial herb which smells like fruity, minty, licorice. This sample presented with raised rust colored pustules on the upper and lower leaf surfaces. All leaves were affected, but the disease appeared to affect the lower leaves first as many had fallen from the plant. Slightly crushing under a plastic coverslip, a wet mount of the pustules revealed characteristic telia of the rust Puccinia. (The morphology of the telia tells me it is in the genus Puccinia.) Some of the characteristic tails, or stalks, of the telia were broken off but many remained intact (see the last photo).

I need to remember to burn the scale into each picture! The software shows the scale on the screen, but doesn't burn into the image unless you go through an extra step. The leaf pictures were taken under the dissecting scope. I don't like this camera as the resolution isn't that great. The teliospore photos are taken using an Olympus camera and their software, MicroSuite Five. I tried using the merge function on the last photo (big clump of spores) to show the 3D effect, but it appears I need more practice. I saved leaves from this sample and will attempt better photos when time permits.

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