Studies of a wilt disease of the potato plant in Israel caused by Erwinia chrysanthemi

Abstract

In Israel field infections of potato plants by Erwinia chrysanthemi are characterized by wilting of the leaves followed by total desiccation of the plants. These symptoms are indistinguishable from those caused by Verticillium dahliae or those that develop during the normal process of plant senescence. Diagnosis of E. chrysanthemi in the spring‐sown (February) crop in Israel is difficult because all three conditions often appear at approximately the same time, late in the growing season in May when the air temperature exceeds 25°C. The symptoms of E. chrysanthemi infection were reproduced in the field when potato seed tubers, tested and found to be contaminated at a low level with E. carotovora pv. carotovora, were inoculated with a strain of E. chrysanthemi isolated from a diseased potato plant. When plants in a growth cabinet at 30°C were stem‐inoculated with E. chrysanthemi, similar symptoms developed when the relative humidity was low (c. 80%). Presence of the disease only on plants grown from seed contaminated with E. chrysanthemi and not from uncontaminated seed suggests that the bacterium is seed borne, as is E. carotovora pv. atroseptica, the blackleg pathogen.

Assessment of recent outbreaks of Dickeya sp. (syn. Erwinia chrysanthemi) slow wilt in potato crops in Israel

“…These symptoms are in accordance with those observed in the field in Israel with natural infections, originating from seed tubers, confirming the first record of Dickeya sp. in Israel (Lumb et al 1986), and with symptoms described for disease expression in the summer in Spain (Palacio-Bielsa et al 2006). The pathogenicity results were in agreement with previous reports, demonstrating extensive stem-rot symptom expression associated with high relative humidity (RH) (100%) under the assay conditions (Palacio-Bielsa et al 2006), whereas lower RH (80%) induced more leaf desiccation and less rotting (Lumb et al 1986).…”

“…The recent outbreak of Dickeya sp. in Israel was strongly associated with seed tubers imported from the Netherlands, reported also in the early 1980s (Lumb et al 1986). In Spain, Dickeya sp.…”

“…causing disease on potato are (biovar 3) strains of D. dadantii and D. zeae, which are pathogens of potato in warm climates, and the more temperate-adapted (biovar 1and 7) strains of D. dianthicola that appear to be spreading on potato in Europe (Samson et al 2005). Disease symptoms are variable, including pre-emergence tuber decay in semi-arid areas (Cother 1980), extensive stem rotting in tropical areas (de Lindo et al 1978), wilt associated with limited stem rot in cool-temperate regions (Tanii and Baba 1971), and wilt without stem rot in Israel (Lumb et al 1986). Highly humid environmental conditions tend to reduce desiccation and favour soft rot of infected tissues (Lumb et al 1986;Serfontein et al 1991).…”

“…Disease symptoms are variable, including pre-emergence tuber decay in semi-arid areas (Cother 1980), extensive stem rotting in tropical areas (de Lindo et al 1978), wilt associated with limited stem rot in cool-temperate regions (Tanii and Baba 1971), and wilt without stem rot in Israel (Lumb et al 1986). Highly humid environmental conditions tend to reduce desiccation and favour soft rot of infected tissues (Lumb et al 1986;Serfontein et al 1991). Disease symptoms in the recent outbreaks in Israel first appear as wilt of the top leaves, which spreads to the lower ones, followed by desiccation.…”

Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola

“…The development of biocontrol tools aimed at D. dianthicola remains an important issue in plant protection, as it is the dominant Dickeya species recovered from plants with blackleg and soft rot symptoms in temperate climates in Europe (73,74). Moreover, most of the published biocontrol assays were directed at the control of the P. atrosepticum, P. carotovorum subsp.…”