19 Effects of Copper-based Compounds, Antibiotics and a Plant Activator on Population Sizes and Spread of Clavibacter michiganensis subsp. michiganensis in Greenhouse Tomato Seedlings

Abstract

Three copper-based compounds (copper hydroxide, copper oxychloride, copper sulphate), two antibiotics (streptomycin and kasugamycin) and a plant activator (ASM) significantly reduced population sizes and spread of C. michiganensis subsp. michiganensis among tomato seedlings in the greenhouse. Streptomycin had the best effect in reducing pathogen population size in all sampling regions. Moreover, this antibiotic completely stopped the spread of C. michiganensis subsp. michiganensis in the region most distant from the inoculum focus. Copper hydroxide mixed with streptomycin significantly limited the pathogen population, compared with copper hydroxide alone, the other copper-based compounds, ASM and kasugamycin. However, combining streptomycin with copper hydroxide did not contribute to its greater efficacy against the pathogen population. Copper-based compounds, in general, were less effective in limiting pathogen population sizes than the other treatments in all three sampling regions, primarily copper oxychloride and the combination of copper hydroxide and mancozeb. Among copper compounds, copper hydroxide was the most prominent in reducing the bacterial population, especially in the region closest to the inoculum focus, while its combination with mancozeb did not improve the effects. Kasugamycin significantly limited pathogen population size, compared to copper bactericides, but it was less effective than the other antibiotic compound, i.e. streptomycin. The plant activator ASM significantly reduced population density, and it was more effective when used three days prior to inoculation than six days before inoculation.

Jedinjenja na bazi bakra (bakar-hidroksid, bakar-oksihlorid, bakar-sulfat trobazni), antibiotici (streptomicin i kasugamicin) i aktivator otpornosti biljaka (acibenzolar-S-metil, ASM) značajno su redukovali veličinu populacije i širenje C. michiganensis subsp. michiganensis na rasadu paradajza u zaštićenom prostoru. Streptomicin je imao najbolji efekat u smanjenju populacije patogena u svim regionima uzorkovanja. Takođe, ovaj antibiotik je potpuno zaustavio širenje C. michiganensis subsp. michiganensis u regionu najudaljenijem od žarišta inokuluma. Mešavina bakar-hidroksida i streptomicina je značajno smanjila populaciju patogena u poređenju sa tretmanom bakar-hidroksidom primenjenim samostalno, drugim bakarnim jedinjenjima, acibenzolar-S-metilom i kasugamicinom. Međutim, kombinovanje streptomicina sa bakar-hidroksidom nije doprinelo poboljšanju njegovog efekta na smanjenje populacije patogena. Bakarni preparati su imali najslabiji efekat u smanjenju populacije patogena na sva tri mesta uzorkovanja, što se pre svega odnosi na bakar-oksihlorid i kombinaciju bakar-hidroksida sa mankozebom. Među bakarnim jedinjenjima najbolji efekat imao je bakar-hidroksid, posebno u regionu najbližem žarištu inokuluma, dok njegova kombinacija sa mankozebom nije poboljšala efekat. Kasugamicin je bio efikasniji od bakarnih jedinjenja, ali znatno slabiji u smanjenju populacije bakterije od drugog antibiotika-streptomicina. Aktivator otpornosti ASM je ispoljio značajan efekat u smanjenju zaraze, pri čemu je bolji efekat ovog jedinjenja ostvaren primenom tri dana pre inokulacije u odnosu na primenu šest dana pre inokulacije.