Breskova bakterijska pegavost (Xanthomonas arboricola pv. pruni) v nasadih breskev in sliv v spodnji Vipavski dolini  

Gabrijel SELJAK¹, Tanja DREO², Maja RAVNIKAR³

¹ Kmetijsko veterinarski zavod Nova Gorica, SI-5000 Nova Gorica, Slovenija  
^2,3 Nacionalni inštitut za biologijo, Ljubljana, Slovenija

Breskova bakterijska pegavost, ki jo povzroča bakterija Xanthomonas arboricola pv. pruni (Smith) Vauterin & al. je v Sloveniji na seznamu A2 karantenskih škodljivih organizmov. Na ta seznam je bila iz seznama A1 prenesena v letu 1996, po močnejšem pojavu simptomov te bolezni po letu 1994 na slivah kitajsko-japonskega izvora v okolici Mirna v Spodnji Vipavski dolini. Leta 1996 se je bolezen množično pojavila v nekaterih breskovih nasadih v okolici Bilj, Bukovice in Prvačine ter na nekoliko bolj oddaljeni lokaciji pod Brjami v srednji Vipavski dolini. Od tedaj se v okuženih breskovih nasadih bolj ali manj redno pojavlja, posledice bolezni pa so odvisne predvsem od vremena, agrotehničnih in varstvenih ukrepov. V letu 1999 je bila bakterija tudi laboratorijsko potrjena, izolirana je bila iz dreves breskev z izraženimi bolezenskimi znamenji. Uporabili smo neselektivna gojišča YDC in NA, ter izolate z ustrezno morfologijo testirali z imunofluorescenčnim testom. Identiteta bakterije je bila potrjena s testom ugotavljanja profila maščobnih kislin v CSL, York, Velika Britanija.

Pri breskvah okužuje bakterija vse zelene dele in enoletne veje, najbolj pa so očitni simptomi na listih in plodovih. Na listih in plodovih so najmočnejše okužbe spomladi in v zgodnjem poletju, medtem ko se enoletne šibe okužijo zlasti med odpadanjem listov.

Na teh delih in na odpadlem listju bakterija tudi prezimi. Glede občutljivosti so med sortami tako pri breskvah kakor pri slivah velike razlike.

Breskovo bakterijsko pegavost je mogoče omejevati predvsem s poostrenim zdravstvenim nadzorom izhodiščnega materiala, sajenjem manj občutljivih ali tolerantnih sort, skrbnim odstranjevanjem in uničevanjem okuženih dreves ali njihovih delov ter uporabo bakrovih fungicidov med odpadanjem listja in pri zimskem škropljenju breskev, v zelo nizkih koncentracijah (50 g čistega bakra na 100 l vode) tudi v rastni dobi.

V prispevku bo natančneje opisana simptomatika, epidemiologija, trenutna razširjenost v Sloveniji, diagnostične metode in možnosti omejevanja bolezni.

ABSTRACT

Bacterial spot of peaches (Xanthomonas arboricola pv. pruni) in peach and plum orchards in Vipava valley

Bacterial spot of peaches, caused by Xanthomonas arboricola pv. pruni (Smith) Vauterin & al. is listed on A2 Slovene quarantine list. It was delivered on A2 list in 1996 from A1 list, after intense symptoms appearance on plums of Chinese – Japan origin in 1994, in surroundings of Miren in Vipava Valley. In 1996, the disease broke out in peach orchards in surrounding of Bilje, Bukovica and Prvačina and in one dislocated location near Brje in middle Vipava Valley. Since then, its appearance could be noticed more or less regularly, while the disease effects  are dependent on the weather, agricultural and plant health measures. In 1999, the bacterium was identified also by laboratory methods. It was isolated from peach leaves with typical symptoms. Common media: YDC and NA were used for isolation and colonies with typical morphology were tested by immuno fluorescence. Identification was additionally confirmed in CSL in York, Great Britain.

Bacterium infects all green parts of peach trees and one-year branches. The most obvious symptoms appear on leaves and fruits, especially in the spring and early summer. In the time of leaf drop, one-year-old branches become infected mostly. Bacteria can overwinter on infected branches and on defoliated leaves. Plum and peach cultivars are differently susceptibility to bacterial spot of peaches.

Bacterial spot could be controlled mainly by using healthy planting material, planting of tolerant or less susceptible cultivars, with eradication of infected trees or their parts or treatment with copper fungicides in the period of leaf drop and during winter period, in low concentration (50 g of copper in 100 l of water) also during the vegetation period.

The paper will describe bacterial spot symptoms, epidemiology, spread in Slovenia, diagnostic methods and the control measures.