Laboratorijska
diagnostika bakterijske pegavosti na paradižniku in papriki
Nacionalni
inštitut za biologijo, Oddelek za rastlinsko fiziologijo in biotehnologijo,
Xanthomonas campestris
patovar vesicatoria (Dodge) Dye 1978 je povzročitelj bakterijske pegavosti
paradižnika in paprike. Bolezen povzroča velike škode zlasti v toplih in vlažnih
klimatih. Čeprav je splošno razširjena v Evropi se nahaja na A2 karantenski
listi, zaradi držav severne Evrope, kjer plodovke gojijo le v zaprtih prostorih
in je zato njeno zatiranje možno. Bakterijska pegavost se razvije na sejančkih
in na odraslih rastlinah. Na sejančkih lahko povzroči močno odpadanje listov,
na odraslih rastlinah pa pege na listih, steblih in plodovih. Poleg bakterijske
pegavosti, ki se v Sloveniji nahaja na A2 listi, lahko papriko in paradižnik
okužujeta še dve bakteriji, ki jih le po bolezenskih znakih ne moremo ločiti
med seboj: Clavibacter michiganensis
patovar michiganensis (karantenska
lista A2) in Pseudomonas syringae
patovar tomato (gospodarsko pomemben
povzročitelj bolezni). V Sloveniji smo bakterijsko pegavost prvič
laboratorijsko diagnosticirali leta 1999 na rastlinah paprike, nabranih na
Novogoriškem in v okolici Kostanjevice. Bakterijo smo izolirali iz rastlin z
izraženimi bolezenskimi znaki na splošna gojišča: NGA, KB in YDC, ter
selektivno gojišče Tween B. Serološko smo jo dokazali z imunofluorecenčnim
testom. Identifikacija je bila potrjena v Central Science Laboratory v Yorku,
Velika Britanija, z analizo profila maščobnih kislin.
Bakterija
lahko prezimi na ostankih rastlin ali na plevelih, prenaša pa se tudi s
semenom, še posebno pri paradižniku, kjer lahko doseže 60% okužbo semena.
Najboljše varstvo pred bakterijo je uporaba zdravega semena, toplotno
tretiranje ali sterilizacija semena, na voljo pa so tudi rezistentni kultivarji.
Za zatiranje bolezni se lahko uporablja baktericide - bakrove pripravke.
Pomembno je predhodno ugotoviti odpornost izolata na baker, ki lahko variira,
povezujejo pa jo s zastopanostjo 200 kb plazmida.
ABSTRACT
Laboratory diagnosis of bacterial spot on
tomato and pepper
Xanthomonas
campestris
pv. vesicatoria (Dodge) Dye 1978 is
the causal agent of bacterial spot of tomato and pepper. The disease causes
significant loss, particularly in warm and humid environments. Although it is
spread in the Europe, it is listed on A2 quarantene list. In the northern
European countries tomato and pepper are grown only in glasshouses, what enables
the control of disease. Bacterial spot develops on seedlings and mature plants.
On seedlings, infections may cause severe defoliation, on older plants, spots
occur on leaves, stem and fruits. Beside bacterial spot, which is listed on A2
in Slovenia, tomato can be infected also with two bacteria, which is impossible
to distinguish only due to the symptoms: Clavibacter
michiganensis pv. michiganensis (EU
list A2) and Pseudomonas syringae pv. tomato
(harmful organism). In Slovenia, bacterial spot was first identified by
laboratory methods in 1999, on pepper plants, grown in Nova gorica and
Kostanjevica regions. Bacteria was isolated from plants with symptoms on common
media: NGA, KB, YDC and selective Tween B medium. Serologically it was
identified by immuno fluorescence. Identification was confirmed in CSL in York,
Great Britain, with analysis of fatty acids profile.
The bacterium persists from
one season to the next in crop debris or on weed hosts. It is seedborne,
particularly in tomato, the incidence in seeds was as high as 60%. The most
efficient control is the use of healthy seed, heat treatment or chemical
sterilization of seeds, or the usage of resistant cultivars. Bactericides with
copper can be applied, although it is important to establish whether selected
isolate carry the resistance against copper, which can vary and is related with
the presence of 200 kb plasmid.