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Abstract. In the field and boundary of certificated field for organic farming in the Institute of Agriculture – Karnobat have been observed and described diseases, pests and weeds in wild and cultivated plants and dependencies between them are reported. The cultural plant diversity at the certified field for organic farming is significant and amounts to 32 species and varieties of cereals. The weeds in crops and in the free areas significantly differed. In crops, the annual broadleaf weeds had greater diversity of species (Anthemis arvensis L., Lathyrus aphaca L., Papaver phoeas L., Polygonum aviculare L., Polygonum convolvulus L.) and at the boundaries – the cereal weeds (Аpera spica-venti L., Hordeum murinum L., Bromus tectorum L., Poa pratensis L.). At the adjacent areas the perennial broadleaf weeds – Cirsium arvense (L.) Scop. and Convolvulus arvensis L. were not found. At the boundaries less pest species and types of diseases were registered than in the crop fields. In cereals the most common pests are Sitobion avenae L., Aelia acuminate L., Eurygaster austriaca Schr. Beneficial insects are Coccinella septempunctata L. The most common diseases are Erysiphe graminis and Rhynchosporium secalis (Oudem.) Davis

Abstract. Over the period of 2014-2015, on the experimental field of the Institute of Agriculture in Karnobat, Bulgaria, was set a field trial with twenty cultivars of barley – 15 two-row: Obzor, Emon, Perun, Orfey, Lardeya, Asparuh, Kuber, Zagorets, Imeon, Sayra, Devinya, Sitara, Krami, Vicky, Potok; 3 four-row: Veslets, Aheloy 2, Tamaris; and 2 six-row cultivars – IZ Bori and Bozhin. All the cultivars were grown in three types of farming: conventional, organic and biodynamic. In conventional farming were applied pesticides and nitrogen fertilization. In the organic production were not used pesticides, mineral and organic fertilizers; and in biodynamic farming was applied biodynamic compost prepared from manure and biodynamic preparations (also organic). In conventional farming, the seeds were disinfected before sowing with Kinto plus (Triticonazole 20 g/l + Prochloraz 60 g/l), at a rate of 150 ml/100 kg seeds. In organic and biodynamic farming were used nondisinfected seeds. In the phenophase of full maturity of barley was conducted monitoring survey for plants infected with loose smut in all 2 the trial variants, the number of infected plants per m were counted and the infection rates were calculated. Infected plants of Tamaris grown in the three types of farming underwent microscopic analysis and measurement of 100 teliospores from each variant. The aim of this experiment was to investigate varietal susceptibility of barley to Ustilago nuda, grown in three types of farming, and to establish if the growing method affects the size of the teliospores of the pathogen. With two-row barley were found plants of Lardeya, Kuber, Devinya, Krami and Vicky infected with Ustilago nuda. Krami manifested the lowest resistance in the three types of farming. With four-row barley, Tamaris was found to be highly susceptible and Veslets was poorly resistant. Both cultivars expressed weaker susceptibility in conventional and biodynamic farming and stronger in organic. With six-row cultivars was found no infection. The cultivars of Obzor, Emon, Perun, Orfey, Asparuh, Zagorets, Imeon, Sayra, Sitara, Potok, Aheloy 2, IZ Bori and Bozhin were resistant to Ustilago nuda and are suitable to be grown in the three types of farming. The size of teliospores in organic farming exceeded the ones in conventional farming with 5.28%, and the ones in biodynamic farming were smaller with 0.93% on average. The differences were not proven, but the tendency can be explained with the various approaches in growing the crops.

Abstract. During the period 2012 – 2014 in the Institute of Agriculture, Karnobat a field experiment was conducted with winter malting barley varieties Emon, Vanessa and Vicky. The influence of broadleaf (dicotyledonous) herbicides alone and in their combination with wild oat (monocotyledonous) in tillering stage of the crop was studied in optimal and double doses. The herbicide selectiveness was assessed according to the EWRS scale. Yields were reported after harvest. In variety Vanessa during the treatment with Derby Super, Granstar Super, Sekator OD and combination of Puma Super 7.5 EW + Sekator OD in optimal doses, the yield does not differ from the weed control. Variety Vicky endures well the treatment with optimal doses in all of the tested herbicides, except Husar Max. In treatment with double doses, only Granstar Super does not affect negatively the yield of grain. Comparing the data from ANOVA about the role of herbicides and year conditions on the malting barley varieties it can be concluded that the yield of variety Emon is the most stable in regard to herbicides applied in optimal doses (5%), followed by Vanessa (17%) and Vicky (18%). At application of the herbicides in double doses, their influence is increased – in variety Emon up to 15%, and in varieties Vanessa and Vicky – up to 23%.

Abstract. On a certified organic field a trial of the hull-less oat variety Mina was conducted, sown after peas-sunflower mixture, maize for silage, and fallow. The aim of this experiment was to evaluate the effect of predecessors on the productivity and phytosanitary condition of hull-less oats in organic farming. The study was conducted in the period 2012 – 2014 under field conditions on leached, moderately loamy to slightly clayey smolniza at the Institute of Agriculture in Karnobat, Bulgaria, on a field certified for organic farming. The trial was conducted with spring hull-less oat, variety Mina. Predecessors – peas-sunflower mixture, maize for silage and fallow. Phytosanitary monitoring was conducted. The insect reporting was performed through direct investigation for plant pests. The weed reporting – species composition and density of weed infestation by a quantity-weight method, at the end of tillering and beginning of ear formation stage. Disease infestation was determined by walking through the plots during crop vegetation, by the route method, by inspection of the plants. The best predecessor for hull-less oats was fallow, followed by peas-sunflower mixture. The yield was high and the level of weed infestation was comparatively lower than after maize for silage. During the studied period a tendency for the effect of predecessor on disease infestation was not formed. The predecessors did not affect the species composition but mainly their density

Abstract. During the period of 2013 – 2015 the influence of farming types (organic and biodinamic) on the phytosanitary status and yield of kamut was studied. Kamut is resistant to diseases and they are not a problem for growing it in an organic and biodynamic way. In both kinds of farming single numbers of five types of pests on kamut were recorded. Two of them were from Order Homoptera (Sitobion avenae L. and Rhopalosiphum maidis (Fitch)) and three from Hemiptera (Philaenus spumarius (L.), Eurygaster integriceps Put. and Aelia acuminata L.).The species diversity of the weeds was greater in biodynamic farming. Kamut yield from biodynamic farming was proven to exceed the organic one. The strength of effect of the type of farming factor was 83.57%.

Abstract. Until recently, Penthaleus major (Dugès) has not been recognized as an economically significant pest for the cereal crops. After climatic changes, its population began to grow and inflict damages around the world. The aim of this study was to investigate its distribution in Bulgaria and establish whether it presents a danger to the cereal crops. In the autumn of 2015 and the spring of 2016, a monitoring survey was conducted to establish Penthaleus major (Dugès) with the cereal crops in Bulgaria. Over 60 sowed fields were investigated from all around the country. Samples were taken to identify the pest. It was established that Penthaleus major (Dugès) inflicted harm to the wheat in north-eastern (12-14 mites per stem) and south-eastern Bulgaria (6-8 mites per stem). Its density was under the threshold of economic harm. There was not found infestation of barley, rye, oat and triticale. On the field boundaries bordering the areas attacked by the mite were reported the following weeds: Capsella bursa pastoris (L.) Medic, Descurania sophia (L.) Welb. et Berth, Senecio spp., Sisymbrium orientale Torn., Taraxsacum officinale Weber, Anthemis spp., Bromus arvensis L., Eragrostis pilosa (L.) P.B. Lolium temulentum L., which can be habitat for Penthaleus major (Dugès).

The aims of this study were to (1) establish the intrapopulation and seasonal variation of Juniperus excelsа essential oil (EO); (2) compare the J. excelsa concrete and resinoid composition with its EO composition; and (3) investigate the potential herbicidal activity of J. excelsa EO against seeds of Papaver rhoeas L., Consolida orientalis (J.Gay) Schrödinger, Anthemis arvensis L., Avena fatua L., and Agrostemma githago L. Four independent studies were performed to meet these objectives. Twenty-eight individual trees were analyzed from two populations to establish intrapopulation and interpopulation variability of EOs yield and composition. In the seasonal dynamic study of leaf EO, samples from the same three trees and in the same population were collected in January, March, May, July, October, and December and their EO yield and composition determined. The EOs (intrapopulation and seasonal) were extracted by hydrodistillation, while the EO for the herbicidal test was obtained by steam distillation in a semi-commercial (SCom) apparatus. Overall, the EO yield varied significantly from 0.93% to 2.57%. α-Pinene (8.85-35.94%), limonene (11.81-50.08%), and cedrol (3.41-34.29%) were the predominant EO compounds in all samples (intrapopulation variability); however, trans-2,4-decadienol and β-caryophyllene were predominant in some individual trees. Four chemical groups were identified in the samples collected from two natural populations (intrapopulation). This is the first report on the compositions of J. excelsa concrete and resinoid. Cedrol (15.39%), 7-hydroxy-4-methyl-coumarin (17.63%), 1-octacosanol (36.85%), tritriacontane (16.08%), and tiacontanoic acid were the main compounds in the concrete and resinoid. Juniperus excelsa EO suppressed seed germination and seedling growth of P. rhoeas, C. orientalis, A. arvensis, A. fatua, and A. githago, demonstrating its potential to be used for the development of new biopesticides. The highest EO yield with high content of limonene and cedrol was obtained from samples harvested during the winter months (December, January, and March)., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Semerdjieva et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Hypericum species and especially H. perforatum L. are well known for their therapeutic applications. The present study assessed the essential oil (EO) composition, and antifungal and aphid suppression activity of seven Bulgarian Hypericum species. The EOs were analyzed by GC-MS-FID. Two experiments were conducted. In the first experiment, H. perforatum , H. maculatum , and H. hirsutum were used. Additionally, the EO composition of H. perforatum extracted via hydrodistillation (ClevA) and via commercial steam distillation (Com) were compared. The second experiment compared the EOs of H. perforatum , H. cerastoides , H. rumeliacum , H. montbretii , and H. calycinum (flowers and leaves) extracted via hydrodistillation and collected with n -hexane. Overall, the EO constituents belonged to four classes, namely alkanes, monoterpenes, sesquiterpenes, and fatty acids. The main class for compounds in H. maculatum and H. perforatum (section Hypericum ) were sesquiterpenes for both experiments except for H. perforatum (Com). Hypericum montbretii (section Drosocarpium ) EO had monoterpenes (38.09%) and sesquiterpenes (37.09%) as major groups, while H. hirsutum EO (section Taeniocarpium ) contained predominately alkanes (67.19%). Hypericum hirsutum EO contained cedrol (5.04%), found for the first time in Hypericum species. Fatty acids were the main compounds in H. cerastoides (section Campylopus ), while monoterpenes were the most abundant class in H. rumeliacum and H. calycinum EOs. α -Pinene and germacrene D were the major EO constituents of all analyzed Hypericum species except for H. hirsutum and H. cerastoides. Hypericum perforatum EO (Com) had significant repellent and insecticidal activity against two aphid species, Rhopalosiphum padi (Bird Cherry-oat aphid) and Sitobion avenae (English grain aphid) at concentrations of 0%, 1%, 2.5%, 3.5%, 4.5%, and 5%. The tested EOs did not show significant activity against selected economically important agricultural fungal pathogens Fusarium spp., Botrytis cinerea , Colletotrichum spp., Rhizoctonia solani , and Aspergillus sp. The EO of the Hypericum species found in the Bulgarian flora could be utilized for the development of new biopesticides for aphid control.

The objective of this study was to assess the biological activity of essential oils (EOs) of four Juniperus species obtained via two different distillation methods and their potential as biopesticides. The studied factors were juniper species ( Juniperus communis L., J. oxycedrus L., J. pygmaea C. Koch., and J. sibirica Burgsd), plant sex (male (M) and female (F)), and distillation method (hydrodistillation via a standard Clevenger apparatus (ClevA) and semi-commercial (SCom) steam distillation). The hypothesis was that the EO will have differential antioxidant, antimicrobial, and insecticidal activities as a function of plant species, plant sex, and distillation method. The two distillation methods resulted in similar EO composition within a given species. However, there were differences in the EO content (yield) due to the sex of the plant, and also differences in the proportions of some EO components. The concentration of α-pinene, β-caryophyllene, δ-cadinene and δ-cadinol was dissimilar between the EO of M and F plants within all four species. Additionally, M and F plants of J. pygmaea , and J. sibirica had significantly different concentrations of sabinene within the respective species. The EOs obtained via ClevA extraction showed higher antioxidant capacity within a species compared with those from SCom extraction. All of the tested EOs had significant repellent and insecticidal activity against the two aphid species Rhopalosiphum padi (bird cherry-oat aphid) and Sitobion avenae (English grain aphid) at concentrations of the EO in the solution of 1%, 2.5%, and 5%. The tested EOs demonstrated moderate activity against selected pathogens Fusarium spp., Botrytis cinerea , Colletotrichum spp., Rhizoctonia solani and Cylindrocarpon pauciseptatum . The results demonstrate that the standard ClevA would provide comparable EO content and composition in comparison with SCom steam distillation; however, even slight differences in the EO composition may translate into differential bioactivity.

Juniperus excelsa M. Bieb and J. sabina L. contain essential oil (EO), while J. sabina also contains podophyllotoxin, which is used as a precursor for anti-cancer drugs. Two studies were conducted. The first assessed the variability in the EO profile and podophyllotoxin concentration of the two junipers, depending on the location and tree gender. The main EO constituents of J. excelsa were α-cedrol, α-limonene and α-pinene, while the constituents in J. sabina were sabinene, terpinen-4-ol, myrtenyl acetate and α-cadinol. The podophyllotoxin yield of 18 J. sabina accessions was 0.07-0.32% ( w/w ), but this was not found in any of the J. excelsa accessions. The second study assessed the effect of hydrodistillation (Clevenger apparatus) and steam distillation (in a semi-commercial apparatus) on the EO profile and bioactivity. The extraction type did not significantly alter the EO composition. The EO profiles of the two junipers and their accessions were different and may be of interest to the industry utilizing juniper leaf EO. Breeding and selection programs could be developed with the two junipers (protected species) in order to identify chemotypes with (1) a high EO content and desirable composition, and (2) a high concentration of podophyllotoxin in J. sabina . Such chemotypes could be established as agricultural crops for the commercial production of podophyllotoxin and EO.