Antifungal activities of silver and selenium nanoparticles stabilized with different surface coating agents.

BACKGROUND: Extensive and growing use of different chemical pesticides that affect both the environment and human health raises a need for new and more suitable methods to deal with plant pathogens. Nanotechnology has enabled the use of materials at the nanoscale with exceptional functionality in different economic domains including agricultural production. This study aimed to evaluate antifungal potential of selenium nanoparticles (SeNPs) and silver nanoparticles (AgNPs) stabilized with different surface coatings and characterized by different surface charge on plant pathogenic fungi Macrophomina phaseolina, Sclerotinia sclerotiorum and Diaporthe longicolla. RESULTS: AgNPs were coated with three different stabilizing agents: mono citrate (MC-AgNPs), cetyltrimethyl ammonium bromide (CTAB-AgNPs) and polyvinylpyrrolidon (PVP-AgNPs). SeNPs were coated with poly-l-lysine (PLL-SeNPs), polyacrylic acid (PAA-SeNPs), and polyvinylpyrrolidon (PVP-SeNPs). Seven different concentrations (0.1, 0.5, 1, 5, 10, 50 and 100 mg L-1 ) of nanoparticles were applied. All AgNPs and SeNPs significantly inhibited the growth of the tested fungi. Among the tested NPs, PVP-AgNPs showed the best inhibitory effect on the tested plant pathogenic fungi, especially against S. sclerotiorum. The similar inhibition of the sclerotia formation was observed for S. sclerotiorum treated with PLL-SeNPs. CONCLUSION: Obtained results provides new insights on fungicide effect of AgNPs and SeNPs stabilized with different coating agents on different plant pathogens. Further work should focus on detailed risk/benefit ratio assessment of using SeNPs or AgNPs in agriculture taking into account whole agroecosystem. © 2020 Society of Chemical Industry.

Xanthium italicum, Xanthium strumarium and Arctium lappa as new hosts for Diaporthe helianthi.

Sunflower (Helianthus annuus) stem canker caused by Diaporthe helianthi is one of the most important sunflower diseases in Croatia. Until recently, sunflower was the only known host for D. helianthi. In our research carried out in the area of Eastern Croatia, isolates of Diaporthe/Phomospis were collected from Xanthium italicum, X. strumarium and Arctium lappa. Using morphological, cultural and molecular ITS rDNA data, isolates from these weeds were identified as D. helianthi. The following isolates were used in the pathogenicity test: one isolate originated from sunflower (Su5/04), three from X. italicum (Xa2, Xa3 and Xa5), two from X. strumarium (Xa9 and Xa12), one from Xanthium sp. (Xa13) and one from A. lappa (Ar3). According to the results, it was determined that isolate Xa5 (originated from X. italicum) was the most pathogenic to sunflower stems. The average length of the lesion was 11.3 cm. The lowest level of pathogenicity was found in Xa9 (isolated from X. strumarium). The length of the lesion was 0.1 cm.