The extraction method is capable of capturing the dynamic response of phytohormones to inducing stresses. JA, ABA and SA levels were determined following stresses designed to elevate specific levels of each hormone (a-c). (a) Following wounding by mechanical damage JA levels increase 8 fold within 5 minutes and increase over the following 2 h. (b) Two hours desiccation of detached leaves (at 60% RH) is sufficient to increase foliar ABA levels 8 fold. (c) Challenge with the virulent bacterial pathogen, DC3000 or the DC3000 hrp mutant elicits increases in SA levels 21 hpi in wild-type but not the SA biosynthetic mutant, sid2. (d) Challenge with virulent DC3000 induces ABA in Arabidopsis leaves within 6 hours post inoculation (hpi).