Alternaria Radicina Research Articles

The influence of modern fungicides on the damage caused by Alternaria radicina meier of carrots in the conditions of the Forest-Steppe of Ukraine

The influence of modern fungicides on the damage caused by Alternaria radicina meier of carrots in the conditions of the Forest-Steppe of Ukraine

First Report of Black Rot of Carrot Caused by Alternaria carotiincultae in China.

China is the world's largest producer and exporter of carrot (Daucus carota L. var. sativa), a well-known and nutritious root vegetable. In the spring seasons of 2021-2023, dark brown lesions were observed on field-grown and cold-stored carrot roots in the Xiamen City, Fujian Province, China. Although just discovered in recent years, the disease has expanded from the initial point to the most planting area in there, and causing over 20% yield loss in the most severely affected fields. This disease symptom is consistent with black rot, a carrot disease found globally and caused by the fungal pathogen Alternaria radicina (Saude et al. 2006). Small pieces of symptomatic roots (3 to 5 mm) from diseased carrot roots were surface disinfested with 75% alcohol for 3 minutes and 10% sodium hypochlorite solution for 8 minutes, and then rinsed in sterile distilled water and cultured on potato dextrose agar (PDA) medium at 28°C with a 12-h dark/light photoperiod. By tissue isolation and single-spore culture, six isolates were obtained from the disease plants in the past three years, and used for morphological and molecular analyses. Unexpectedly, the morphological characteristics of conidia of the six isolates, shape (long and ellipsoid), size (27 to 60 × 17 to 21 μm, n =50), and color (dark olive-brown) were similar to those of A. radicina, but with more transverse septae (Figure 1, Trivedi et al. 2010). Meanwhile, compared to A. radicina, the colony's margin was highly uniform and smooth, without an accumulation of yellow pigment and with fewer dendritic rhizomycin crystals at the bottom of agar media. These characteristics were similar to those of Alternaria carotiincultae, but not to those of A. radicina (Park et al. 2008). Genomic DNA of the six isolates was extracted and further molecular identification was performed. The EF-1α gene was amplified using EF-1/EF-2 primer pairs and sequenced (O'Donnell et al. 1998.). The EF-1α gene sequences of the six isolates were compared using DNAMAN 5.2.9 software. They were found to be 100% identical, and the sequences has been deposited in GenBank under accession number OR449062. BLAST analysis of the amplicon revealed 100% nucleotide sequence identity with the A. carotiincultae strain YZU 151039 (GenBank accession No. MK279390), while 2bp difference between the sequences of A. radicina strains present in GenBank. Pathogenicity tests of the isolate were carried on the unwounded carrots (5 roots each, with three replications). These tap roots were surface disinfected with 75% alcohol and disinfected by immersion in 0.75% sodium hypochlorite solution for 10 minutes, then immediately rinsed with sterile water and dried with sterile filter paper. Mycelial plugs (6 mm diameter) were taken from the margin of a vigorously growing colony and inoculated into the sterilized carrot roots. Another group of sterilised tap roots inoculated with sterile agar plugs were used as negative control. All the roots were incubated in the dark at 25°C with 80% humidity. After 2 days, colonies were observed on the surface of the roots that had been inoculated with the mycelial plugs. After 7 days, the inoculated tap roots showed symptoms of black rot with dark brown sunken lesions as the diseased plants in the field. However, no disease was observed on the control roots. Following the previous method, a strain was re-isolated from the inoculated carrot roots and again identified as A. carotiincultae, thus fulfilling Koch's postulates, and confirming that A. carotiincultae is the pathogen causing dark brown lesions of carrots. To our knowledge, this is the first report of A. carotiincultae causing carrot black rot in China. Attention should be paid to the damage caused by this pathogen during the production and storage stages of carrots, and strategies should be developed to prevent its spread.

Complete genome sequence of the carrot black rot pathogen Alternaria radicina isolate CBR2

Black rot, caused by Alternaria radicina, seriously endangers carrots throughout the growing season, affecting both leaves and fleshy roots. In this study, we sequenced and assembled the genome of the A. radicina isolate CBR2. The genome was 34.6 Mb in size and consisted of 6 scaffolds. The sequence information provided in this genome will be used as a reference for further comparative genomics analysis of Alternaria species and will contribute to disease control in carrot production.

The heritability of tolerance to pathogenic fungi <i>Alternaria dauci</i> and <i>Fusarium oxysporum</i> by carrot hybrids

Relevance. Alternaria dauci, Alternaria radicina and Fusarium oxysporumare wide spread and harmful fungal diseases of carrot (Daucus carota L.) in the Russian Federation and in the world. Total losses of roots from these diseases are 35-70%. Obtaining of new varieties and hybrids resistant to these pathogens is complicated by the fact of polygenic control resistance traits to fungal diseases of Alternaria and Fusarium genus. Interaction of polygenic resistance traits with environmental factors causes the soft character of changing these traits: effects of interactions between alleles and genes are changed, the dominant effect become weaker, additive effect become stronger. So, we can say about of the tolerance to complex pathogens for that case.The goal of our study is to determine the heritability of tolerance to fungal pathogens Alternaria dauci and Fusarium oxysporum by hybrids F1 of carrot.Materials and methods. Materials of studies were 7 basic lines with different types of roots; 7 prospective hybrids F1 and mycelium of Alternaria dauci and Fusarium oxysporum with spores (for inoculation). Methods of studies were: evaluation resistance of lines and hybrids F1 (seedlings, adult plants and roots) at different types of infection backgrounds; dispersion and correlation analysis. Resistance the basic lines of carrot to fungi of Alternaria and Fusarium genus was evaluated step-by-step, using several types of artificial and natural infection backhybrids F1. Tolerant samples were selected and they were used in crossings. F1 – hybrids have been obtained and they have been evaluated at artificial and natural backgrounds.Results: 1. One tolerant male form № 1268 and 6 female forms with weak sensitivity to fungi of Alternaria and Fusarium genus were selected from basic material. They were used in crossings. hybrids F1 have been obtained. 2. Analysis the heritability of carrot resistance to fungal pathogens Alternaria dauci and Fusarium oxysporum identified, that such type of resistance inherited by father’s type. 3. Using tolerant carrot line № 1268 in crossings as the male form and 6 female forms with weak sensitivity to fungal pathogens Alternaria dauci and Fusarium oxysporum increased significantly the percent of tolerant plant in 3 F1 – hybrid population under artificial infection on provocative infection background.

Detection of the Enzymes and Toxins Produced by the Pathogenic Fungi that Cause Chias Pollen Disease on Different Date Palm Cultivars in Iraq

Mohamed, Kh.A. and M.A. Alfahd. 2023. Detection of the Enzymes and Toxins Produced by the Pathogenic Fungi that Cause Chias Pollen Disease on Different Date Palm Cultivars in Iraq. Arab Journal of Plant Protection, 41(1): 65-70. https://doi.org/10.22268/AJPP-41.1.065070 This study aimed to determine the exo-enzyme activity of some inflorescence-rot causing fungi that were isolated from different date palm cultivars such as Mauginiella scaettae, Fusarium solani, Fusarium oxysporium and Alternaria radicina and their ability to produce protease and cellulase enzymes on Czapek dox (CD) liquid media supplemented with carboxy methyl cellulose (CMC), as well as their ability to produce Fumonisin B1 toxin using the enzyme linked immunoassay assay (ELISA). The results obtained showed a discrepancy in the amount of enzymes and toxins produced by these pathogens. The fungus F. oxysporum produced the highest cellulase enzyme activity, which amounted to 1.1933 units/ml, whereas Alternaria radicina produced the highest protease enzyme activity which amounted to 50,964 units/ml. The pathogen M. scaettae produced the highest toxin concentration of 38.465 µg/kg, whereas the pathogen Fusarium solani did not produce this toxin. Keywords: Mauginiella. Scaettae, enzymes, fumonisin B1, toxins.

Fungistatic Activity Mediated by Volatile Organic Compounds Is Isolate-Dependent in Trichoderma sp. "atroviride B".

Trichoderma spp. produce multiple bioactive volatile organic compounds (VOCs). While the bioactivity of VOCs from different Trichoderma species is well documented, information on intraspecific variation is limited. The fungistatic activity of VOCs emitted by 59 Trichoderma sp. "atroviride B" isolates against the pathogen Rhizoctonia solani was investigated. Eight isolates representing the two extremes of bioactivity against R. solani were also assessed against Alternaria radicina, Fusarium oxysporum f. sp. lycopersici and Sclerotinia sclerotiorum. VOCs profiles of these eight isolates were analyzed using gas chromatography-mass spectrometry (GC-MS) to identify a correlation between specific VOCs and bioactivity, and 11 VOCs were evaluated for bioactivity against the pathogens. Bioactivity against R. solani varied among the fifty-nine isolates, with five being strongly antagonistic. All eight selected isolates inhibited the growth of all four pathogens, with bioactivity being lowest against F. oxysporum f. sp. lycopersici. In total, 32 VOCs were detected, with individual isolates producing between 19 and 28 VOCs. There was a significant direct correlation between VOC number/quantity and bioactivity against R. solani. 6-pentyl-α-pyrone was the most abundant VOC produced, but 15 other VOCs were also correlated with bioactivity. All 11 VOCs tested inhibited R. solani growth, some by >50%. Some of the VOCs also inhibited the growth of the other pathogens by >50%. This study demonstrates significant intraspecific differences in VOC profiles and fungistatic activity supporting the existence of biological diversity within Trichoderma isolates from the same species, a factor in many cases ignored during the development of biological control agents.

Antimicrobial Natural Products from Plant Pathogenic Fungi.

Isolates of a variety of fungal plant pathogens (Alternaria radicina ICMP 5619, Cercospora beticola ICMP 15907, Dactylonectria macrodidyma ICMP 16789, D. torresensis ICMP 20542, Ilyonectria europaea ICMP 16794, and I. liriodendra ICMP 16795) were screened for antimicrobial activity against the human pathogenic bacteria Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, Mycobacterium abscessus, and M. marinum and were found to have some activity. Investigation of the secondary metabolites of these fungal isolates led to the isolation of ten natural products (1-10) of which one was novel, (E)-4,7-dihydroxyoct-2-enoic acid (1). Structure elucidation of all natural products was achieved by a combination of NMR spectroscopy and mass spectrometry. We also investigated the antimicrobial activity of a number of the isolated natural products. While we did not find (E)-4,7-dihydroxyoct-2-enoic acid (1) to have any activity against the bacteria and fungi in our assays, we did find that cercosporin (7) exhibited potent activity against Methicillin resistant Staphylococcus aureus (MRSA), dehydro-curvularin (6) and radicicol (10) exhibited antimycobacterial activity against M. marinum, and brefeldin A (8) and radicicol (10) exhibited antifungal activity against Candida albicans. Investigation of the cytotoxicity and haemolytic activities of these natural products (6-8 and 10) found that only one of the four active compounds, radicicol (10), was non-cytotoxic and non-haemolytic.

Fungal Diversity Profiles in Pit Mud Samples from Chinese Strong-Flavour Liquor Pit.

Pit mud, a specific fermented soil, is an essential material for the fermentation of Chinese strong-flavour liquor. However, few studies to date have sought to characterize the spatial profiles of pit mud fungal communities in fermentation cellars from Chinese strong-flavour liquor distilleries. In this analysis, differences in fungal community structures and physicochemical properties in pit mud samples from different spatial positions within fermentation cellars were analyzed, revealing unique characteristic multidimensional pit mud fungal community profiles. Penicillium roqueforti, Pichia kudriavzevii, Aotearoamyces nothofagi, Penicillium robsamsonii, Alternaria arborescens, Trichosporon insectorum, Seltsamia ulmi, Trichosporon coremiiforme, Malassezia restricta were dominant in the pit mud samples form the upper cellar wall, whereas Metarhizium frigidum, Calonectria pseudoreteaudii, Penicillium clavigerum, Fusarium equiseti, Simplicillium chinense, Aspergillus intermedius, Trichosporon coremiiforme, Fusarium circinatum, Alternaria radicina, Aspergillus heterocaryoticus were predominant in the middle cellar wall. Alternaria radicina, Cladosporium chasmanthicola, Alternaria helianthiinficiens, Penicillium argentinense, Antarctomyces psychrotrophicus, and Trichosporon inkin are majorly present in the down cellar wall layer. Bipolaris axonopicola, Ramgea ozimecii, Penicillium argentinense, Calonectria queenslandica, Metarhizium robertsii, and Penicillium roqueforti were identified as the dominant fungi in pit mud samples from the cellar bottom. Additionally, Alternaria destruens and Alternaria doliconidium are present at notably high levels in all layers of pit mud samples. Moisture, pH, PO43-, acetic acid, humus, K+, Mg2+, Ca2+, butyric acid, and caproic acid levels in these different pit mud positions exhibited a rising incremental pattern from the upper wall layer to the bottom layer, whereas lactic acid levels were significantly lower in the bottom pit mud layer relative to these other layers. Moisture, pH, and NH4+-N were identified as the three most significant factors associated with fungal community composition through a redundancy analysis. Overall, these findings may offer a theoretical foundation for future efforts to improve or standardize artificial pit mud.

Health status of carrots Daucus carota L. ssp. sativus grown in integrated and organic farming systems

Carrot culrivars ‘Bolero’, ‘Fayette F1’, ‘Flakke, Koral’, ‘Nantes’, ‘Perfekcja’ and ‘Sukces’ were grown in integrated and organic farming systems. The severity of Alternaria leaf blight and root diseases was evaluated at harvest and after five months of storage. Fungi were isolated from carrot roots. Disease severity was affected by the years of the study, farming system and cultivar. The severity of Alternaria leaf blight was lower in the integrated farming system than in the organic system. Carrots of cvs. ‘Bolero’ and ‘Fayette F1’ were healthiest. In both production systems, the symptoms of mixed rot (soft rot, Pectobacterium carotovorum subsp. carotovorum and Sclerotinia rot, Sclerotinia sclerotiorum), dry rot (Fusarium spp.), common scab (Streptomyces scabies), crater rot (Rhizoctonia carotae) and black rot (Alternaria radicina, A. dauci) were encountered sporadically, and their severity was low on carrot roots analyzed at harvest. Disease symptoms became more severe during storage, and they were more frequently observed on carrot roots in the organic farming system. Cultivars exerted varied effects on the severity of the analyzed root diseases. The fungal pathogens isolated from carrot roots confirmed the presence of disease symptoms.

In Vitro Antibacterial, Antifungal, Nematocidal and Growth Promoting Activities of Trichoderma hamatum FB10 and Its Secondary Metabolites.

Microbial natural biocides have attracted much more attention in recent years in order to avoid the unrestricted use of chemical biocides in the environment. The aim of this study is to analyze the antibacterial and antifungal activities of secondary metabolites and growth promoting, nematicidal, and soil enzyme activity mediated by Trichoderma hamatum FB10. The bactericidal and fungicidal activities were performed using cell-free extract. Results revealed that the selected strain exert antibacterial activity against Acidovorax avenae, Erutimacarafavora, and Xanthomonas campestris. The selected fungal strain FB10 showed antagonistic activity against fungal pathogens such as, S. sclerotiorum, Rhizoctonia solani, Alternaria radicina, Alternaria citri, and Alternaria dauci. Among the bacterial pathogens, A. avenae showed least MIC (30 ± 2.5 µg/mL) and MBC (70 ± 1.25 µg/mL) values. T. hamatum FB10 strain synthesized bioactive volatile secondary metabolite, which effectively inhibited the growth of bacteria and fungi and indicated the presence of 6-pentyl-alpha-pyrone as the major compound (67.05%). The secondary metabolite synthesized by T. hamatum FB10 showed nematicidal activity against M. incognita eggs. Egg hatch inhibition was 78 ± 2.6% and juvenile stage mortality rate was 89 ± 2.5% when the strain FB10 was treated with nematode. The cell free extract of T. hamatum FB10 showed protease, amylase, cellulase, chitinase, glucanase activities. T. hamatum FB10 inoculated with green gram increased 11% plant height, compared to the control. The fresh weight of the experimental group inoculated with T. hamatum FB10 increased 33.6% more compared to the control group. The green gram seedlings inoculated with T. hamatum FB10 increased 18% more dry weight than control group. Soil enzymes such as, urease, phosphatase, catalase and saccharase were improved in the soil inoculated with T. hamatum FB10. These biochemical components play potent role in soil fertility, energy conversion, and in soil organic matter conversion.

Effects of Plant Extracts and Disinfectant Huva-San TR 50 on the Quality of Carrot (Daucus carota L.) Seeds

Abstract The aim of the study was to determine the effect of Aloe vera (L.) Burm.f. (Aloe) and Morinda citrifolia L. (Indian mulberry) plant extracts and disinfectant Huva-San TR 50 (hydrogen peroxide stabilized with silver ions) on carrot seed quality. The seeds of two carrot cultivars Amsterdam (sample I) and Berlikumer 2 (sample II), were soaked in solutions of Aloe and Indian mulberry extracts and Huva-San TR 50 at concentrations of 0.025 %, 0.05 % and 0.1 % for 30 min. Untreated seeds and seeds soaked in distilled water for 30 min were used as controls. Seed germination was assessed after 7 and 14 days of incubation. The speed and uniformity of seed germination (vigour) were evaluated. Mycological analysis was performed using a deep-freeze blotter test. Sample I was characterized by lower germination at the first and the final counts than sample II and higher seed infestation with Alternaria radicina. Treating seeds of sample I with Morinda citrifolia plant extract at concentrations of 0.025 and 0.05 % reduced their infestation with Alternaria alternata and A. radicina, increased germination at the first and the final counts, and did not affect seed vigour. The effects of Aloe extract and disinfectant Huva-San TR 50 on seed quality parameters varied depending on their concentration. Hence, further studies are necessary to establish the optimal conditions for carrot seed treatment.

The Influence of Trichoderma harzianum Rifai T-22 and Other Biostimulants on Rhizosphere Beneficial Microorganisms of Carrot

The principles of good agricultural and horticultural practice, which consider both giving environmental protection and high yielding of plants, require modern cultivation methods. Modern cultivation of horticultural plants uses, for example, cover crops, living mulches, plant growth-promoting microorganisms (PGPMs), plant growth regulators (PGRs) and other biostimulants protecting the soil against degradation and plants against phytopathogens and stress. The purpose of field and laboratory studies was to determine the effect of Trianum P (containing Trichoderma harzianum Rifai T-22 spores), Beta-Chikol (a.s.—chitosan), Timorex Gold 24 EC (based on tea tree oil) and fungicide Zaprawa Nasienna T 75 DS/WS (a.s.—tiuram 75%) on the health of carrot (Daucus carota L.) plants and the microorganism population in the rhizosphere of this plant. Moreover, the antagonistic effect of rhizosphere fungi on selected carrot fungal pathogens was determined. Laboratory mycological analysis allowed one to determine the qualitative and quantitative composition of fungi colonizing the underground parts of carrot plants. In addition, the total population of fungi and bacteria was determined (including Bacillus sp. and Pseudomonas sp.) based on the microbiological analysis of the rhizosphere soil. The application of the plant growth-promoting fungus (Trichoderma harzianum T-22), chitosan and tea tree oil positively influenced the growth, development and health status of carrot plants. T. harzianum T-22, chitosan and fungicide most effectively protected carrots against infection by soil-borne fungi from the genus Alternaria, Fusarium, Haematonectria, Sclerotinia and Rhizoctonia. The rhizosphere population of Bacillus sp. and Pseudomonas sp. in the treatments with Trianum P or Zaprawa Nasienna T 75 DS/WS was bigger than in the other experimental treatments. A reverse relationship was observed in the population of rhizosphere fungi. T. harzianum T-22, chitosan and tea tree oil promoted the growth of antagonistic fungi (Albifimbria sp., Clonostachys sp., Penicillium sp., Talaromyces sp. and Trichoderma sp.) in the carrot rhizosphere. Antagonistic activity of these fungi towards Alternaria dauci, Alternaria radicina, Sclerotiniasclerotiorum and Rhizoctonia solani was higher after the application of the preparations compared to control. Consequently, Trianum P, Beta-Chikol and Timorex Gold 24 EC can be recommended as plant biostimulants in ecological agricultural production, including Daucus carota cultivation.

ANTAGONISTIC ACTIVITY OF A NEW STRAIN OF TRICHODERMA VIRIDE AND ITS EFFECT ON MICROMYCETES POPULATIONS IN THE ROOT ZONE OF CORN PLANTS

Goal. To investigate the antagonistic activity of a new strain of Trichoderma viride F-100076and its effect on the formation of micromycetes populations in the root zone of corn plants underfield conditions. Methods. The antagonistic activity of T. viride F-100076 was studied by the method of mixed (counter) cultures on wort agar using phytopathogenic fungi, which were isolated andidentified in the Laboratory of Plant-Microbial Interactions. The appearance and type of relationship were registered using a scale modified by Symonian and Mamikonian. The number of micromycetes was determined by the method of soil dilutions. Isolation, accounting and cultivation of fungiwas carried out according to conventional methods. Micromycetes were identified according to thedeterminants appropriate for a specific systematic group of micromycetes. Results. It was foundthat T. viride IMB F-100076 is characterized by high antagonistic activity against a wide range ofphytopathogenic fungi, showing hyperparasitism as early as on the eighth day. The highest antagonistic activity of the strain was found against: Alternaria radicina, Acremonium strictum, Acremonium сucurbitacearum, Fusarium oxysporum var. orthoceras, Fusarium moniliforme var. lactis, Torula expansa (5 points on the corresponding Symonian and Mamikonian scale). Data from the mycological analysis of the sod-podzolic soil of the corn rhizosphere showed that the mycocenosis ofthe sod-podzolic soil of the corn rhizosphere was formed by micromycetes belonging to the generaAcremonium Link, Cladosporium Corda, Fusarium Link:Fr, Gliocladium Corda, Mucor Mich, Penicillium Link:Fr, Rhizopus Ehrenb, Trichoderma Hers, among which the most represented were micromycetes of the genus Penicillium (59 %). The total number of fungi in the control variant was291.00 ± 79.67 thousand CFU/g of soil. The introduction of straw affected both the total number ofmicromycetes and the genus composition of fungi. The total number of fungi in the variant withstraw increased 2.6 times and amounted to 744.00 ± 114.67 thousand CFU/g of soil. The number ofrepresentatives of all studied genera of micromycetes also increased. In addition, the introductionof straw provoked the development of fungi of Bipolaris and Fusarium genera, which can be considered a negative outcome since representatives of these species are commonly recognised as pathogens of root diseases. Application of the fungus antagonist T. viride IMB F-100076 to the soilalong with straw did not significantly affect the total number of micromycetes. At the same time, a displacement of fungi of the genus Bipolaris and Fusarium from the rhizosphere of corn was registered.The number of fusaria decreased from 96.00 ± 5.44 to 23.00 ± 2.32 thousand CFU/g of soil or almost4 times and reached the level of the control variant. Fungi of the genus Bipolaris in the variant withthe introduction of trichoderma were not detected. Conclusion. The antagonist fungus T. virideF-100076, introduced into the soil along with straw, strikes root in the soil and exhibits antagonisticactivity against micromycetes of the genera Bipolaris and Fusarium, which are commonly represented by root rot pathogens of many crops. Thus, the new strain T. viride F-100076 allows increasing theantagonistic potential of the rhizosphere soil of corn and protecting plants from pathogens.

Eco-friendly quaternization of nicotinamide and 2-bromoacetophenones in deep eutectic solvents. Antifungal activity of the products

Most organic solvents used in quaternization reactions are volatile, hazardous, toxic and form by-products, thus inducing health issues and pollution. Deep eutectic solvents are greener alternatives, but they have not been tested yet in the quaternization reaction. Here we propose eutectic solvents in the quaternization reaction of nicotinamide with substituted 2-bromoacetophenones. The reaction was performed at 80 °C by three synthetic approaches: conventional during 2–6 h, microwave during 20 min and ultrasonic during 3 h. The highest yields of about 98% were obtained by microwave. The most suitable eutectic solvents were choline chloride with either urea, oxalic or levulinic acid. The use of deep eutectic solvents has several advantages: environmental benignity, biodegradability, easy purification and simple preparation. All tested compounds showed antifungal activities against Botrytis cinerea, Colletotrichum acutatum, Alternaria radicina and Fusarium graminearum at 10 and 100 µg/mL.

Sredstva za zaštitu korenastog povrća

The production, value and quality of root vegetables are endangered by numerous phytopathogenic fungi and pests. Numerous causal agents cause economically significant diseases of root vegetables like carrot leaf blight and black rot of carrots (Alternaria dauci and Alternaria radicina), powdery mildew of carrot and sugar beet (Erysiphe heraclei and Erysiphe betae), Cercospora leaf spot of carrot (Cercospora carotae), black blight (Septoria apiicola), leaf bright parsley (Septo-ria petroselini), downy mildew (Peronospora farinosa f.sp. betae and P. farinosa f.sp. spinaciae), rust (Puccinia spp.) etc. Nine fungicides based on nine different active substances have been registered in the Republic of Serbia for the control of phytopathogenic fungi in root vegetable crops. The most important pests of root vegetables are wireworms (Elateridae), carrot flies (Psila rosae), celery flies (Acidia heraclei), onion flies (Delia antiqua), aphids (Aphididae), common spider mite (Tetranychus urticass), cabbage moth (Mamestra brassicae), cotton bollworm (Helicoverpa armigera) and others. The overall number of insecticides, registered in our country, for the control of root vegetable pests is eight, based on seven different active substances. The aim of this paper is to present registered plant protection products for the control of the most economically import-ant pathogens and pests of root vegetables, in the Republic of Serbia, classified according to the mode of action.

Use of water restriction in the inoculation of carrot seeds

Abstract: This study aimed at evaluating the method of inoculation of carrot seeds in a potato-dextrose-agar medium (PDA) added of mannitol. Alternaria radicina was the fungus chosen to test such methodology. The osmosis-controlling agent was employed to obtain the osmotic potentials of 0.6 MPa, 0.8 MPa, 1.0 MPa and 1.2 MPa. In comparison with the control treatment, no significant mycelial growth inhibition was noticed at any of the osmotic potentials considered. The seeds were distributed over the fungal colonies for infection, where they remained for 48, 72, 96, 120 and 144 hours, at the osmotic potentials of 0.0 MPa (control), 0.6 MPa, 0.8 MPa, 1.0 MPa and 1.2 MPa, respectively. Tests of germination, sanitization and emergence were performed to evaluate the effects of colonization. Regarding the germination, the different osmotic potentials resulted in similar percentages of abnormal seedlings and dead seeds. As for the sanitization testing, higher infection rates were observed at the osmotic potentials of 1.0 MPa and 1.2 MPa. The lowest percentage of emergence was found at -1.2 MPa, therefore suggesting that this osmotic potential (produced with mannitol) might be used for infecting carrot seeds for research purposes.

Survey of the Fungi that Infect Imported Carrot (Daucus Carota L.) in the Areas of Baghdad

An extensive survey of fungi associated with post-harvest carrot degradation in different parts of the Baghdad market. samples were collected from three different regions of Adhamiya, Kadhimiya and Sadiyah . Five fungal species, such as , Aspergillus nige, Altinaria radicina, Sclerotinia sclerotorum, Geotrichum candidum and Rhizoctonia carotae, which isolated from the decayed samples. In this context, Altinaria radicina showed the highest frequency of 23.3%. Both Sclerotinia sclerotiorum, Aspergillus nige, Geotrichum candidum at 20% While Rhizoctonia carotae showed the lower frequency at 16.7%. Pathogenic exam showed that all isolated fungi were pathogenic to host roots Storage. However, Aspergillus nige was found to be more pathogenic to carrots resulting in a rapid disintegration of infected roots by 90%during the incubation period. While Alternaria radicina, Sclerotinia sclerotiorum, was 80% followed by Geotrichum candidum 75% and Rhizoctonia carotae less than 70% .

Antagonistic activity of selected fungi of the soil environment of carrot

The present studies aim at determining the antagonistic effect of selected fungi species occurring in the soil under carrot cultivation towards Altenaria dauci (J.G. Kühn) J.W. Groves & Skolko, Alternaria radicina Meier, Drechsler & E.D. Eddy, Fusarium oxysporum E.F. Sm & Swingle, Rhizoctonia solani J.G. Kühn and Sclerotinia sclerotiorum (Lib.) de Bary. The field experiment considered cover crops (oats, tansy phacelia and vetch). The control consisted of traditional carrot cultivation (without cover crops). Statistically, the smallest population of fungi was found in 1 g of soil dry weight after the application of oats, and a slightly bigger – after tansy phacelia and vetch. The largest population of fungi was obtained in the traditional cultivation of carrot. Cover crops contributed to the increase of the population of antagonistic Clonostachys spp., Myrothecium spp., Penicillium spp. and Trichoderma spp. in the soil. Regardless of the experimental treatment, those antagonistic fungi were the most effective in limiting the growth of S. sclerotiorum, A. dauci and A. radicina. The effect of those fungi was a little smaller towards F. oxysporum and R. solani. Oats as a cover crop had the best effect on the antagonistic activity of the studied fungi occurring in the soil environment of carrot.

Antagonistic activity of selected bacteria of the soil environment of carrot

The purpose of the present studies was to determine the antagonistic effect of bacteria Bacillus spp. and Pseudomonas spp. towards selected fungi from the soil environment of carrot. Oats (Avena sativa L.), tansy phacelia (Phacelia tanacetifolia Bentham) and vetch (Vicia satica L.) were used as cover crops in the cultivation of this plant. In the traditional cultivation of carrot the population of bacteria was the smallest, while after the application of oats it was the largest. Laboratory tests showed that cover crops promoted the development of antagonistic Bacillus spp. and Pseudomonas spp. Irrespective of the experimental treatment, those bacteria were the most effective in limiting the growth and development of Fusarium oxysporum and Thanatephorus cucumeris (syn. Rhizoctonia solani), while being less effective towards Altenaria dauci and Alternaria radicina, and the least towards Sclerotinia sclerotiorum. The best total antagonistic effect of Pseudomonas spp. and Bacillus spp. towards the tested fungi was found after using oats and vetch, while the worst – in the traditional cultivation of carrot.

CHARACTERIZATION OF ISOLATES OF ALTERNARIA AND FUSARIUM FOUND IN CARROT FROM DIFFERENT ECOLOGICAL AND GEOGRAPHIC ZONES

Selection of infected material for research was carried out in experimental carrot plots at GNU VNIIO (Moscow region), Voronezh OOS (Voronezh oblast), Baraccudas OOS (Rostov region) and Israel. The first year plants of carrot, the roots, were used for the study. There are many scientific papers cited where many different methods of artificial infection of plants with fungal disease pathogens were given to control the stability of carrot genotypes in various phases of plant development. One of the ways to lead the purposed breeding program for resistance is the extraction of pathogens isolates and the method of fast assessment on the basis of determining the aggressiveness of new strains and their use in breeding work. This article presents a method of inoculation of cut-discs of root. A great advantage of the method is in its efficiency and the current results can be obtained within 2 weeks from the moment of infection. As a result, the work on the isolation of fungi from carrot plants, the pure culture collection of strains: Alternaria radicina and Fusarium avenaceum was obtained. The characteristics and morphology description of colonies of isolates of RR. Alternaria and Fusarium found in carrot plants taken from different ecological and geographical zones were given. The most aggressive isolates of the following ecological and geographical zones as Alternaria at Moscow and Rostov regions, Fusarium at Voronezh and Moscow regions were revealed. These isolates will be used as standards of aggressiveness for the test of newly isolated strains regarded as inoculum to conduct immunological experiments in carrot breeding for resistance to Fusarium and Alternaria.