A survey of in vitro and in vivo sensitivity of Verticillium dahliae and Fusarium oxysporum to several commercial fungicides and biofungicides was undertaken. In in vitro assays, the tested isolate of V. dahliae proved to be very sensitive to difenoconazole (EC50 = 0.02 mg/l). However, under greenhouse conditions, the highest efficacy in V. dahliae control on inoculated pepper plants was recorded for a product based on thiophanate-methyl (83.10% compared to control). Among the tested fungicides, the lowest efficacy was recorded for a product based on azoxystrobin (23.10 %) with no significant difference compared to control (p > 0.05). In in vitro assays, the tested F. oxysporum isolate was the most sensitive to prochloraz (EC50 = 0.07 mg/l) and the least sensitive to fluopyram (EC50 = 1075.01 mg/l). In in vivo assay, the highest efficacy was achieved by products based on captan (95.60%), and the lowest by a product based on thiophanate-methyl (54.40%). Antagonistic activity of the bacterium B. subtilis under laboratory conditions was not satisfying. Also, the antifungal activity and spectrum of a tested product based on tee tree oil was not efficient in suppressing pepper wilting caused by V. dahliae and F. oxysporum.

Brown rot caused by Monilinia spp. is one of the main causes of pre- and postharvest losses in stone and pome fruit production. The use of beneficial microorganisms is considered one of the most promising, safe and effective alternative methods for controlling these pathogens. This study aimed to investigate the antagonistic potential of 33 Bacillus spp. strains, in order to identify the best candidate for brown rot biocontrol. Strains identified as Bacillus amyloliquefaciens B-241 and Bacillus subtilis B-313 and B-358 were chosen for further ex situ studies on detached apple fruit. The efficacy of B-241 (87.1–93.7%) did not differ significantly from a commercially available synthetic fungicide (p > 0.05). The putative mode of action of B. amyloliquefaciens B-241 against Monilinia species is competition for nutrients and antibiosis. The ethyl acetate extract of the strain, applied at 5 and 12.5 mg/mL, was bioactive in vitro and ex situ. A HPLC analysis confirmed the presence of surfactin and bacillomycin D in the extract. However, before developing a shelf-stable product and commercial production, the spectrum and efficacy on a larger scale of the B-241 strain should be determined, and its efficacy in combination with commercial biofungicides and fungicides tested in vivo.

Strawberry production is a popular, fast-growing agricultural business in Serbia. Its cultivar selection has been changing fast, following market demands. One of the limiting factors of strawberry production worldwide is black root rot, primarily caused by binucleate Rhizoctonia. Recently, outbreaks of black root rot of strawberry have occurred in Serbia and the estimated disease incidence was up to 30%. Isolates of binucleate Rhizoctonia AG-A were recovered from symptomatic strawberry plants, and characterized on the bases of morphological, molecular and pathogenic features. Despite their uniform morphological characteristics, the isolates demonstrated genetic variability within ITS rDNA, grouping into three different phylogenetic sub-clusters which comprise AG-A isolates originating from Italy, Israel, Japan and the USA. The binucleate Rhizoctonia AG-A from Serbia exhibited uniform virulence on strawberry after inoculation of daughter plants and detached leaf petioles, as well as on seedlings of bean, carrot and sunflower, while they were non-pathogenic to wheat, maize, tomato, pepper, tobacco, cucumber, lettuce, peas, cabbage, rapeseed and sugar beet.

A study of in vitro sensitivity of five Alternaria solani isolates to cooper-oxychloride, chlorothalonil, difenoconazole, pyraclostrobin and a biofungicide based on tea tree essential oil was carried out. The isolates were obtained from infected tomato leaves collected from five different locations in Serbia. The tested isolates showed the highest sensitivity to pyraclostrobin with EC50 values ranging from 0.0014 to 0.0041 ?g ml-1. The EC50 values of difenoconazole were 0.018-0.037 ?g ml-1, chlorothalonil 2.99-4.54 ?g ml-1, and cooper-oxychloride 13.27-15.63 ?g ml-1. All tested A. solani isolates were the least sensitive to tea tree oil (1323.97-3307.08 ?g l-1).

Lettuce (Lactuca sativa L.) is the world's most popular leafy salad vegetable. One of the major challenges facing lettuce producers are fungal diseases that could, under favorable conditions, devastate the harvest (Raid, 2004). During February 2021, poor growth, plant stunning and blanching of leaves of lettuce plants, cultivated in unheated plastic tunel in Potočanje (Zlatibor region), Serbia, were observed. The crowns were softened with spreading decaying lesions covered with white mycelium, particulary on the leaves near the soil surface. Approximately 2 to 3 weeks before harvest, diseased plants began to wilt and collapse. Estimated disease incidence was 50-55%. In order to identify the causal agent, symptomatic tissues from diseased plants were cut into small pieces, surface sterilized with 70% ethanol for 1 min, rinsed three times in sterile distilled water and placed on potato dextrose agar (PDA). Five isolates with uniform morphology were derived from infected tissue. The colonies had fast-growing, white, cottony aerial mycelium, producing profuse numbers (184 sclerotia/ Petri plate in average) of small, black, irregularly shaped sclerotia, less than 2 mm in diameter. Based on morfological features, the isolates were identified as Sclerotinia minor Jagger (Kohn, 1979). To confirm the species identity, the internal transcribed spacer region of nuclear rDNA of a representative isolate 15-2 was amplified using the primer pair ITS1/ITS4 (White et al. 1990). Sequence analysis of ITS region revealed 100% nucleotide identity between the isolate 15-2 (GenBank Accession No. OL423632.1) and 14 isolates of S. minor from different parts of the world (e.g., accession Nos. MK356551.1, KY707828.1, JF2798801.1). Pathogenicity tests were conducted by artificial inoculation of 55-day-old lettuce plants cv. 'Majska kraljica', grown on commercial growth substrate in l L pots. The obtained isolates were grown on PDA for 7 days and mycelial plugs, 5 mm in diameter, were cut from the margin of the colony and placed mycelium-side down on undamaged ground-level leaves of lettuce plants. Two plugs per isolate were placed onto five plants each for a total of ten replicates per isolate. Negative control plants (5) were inoculated similarly with sterile PDA plugs. Inoculated plants were covered with transparent plastic bags, sprayed with water (under the plastic) twice a day for 3 to 5 days to maintain high humidity, and kept in a growth chamber at 22°C (13 h light). After 7 to 10 days, all pathogen-inoculated plants developed lettuce drop disease symptoms, whereas the control plants remained symptomless. The pathogen was reisolated from symptomatic leaves and Koch's postulates were completed by confirming the identity of the isolates. To our knowledge, this is the first report of S. minor on lettuce in Serbia. More research is needed to better understand this disease, establish control strategies and minimize the spread of the pathogen to other lettuce-producing areas of the country. References: Kohn, L. M. 1979. Delimitation of the economically important plant pathogenic Sclerotinia species. Phytopathology 69: 881-886. White, T. J., et al. 1990. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. Raid, R.N., 2004. Lettuce diseases and their management. In Diseases of Fruits and Vegetables: Volume II (pp. 121-147). Springer, Dordrecht. Founding: This work was funded by the Ministry of Education, Science and Technological Development (contract 451-03-9/2021-14/200214).

In vitro and in vivo sensitivity of Rhizoctonia solani to several commercial fungicides and biofungicides was studied. An isolate of R. solani, derived from diseased pepper plants originating from a greenhouse in Knjazevac, Serbia, was used. The highest efficacy in R. solani control under greenhouse conditions was achieved by iprodione (95.80%, compared to control), although differences in the effectiveness of iprodione, tea tree oil, azoxystrobin and thiophanate-methyl were not statistically significant. The isolate was sensitive to all tested products in vitro. The obtained EC50s were: 0.43 mg/l for iprodione, 1.84 mg/l for thiophanate-methyl, 13.84 mg/l for prochloraz, 430.37 mg/l for fluopyram, 596.60 mg/l for azoxystrobin, and 496.79 mg/l for tea tree oil.