Noviji nalazi i stepen pojave prstenaste nekroze krtola krompira (potato virus y, pvyntn) u Srbiji

Potato virus Y i.e. its necrotic strain (PVYNTN) is among the most economically harmful agents of potato diseases in Serbia and in many countries across the world. Damage caused by the virus involves reduced yields of infected plants, its spread i.e. a high percentage of infected plants at the country level and a high rate of annual infections (infestation of healthy plants) during the growing season. In most widely grown potato cultivars, the necrotic strain of potato virus Y causes symptoms only on aboveground parts, depending on cultivar and time of infection (primary and secondary). The necrotic strain of potato virus Y causes additional problems to some potato cultivars including symptoms of necrotic ringspot disease on tubers, resulting in their reduced quality or rendering them unmarketable. Experience shows that these are mostly cultivars that have a high dry matter content in tubers and that are processed into potato chips. This study presents results on the susceptibility of some potato cultivars to tuber necrotic ringspot disease as well as on the incidence of the disease under conditions characterised by a high potential for infection with the necrotic strain of potato virus Y.Y virus odnosno nekrotični soj (PVYNTN) ovog virusa je jedan od ekonomski najštetnijih prouzrokovača bolesti krompira u Srbiji i mnogim zemljama sveta. Štetnost virusa se ogleda u smanjenju prinosa zaraženih biljaka, njegovoj raširenosti odnosno visokom procentu zaraženih biljaka krompira na području države i velikoj brzini jednogodišnjeg širenja (zaražavanja zdravih biljaka) u toku vegetacije. Nekrotični soj Y virusa, na većini široko rasprostranjenih sorti u proizvodnji krompira, prouzrokuje simptome samo na nadzemnom delu biljke krompira u zavisnosti od sorte kromira i vremena zaraze (primarna i sekundarna). Nekrotični soj Y virusa krompira predstavlja dodatni problem za neke sorte krompira na čijim krtolama prouzrokuje simptome prstenaste nekroze što umanjuje njihov kvalitet ili ih čini tržišno neupotrebljivim. Dosadašnja iskustva govore da su to uglavnom sorte sa visokim sadržajem suve materije u krtolama i koje se koriste za preradu u oplemenjene proizvode. U ovo radu su prikazani rezultati osetljivosti nekih sorti krompira na prstenastu nekrozu krtola i stepen pojave bolesti u našim uslovima koje karakteriše visok infekcioni potencijal nekrotičnim sojem Y virusa

Antifungal activity and genetic diversity of selected Pseudomonas spp. from maize rhizosphere in Vojvodina

Antibiotic production by plant-associated microorganisms represents an environmentally compatible method of disease control in agriculture. However, a vide application of bacterial strains needs careful selection and genetic characterization. In this investigation, selected Pseudomonas strains were characterized by rep-PCR methods using ERIC and (GTG)5 primers, and partial 16S rDNA sequence analysis. None of strains produced homoserine lactones (C4, C6, C8) as quorum sensing signal molecules. Very poor production of phenazines and no significant fungal inhibition was observed for PS4 and PS6 strains. High amount of phenazines were produced by Pseudomonas sp. strain PS2, which inhibited mycelial growth of 10 phytopatogenic fungi in percent of 25 (Verticillium sp.) to 65 (Fusarium equiseti). Genetic characterization of the Pseudomonas sp. PS2 and evaluation of phenazines production, as the main trait for growth inhibition of phytopathogenic fungi, will allow its application as a biosafe PGPR for field experiments of plant disease control.Ekološki prihvatljiv metod kontrole bolesti bilja u poljoprivredi obuhvata primenu rizosfernih mikroorganizama koji produkuju antibiotike. Široka primena bakterija zahteva njihovu pažljivu selekciju i genetičku karakterizaciju. Ova istraživanja obuhvatila su karakterizaciju selektovanih Pseudomonas sojeva na osnovu rep-PCR metode korišćenjem ERIC i (GTG)5 prajmera, kao i parcijalne sekvence 16S rDNA. Nije detektovana produkcija acil-homoserin laktona (C4, C6, C8) kao QS molekula. Sojevi PS4 i PS6 su vrlo oskudno produkovali fenazine i nisu značajno inhibirali rast fitopatogenih gljiva. Soj Pseudomonas sp. PS2 je obilno produkovao 2-OH-PCA i PCA i inhibirao rast micelija 10 fitopatogenih gljiva od 25% (Verticillium sp.) do 65% (Fusarium equiseti). Genetička karakterizacija soja Pseudomonas sp. PS2 i detekcija produkcije fenazina kao glavnog inhibitora rasta fitopatogenih gljiva omogućiće primenu ovog soja kao bezbednog PGP agensa za biološku kontrolu u budućim ogledima u polju

Detection of Stolbur phytoplasma on blackberry: A new natural host in Serbia

During the late summer of 2007, a severe phytoplasma-like disease was observed for the first time in blackberry plants (Rubus fruticosus), commercial cv. Čačanska beztrna. Redness and downward rolling of leaves were symptoms observed in three localities in Central Serbia. The presence of Stolbur phytoplasma, belonging to the taxonomic subgroup 16SrXII-A, in diseased samples was confirmed by the PCR - RFLP analysis of 16S rDNA genes and elongation factor Tu (tuf) gene. A sequence analysis of the tuf gene confirmed homology with phytoplasmas stolbur tuf-type II detected previously in Italian grapevines and red clovers in the Czech Republic. This is the first report of Stolbur phytoplasma 16SrXII-A group tuf-type II on blackberries in Serbia.Simptomi nalik fitoplazmi prvi put su uočeni tokom leta 2007 g. na kupini (Rubus fruticosus) sorte Čačanska beztrna. Crvenilo i uvrtanje listova kao najčešći simptomi primećeni su na 3 lokaliteta u centralnoj Srbiji. Prisustvo Stolbur fitoplazme, koja pripada 16SrXII-A taksonomskoj podgrupi, utvrđeno je PCR - RFLP analizom 16S rDNK gena i gena za elongacioni faktor Tu (tuf) u uzorcima sa izraženim simptomima. Potvrđena je homologija dobijene sekvence tuf gena sa fitoplazmama Stolbur tuf- II tipa detektovanim na vinovoj lozi u Italiji i crvenoj detelini u Češkoj Republici. Ovo je prvi nalaz Stolbur fitoplazme 16SrXII-A grupe tuf- II tipa na kupini u Srbiji

Efikasnost mešavine kalijum fosfita i kaptana u suzbijanju Venturia inaequalis u jabučnjacima

Venturia inaequalis is a common apple disease in Serbia and its intensity depends on weather conditions. The most successful method of combating apple scab is to use a lower dose of an active ingredient and increase its effectiveness by adding substances that do not cause environmental damage. The effectiveness of a fungicide mixture of captan and potassium phosphite against V. inaequalis was investigated in apple orchards in 2008 and 2009. A relevant EPPO standard method was used in all trials. Captan 50 WP was used as a standard fungicide. In order to determine the exact conditions marking the onset of apple infection, key meteorological conditions were monitored in the orchards using an automated iMetos weather station and a Lufft electronic instrument. The results showed high efficacy of the tested fungicides which remained similar in both years of investigation. The intensity of leaf infection after treatment with the mixture of captan and potassium phosphite was 0.7-2.4%, while fruit infection was 0.5-3.0%. The efficacy of this mixture ranged from 96.3-97.9% on leaves and 87.4-98.7% on fruits. The standard fungicide Captan 50 WP showed an efficacy ranging from 95.3-96.7% on leaves and from 87.8-99.3% on fruits. No statistically significant differences were found between the fungicide tested and the standard fungicide.Venturia inaequalis je široko rasprostranjena bolest jabuke u Srbiji, a njen intenzitet zavisi od vremenskih uslova. Najuspešniji metod borbe protiv čađave krastavosti jabuke je korišćenje manjih doza aktivnih materija uz istovremeno povećavanje efikasnosti dodavanjem supstanci koje ne prouzrokuju štetu u životnoj sredini. Tokom 2008 i 2009 godine, proučavana je efikasnost fungicidne mešavine kaptana i kalijum fosfita protiv V. inaequalis u jabučnjacima. U svim ogledima je korišćen standardni EPPO metod. Captan 50 WP je korišćen kao standardni fungicid. Kako bi se tačno odredili uslovi za početak zaraze na jabuci, praćeni su osnovni meteorološki parametri u voćnjacima pomoću iMetos stanice i elektronskog uređaja Lufft. Rezultati su pokazali visoku efikasnost testiranih fungicida koja je bila slična u obe godine istraživanja. Intenzitet zaraze lista nakon tretmana mešavinom kaptana i kalijum fosfita bio je 0.7-2.4%, dok je zaraženost plodova bila 0.5-3.0%. Efikasnost mešavine bila je 96.3-97.9% na listovima, a 87.4-98.7% na plodovima. Standardni fungicid Captan 50 WP pokazao je efikasnost u opsegu 95.3-96.7% na listovima i 87.8-99.3% na plodovima. Nisu konstatovane statistički značajne razlike između ispitivanog i standardnog fungicida

Molecular characterization of potato virus Y inducing potato tuber necrotic ringspot disease in Serbia

The Potato virus Y (PVY) is the most important limiting factor for potato seed production in Serbia. Currently, PVY is a major concern for the potato seed growers. Initially, serological (ELISA) tests were carried out on 100 potato seed tubers from each of the seven potato cv. during 2013. The infection rates with the PVYN was between 5 and 36%. A complete genome sequencing of the most common Serbian isolate of PVY (3D), followed by molecular characterization and phylogenetic analysis has been performed to show what group it belongs to. Our isolate's complete genome sequence (KJ946936) showed that the Serbian PVY isolate (3D) is 99.7% identical at nt level, with other tuber necrosis strain group (PVYNTN) from Europe. Phylogenetic analysis revealed three consistent lineages of isolates, showing that our isolate was clustered with the isolates from Europe and North America in the PVYN lineage which induces potato tuber necrotic ringspot disease (PTNRD). The Serbian isolate of PVYNTN together with the isolates from Europe was clustered in the branch of European sublineage, with a high bootstrap support and no genetic diversity. This is the first study in Serbia demonstrating phylogenetic distinction between our isolate and other isolates of PVY