bleach spray

[ChrisK]

Yes, this is exactly what I think is happening. Plus, you get some sanitizing action on healthy uninfected tissue.

Originally Posted by greentiger87

Some speculative questions:

5. Speculating on a mechanism... sorry if I'm stating the obvious. Oxidative stress is applied on all the cells on the leaf surface. Cells damaged by pathogens allow oxidizing ions to enter, and can't detoxify the reactive oxygen species fast enough. Intact cells keep out most of the oxidizing ions and detoxify the rest. Oxidative damage triggers the hypersensitive response. The combination of outside oxidation and HR causes the plant to shed diseased tissue.