In vitro and in vivo toxicity of fungicides and biofungicides for the control of verticillium and fusarium wilt of pepper

A survey of in vitro and in vivo sensitivity of Verticillium dahliae and Fusarium oxysporum to several commercial fungicides and biofungicides was undertaken. In in vitro assays, the tested isolate of V. dahliae proved to be very sensitive to difenoconazole (EC50 = 0.02 mg/l). However, under greenhouse conditions, the highest efficacy in V. dahliae control on inoculated pepper plants was recorded for a product based on thiophanate-methyl (83.10% compared to control). Among the tested fungicides, the lowest efficacy was recorded for a product based on azoxystrobin (23.10 %) with no significant difference compared to control (p > 0.05). In in vitro assays, the tested F. oxysporum isolate was the most sensitive to prochloraz (EC50 = 0.07 mg/l) and the least sensitive to fluopyram (EC50 = 1075.01 mg/l). In in vivo assay, the highest efficacy was achieved by products based on captan (95.60%), and the lowest by a product based on thiophanate-methyl (54.40%). Antagonistic activity of the bacterium B. subtilis under laboratory conditions was not satisfying. Also, the antifungal activity and spectrum of a tested product based on tee tree oil was not efficient in suppressing pepper wilting caused by V. dahliae and F. oxysporum.

Nephroprotective effect of aqueous acetonic extract of Morus alba and its underlying mechanisms against glyphosate-induced toxicity - in vivo model

Glyphosate, the active substance in RoundupR, is the most widely used pesticide in the world and may be present as a residue in derived foods and drinking water. Previous reports have confirmed that extracts from leaves of Morus alba exert many pharmacological activities. However, renoprotective effects of M. alba extract and its underling molecular mechanism is still unknown. Wistar rats (180-200 g) were used in this study (n=5-6). A control group received 0.2 ml normal saline intraperitoneally (i.p) once daily for two weeks. Control animals received standard diet. Treated groups received either polyphenolic extract (100 mg/kg,i.p) or glyphosate (100 mg/kg, i.p), or co-administration (extract ?g ml?1 kg b.w. and glyphosate 100 mg kg?1 b.w, i.p), daily until the 15thday of treatment. Lactate deshydrogenase LDH, serum concentrations of blood urea, creatinine and nitric oxide were measured using standard coloromertic methods. Renal oxidative stress, evidenced by increased malondialdehyde (MDA) and protein carbonyl levels and decline in superoxide dismutase (SOD) activity, was significantly alleviated by mulberry leaves extract (MLE) administration. MLE also appears to be able to modulate altered biochemical parametres by maintaining free iron and Ca2 + homeostasis, and regulate the endogenous antioxidant enzymes system. It seems that concurrent use of the aqueous acetonic fraction of M. alba, rich in chlorogenic acid and its isomeres, can protect kidneys from glyphosate-induced nephrotoxicity. Overall, MLE may possess protective activity against glyphosate-induced toxicity, which may be attributed to chlorogenic acid and its isomers, the most abundant phenolic acids present in its extracts. Mulberry leaves are a source of phenolic compounds and can be a good start towards discovering a new chemical compound which may lead to a new drug. A mulberry extract supplement could serve as a candidate for developing a safe, and promising nutraceutical product for the management of nephrotoxicity.

A study on the allelopathic tolerance of garden pea varieties to Sorghum halepense (L.) Pers. extracts

The present research study identified garden pea varieties with pronounced tolerance to the allelopatic action of Sorghum halepense. Nine varieties were selected to study the effects of shoot and root weed biomass, applied in three extract concentrations (1, 5 and 10%), on seed germination and initial germ growth. A variance analysis of data revealed significant influence (p <0.05) of three studied factors (variety, type and concentration of extracts) on the investigated parameters. Statistically insignificant was only the influence of extract type (root/aboveground biomass) on seed germination. Based on absolute values of the allelopathic indicator RI, which determines the degree of allelopathic inhibition in terms of germination, germ length and weight in different varieties, the variation was as follows: from -0.30 to -0.04, from -1.31 to -2.96 and from -0.47 to 0.02. The total effect of allelopathic action of S. halepense on all studied parameters, presented as a GGE-biplot analysis, defined Pulpudeva and Puldin varieties as exhibiting higher tolerance, in contrast to Denitsa and Vyatovo, which were sensitive. Ran I, Mira, Musala and Vechernitsa occupied an intermediate position. Cultivation of allelopathic tolerant varieties is a promising addition to the current weed control strategy, especially in organic production.

Protection of organic cereals from insect and rodent pests in a warehouse by combined use of traps and sticky tapes

Several options of protection of organic cereals (winter and spring wheat, rye and maize) from insect and rodent pests, using a combination of traps (with or without pheromone/ attractant) and sticky tapes and no chemicals, were tested in a warehouse over the summerspring season of 2019/2020. Temperature in the warehouse was 14-29?C and humidity around 50%. The average grain moisture of winter and spring wheat and rye was 10-11%, while it was 12-14% in maize grain, and the average grain temperature of all cereals was 13-27?C. Regarding stored-product insect pests, five coleopteran, two moth and one Psocoptera species were detected, and the coleopterans predominated (98.5%) along with secondary pest insects (94.0%). Regarding rodents, only specimens of Mus musculus were found throughout the test period, their maximum monthly frequency being 72 (in January 2020). A combination of traps (with or without pheromones) and sticky tape barriers was found to provide an effective tool for trapping insects. Also, snap traps and trapping boxes for killing rodents, when used simultaneously with sticky tape barriers, were found to provide good protection of cereals from house mice. The pest control effect was also confirmed by collecting samples of organic cereal grain, which showed no significant presence of stored-product insects or grain damage (0.94% and 0.96% in spring wheat and rye, respectively) at the end of the test period. The results showed a great potential of combined application of traps and sticky tapes for protecting organic cereals in horizontal bulk storages, but the use of chemicals approved for organic food production would be required under extended storage periods.

Aggressiveness and trichothecene production of Fusarium graminearum isolates from cereals in Serbia

The aim of this study was to assess variations in aggressiveness and trichothecene production of F. graminearum isolates originating from maize, wheat and barley in Serbia. Analyzing F. graminearum isolates (98) obtained from various agroecological conditions of Serbia over the period from 1993 to 2010, using the HPLC method, the following two chemotypes were observed: 3-acetyl-deoxinivalenol (3ADON) and 15-acetyl-deoxinivalenol (15ADON). A great diversity in the production of deoxinivalenol (DON) derivatives was observed. A majority of F. graminearum isolates, regardless of their origin (maize, wheat or barley) belonged to the 15ADON chemotype. The 3ADON chemotype was also detected, but in a significantly smaller number (13/98) samples, compared to the 15ADON chemotype (85/98). None of the tested isolates belonged to the NIV chemotype. The examined isolates showed different pathogenicity on barley leaf, wheat class and maize ears. The average pathogenicity of the tested isolates was the highest on barley leaf. It was observed that isolates originating from wheat had the highest average daily increase in mycelium growth rate (27.37 mm). Statistical analysis of the obtained results for mycotoxins synthesis showed that there was a highly significant statistical correlation between the production potentials of total DON, 3ADON and 15ADON in F. graminearum isolates belonging to various chemotypes. However, there was no statistically significant correlation between the aggressiveness of isolates and the production of total DON in isolates belonging to 3ADON and 15ADON chemotypes.

Efficacy of fungicides in control of turmeric leaf spot caused by Colletotrichum capsici at Tepi, Southwestern Ethiopia

Turmeric leaf spot, caused by the pathogen Colletotrichum capsici, is the greatest damaging disease that limits the production and productivity of turmeric, and reduces qualitative and quantitative rhizome yields in Southwestern Ethiopia. A field trial was conducted to evaluate the efficacy of different fungicides against a disease epidemic of turmeric leaf spot in Southwestern Ethiopia. The field experiment was performed at Tepi Agricultural Research Center during the 2019 and 2020 main cropping seasons using four fungicides: Ethiozeb 80% WP (mancozeb), Prozole 255 EC (propiconazole), Mancolaxyl 72% WP (mancozeb + metalaxyl) and Ridomil Gold MZ 68 WG (metalaxyl-M), which were applied either as seed rhizome treatments plus foliar spray, or as foliar spray alone for control of leaf spot infection. The field experiment was laid out in a randomized complete block design with nine treatments and three replications. The results of the experiment indicated that both rhizome treatment + foliar spray, and foliar fungicide spray treatments significantly affected the turmeric leaf spot epidemics. The effect of the foliar spray Prozole 255 EC (propiconazole) was significantly higher than the other treatments in reducing disease severity (27.0) and maximizing rhizome fresh yield (34.1 ton/ ha). The maximum cost benefit ratio (1:2.65) was achieved by the foliar spray fungicide Prozole 255 EC (propiconazole). Amongst different fungicides considered, the foliar spray Prozole 255 EC (propiconazole) reduced leaf spot disease incidence up to 47.1% over the control on the last day of disease evaluation. The whole outcome of this experiment showed that foliar Prozole 255 EC (propiconazole) fungicide sprays were effective in alleviating the epidemic of turmeric leaf spot and boosting turmeric production and productivity.

Application of different combinations of lactic acid, phototrophic bacteria and yeast mixtures in control of seed and seedlings pathogens of tomato and pepper

Application of three combinations of lactic acid bacteria (Lactobacillus plantarum, Lactobacillus rhamnosus), phototrophic bacteria (Rhodopseudomonas palustris) and yeast (Saccharomyces cerevisiae) with sugar cane molasses, marked as: EM1, EM5 and EM AGRO, against the phytopathogenic fungi of tomato and pepper: Fusarium oxysporum, Alternaria alternata, Botrytis cinerea, Colletotrichum sp., Verticilium dahliae and Pythium aphanidermatum was evaluated in vitro and in vivo. A combination of bacteria and yeast named EM5 showed the highest mycelium growth inhibition against B. cinerea (38.4%) in a double agar diffusion test. In a microdilution test, the combination EM1 showed the highest inhibitory effect on B. cinerea (MIC 1x10-3 ?l/ml), while EM5 showed a similar inhibitory effect towards F. oxysporum, A. alternata and Colletotrichum sp. (MIC 10 ?l/ml). The use of EM1 (in concentrations 10 and 100 ?l/ml) and EM AGRO (10 ?l/ml) is recommended for tomato seedling protection. ??1 (100 ?l/ml), ??5 and ?? AGRO (10 ?l/ml) are recommended for pepper seedling protection.

Impact of water quality on pesticides and fertilizer compatibility

Mixtures of two or more pesticides are very common in contemporary agriculture. However, changes in their efficacy or biological activity, such as synergism and antagonism, phytotoxicity, persistence, toxicity to non-target organisms, may occur as a consequence. This study was conducted in order to evaluate the compatibility of insecticides (cyantraniliprole - Exirel, chlorantraniliprole - Coragen 20 SC), a fungicide (captan - Merpan 50 WP) and a foliar fertilizer (Folia Stim Mix TE), as well their mixtures, in spray liquids, depending on water quality (well water from two locations in Serbia - Mala Remeta and Cerevic). These products are used to control the most significant peach pests, and as an additional source of nutrients. Water analysis (pH, hardness, electroconductivity, chloride, nitrate, nitrite, ammonia, calcium and iron content) and tests of physico-chemical properties of the spray liquids (pH, suspensibility, dispersibility, surface tension, and electroconductivity) were performed in a laboratory experiment according to standard methods. The physico-chemical properties of the liquids changed depending on water quality and components incorporated in the mixture. However, all tested spray liquids showed consistency and compatibility over a period of 24 hours.

Impact of natural products on Acyrthosiphon pisum density on Pisum sativum L. and forage quality

A field trial was conducted at the Institute of Forage Crops (Pleven, Bulgaria) from 2015 to 2017. It studied the effects of natural products on Acyrthosiphon pisum density, as well as changes in the chemical composition, content of plant fibre components and enzyme degradability in forage pea. Treatments with the natural insecticides Madex and Agricolle, applied alone or in combination with the organic fertilizers Lithovit and Nagro were performed twice - at the beginning of the flowering stage and one week later. The fertilizers used in the trial are environmentally safe and approved for use in organic production. The synthetic products Kristalon, a foliar fertilizer, and Proteus 110 OD, an insecticide, were used for comparison. The application of natural products, either alone and in combination, resulted in a reduction in pea aphid density. Applying Agricolle with Nagro, followed by Lithovit with Agricolle, led to the highest aphid number decrease (70.0 and 51.1%, respectively). An optimal combination of decrease in the content of plant cell wall fibre components, cellulose and lignification degree with a significant increase in forage in vitro enzyme digestibility was established after applying Agricolle with Lithovit and Agricole with Nagro. Digestibility reached 71.8 and 69.8%, respectively, an increase of 8.2-5.2%, while ADF, cellulose and lignification degree decreased from 7.1 and 7.7%, 8.0 and 23.4%, amd 10.5 and 6.8% after applying Agricolle with Lithovit and Agricole with Nagro, respectively. In comparison, the synthetic products Kristalon and Kristalon with Proteus increased forage quality, but to a relatively lesser extent. A stronger linear relationship was found between aphid density and dry matter digestibility, compared to the content of neutral detergent fibres. Pea forage with low content of plant cell wall fibre components, cellulose and lignification degree, high protein content, and digestibility after treatment with the natural product Agricolle, and its combinations with Lithovit and Nagro, make it a very good complement to other forages in dairy cow rations.

Etiology of bacterial diseases of young walnut trees in Serbia

In the summer and autumn of 2019-2020, young walnut orchards were monitored for the presence of bacterial diseases. Diseased walnut samples comprising trunks and branches with symptoms of vertical oozing canker (VOC), walnut bacterial blight (WBB) and superficial bark necrosis were collected from eight locations in Serbia. Based on phenotypic features, pathogenicity, and molecular assays using PCR with specific primers, 49 isolates obtained from samples showing VOC and WBB symptoms were identified as Xanthomonas arboricola pv. juglandis, while further two isolates obtained from bark necrosis were identified as Brenneria rubrifaciens. One tested X. a. pv. juglandis isolate obtained from a VOC sample produced deep cankers in the bark of inoculated trunks of young walnut trees (cultivars Chandler, Franquette and Sejnovo). Therefore, this is the first report of an association between X. a. pv. juglandis and VOC symptom in Serbia. Considering that X. a. pv. juglandis significantly endangers walnut production, the presence of this pathogen in walnut transplant imports needs to be assessed by an authorised laboratory. Furthermore, as this is also the first report of B. rubrifaciens on walnut trees in Serbia, it is noteworthy that this pathogen is not particularly harmful to young walnut trees.