Search

The use of artificial fertilizers follows the intensification of agricultural production as a consequence of population growth, which leads to soil depletion, loss of organic matter, and pollution of the environment and production. This can be overcome by increasing the use of organic fertilizers in agriculture. In the present study, we investigated the effect of using vermicompost, biochar, mineral fertilizer, a combination of vermicompost and mineral fertilizer, and an untreated control on alluvial-meadow soil on the development of fodder winter barley Hordeum vulgare L., Zemela cultivar. We used a randomized complete block design of four replications per treatment. Barley grain yield, number of plants, and soil and microbiological parameters were studied. We found statistically proven highest grain yield and grain protein values when applying vermicompost alone, followed by the combined treatment and mineral fertilizer. The total organic carbon was increased by 70.2% in the case of vermicompost and by 44% in the case of combined treatment, both compared to the control. Thus, soil microbiome activity and enzyme activities were higher in vermicompost treatment, where the activity of β-glucosidase was 29.4% higher in respect to the control, 37.5% to the mineral fertilizer, and 24.5% to the combined treatments. In conclusion, our study found the best overall performance of vermicompost compared to the rest of the soil amendments. [ABSTRACT FROM AUTHOR]

Multispectral remote sensing is a new effective technique to evaluate crops phenology, plant health and the weeds presence. The study aims to exploit the possibilities of multispectral imaging for detection the weeds in winter wheat. The phenological changes of different weeds was also investigated, employing the calculation of six vegetation indexes during a period of three months. The vegetation indexes were as follows: CIG, GRNDVI, GRVI, CVI, NDWI2, NDVI. The influence of weed species on the value of the corresponding vegetation index within each reporting period was investigated. The control value was the one calculated for areas sown with wheat without weeds. It is established that the factors: phenophase and weed type have a statistically significant influence on the researched indexes. The GRVI is the only index on which plant phenophase does not have a significant effect. Regarding the NDVI values, no permanent trend for the presence/absence of a certain weed was found. In almost all phenophases, high values of the index were calculated in both weed varieties and weed free wheat. [ABSTRACT FROM AUTHOR]

Rye (Secale cereale L.) is an important crop used for food, animal feed and bioenergy. Weeds are one of the main factors limiting the growth and development of the crop. The aim of the present study was to determine the efficacy of foliar herbicides against broadleaf weeds and the treatments' influence on growth and reproductive performance of rye, "Millennium" cultivar. During the period 2021/2022 and 2022/2023, a field experiment with rye was carried out on the experimental field of the Agricultural University of Plovdiv, Bulgaria. The herbicidal products Sekator OD - 0.15 l ha-1, Axial One - 1.00 l ha-1, Biathlon 4D - 55 g ha-1, Granstar 75 DF - 15 g ha-1, and Aminopielik 600 SL - 2.00 l ha-1 applied in tillering stage of rye (BBCH 29) were evaluated. The efficacy of the studied products by the 10-score visual scale of EWRS was reported. The application of Biathlon 4D - 55 g ha-1 provides the best control against Papaver rhoeas L., Descurainia sophia L., Consolida orientalis J. Gay, Capsella bursa-pastoris L., Lamium purpureum L. and Fumaria officinalis L. At the same treatment rye yields as well as accompanying biometric indicators were the highest. [ABSTRACT FROM AUTHOR]

Allelopathic activity of Cuscuta epithymum L. (CVCEY), Cuscuta campestris Yuncker (CVCCA), Phelipanche ramosa (L.) Pomel (ORARA), Phelipanche mutelii (Schultz) Reuter (ORARM) and Phelipanche spp. (PHESS) on germination and initial development of test plats of Lactuca sativa L. cultivar 'Great Lakes' was studied under laboratory conditions. It was found that, water exracts of the parasitic weed species in concentrations 0.4, 0.8, 1.6, 3.2, 6.4 and 12.8% w/v have a relatively high inhibitory effect on the seed germination of test plants. The inhibiting rate of parasitic weed species from family Convolvulaceae ranges from 6.24 to 100.0% and for the species of family Orobanchaceae from 42.1 to 100.0%. Parasitic weed species from family Orobanchaceae (Ph. ramosa, Ph. mutelii and Phelipanche spp.) showed a considerably stronger allelopathic effect (GIaverage 17.9), as compared with the applied concentrations of water exracts of species from family Convolvulaceae (C. epithymum and C. campestris) (GIaverage 22.7).

The application of various chemical products for plant protection and plant biostimulans increases financial costs, which is a prerequisite for their combined application in tank mixtures. During 2021 and 2022 on the experimental field of the Agricultural University of Plovdiv, Bulgaria, a field experiment with the rye variety “Milenium” was performed. The aim of the trial was to study the application of plant protection products in tank mixture with biostimluant and its influence to the rye grain yield and quality. The trial included the following treatments: 1. Untreated control; 2. Granstar 75 DF - 15 g ha-1 (herbicide); 3. Granstar 75 DF - 15 g ha-1 + Zantara 216 EC - 1.25 l ha-1 (fungicide); 4. Granstar 75 DF - 15 g ha-1 + Amino Expert Impuls - 3.00 l ha-1 (biostimulant); 5. Granstar 75 DF - 15 g ha-1 + Zantara 216 EC - 1.25 l ha-1 + Amino Expert Impuls - 3.00 l ha-1. The highest rye grain yield, absolute and hectoliter seed mass, grain wet gluten and crude protein for treatment 5 were recorded. [ABSTRACT FROM AUTHOR]

In 2020 and 2021, a field trial with the maize hybrid P 9241 in the experimental field of the Agricultural University - Plovdiv, Bulgaria was conducted. The herbicidal products Stomp Aqua - 4.00 l ha-1 and Gardoprim Plus Gold - 3.50 l ha-1 applied to soil, as well as Adengo - 0.44 l ha-1 and Camix - 2.50 l ha-1 applied in the 1st - 2nd leaf stage of maize were evaluated. The efficacy of the studied products by the 10-score visual scale of EWRS was reported. Selectivity was also assessed using the 9-score scale of EWRS. The highest herbicidal efficacy against Amaranthus retroflexus L., Xanthium strumarium L., Abutilon theophrasti Medik., Solanum nigrum L., Sorghum halepense (L.) Pers. developed from seeds was reported after the application of Adengo. Of the studied herbicides, the highest control against Chenopodium album L. was reported for Camix. The biological yields of maize, as well as the structural elements of the maize yield were the highest after the application of Adengo and Camix applied in 1st - 2nd leaf stage of the crop. [ABSTRACT FROM AUTHOR]

An uncontrolled weed flora can decrease winter barley's grain yield and quality. Winter barley (Hordeum vulgare L.) variety 'Emon' field trial was conducted in the growing seasons 2020/2021 and 2021/2022. The trial was stated in the experimental field of the Agricultural University-Plovdiv, Bulgaria. The experiment aimed to study the efficacy of herbicides for broadleaf weed control in barley. The following herbicides efficacy was evaluated: Sekator OD - 0.15 l ha-1; Axial One - 1.00 l ha-1; Biathlon 4 D - 55 g ha-1; Granstar 75 DF - 15 g ha-1; Aminopielik 600 SL - 2.00 l ha-1. The herbicides were applied in spring at the phenophase end of tillering - the beginning of spindling of the crop (29-31). The herbicide efficacy was recorded by the 10-score visual scale of EWRS (European Weed Research Society). At the particular infestation with Sinapis arvensis L., Anthemis arvensis L., Galium aparine L., Consolida regalis Gray., and Viola arvensis L. the highest overall efficacy and highest yield were recorded when Biathlon 4 D - 55 g ha-1 was applied. [ABSTRACT FROM AUTHOR]

During 2019-2020 and 2020-2021 on the experimental field of the Agricultural University of Plovdiv, Bulgaria, a field experiment with winter wheat variety 'Enola' was performed. The trial included the following herbicidal treatments: Quelex + Trend 90 (37.5 g ha-1 + 0.1%); Quelex + Trend 90 (50 g ha-1 + 0.1%); Quelex + Aminopielik 600 SL (37.5 g ha-1 + 0.4 l ha-1); Quelex + Aminopielik 600 SL (50 g ha-1 + 0.4 l ha-1); Quelex + Mustang 306,25 SC (37.5 g ha-1 + 0.3 l ha-1); Derby super one + Trend 90 (33 g ha-1 + 0.1%); Mustang 306,25 SC (0.6 l ha-1); Sekator OD (1.25 l ha-1); Sekator OD (1.50 l ha-1) and Biathlon 4D + Dash (55 g ha-1 + 0.5 l ha-1). The herbicides were applied in phenophase tillering of the winter wheat (BBCH 21-29). The application of Quelex + Mustang 306,25 SC (37.5 g ha-1 + 0.3 l ha-1) and Quelex + Aminopielik 600 SL(50 g ha-1 + 0.4 l ha-1) ensured excellent efficacy against Anthemis arvensis L., Papaver rhoeas L., Consolida orientalis J.Gay, Vicia hirsuta L., Galium aparine L., Sinapis arvensis L., Lamium purpureum L., and Fumaria officinalis L.. The wheat biological yield as well as the supplementary biometrical indicators for the concrete two treatments was the highest. [ABSTRACT FROM AUTHOR]

The field experiment was conducted in the experimental field of the Institute of Maize - Knezha in the period 2016 - 2018. After sowing of maize hybrid Kneja-613 before weed emergence Stomp New 330 EC (330 g/l pendimethalin) was used in a dose of 400 ml/da. In phase 5th leaf of the culture it was treated with Chemnico 24 SC (240 g/l nicosulfuron) at a dose of 21 ml/da. Simultaneously with Chemnico 24 SC were used: Amalgerol - growth stimulator; Microelements for Maize; Vertex H-34 and Foliar Extra - foliar fertilizers. Highest positive effect on grain yield has the system of pendimethalin and nicosulforone, Microelements for Maize and Amalgerol. The average grain yield for the period is 731.73 kg/da and its increase by 14.16% is statistically proven. The system of pendimethalin and nicosulforone at combination with Amalgerol, with Microelements for Maize, with Vertex H-34 or with Foliar Extra increases the protein content to 9.29%, the fat content to 5.61%, and the starch content to 76, 68% of the grain of the Knezha-613 hybrid. [ABSTRACT FROM AUTHOR]

During 2018 and 2019 a field plot trial with maize (hybrid Blason Duo) was conducted. The study was situated on the experimental field of the Agricultural University of Plovdiv, Bulgaria. The trial was performed by the randomized block design in 4 replications. The florasulam-containing herbicide products Derby Super, Starane Gold and Kabadex Extra were under evaluation. The studied herbicide products were applied in two phenological stages of maize - BBCH 15 (3rd - 5th true leaf) and BBCH 18 (8th - 9th true leaf). The efficacy of the studied products by the 10-score visual scale of EWRS was reported. The selectivity by the 9-score scale of EWRS was also evaluated. The efficacy of the herbicide was higher after the application in BBCH 15 in comparison to that in BBCH 18. The highest herbicide efficacy against the weeds Chenopodium album L., Amaranthus retroflexus L., Xanthium strumarium L., Abutilon theophrasti Medik. and Solanum nigrum L. after the application of Kabadex Extra - 0.45 l ha-1 in BBCH 15, followed by Derby Super - 33 g ha-1 treated in the same stage was recorded. For the treatment with Kabadex Extra - 0.45 l ha-1 in BBCH 15 the studied parameters ear length, ear diameter, number of seeds per ear, absolute seed mass and grain yield were the highest. For all treatments accept for Starane Gold in BBCH 15, visual symptoms of phytotoxicity on the 7th day after application were recorded. The symptoms completely disappear on the 28th day after application. [ABSTRACT FROM AUTHOR]

Herbicides are powerful means for weed control in modern agriculture. However, in some cases they can negatively affect the crops, for example after herbicide drift. One suitable approach, aimed to improve recovery of herbicide-damaged crops, is the therapeutic biostimulant application. The aim of our study was to evaluate the potential of the plant biostimulant Amino Expert® to ameliorate recovering of florasulam + aminopyralid-potassium (Derby® Super) - damaged oilseed rape plants. The experiment included five treatments: 1. Untreated plot, accepted as a control. Treatments 2 and 3 represented Derby® Super 100% (of the registered rate) and Derby® Super 20% respectively. The treatments 4 and 5 included two applications - first by the herbicide and second - by the biostimulant four days later. The observations showed that the herbicide drift caused negative effect on oilseed rape plants distinguished by yellowing and growth retardation, which was visible to the beginning of flowering. On the contrary, the plants received an additional therapeutic application by Amino Expert® Impuls recovered faster and finally developed a higher silique number plant-1 as well as biological yield. The physiological parameters such as photosynthetic rate and pigments content also confirmed the ameliorative effect of the plant biostimulant application. [ABSTRACT FROM AUTHOR]

During 2016-2017 and 2017-2018 a field trial with winter wheat variety "Enola" was performed. The experiment was situated on the experimental field of the Agricultural University of Plovdiv, Bulgaria. Herbicide products with mixed mode of action were evaluated - Osprey Extra, Atlantis WG, Abak and Atlantis Flex. The application of Atlantis WG - 0.50 kg ha-1 + 1.00 l ha-1 showed the highest control against Anthemis arvensis, Papaver rhoeas and Sinapis arvensis. The highest efficacy against the weeds Lamium purpureum and Avena fatua after the application of Abak + Mero - 0.25 kg ha-1 + 1.00 l ha-1 was reported. The treatment with Osprey Extra + Biopower - 0.33 kg ha-1 + 1.00 l ha-1 showed highest efficacy against Lolium rigidum and Galium aparine. The most difficult-to-control weeds were the volunteer of Clearfield® oilseed rape and Veronica hederifolia. The height of the plants, length of the central ear, average number of grains per ear, average grain weight per ear, 1000 grain weight and yields were the highest after the treatment with Atlantis WG - 0.50 kg ha-1 + Biopower - 1.00 l ha-1 and Abak - 0.25 kg ha-1 + Mero - 1.00 l ha-1. [ABSTRACT FROM AUTHOR]

In the winter wheat vegetation period of 2019/2020 a field experiment with Sekator OD (100 g/l amidosulphuron + 25 g/l iodosulfuron + 250 g/l mefenpyr-diethyl) was conducted. The trial was situated on the experimental field of the Agricultural University of Plovdiv, Bulgaria. Variants of the trial were: 1. Untreated control; 2. Sekator OD - 0.10 l ha-1; 3. Sekator OD - 0.15 l ha-1 and 4. Sekator OD - 0.20 l ha-1. The herbicide application was performed in tillering stage (BBCH 21-29) in spring. For the study's purposes, the "Avenue" variety was grown. As well as the efficacy and the selectivity of the herbicide product, several quantitative and qualitative indicators were evaluated. The highest efficacy against the existing broadleaf weeds for the rate of 0.20 l ha-1 was recorded. There were no visual phytotoxic symptoms for the crop for any of the evaluated rates. By using the statistical criterion of Student Test, a positive and significant increase in the values of stem height at the rate of 0.10 l ha-1 and the number of ears at the rate of 0.20 l ha-1 were found. [ABSTRACT FROM AUTHOR]

In 2020 a field trial with the maize hybrid "Blason Duo" was conducted. The trial was stated on the experimental field of the Agricultural University of Plovdiv, Bulgaria. The performance of the herbicide product Starane Gold (100 g/l fluroxypyr + 1 g/l florasulam) in increased rates (1.20, 1.80 and 2.40 l ha-1) was evaluated. Untreated plot was accepted as a control. The efficacy and the selectivity of the herbicide, several biometrical parameters, and as well as the yields and its components were studied. The highest biological efficacy against the existing broadleaf weeds at the rates of 1.80 and 2.40 l ha-1 were reported but phytotoxic symptoms score 4 (by the 9-score scale of European Weed Research Society) for the rate of 2.40 l ha-1 were reported. Simultaneously with the decrease of the density of the broadleaf weeds a significant increase in the values of the studied traits as stem height and ear number per plant were found. The absolute and hectoliter seed mass as well as the yields were the highest for the treatment with application rates of 1.20 and 1.80 l ha-1. [ABSTRACT FROM AUTHOR]

The monitoring shows that in the oilseed rape fields of Bulgaria the dominating weed species are Sinapis arvensis L., Raphanus raphanistrum L., and on separate fields Papaver rhoeas L. The most common cereal weeds are Lolium ssp., Avena fatua L.. and wheat self-seeding. Perennial weeds are relatively limited. Species of the genus Phelipanche are most common in southern Bulgaria. The reasons for the mass distribution of these weed species are the violated crop rotations, seeding of oilseed rapes in short period of time - in 1-2 years on the same field, insufficient quality of the soil tillage, limited choice of herbicides for control of parasitic weeds, etc. The implementation of alternative cropping technologies like Clearfield®, their constant improvement, as herbicide content and selection process showed positive effect for decreasing the density and range of distribution of these weeds in the oilseed rape fields. [ABSTRACT FROM AUTHOR]

In 2018-2019, on the experimental field of the Agricultural University of Plovdiv, Bulgaria, a field experiment with maize hybrid P1114 was performed. The experiment included the following herbicide treatments: Callam (0.40 kg ha-1) + Kelvin OD (1.00 l ha-1) + Dash (1.00 l ha-1), Callam (0.50 kg ha-1) + Kelvin OD (1.25 l ha-1) + Dash (1.25 l ha-1), Callam (0.30 kg ha-1 ) + Kelvin OD (1.25 l ha-1) + Dash (0.625 l ha-1), Callam (0.30 kg ha-1) + Kelvin OD (1.25 l ha-1), Cambio SL (2.00 l ha-1) + Kelvin OD (1.25 l ha-1) and Arat (0.20 kg ha-1) + Kelvin OD (1.25 l ha-1). The application was done in 4th - 6th true leaf of maize (BBCH 14-16). The dominant weeds on the field were Sorghum halepense (L.) Pers. developed from seeds and rhyzomes, Setaria viridis (L.) P. Beauv., Chenopodium album L., Amaranthus retroflexus L., Xanthium strumarium L., Abutilon theophrasti Medik., Datura stramonium L. and Solanum nigrum L. The nicosulfuron-containing herbicide in combination with other products showed good to excellent efficacy depending on the weed species. For all variants treated whit herbicides 1000 grain weight, hectolitre mass and the yield, were higher and with statistically proved differences in comparison to the untreated control. [ABSTRACT FROM AUTHOR]

Maize is the third most important crop in Bulgaria. Weed infestation is one of the key factors responsible for the lower productivity and poor quality of the maize production. Reduction in grain yield ranges from 33 to 50% or even more depending on the intensity and nature of the weed flora. During 2018 and 2019 cropping seasons field trials were conducted in the region of Plovdiv, Bulgaria. The trials were situated on the base for training and implementation of the Agricultural University - Plovdiv. The experiments were carried out in non-irrigated conditions. The aim of the resent research is to establish the suitability of applying some new herbicide products and to investigate their efficacy in different application timings: pre-emergence (BBCH 00) and early post-emergence (BBCH-13). Several herbicides and mixtures were tested: mezotrione 50 g/l + terbutilazine 326 g/l SC - 180 ml/da; mezotrione 50 g/l + terbutilazine 326 g/l SC - 230 ml/da; mezotrione 75 g/l + terbutilazine 375 g/l + clomazone 40 g/l - 150 ml/da; mezotrione 75 g/l + terbutilazine 375 g/l + clomazone 40 g/l - 200 ml/da; S-metolchlor 312.5 g/l + terbutilazine 187.5 g/l - 350 ml/da. The obtained data was compared with untreated control. The experimental field was naturally infested with Sorghum halepense (L.) Pers., Setaria viridis L., Chenopodium album L., Xanthium strumarium L., Amaranthus blitoides L., Datura stramonium L., Solanum nigrum L. and Portulaca oleracea L. After evaluating the efficacy of the herbicides we concluded that during the testing period when the soil was very dry the efficacy of the herbicides applied during the early post emergence (BBCH-13) showed higher efficacy against the weeds existing on the field. [ABSTRACT FROM AUTHOR]

Changes in the leaf gas exchange and photosynthetic pigments of Oriental tobacco plants, parasitized by Phelipanche ramosa L. and Phelipanche mutelii SCH, were determined after treatment with glyphosate. The study was carried out in two consecutive years. The plant samples were collected from the experimental field of the Institute of Tobacco and Tobacco Products in Markovo, Plovdiv region: leaves of untreated plants; leaves from the upper part of the plant, treated with 0.144 l/ha a.s. glyphosate; leaves from the lower part of the plant, treated with 0.144 l/ha a.s. glyphosate; leaves from the upper part of the plant, treated with 0.240 l/ha a.s. glyphosate; leaves from the lower part of the plant, treated with 0.240 l/ha a.s. glyphosate. It was found that the decrease in the rate of net photosynthesis in tobacco plants treated with glyphosate, was due to the decreased content of photosynthetic pigments. Under the conditions of the present study, the total content of chlorophyll A and chlorophyll B in the plants treated with 0.240 l/ha glyphosate was reduced from 16% to 18% compared to the untreated plants. The intensity of transpiration in tobacco plants was influenced more strongly by environmental conditions and less by the treatment with glyphosate. The differences in stomatal conductance values of untreated and glyphosate-treated tobacco leaves were small and did not show statistical significance. [ABSTRACT FROM AUTHOR]

Chemical weed control is one of the most distributed weed management methods around the globe. As herbicide-resistant weeds often develop, dosage increases are required, leading to environmental pollution. An effective environmental strategy for the degradation of herbicides is to detect and apply microorganisms capable of breaking down and transforming the herbicides. The study aims to determine the degradation of the herbicide Merlin Flexx SC 480 (240 g/l isoxaflutole + 240 g/l cyprosulfamide - antidote) by the soil microorganisms. The current research was conducted with microbial communities from the maize rhizosphere that are resistant to isoxazoles. The soil was treated with two rates of isoxaflutole - 420 and 840 ml ha-1. The biodegradation of isoxaflutole to diketonitrile and benzoic acid derivative was measured by HPLC. The main representatives of the microflora were bacteria, mold fungi, and nitrogen-fixing bacteria to a greater extent. A decrease in the number of bacteria and an increase in the number of mold fungi in the treated soils was found. The number of nitrogen-fixing bacteria increased by increasing the amount of Merlin Flexx in the soil. [ABSTRACT FROM AUTHOR]

During the period of 2017-2019 a field trial with Clearfield oilseed rape (hybrid PT 200 CL) on the experimental field of the Agricultural University of Plovdiv, Bulgaria was conducted. The experiment included the application of imazamox - containing herbicide products - Cleranda SC, Cleravis SC, Cleravo SC and Clentiga SC together with the adjuvant Dash. The herbicide products were applied at BBCH 11-12 (1st-2nd true leaf) of the crop. The efficacy of the studied herbicides was evaluated by the 10-score scale of EWRS. The highest efficacy against Anthemis arvensis L., Papaver rhoeas L., Galium aparine L., Capsella bursa-pastoris (L.) Medik, Lolium temulentum L., Avena fatua L. and the volunteer Triticum aestivum L. after the application of Cleranda SC + Dash in rates of 2.00+1.00 l/ha, followed by Cleranda SC + Dash in rates of 1.40+1.00 l/ha and Cleravis SC+ Dash in rates of 2.00+1.00 l/ha was reported. For these treatments, the values for plant height, number of brunches per plant, silique number per plant, length of the central silique and yield were the highest. [ABSTRACT FROM AUTHOR]

The data analyses from the research showed that in the sunflower fields of Bulgaria a significant dynamics of the weed species and densities that form the weed associations has occurred. In the beginning of the monitoring the dominating weed species were Xanthium strumarium L., Sinapis arvensis L., and on separate fields Cannabis ruderalis Janisch. in high densities was prevailing. The reasons for the mass distribution of these weed species are the violated crop rotations, seeding of sunflowers in short period of time - in 1-2 years on the same field, insufficient quality of the soil tillage, the limited choice of herbicides for their control, etc. The implementation of the alternative cropping technologies like Clearfield® and ExpressSun®, their constant improvement, as herbicide content and selection process showed positive effect for decreasing the density and range of distribution of these three weeds in the sunflower fields. From the other hand led to clearly expressed compensatory processes and mass distribution Chenopodium album L. and Portulaca oleracea L. to a lower extent. It is known that imazamox and tribenuron-methyl have limited efficacy against Chenopodium album and Portulaca oleracea. [ABSTRACT FROM AUTHOR]

One of the most difficult to control weeds in winter wheat is Convolvulus arvensis L. In wheat, chemical weed control is preferred of its better efficiency. The aim of the current study is to find effective solutions for Convolvulus arvensisL. The experiments were situated in the experimental field of Agricultural University in Plovdiv. The trialswereconducted in 3 replications. The following treatments are included: 1. Untreated; 2. Aminopyralid+Florasulam- 33 g/ha; 3. Florasulam +Fluroxypyr- 1.5 l/ha; 4. Florasulam +Fluroxypyr- 1.8 l/ha; 5. Fluroxypyr- 0.7 l/ha; 6. Fluroxypyr- 0.9 l/ha7. Amidosulfuron +Iodosulfuron - 100 ml/ha. The herbicides were applied in phenophase BBCH 32-33. The efficacy of the studied herbicides and rates against Convolvulus arvensis L. was evaluated by the scale of EWRS on the 14th, 28th and 56th day after application. External symptoms of phytotoxicity were not observed. The highest efficacy was recorded for Florasulam +Fluroxypyr -1.8 l/ha; and Fluroxypyr- 0.9 l/ha. [ABSTRACT FROM AUTHOR]

It has been found that dry biomass of sunflower broomrape (Orobanche cumana Wallr.) has an inhibitory effect on seed germination and the initial development of five tested sunflower varieties. Sunflower broomrape with the highest overall allopathic potential (OAP) can be identified with originating in Tyulenovo and Radnevo with average OAR 0.22. Sunflower broomrape with the lowest overall allopathic potential (OAP) can be identified with originating in the ecological areas of Senokos and Shumen with average OAR 0.10. High allelopathic tolerance was observed in the seed germination and in the initial development of the sunflower varieties San Luka and Diveda. Their index of initial plant development (GI) ranged from 72.9 to 127.0 at higher studied concentrations 16.00% w/v and 32.0% w/v. The lowest allelopathic tolerance was observed in the seed germination and in the initial development of the sunflower variety Enigma. Its index of initial plant development (GI) ranged from 39.4 to 68.5. It has been found an equivalent between the allelopathic effect of dry biomass of Orobanche cumana Wallr. and the allelopathic tolerance of Helianthus annuus L. varieties, according to the common allelopathic potential of Orobanche cumana Wallr. and the Initial Development Index (IDI) of the sunflower plants. [ABSTRACT FROM AUTHOR]

In 2018 a field experiment with the sunflower hybrids SY Bacardi CLP and SY Diamantis CL was conducted. The experiment included the following treatments: 1. Untreated control; 2. Pulsar 40 - 1.25 l ha-1; 3. Pulsar 40 - 2.50 l ha-1; 4. Pulsar Plus - 1.20 l ha-1, 5. Pulsar Plus - 2.40 l ha-1. The herbicides were applied in phenophase 4th-6th true leaf of the crop. The efficacy and the selectivity of the studied herbicides were evaluated. The highest efficacy against S. halepense from rhizomes was recorded for treatment 5 (Pulsar Plus - 2.40 l ha-1). S. halepense developed from seeds, S. viridis, A. retroflexus, Xa. strumarium, S. nigrum and S. arvensis were successfully controlled by application of Pulsar 40 or Pulsar Plus in the low examined rates. Ch. album and A. theophrasti can be controlled by Pulsar Plus at the lower rate - 1.20 l ha-1. The absolute seed mass of 1000 seeds and the yield as well as the seed oil content from the plants treated with the registered and double herbicide rates, independently the herbicide product and studied hybrid, were higher than those of the untreated controls highly infested with weeds. [ABSTRACT FROM AUTHOR]

In the growing season of 2018, a field pot experiment with the pumpkin (Cucurbita pepo L.) hybrid ʻPrinceʼ F1 was conducted. In the trial, the selectivity of soil herbicides was evaluated. The variants of the trial were: 1. Untreated control; 2. Dual Gold (960 g/l S-metolachlor) - 1200 ml/ha; 3. Dual Gold - 1200 ml/ha; 4. Stomp New (330 g/l pendimethalin) - 4000 ml/ha; 5. Stomp New - 5000 ml/ha; 6. Spectrum (720 g/l dimethenamid-P) - 800 ml/ha and 7. Spectrum - 1400 ml/ha. The selectivity of the herbicides was reported by 9-score phytotoxicity scale of EWRS on the 7th and on the 14th day after germination (0 - no damage, and 9 - complete crop destruction). The earliest germination was found for the untreated control - 6 days after sowing, and for the plants of treatment 5 germinated last - 12 days after sowing. For variant 2 the phytotoxicity was score 0 and on both evaluation dates. For variants 4 to 9 the phytotoxicity was from score 2 to score 4 on the first reporting date, but on the second date, the phytotoxicity reached lethal scores of 8 to 9. The earliest flowering time was reported for the control, while the latest flowering time was found to be for treatment 3-10 days after the control. At the end of the vegetation, the control plants were the longest - 3.09 m, and the shortest was the pumpkins from treatment 3-2.46 m. The control had the highest number of fruits - 2.40 per plant. [ABSTRACT FROM AUTHOR]

Three hybrids of maize of Pioneеr Company (P9241, P9900 and P0023) grown at different plant densities (40000, 46000, 56000, 69000 number per ha) were studied in the experimental field of Agricultural University of Plovdiv in 2015 and 2016. The purpose of this study was to trace the influence of sowing density of maize hybrids on growth and yield. The experiments were carried out by split-plots method. The experimental areas were fertilized with a nitrogen fertilizer rate of 240 kg/ha - ½ CO(NH2)2, applied in the 5-6 leaf stage of the plant and ½ NH4NO3, applied into the 10th leaf stage. A hybrid P9900 has the highest plants at the end of vegetation. There was no significant difference between variants with plant densities - from 279.4 cm (40000 plants/ha) to 284.4 cm (56000 plants/ha). Height of plants of hybrid P9241 was the smallest - 260.5 cm at a sowing density of 40000 plants/ha. The highest yield between 3 hybrids was obtained at a sowing density of 69000 plants per ha. Hybrid P9241 showed yield of 13800 kg/ha, while hybrid P9900 - 14257 kg/ha. [ABSTRACT FROM AUTHOR]

During the period of 2017-2018 a field study with maize (Zea mays L.) was conducted. The experiment was situated on the experimental field of the Agricultural University of Plovdiv, Bulgaria. Variants of the trial were as follows: 1. Untreated control; 2. Equip OD (75 g/l mesotrione + 30 g/l nicosulfuron) - 2500 ml/ha; 3. Elumis OD (75 g/l mesotrione + 30 g/l nicosulfuron) - 2000 ml/ha; 4. Arigo WG (360 g/kg mesotrione + 120 g/kg nicosulfuron + 30 g/kg rimsulfuron) + Trend 90 - 330 g/ha + 1000 ml/ha; 5. Samson Extra 6 OD (60 g/l nicosulfuron) - 750 ml/ha; 6. Samson 4 OD (40 g/l nicosulfuron) - 1250 ml/ha; 7. Principal Plus WG (552 g/kg dicamba + 92 g/kg nicosulfuron + 23 g/kg rimsulfuron) + Trend 90 - 440 g/ha + 1000 ml/ha; 8. Capreno SC (345 g/l tembotrione + 68 g/l thiencarbazone-methyl + 134 g/l isoxadifen-ethyl) + Mero - 290 ml/ha + 2000 ml/ha. The grown maize hybrid was "P 9241". The efficacy of the studied herbicide products against the weeds was evaluated. The highest yield was achieved after the application of Principal Plus WG -- 1.53 t/ha average for both years. [ABSTRACT FROM AUTHOR]

The aim of the study is to evaluate the efficacy of the herbicide products Gardoprim® Plus Gold 550 SC (312.5 g/l s-metolachlor + 187.5 g/l terbuthylazine) and Spectrum® 720 EC (720 g/l dimethenamid-p) in low rates. The field trial was conducted in 2016 and 2017 with the conventional sunflower hybrid P64 LL 125. The experiment was stated in the experimental field of the base for training and implementation of the Agricultural University of Plovdiv, Bulgaria. The trial was conducted by the randomised block design in 4 replications, and the efficacy was recorded by the 10 score visual scale of EWRS. The usage of tank mixtures of both studied herbicides lead to increased efficacy against some dicotyledonous weeds as Solanum nigrum L., Abutilon theophrasti L. and Amaranthus retroflexus L. Average for the period, for the treatments with Gardoprim® Plus Gold 550 SC in rate of 4000 ml ha-1 and the tank mixture of the herbicides the highest seed yields are recorded - 2.00 and 1.90 t ha-1, respectively. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is main grain, forage and strategical field crop in Bulgaria. One of the main negative factors for maize growing is the weeds. The aim of our study conducted in 2016 and 2017 is to evaluate the biological efficacy of some soil herbicides at maize hybrid P 1114. The experiment was stated on the experimental field of the base for training and implementation of the Agricultural University of Plovdiv, Bulgaria. The trial was conducted by the randomized block design in 4 replications, and the efficacy was recorded by the 10 score visual scale of EWRS. The herbicides Merlin® Duo (37.5 g/l isoxaflutole + 375 g/l terbutilazin), Adengo® 465 SC (225 g/l isoxaflutole + 90 g/l thiecarbazone-methyl + 150 g/l cyprosulfamide - antidote), Lumax® 538 SK (37.5 g/l mesotrione + 375 g/l smetolachlor + 125 g/l terbutilazine) were examined. The herbicides were applied after sowing before germination of the crop (BBCH 00). The highest herbicide efficacy and the highest yields (11.86 t ha-1) were obtained for the treatment with Merlin® Duo at rate of 2000 ml ha-1. All evaluated herbicides were selective for the grown maize hybrid. [ABSTRACT FROM AUTHOR]

Allelopathic activity of Cuscuta epithymum L. (CVCEY), Cuscuta campestris Yuncker (CVCCA), Phelipanche ramosa (L.) Pomel (ORARA), Phelipanche mutelii (Schultz) Reuter (ORARM) and Phelipanche spp. (PHESS) on germination and initial development of test plants of Lactuca sativa L. cultivar "Great Lakes" was studied under laboratory conditions. It was found, that water exracts of the researched parasitic weed species in concentrations 0.4, 0.8, 1.6, 3.2, 6.4 and 12.8% w/v have a relatively high inhibitory effect on the seed germination of the test plant. The inhibiting rate of parasitic weed species from family Convolvulaceae ranges from 6.24 to 100.0% and for the species of family Orobanchaceae from 42.1 to 100.0%. Parasitic weed species from family Orobanchaceae [Ph. ramosa, Ph. mutelii and Phelipanche spp.] showed a considerably stronger allelopathic effect (GIaverage 17.9), as compared with the applied concentrations of water exracts of species from family Convolvulaceae [C. epithymum and C. campestris] (GIaverage 22.7). [ABSTRACT FROM AUTHOR]

During the period from 2014 to 2016, a field trail with the oilseed rape (Brassica napus L.) hybrid "PX 111 CL" (Clearfield® hybrid) was conducted. The experiment was carried out in the experimental base of the department of "Agriculture and Herbology" of the Agricultural University of Plovdiv, Bulgaria. The aim of the study was to establish the possibilities of chemical weed control during the vegetation of the oilseed rape with perspective herbicides. The following 6 herbicide product were evaluated: Salsa 75 WG (750 g/kg Ethametsulfuron-Methyl), Galera Super (240 g/l clopyralid + 80 g/l picloram + 40 g/l aminopyralid), Modaon 4 F (480 g/l bifenox), Fusilade Forte 150 EC (150 g/l fluazifop-p-butyl), Stratos Ultra (100 g/l cycloxydim + tenzid) and Cleranda SC (17.5 g/l imazamox + 375 g/l metazachlor). The efficacy of the products was recorded by the 10 score scale of EWRS (European Weed Research Society). The productivity of the oilseed rape was also studied. The dispersion analyses showed that there were proved differences between the variants of the tail. The highest herbicide efficacy against the existing weed infestation as well as the highest yield (4.098 t.ha-1) was recorded for the variant with the combine application of the herbicide products Galera Super + Fusilade Forte 150 EC. [ABSTRACT FROM AUTHOR]

A field trial with winter wheat (Triticum aestivum L.), variety "Enola" was conducted in 2015. The trial was state don the experimental field of the Dobroudja Agricultural Institute, General Toshevo, Bulgaria. The study was performed by the randomized block designin 4 replications. Theaim of the study was to establish the opportunities for singleand combine application of herbicides for weed management at winter wheat. The efficacy of the following 6 herbicides applied alone and in combinations was evaluated: Derby Super (150.2 g/kg florasulam + 300.5 g/kg aminopyralid-potassium), Secator OD (100 g/l amidosulphuron + 25 g/l iodosulfuron + 250 g/l mefenpyr-diethyl), Maton 600 EC (600 g/l 2.4 D ester), Pallas 75 WG (75 g/kg pyroxsulam), Hussar Max OD (7.5 g/l mezosulfuron + 7.5 g/l iodosulfuron + 22.5 g/l mefenpyr-diethyl) and Puma Super 7.5 EW (69 g/l fenoxaprop-p-ethyl + antidot). The herbicides were applied in the spring at phenophase end of tillering - beginning of spindling of the winter wheat (BBCH 29-31). The efficacy of the studied products was recorded by the 10 score visual scale of EWRS (European Weed Research Society). The obtained results were compared with un treated control. The selectivity of the single and combine application of herbicides against the wheat was established by the 9 score scale for phytotoxicity of EWRS. At the particular weed infestation the highest herbicide efficacy and the highest yield (5.78 t.ha-1) were recorded at the variant with combine application of Pallas 75 WG + Derby Super. [ABSTRACT FROM AUTHOR]

Three block design field experiments were carried out in the period 2012 - 2015, following the same methods, on three different sites in the country, which differ significantly in the spectrum of the available weeds. The subject of the experiments was the improved version of the Clearfield Plus technology. In all the three years the sunflower hybrid ES Candimis CL Plus was planted on the three sites. The major aim of the experiments on the three sites was to establish the selectivity for sunflower and the efficacy of Pulsar 40 (40 g/l imazamox) against almost all the economically important weeds in that crop. The reported phytotoxicity caused to sunflower on the three sites in the three years was expressed in a slight discoloration of the treated sunflower plants, which was totally overcome between the 14th and 20th day. The results of the experiments show that the greatest differences in the efficacy of Pulsar 40 were reported about its activity against perennial weed species. When Pulsar 40 was applied separately without DASH, its efficacy against Johnson grass, corn thistle, field bindweed, hemp agrimony, rough cocklebur, white goosefoot, purslane and broomrape was significantly reduced. Referring to its efficacy against the annual broad-leaved weed species redroot pigweed, charlock mustard, wild radish, clea-vers, black nightshade, etc., it was 100% and no differences were observed between the rates of 80, 100 and 125 ml/da. The separate use of the herbicide at a rate of 125 ml/da shows the same efficacy against more stubborn weeds, as that of Pulsar applied at the rate of 80 ml/da together with 80 ml/da of the adjuvant DASH. [ABSTRACT FROM AUTHOR]

A field trial on chemical control of rat's tail fescue (Festuca myuros) in rapeseed fields was carried out in the period 2012-2014. The following herbicides registered for application in rapeseed, were used in the experiment: Butisan 400 SC (metazachlor - 400 g/l), Butisan Max (metazachlor - 200 g/l + dimethenamid-P - 200 g/l + quinmerac - 100 g/l), Stratus ultra (100 g/l cycloxydim + tensid), Agil (100 g/l propaquizafop + surfactant), Fusilade forte (150 g/l fluazifop-P-butyl) and Cleranda (17,5 g/l imazamox + 375 g/l metazachlor). It was established that very good results were achieved in the control of rat's tail fescue after timely treatment with the herbicide chemical Butisan 400 SC. Another reliable alternative for control of that weed species was the application of the herbicide Cleranda at the rate of 150-200 ml/dka, when using Clearfield technology. The results of the trial showed that three of the registered herbicides against grassy weeds in rapeseed - Stratus ultra, Fusilade Forte and Agil, did not display any herbicide efficacy against rat's tail fescue, regardless of treatment rate and time of application. The only vegetation herbicide showing very good results is Cleranda. The results of the present study show that treatment applied at the stage of 4th-6th leaf has a slightly better effect compared to the variants with earlier (2nd-4th leaf) and later (6th-8th leaf) treatments. The earlier treatment is more risky for secondary weed infestation, the level of which can be lower or higher in the different years. The delayed treatment, especially if carried out in spring, reduces the herbicide effect of the active substance imazamox against grassy weeds, including rat's tail fescue. [ABSTRACT FROM AUTHOR]

Field trials were carried out with the wheat cultivar Enola in the period 2013-2014, using the same method in two different sites - the Experimental fields of the Agricultural University - Plovdiv and in the village of Krumovo near Plovdiv. The fields were infested by the following important broad-leaved weeds: black-bindweed (Falopia convolvulus L.); common poppy (Papaver rhoeas L.); charlock mustard (Sinapis arvensis L.); flixweed (Descurainia sophia L.); cleavers (Galium aparine L.); field larkspur (Delfinium consolida L.); creeping thistle (Cirsium arvense L.); corncockle (Agrostemma githago L.) and the grassy weed wild oats (Avena fatua L.). The efficacy, selectivity and tank-mixability of the tested herbicides and their combinations were studied: ready mixture Ergon WG (68 g/kg metsulfuron-methyl + 682 g/kg thifensulfuron-methyl) at the rates of 6, 7, 8, 9 and 18 g/da, ready mixture Granstar super (250 g/kg tribenuron-methyl + 250 g/kg thifensulfuronmethyl) - 4 g/da, mixture of Ergon WG - 7 g/da + Puma Super 7,5 EW (69 g/l fenoxaprop-P-ethyl) - 100 ml/ da, mixture Ergon WG - 7 g/da + Topic 080 EC (80 g/l clodinafop) - 50 ml/da and mixture Ergon WG - 7 g/ da + Axial 050 EC (50 g/l pinoxaden) - 90 ml/da. All the products were tested at the rates registered in Bulgaria and they were compared to untreated control areas. The treatments were carried out during the tillering stage untill 2nd node of the crop (ВВСН 29- 31). All the trials were conducted on plots of 25 m² in 4 replicates and a demonstration trial on 20 da was implemented. The trials were carried out based on EPPO Standards of the EU. Climatic conditions in 2013 were normal, but in 2014 it was unusually rainy. Ergon WG herbicide applied at the rate of 70 g/ha, successfully controlled most of the broad-leaved weed species on the three sites. The efficacy of Ergon WG, against Galium aparine (L.) and Cirsium arvense (L.) was excellent only when applying the higher rates of 8 and 9 g/da. Mixtures of the products Ergon WG + Puma Super 7,5 EW; Ergon WG + Topic 080 EC and Ergon WG + Axial 050 EC showed excellent tank-mixability, without any antagonism in the efficacy against both broad-leaved and grassy weed species. Ergon WG showed very high selectivity for the crop even when used at the double rate of 18 g/da. External symptoms of phytotoxicity were not observed in the crop after treatment with any of the herbicides and their mixtures. [ABSTRACT FROM AUTHOR]