Erwinia tracheiphila. [Descriptions of Fungi and Bacteria].

A description is provided for Erwinia tracheiphila. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Cucumis spp., Cucurbita spp., and Citrullus spp. Elliott lists hosts in three other genera, all Cucurbitaceae. DISEASE: Bacterial wilt of cucumber. The symptoms are similar to those of other wilts, leaves and later entire branches wilt and shrivel. Infected stems may exude sticky bacterial slime when cut, which helps to distinguish this disease from other wilts. GEOGRAPHICAL DISTRIBUTION: Widespread in Canada and U.S.A., also reported sporadically in South Africa, Congo, Japan, China, U.S.S.R., and several countries in Europe (CMI Map 456). TRANSMISSION: The usual vectors in North America are the cucumber beetles, Diabrotica spp., but other insects that cause wounds may also be able to transmit the disease, e.g. grasshoppers (Chupp & Sherf, 1960). It has not been conclusively shown that woodlice play an important role in transmission in the absence of Diabrotica spp., and statements to this effect seem to originate from the conjecture of Bewley in his Diseases of Glasshouse Plants (3: 94). Mechanical transmission on tools or hands of workers also occurs. Infection without wounding does not normally take place, but there is one report of infection along the margins of unwounded leaves that had been artificially water-congested (28: 26). Seed transmission does not occur.