Screening of plant protection products against downy mildew on cucumbers (Pseudoperonospora Cubensis (Berkeley & M. A. Curtis) Rostovzev) in cultivation facilities

S. Masheva, N. Velkov, N. Valchev, V. Yankova
Abstract. Screening of plant protection products (PPP) against downy mildew in cucumbers Pseudoperonospora cubensis (Berkeley & M. A. Curtis) Rostovzev was carried out during the period 2006-2011 in the “Maritsa” Vegetable Crops Research Institute, Plovdiv. Their toxicity to the imago of the bioagent Encarsia formosa Gah. were studied. High effectiveness (over 85.00 %) of the PPP with active ingredients: dimethomorph (Zampro SC, Acrobat paplus SC); symoxanil (Korsate Pro WG, Korsate R DF), strobilurins (Eclair 49 WG, Quadris 25 SC) was established. With the lowest effectiveness to the agent of downy mildew is Timorex 66 EC. All studied products are suitable for including in the systems for control of this disease. A non-toxic product to E. formosa is the botanical fungicide Timorex 66 EC, medium toxic products are those containing a.i. strobilurin and propamocarb-hydrochloride. The remaining PPP are slightly or medium toxic to the bioagent. Therefore E. fоrmosa could be applied parallel with slightly toxic fungicides against P. cubensis.
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Investigations on liver function in mulards with experimentally induced aflatoxicosis

N. Grozeva, I. Valchev, D. Kanakov, Ts. Hristov, L. Lazarov, R. Binev, Y. Nikolov

Abstract. Ducklings are among the most sensitive avian species to the toxic effects of aflatoxin В (AFB ). In this experiment, the toxic effects of AFB on liver 1 1 1 morphology, blood plasma aspartate amino-transferase (AST), alanine amino-transferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), γ-glutamyltransferase (γ-GT), albumin, blood glucose, and plasma total protein (TP) were established in mulard ducks. The experiment was carried out with four groups of 20 10-day-old ducklings each. Each group included three subgroups with 10 birds. The groups were as followed: group І – control (which received standard feed according to the species and age), group ІІ – experimental, which received compound feed with 0.5 mg/kg AFB , group ІІI– receiving 1 compound feed supplemented with 0.8 mg/kg AFB and group IV – compound feed supplemented with 0.5 mg/kg AFB and 2g/kg Mycotox NG. The 1 1 experiment lasted for 42 days. Blood biochemical data on the 21st day of the experiment showed increased activity of assayed enzymes and reduced concentrations of albumin, total protein and glucose in groups receiving only AFB . The observed changes tended to become more pronounced by the 42nd 1 day of the trial. Macroscopically, livers were enlarged, rounded, with yellowish colour and a frail consistency. Histopathologically, a various extent of dystrophy was detected depending on the dose of ingested toxin. The addition of 2 g/kg Mycotox NG to the feed of experimental group IV (containing 0.5 mg/kg AFB ) 1 reduced the harmful effects of AFB on blood biochemical indices and significantly lowered the severity and frequency of observed histological lesions.

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Investigations on production traits of mulard ducks with experimentally induced aflatoxicosis

I. Valchev, N. Grozeva, L. Lazarov, D. Kanakov, Ts. Hristov, R. Binev, Y. Nikolov

Abstract. The purpose of this study was to investigate the toxic effects of aflatoxin В (AFB ) on production traits (live body weight, weight gain, feed intake and 1 1 feed conversion) and relative weights (g/100 g body weight) of visceral organs (liver, kidneys, thymus, spleen, Bursa of Fabricius, heart, gizzard and proventriculus) in mulard ducklings. The experiment was carried out with four groups of 30 10-day-old ducklings each over 42 days. The groups were as followed: group І – control, which received standard feed according to the species and age, group ІІ – experimental, which received compound feed with 0.5 mg/kg AFB , group ІІI – receiving compound feed supplemented with 0.8 mg/kg AFB and group IV – compound feed supplemented with 0.5 mg/kg AFB and 2 1 1 1 g/kg Mycotox NG. In experimental groups II and III, the body weight, weight gain, feed intake were lower, feed conversion ratio was higher as well as the relative weights of liver, kidneys, heart, pancreas, gizzard and proventriculus. At the same time, the relative weight of the thymus, bursa of Fabricius and the spleen were considerably reduced. The supplementation of feed of group IV with Mycotox NG protected birds from the negative effects of AFB on production traits and 1 prevented changes in the weights of visceral organs.

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Toxicity of plant protection products towards the imago of Encarsia Formosa Gah

V. Yankova, S. Masheva, B. Boev, K. Toskov
Abstract. The endoparasite Encarsia formosa Gah. is one of the well-known and frequently used bioagents for control of greenhouse whitefly (Trialeurodes vaporariorum Westw.). The effect of many applied pesticides is negative towards this useful species. Successful combination of chemical products and biological method in the integrated plant protection systems requires recognition of their side-effect toward the useful species. Laboratory tests for establishment of the plant protection product toxicity to the imago of the parasite E. formosa were carried out in the Maritsa Vegetable Crops Research Institute, Plovdiv during the period 2007-2011. The products BioNeem Plus 1.5 ЕC 0.25% (i. a. azadirachtin), Preferal WG 0.1% – 0.2% (Paecilomyces fomoso-roseus), Timorex 66 EC 1.0% (i. a. extract from Malaleuca alternifolia), Rubin 72 WP 0.25% (i. a. metalaxil-mancoceb) are non-toxic to E. formosa parasite. These products could be applied in the integrated plant protection systems. The insecticides Bi 58 0.1% (i. a. dimethoat), Confidor energy OD 0.08% (i. a. imidacloprid+deltametrin) and Decis 2.5 ЕC 0.05% (i. a. deltametrin) that are strongly toxic should be avoided in use of the parasite E. formosa.

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