Factors affecting development of potato tubers soft rot during storage

الملخص EN

Five soft rot bacteria with different degree(s) of virulence were selected out of 25 isolates previously recovered from marketed potato and storehouses in Sharkia Governorate.

Pathogenicity test of these isolates to produce soft rot symptoms on Diamant potato tubers was verified.

Bacteriological properities of the identified isolates revealed identity with Erwinia carotovora subsp.

carotovora (Jone 1901) Bergey et al.

(1923).

The five selected pathogenic isolates namely FS5, FM3, ES8, EM1 and EM2 were arranged in descending order according to their pathogenic potential.

Medium to low growth temperature range from 5-20ºC, acidity (pH4.5), usual ventilation during storage and late physiological maturity were unfavorable for greater rot development.

Higher growth temperature (30- 35 ºC), anaerobic condition, alkalinity (pH 8.5) and early maturity parameters (90-100 days) increased disease development during storage.

Tubers susceptibility to rot revealed that potato Spunta cultivar was the highest one followed by Diamant and King Edward.

Liability to Erwinia soft rot differed according to the hosts.

It was enormously recognized on garlic, onion bulb, tomato, eggplant and pepper compared limited soft rot on cucumber, squash and some fruitiness.