“Killer Joules”: spores of Bipolaris sorokiniana and fusarium species are susceptible to microwave radiation

Abstract

Cereal production in Australia is severely impacted by diseases such as Fusarium crown rot (caused predominantly by Fusarium pseudograminearum) and common root rot (caused by Bipolaris sorokiniana). These diseases are particularly difficult to manage because inoculum can survive at least three years within cereal stubble, or four years in soil in the case of B. sorokiniana. Microwave radiation may be able to reduce or eliminate inoculum within stubble and soil. Several cereal pathogens have been previously shown to be susceptible to microwave radiation, but the energy requirements to achieve a significant decrease in pathogen populations were not defined. Laboratory based microwave dose-response experiments on conidia of B. sorokiniana and macroconidia of F. pseudograminearum and F. cerealis revealed that all three pathogens are susceptible to microwave radiation, with lethal dose (LD) thresholds estimated for each pathogen. Bipolaris sorokiniana conidia required 103.8 Jg− 1 and 236.6 Jg− 1 of microwave radiation energy for LD50 and LD99, respectively, whilst F. pseudograminearum required 78.4 Jg− 1 and 300.8 Jg− 1 and F. cerealis required 95.3 Jg− 1 and 152.7 Jg− 1 for LD50 and LD99, respectively. These results were derived from experiments whereby samples were microwaved for up to 10 s using a domestic 1100 W microwave oven. These timing and energy requirements serve as a starting point to define requirements for further development of microwave radiation treatments under field conditions.