Integration of biological and chemical methods in control of pepper bacterial spot

Bakteriozna pegavost koju prouzrokuje Xanthomonas euvesicatoria je najrasprostranjenija i ekonomski najštetnija bakterioza paprike u Srbiji. Raspoložive mere zaštite često bivaju izostavljene ili nisu dovoljno efikasne, stoga zaštita paprike od ovog patogena predstavlja stalan izazov, posebno pri povoljnim uslovima za razvoj bolesti. Kontrolu bolesti dodatno otežava pojava novih rasa bakterije i razvoj sojeva rezistentnih prema antibioticima i jedinjenjima bakra. Stoga postoji potreba za razvojem nove održive strategije u kontroli bolesti. Biološke metode kao što su primenа bаkteriofаgа, virusa koji parazitiraju bakterije, i neke novije аlternаtivne metode primena аktivаtora sistemične opornosti biljaka, ukаzuju nа mogućnost rаzvojа efikаsne strаtegije zа suzbijаnje X. euvesicatoria. Integralna zaštita paprike upotrebom bioloških i hemijskih metoda može predstavljati novi alternativan metod koji bi omogućio efikasnu i održivu zaštitu paprike od ove bolesti. U ovom radu, u cilju razvoja integralnog programa zaštite paprike od bakteriozne pegavosti, proučena je efikasnost bioloških agenasa bakteriofaga (soj KΦ 1), Bacillus subtilis (sojevi AAac i QST 713), aktivatora sistemične otpornosti (acibenzolar-S-methil - ASM), komercijanog mikrobiološkog đubriva (Slavol), bakarnih preparata (bakar-hidroksid i bakar-oksihlorid), primenjenih samostalno ili u kombinaciji sa mankozebom i antibiotika (streptomicin sulfata i kasugamicina). Na osnovu efikasnosti pojedinačnih tretmana, različite kombinacije tretmana su integrisane radi proučavanja efikasnosti u tri zasebna eksperimenta u uslovima otvorenog polja. Takođe, proučen je uticaj ASM na porast i prinos biljaka paprike u uslovima fitokomore i uslovima otvorenog polja. Koncentracija ASM od 0,0015% pokazala se kao veoma efikasna u kontroli bolesti, pri čemu je ispoljila minimalan negativan uticaj na porast i prinos biljaka paprike. Svi pojedinačni tretmani su značajno umanjili intenzitet oboljenja u poređenju sa netretiranom inokulisanom kontrolom izuzev tretmana mikrobiološkim đubrivom i antagonističkim sojem B. subtilis AAac. Tretmani bakarnim preparatima, antibioticima, ASM i bakteriofagima pokazali su visok nivo efikasnosti, dok je tretman sojem B. subtilis QST 713 bio manje efikasan...Bacterial spot caused by Xanthomonas euvesicatoria is one of the widespread and economically most important pepper diseases in Serbia. Available management practices are often omitted or failed to provide satisfactory disease control, especially when weather conditions favoured spread of the pathogen. Occurence of new pathogen races, as well as antibiotics and copper resistance development, make the disease control even more difficult. Therefore, development of new more sustainable disease management strategies is needed. Biological methods such as use of bacteriophages, viruses that infect bacteria, and some recent alternative treatments like systemic acquired resistance (SAR) inducers, provided the possibility of developing an effective strategy for X. euvesicatoria control. Integration of classical and biological treatments could be a succesful and environmentally safe option for reducing pepper bacterial spot severity. In order to develop an efficient integrated disease management program for peper bacterial spot control, we studied efficacy of biocontrol agents: bacteriophages (strain KФ1) and two strains of Bacillus subtilis (AAac and QST 713), systemic acquired resistance (SAR) inducer (acibenzolar-S-methyl - ASM), a commercial microbial fertilizer (Slavol), copper based compounds (copper hydroxide and copper oxychloride) in combination with or without mancozeb, and antibiotics (streptomycin sulphate and kasugamycin). Based on the single treatment efficacy, various combinations of treatments were integrated for further testing in three separate field experiments. Additionally, we evaluated potential negative effect of ASM on pepper growth and yield in the growth chamber experiments and field. Spraying of ASM in concentration of 0.0015% effectively controlled the disease intensity and caused minimal negative effect on pepper growth and yield. All the tested single treatments significantly reduced disease severity compared to the untreated inoculated control (UTC), except microbiological fertilizer and the antagonistic strain B. subtilis AAac. Copper compounds, antibiotics, ASM and bacteriophages treatments showed high efficacy, while B. subtilis strain QST 713 was less effective. All integrated treatments of biocontrol agents, ASM and copper hydroxide, tested in three separate field experiments, significantly reduced disease severity as compared to the UTC..