The development of a sensor system for the early detection of soft rot in stored potato tubers

A number of sensor types were fabricated and tested for their electrical re sistance changes to compounds known to be evolved by potato tubers with sof t rot caused by the bacterium Erwinia carotovora. On the basis of these tes ts, three sensors were selected for incorporation into a prototype device. The device was portable and could be used without computer control after th reshold values and sensor settling criteria had been downloaded. The protot ype was assessed for its discriminating power under simulated storage condi tions. The device was capable of detecting one tuber with soft rot in 100 k g of sound tubers in a simulated storage crate. The device was also able to detect a tuber inoculated with E. carotovora, but without visible signs of soft rot, within 10 kg of sound tubers. The same system was able to follow the progression of the disease in a tuber stored amongst 10 kg of sound tu bers when operated at 4 degreesC and 85% relative humidity (conditions typi cal of a refrigerated storage facility).