Essential oils and hydrolates in control of plant pathogens

Under conditions of intensive plant production and intensive international trade with plant material, coupled with climate changes, plant pathogens became one of the major limiting factors in food and feed production. Besides these extremely favorable conditions for reproduction and dissemination of plant pathogens, resistance development to available control tools and ecotoxicological properties of these tools show that plant pathogen control has never been more challenging. Development of alternative, eco-friendly control tools against phytopathogens, became a necessity of contemporary agriculture. Essential oils are mixtures of complex volatile compounds. They are synthesized through secondary metabolic pathways in many plant species. Essential oils are normally extracted by hydro-distillation or steam distillation of plant tissues. Hydrolates are co-products of the distillation formed in significantly higher quantities than the target substance. Hydrolate represents aromatic water containing approximately 0.1% essential oil compounds

Uticaj etarskih ulja i hidrolata etarskih ulja na razvoj prouzrokovača gorke truleži jabuke

Vrste roda Colletotrichum, prouzrokovači gorke truleži jabuke, predstavljaju jedne od najznačajnijih prouzrokovača truleži plodova jabuke u skladištu. Zbog dominantne zastupljenosti u odnosu na druge vrste ovog roda posebno su značajne vrste C. acutatum i C. gloeosporioides. S obzirom da upotreba fungicida nakon berbe i tokom skladištenja nije dozvoljena zbog njihovih nepovoljnih ekotoksikoloških svojstava, a plodovi ostaju nezaštićeni tokom skladištenja, neophodno je definisanje alternativnih rešenja. Prethodna istraživanja su dokazala značajan antifungalni potencijal etarskih ulja i njihovih hidrolata (sporednih proizvoda koji se dobijaju pri proizvodnji etarskih ulja), te mogu predstavljati adekvatnu zamenu fungicidima. U ogledu je ispitan uticaj etarskih ulja čubra (Satureja hortensis), bosiljka (Ocimum basilicum), muskatne žalfije (Salvia sclarea) i divljeg origana (Origanum vulgare), kao i hidrolata etarskih ulja čubra, bosiljka i muskatne žalfije na izolate KA7 (C. acutatum) i MRMCD6 (C. gloeosporioides)

Improved Aflatoxins and Fumonisins Forecasting Models for Maize (PREMA and PREFUM), Using Combined Mechanistic and Bayesian Network Modeling—Serbia as a Case Study

Contamination of maize with aflatoxins and fumonisins is one of the major food safety concerns worldwide. Knowing the contamination in advance can help to reduce food safety risks and related health issues and economic losses. The current study aimed to develop forecasting models for the contamination of maize grown in Serbia with aflatoxins and fumonisins. An integrated modeling approach was used, linking mechanistic modeling with artificial intelligence, in particular Bayesian network (BN) modeling. Two of such combined models, i.e., the prediction model for aflatoxins (PREMA) and for fumonisins (PREFUM) in maize, were developed. Data used for developing PREMA were from 867 maize samples, collected in Serbia during the period from 2012 to 2018, of which 190 were also used for developing PREFUM. Both datasets were split randomly in a model training set and a model validation set. With corresponding geographical and meteorological data, the so-called risk indices for total aflatoxins and total fumonisins were calculated using existing mechanistic models. Subsequently, these risk indices were used as input variables for developing the BN models, together with the longitudes and latitudes of the sites at which the samples were collected and related weather data. PREMA and PREFUM were internally and externally validated, resulting in a prediction accuracy of PREMA of, respectively, 83 and 70%, and of PREFUM of 76% and 80%. The capability of PREMA and PREFUM for predicting aflatoxins and fumonisins contamination using data from the early maize growth stages only was explored as well, and promising results were obtained. The integrated approach combining two different modeling techniques, as developed in the current study, was able to overcome the obstacles of unbalanced data and deficiency of the datasets, which are often seen in historical observational data from the food safety domain. The models provide predictions for mycotoxin contamination at the field level; this information can assist stakeholders of the maize supply chain, including farmers, buyers/collectors, and food safety authorities, to take timely decisions for improved mycotoxin control. The developed models can be further validated by applying them into practice, and they can be extended to other European maize growing areas.</p

Etarska ulja u suzbijanju prouzrokovača vlažne truleži krtola krompira iz roda Pectobacterium

Vrste roda Pectobacterium su proteklih godina postale jedne od deset najproučavanijih fitopatogenih bakterija. Pažnju zavređuju zbog sve učestalije pojave novih vrsta, ekstremnoj adaptivnosti različitim domaćinima i uslovima životne sredine. Intenzivna trgovinska razmena dovodi do povećanja mogućnosti dospevanja novih vrsta na udaljena područja proizvodnje krompira, uzimajući u obzir da je glavni izvor inokuluma zaražen vegetativni materijal namenjen za sadnju. Štete uzrokovane vrstama Pectobacterium dosežu velike razmere, s obzirom na to da svoju aktivnost nastavljaju i po završetku vegetacije – prilikom transporta, prerade i u uslovima skladišta. Suzbijanje ovih patogena postaje ekstremno zahtevno uzimajući u obzir opšti nedostatak baktericida, te su mnogobrojni napori učinjeni sa ciljem iznalaženja načina suzbijanja prouzrokovača vlažne truleži krtola u uslovima skladišta. Mnoga istraživanja ukazuju na visoku efikasnost biljnih ekstrakata i etarskih ulja, kao moćnih agenasa zaštite. U cilju utvrđivanja efekata etarskih ulja (EU) bosiljka (Ocimum basilicum), čubra (Satureja hortensis), divljeg origana (Origanum vulgare), vreska (Calluna vulgaris) i timjana (Thymus vulgaris) na vrste P. carotovorum (Pc), P. brasiliense (Pb) i P. punjabense (Pp), sproveden je ogled in planta, na krtolama krompira sorte Lady Claire, jedne od najosetljivijih sorti na Pectobacterium spp

Emerging Fusarium Mycotoxins Fusaproliferin, Beauvericin, Enniatins, and Moniliformin in Serbian Maize

Emerging mycotoxins such as moniliformin (MON), enniatins (ENs), beauvericin (BEA), and fusaproliferin (FUS) may contaminate maize and negatively influence the yield and quality of grain. The aim of this study was to determine the content of emerging Fusarium mycotoxins in Serbian maize from the 2016, 2017, and 2018 harvests. A total of 190 samples from commercial maize production operations in Serbia were analyzed for the presence of MON, ENs, BEA, and FUS using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The obtained results were interpreted together with weather data from each year. MON, BEA, and FUS were major contaminants, while other emerging mycotoxins were not detected or were found in fewer samples (&lt;20%). Overall contamination was highest in 2016 when MON and BEA were found in 50&ndash;80% of samples. In 2017 and 2018, high levels of MON, FUS, and BEA were detected in regions with high precipitation and warm weather during the silking phase of maize (July and the beginning of August), when the plants are most susceptible to Fusarium infections. Since environmental conditions in Serbia are favorable for the occurrence of mycotoxigenic fungi, monitoring Fusarium toxins is essential for the production of safe food and feed

Sensitivity of Cercospora beticola Isolates to Azoxystrobin

Sugar beet leaf spot, caused by the air-borne fungus Cercospora beticola Sacc., leads to a decrease in sugar beet leaf mass and the consequent regrowth of leaves based on exploiting the sugar reserves stored in the plant’s roots, thus ultimately resulting in lower yields and sugar contents of sugar beets. Azoxystrobin belongs to the group of QoI fungicides, which inhibit mitochondrial respiration by blocking cytochrome c reductase. The QoI fungicides are characterized by a very high risk of resistance interfering with their biological activity. For the purpose of testing the azoxystrobin sensitivity of the Cercospora beticola population found at the site of Rimski Šančevi, a collection of 84 isolates was assembled and tested for sensitivity to azoxystrobin by measuring the mycelial growth on fungicide-amended media with the addition of SHAM. The results obtained indicate that none of the isolates tested exhibited complete sensitivity to azoxystrobin, 4% were found to have reduced sensitivity, 26% were moderately resistant and 70% were highly resistant. A higher proportion of resistant isolates recorded is associated with the loss of azoxystrobin biological efficacy at the experimental site

Biological Control of Aflatoxin in Maize Grown in Serbia

Aspergillus flavus is the main producer of aflatoxin B1, one of the most toxic contaminants of food and feed. With global warming, climate conditions have become favourable for aflatoxin contamination of agricultural products in several European countries, including Serbia. The infection of maize with A. flavus, and aflatoxin synthesis can be controlled and reduced by application of a biocontrol product based on non-toxigenic strains of A. flavus. Biological control relies on competition between atoxigenic and toxigenic strains. This is the most commonly used biological control mechanism of aflatoxin contamination in maize in countries where aflatoxins pose a significant threat. Mytoolbox Af01, a native atoxigenic A. flavus strain, was obtained from maize grown in Serbia and used to produce a biocontrol product that was applied in irrigated and non-irrigated Serbian fields during 2016 and 2017. The application of this biocontrol product reduced aflatoxin levels in maize kernels (51&ndash;83%). The biocontrol treatment had a highly significant effect of reducing total aflatoxin contamination by 73%. This study showed that aflatoxin contamination control in Serbian maize can be achieved through biological control methods using atoxigenic A. flavus strains