Survey on Erwinia chrysanthemi (Dickeya spp.) in potato Andrej Potočnik Ministry of Agriculture and the Environment, Slovenia Beograd, April 2012

2 Identity and names Preferred name: Dickeya chrysanthemi Other name: Erwinia chrysanthemi Arsenijević mentioned 6 pathovars, 1988 : E. ch. pv. chrysanthemi Dickeya chrysanthemi E. ch. pv. dianthicola Dickeya dianthicola E. ch. pv. Dieffenbachiae Dickeya dieffenbachiae E. ch. pv. paradisiaca E. ch. pv. parthenii E. ch. pv. zeae Dickeya zeae Many of them are harmful organisms for potato, e. g. D. dianthicola, D. zeae, D. chrysanthemi, D. dadantii…

3 Dickeya spp. - host plants and names of the diseases There are a lot of quite different plant species as a host of these harmful organisms. A big diversity is expressed also in the names of the diseases they caused: Dickeya chrysanthemi Bacterial wilt of ornamentals Dickeya dianthicola Bacterial wilt of carnation, bacterial wilt of dahlia, black leg of potato Dickya zeae Bacterial stalk rot of maize, bacterial soft rot of tobacco Dickeya dieffenbachiae Bacterial leaf rot of diefenbachie

4 Pest quarantine status In the former Yugoslavia E. chrysanthemi had been regulated as a quarantine organism. It is placed in the EPPO A2 list: Dickeya (Erwinia) chrysanthemi or D. dianthicola (E. chr. pv. Dianthicola) The Data Sheet on this organism includes several synonims connected with parthenii, chrysanthemi and dianthicola

5 Pest quarantine status in EU Annex II.A.II (Organisms known to occur in the EU and subject to control when found on certain plants or their parts) – it is regulated if D. dianthicola (E. ch. pv. dianthicola) would be present on plants of Dianthus intended for planting, other than seed Annex IV.A.I (Import from third countries) – requirements apply only to the plants of Dianthus species Annex IV.A.II (Movement within EU) – requirements apply only to the plants of Dianthus species

6 Dickeya spp. – surveys and measures Other than references in Annexes II. and IV. and seed potato marketing directive, there is no other planth health regulative (directives or decisions) concerning Dickeya spp.. There is no legal basis for performing regular official surveys for Dickeya spp., however, observation of this pest is included into other potato surveys (ring rot, brown rot, nematodes and potato wart disease). In the case of findings or outbreaks of this pest in potato production there is also no legal basis for ordering special phytosanitary measures, it is only possible to issue recommendations.

7 Seed potato production regulation Council Directive 2002/56/EEC on the marketing of seed potatoes is implemented by Rules on the marketing of seed potatoes (Official Gazette of the Republic of Slovenia, No 105/06) – SI seed potatoes certification scheme

Regulated conditions regarding black leg and soft rots of the potato tubers at the seed potato production – allowed % of plants or tubers infected by all causative agent of these disease (Erwinia spp., Dickeya spp…) Seed category Allowed % of plants in the field Allowed % by weight of tubers before or during marketing potato lots Minimal EU conditions Basic 2 1 Certified 4 1 SI conditions for seed potato certification Basic 0 – 0,1 0,5 Certified 0, ,5

9 Dickeya spp. – symptoms on the potato plants The tissue which is infected by Dyckeya spp. at the begininng of infection is more or could be brown. In the case of Eca the infected parts are usually more black. The infected potato stem in the case of Dyckeya spp. could be separated or interrupted by undamaged tissue. There are infections or symptoms just on the the upper parts of the plants even just on the leaves. Eca causes lesions which are uninterrupted.