Prey size selectivity of pikeperch (Sander Lucioperca L.) fed with topmouth gudgeon (Pseudorasbora Parva Temminck & Schlegel)

M. Gevezova-Kazakova*, M. Yankova, T. Hubenova, A. Zaikov, G. Rusenov

Institute of Fisheries and Aquaculture, 4003, Plovdiv, Bulgaria
(Manuscript received 29 May 2017; accepted for publication 29 July 2017)

Abstract. The aim of this study is to examine the size selectivity of the pikeperch fed with one of the most widespread weed fish in fish farms, such as topmouth gudgeon (Pseudorasbora parva Temminck & Schlegel). Topmouth gudgeon (Pseudorasbora parva Temminck & Schlegel), separated in two size groups: large – group 1 (body weight of the specimens 8.63 ± 2.68 g, total length 9.58 ± 0.92 cm, and height of the body 2.06 ± 0.33 cm) and small – group 2 (body weight of the specimens 1.10 ± 0.36 g, average total body length of 5 ± 0.62 cm, and height of 0.85 ± 0.13 cm), were used for prey. The experiment was carried out under controlled laboratory conditions, in the course of 40 days, in 7 tanks. One pikeperch and 10 topmouth gudgeons from both size groups, in total 20 preys were placed in each tank. During the experimental period it was observed that pikeperch preferred to feed on smaller individuals, the difference in the number of consumed small and large fish is approximately 2 times (70 to 34, respectively).

Selectivity and stability of herbicides and their tank mixtures for the seed yield of sunflower (Helianthus Annuus L.)

G. Delchev1*, T. Barakova2

1Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Field Crops Institute, 6200 Chirpan, Bulgaria

(Manuscript received 16 May 2016; accepted for publication 11 August 2016)

Abstract. The research was conducted during 2012 – 2014 on pellic vertisol soil type. Under investigation were 4 sunflower hybrids (Helianthus annuus L.): hybrid Bacardy (an imitolerant hybrid by ClearField plus technology), hybrid Estiva (an imitolerant hybrid by ClearField technology), hybrid Sumico (a tribenuron-methyl tolerant hybrid by ExpessSun technology) and hybrid Arizona (a hybrid by conventional technology). Factor A included the years of investigation. Factor B, herbicides and tank mixtures, included 20 rates. It includes 3 variants by ClearField plus technology, 5 variants by ClearField technology, 5 variants by ExpessSun technology and 7 variants by conventional technology. All variants are on herbicide Gardoprim plus gold 500 SC (S- metolachlor + terbuthylazine) – 3.5 l/ha, which treated after sowing before emergence of the sunflower. It is found that the highest seed yield is obtained at herbicide tank mixture Pulsar plus + Stomp aqua by ClearField plus technology. Tank mixture Listego + Dash + Sharpen by ClearField technology and Express + Trend + Select super by ExpressSun technology also lead to obtaining high seed yields. The most unstable are secondary weed infested checks by the fourth technologies for sunflower growing which are treated with soil-applied herbicide Gardoprim plus gold only. Technologically the most valuable are herbicide combination Pulsar plus + Stomp aqua and herbicide Pulsar by ClearField plus technology, tank mixtures Listego + Dash + Sharpen and Listego + Dash by ClearField technology and Express + Trend + Select super and Express + Lactofol B + Select super by ExpressSun technology. Tank mixtures of herbicides Smerch, Pendigan, Wing, Raft, Pledge and Modown with Amalgerol premium by conventional technology have low estimates due to insufficient control of some weeds in sunflower crops.

Selectivity and stability of herbicides and herbicide combinations for the grain yield of maize (Zea Mays L.)

G. Delchev1*, T. Barakova2

1Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Field Crops Institute, 6200 Chirpan, Bulgaria

(Manuscript received 16 May 2016; accepted for publication 9 August 2016)

Abstract. The research was conducted during 2012 – 2014 on pellic vertisol soil type. Under investigation was cycloxydim tolerant maize hybrid Ultrafox duo (Zea mays L.). Factor A included the years of investigation. Factor B included no treated check and 3 soil-applied herbicides – Adengo 465 SC (isoxaflutol + tiencarbazon) – 440 ml/ha, Wing P (pendimethalin + dimethenamid) – 4 l/ha and Lumax 538 SC (S-metolachlor + terbuthylazine + mesotrione) – 4 l/ha. Factor C included no treated check and 5 foliar-applied herbicides – Stellar 210 SL (topramezon + dicamba) – 1 l/ha, Principal plus (nicosulfuron + rimsulfuron + dicamba) – 380 g/ha, Ventum WG (foramsulfuron + iodosulfuron) – 150 g/ha, Monsun active OD (foramsulfuron + tiencarbazon) – 1.5 l/ha and Laudis OD (tembotrione) – 2 l/ha. In addition to these variants by conventional technology for maize growing one variant by Duo system technology is also included in the experiment. It includes soil-applied herbicide Merlin flex 480 SC (isoxaflutole) – 420 g/ha and tank mixture of antigraminaceous herbicide Focus ultra (cycloxydim) – 2 l/ha + antibroadleaved herbicide Kalam (tritosulfuron + dicamba) – 300 g/ha. It is found that herbicide combination of soil-applied herbicide Merlin flex with tank mixture Focus ultra + Kalam by Duo system technology leads to obtaining high grain yield. High yields of maize grain are also obtained by herbicide combinations Lumax + Principal plus, Lumax + Laudis and Wing + Principal plus. The most unstable are the non-treated check and single use of soil- applied herbicides Adengo, Wing and Lumax. Technologically the most valuable are herbicide combination Merlin flex + Focus ultra + Kalam by Duo system technology, followed by combinations of foliar-applied herbicides Principal plus and Laudis with soil-applied herbicides Adengo, Wing and Lumax by conventional technology. Single use of herbicides has low estimate due to must to combine soil-applied with foliar-applied herbicides for full control of weeds in maize crops

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Selectivity and stability of new herbicides and herbicide combinations for the seed yields of some field crops

G. Delchev*

Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
(Manuscript received 28 January 2016; accepted for publication 30 May 2016)

Abstract. During 2013 – 2015 on pellic vertisol soil type was conducted a field experiment. Under investigation was Bulgarian milk thistle cultivar Silmar (Silybum marianum Gaertn.). Factor A included the years of investigation. Factor B included no treated check, 6 soil-applied herbicides – Tendar EC, Sharpen 33 EC, Merlin flex 480 SC, Smerch 24 ЕC, Raft 400 SC, Eagle 75 DF and 5 foliar-applied herbicides – Kalin flo, Eclipse 70 DWG, Sultan 500 SC, Granstar super 50 SG, Starane 250 EK. Factor C included no treated check and 1 antigraminaceous herbicide – Tiger platinium 5 EC. All herbicides, herbicide combinations and herbicide tank-mixtures were applied in a working solution of 200 l/ha. Mixing of foliar-applied herbicides was done in the tank on the sprayer. Soil-applied herbicides were treated during the period after sowing before emergence. Foliar-applied herbicides were treated during rosette stage of the milk thistle. Tank mixtures of antigraminaceous herbicide Tiger platinum with foliar herbicides Kalin flo, Eclipse, Sultan, Granstar super and Starane leads to obtaining high seed yields of milk thistle. High yields seeds are also obtained by foliar treatment with Tiger platinum after soil-applied herbicides Raft, Sharpen and Eagle. The use of the soil-applied herbicides Smerch, Merlin flex and Tendar does not increase the seed yield due to its higher phytotoxicity against milk thistle. Herbicide Tendar and herbicide combination Tendar + Tiger platinum are the most unstable, followed by herbicide Merlin flex. Herbicide tank-mixtures Kalin flo + Tiger platinum and Eclipse + Tiger platinum and herbicide combination Raft + Tiger platinum are technologically the most valuable. They combine high seed yield with high stability with relation to different years. Single application of soil-applied or foliar-applied herbicides have low estimate; due to that they must be combined for full control of weeds in milk thistle crops.

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Selectivity and stability of vegetation-applied herbicides in cotton (Gossypium hirsutum L.)

T. Barakova1*, G. Delchev2

1Field Crops Institute, 6200 Chirpan, Bulgaria
2Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
(Manuscript received 16 May 2016; accepted for publication 26 May 2016)

Abstract. An experiment was carried out during 2013 – 2015 in the experimental field of the Field Crops Institute, Chirpan, with two cotton cultivars − Helius and Darmi (Gossypium hirsutum L.). Herbicides: Goal 2 E, oxyfluorfen (80 ml/da); Linuron 45 SC, linuron (200 ml/da); Wing-P, pendimethalin + dimethenamid (400 ml/da); Merlin 750 WG, isoxaflutol (5 g/da); Bazagran 480 SL, bentazone (150 ml/da) were investigated. They were treated separately or combined with growth regulator Amalgerol (500 ml/da) or foliar fertilizer Lactofol O (500 ml/da) in the budding stage of the cotton. It was established that selectivity is the lowest in the two cotton cultivars with herbicides Linuron 45 CK and Merlin 750 WG. The purpose of this investigation was to establish the selectivity and stability of some herbicides and their tank mixtures on the cotton by influence of different meteorological conditions. It has been found that the highest phytotoxicity on cotton is given the vegetation-applied herbicides Merlin and Linuron. Foliar fertilizer Laktofol O reduces phytotoxicity of herbicides Goal, Wing, Merlin and Bazagran in two cotton cultivars. Herbicides Wing and Bazagran have excellent selectivity for the two cotton cultivars – Helius and Darmi. The highest yield was obtained by vegetation treatment with herbicide Bazagran, followed by herbicides Wing and Goal. Tank mixtures of Goal, Bazagran and Wing with Laktofol, followed by those with Amalgerol are technologically the most valuable. They combine high yield with high stability over the years. Аlone application of herbicides Linuron and Merlin and their tank mixtures with Amalgerol and Laktofol have low estimate.

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Selectivity and stability of new herbicides and herbicide combinations for the seed yields of some field crops I. Effect at Coriander (Coriandrum Sativum L.)

G. Delchev*

Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria (Manuscript received 28 January 2016; accepted for publication 2 March 2016)

Abstract. . The research was conducted during 2013 – 2015 on pellic vertisol soil type. Under investigation was Bulgarian coriander cultivar Lozen 1 (Coriandrum sativum L.). The purpose of the investigation was to establish the selectivity and stability of some herbicides, herbicide combinations and herbicide tank mixtures on the coriander. Factor A included the years of investigation. Factor B included no treated check, 6 soil-applied herbicides – Tendar EC, Silba SC, Sharpen 33 EC, Merlin flex 480 SC, Smerch 24 ЕC, Raft 400 SC and 5 foliar-applied herbicides – Kalin flo, Eclipse 70 DWG, Sultan 500 SC, Corrida 75 DWG, Lontrel 300 EC. Factor C included no treated check and 1 antigraminaceous herbicide – Tiger platinium 5 EC. Soil-applied herbicides were treated during the period after sowing before emergence. Foliar-applied herbicides were treated during rosette stage of the coriander. It is found that tank mixtures of Tiger platinum with foliar herbicides Kalin flo, Eclipse, Sultan, Corrida and Lontrel lead to obtaining of high seed yields. High yields of coriander seeds also are obtained by foliar treatment with antigraminaceous herbicide Tiger platinum after soil-applied herbicides Raft, Smerch, Sharpen, Silba and Tendar. The use of the soil-applied herbicide Merlin flex does not increase the seed yield, due to its higher phytotoxicity on coriander. The most unstable are herbicide Merlin flex and herbicide combination Merlin flex + Tiger platinum. Technologically the most valuable are herbicide combination Raft + Tiger platinum and herbicide tank- mixture Kalin flo + Tiger platinum. Self-use of soil-applied or foliar-applied herbicides have low estimate due to they must to combine for full control of weeds in coriander crops.

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Efficacy and selectivity of herbicides and herbicide combinations at winter oilseed canola, grown by conventional and Clearfield technologies

Gr. Delchev*
Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

Abstract. During the period 2010 – 2012, on the experimental field of the Field Crops Institute, Chirpan a field experiment was carried out with imitolerant hybrid winter oilseed canola PT200CL (Brassica napus L.). A total of 16 variants were investigated. They include antigraminaceous herbicides, antibroadleaved herbicides and plant growth regulators. Herbicide Cleranda by Clearfield technology has very good efficacy against all graminaceous and broadleaved weeds and volunteers, including Sinapis arvensis and Raphanus raphanistrum and volunteers of Coriandrum sativum. Herbicides Salsa and Modown have very good efficacy against all broadleaved weeds, including against cruciferous weeds Sinapis arvensis and Raphanus raphanistrum and volunteers of Coriandrum sativum. They must be combined with antigraminaceous herbicide by mixed weeding with graminaceous and broadleaved weeds. Vegetation-applied herbicide Runway has no efficacy against Sinapis arvensis and Raphanus raphanistrum and poorer efficacy against volunteers of Coriandrum sativum. Autumn treatment by herbicide Modown causes poor phytotoxicity in canola. Spring treatment with Modown leads to a high and more difficult to overcome phytotoxicity. The highest seed yields are obtained by the variants Cleranda + Caramba and Salsa + Pantera + Folicur, followed by variants Modown + Agil + Orius and Runway + Pantera + Folicur.

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Efficacy and selectivity of some herbicides on winter oilseed rape

M. Dimitrova*, I. Zhalnov, D. Stoychev

Department of Farming and Herbology, Faculty of Agronomy, Agricultural University, 12 Mendeleev, 4000 Plovdiv, Bulgaria

Abstract. Within the period 2011 – 2014 in the experimental field of the Agricultural University, Plovdiv, field experiments were conducted using the herbicides Teridox (500 g/1 dimetochor), Butizan S (500 g/1 metazachlor), which were applied to the soil after planting the crops and before their germination, and also Modaon 4F (48 g/1 bifenox) and Butizan S, which was applied to the leaves during the vegetation period of the rape. The experiments were made using the block method over an area of 25 m2 in four repetitions. It has been established that the herbicides demonstrate excellent selectivity for this crop, which was measured on the EWRS scale in marks and control the existing annual types: Amaranthus retroflexus L., Portulaca oleraceae L., Chenopodium album L., Solanum nigrum L., Setaria spp., Stellaria media L. and self seeded wheat plants. The weeds in the control sample without herbicides have very high density and on the 40th day after treatment their number reaches 123 plants/m2. On average for the period of the survey (2011 – 2014), the efficiency of the applied preparations Teridox, Butizan S and Modaon 4F on the 20th day after treatment ranges from 70.5% to 79.4% for the soil herbicides and from 72.8% for 76.9% for the leaf herbicides. This dependence is preserved to the 45th day after treatment.

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Efficacy and selectivity of antibroadleaved herbicides at durum wheat against volunteers of coriander, Clearfield canola, Clearfield sunflower and ExpressSun sunflower

G. Delchev
Abstract. During the period 2010 – 2012, on the experimental field of the Field Crops Institute, Chirpan was carried out a field experiment with durum wheat cultivar Elbrus (Triticum durum var. valenciae). A total of 24 variants were investigated. They include vegetation-applied herbicides, soil-applied herbicides and herbicide tank mixtures. Volunteers of Clearfield canola in the durum wheat crops are controlled successfully by vegetation-applied herbicides Derby, Mustang, Sunsac and Weedmaster and soil-applied herbicides Marathon, Stomp and Cougar. Volunteers of Clearfield and ExpressSun sunflower are controlled by herbicides Arat, Derby, Derby super, Mustang, Sunsac, Secator, Lintur, Weedmaster, Marathon, Stomp, Racer and Cougar. Volunteers of coriander in wheat crops are controlled by herbicides Derby, Mustang, Sunsac, Secator, Lintur, Weedmaster, Granstar super, Eagle and Cougar. Herbicide tank mixtures Derby super + Sanafen, Secator + Sanafen, Granstar super + Starane, Laren + Dicotex and Ally max + Sanafen control successfully volunteers of coriander, Clearfield canola, Clearfield and ExpressSun sunflower. Herbicide Cougar causes phytotoxicity on durum wheat. The highest grain yield was obtained by treatment with herbicide tank mixture Granstar super + Starane, Derby super + Sanafen, Secator + Sanafen, Ally max + Sanafen and Laren + Dicotex and herbicides Derby super, Derby, Secator, Sunsac, Mustang , Weedmaster and Arat.

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Efficacy and selectivity of vegetation-applied herbicides and their mixtures with growth stimulator Amalgerol premium at oil-bearing sunflower grown by conventional, Clearfield and ExpressSun technologies

G. Delchev
Abstract. During the period 2010 – 2012, on the experimental field of the Field Crops Institute – Chirpan was carried out a field experiment with oil-bearing sunflower (Helianthus annuus). A total of 18 variants from the three technologies for oil-bearing sunflower growing were investigated – conventional (hybrid Arena), Clearfield (hybrid Alego) and ExpressSun (hybrid P64LE20). Vegetation-applied herbicides Goal, Raft and Pledge combined with the soil-applied herbicide Pelican provide good control of annual broadleaved weeds in conventional technology for sunflower growing. Combinations of herbicides Stomp, Wing with herbicide Pelican can be applied to mixed weeding from annual grassy and some broadleaved weeds, but with the absence of Xanthium strumarium, Cirsium arvense and Convolvulus arvensis. Herbicide combination Modown + Pelican should be used in secondary weeding primarily from annual broadleaved weeds, but with the absence of Xanthium strumarium. Herbicide tank mixtures Pulsar + Stomp by Clearfield technology and Express + Stratos ultra by ExpressSun technology completely destroyed all annual and perennial grassy and broadleaved weeds. Vegetation use of herbicides by conventional technology causes high phytotoxicity on sunflower. Phytotoxicity was the highest by herbicide Goal, followed by Pledge. Phytotoxicity is weaker by herbicides Stomp, Raft, Wing and Modown. Treatment of growth stimulator Amalgerol premium with herbicides Goal, Raft, Wing, Pledge and Modown as tank mixtures increases the selectivity of these herbicides.
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