Metalaxyl Research Articles

Evaluation of Fungicides and Fungicidal Spray Schedule for the Management of Angular Leaf Spot of Common Bean

Angular Leaf Spot (ALS), caused by Phaeoisariopsisgriseola (Sacc.), is one of the major diseases of common bean in the Southern Ethiopia.The objective of the experiment was to select fungicides and spray intervals to recommend low cost management options for the control of ALS disease. The experiment was carried out under natural epidemic at Awassa Agricultural Research Center in Southern Ethiopia during 2013 -2014. The study consisted of five different fungicides (Ridomil Gold, Penncozeb, Curzate, Tilt 250 EC and Bumper 25 EC) in combination with two spray intervals ( 7 and 14 days) using two common bean varieties (HawassaDume and Red Wolaita) having dissimilar levels of reaction to ALS. The treatments were laid using Randomized Complete Block Design (RCBD) in factorial arrangement. All fungicides tested were found to be effective in controlling the ALS disease as compared to unsprayed treatment. Ridomil Gold was the most effective fungicide in reducing the disease severity and yield loss,followed by Curzate and Penncozeb, where asPropiconazole fungicides (Tilt 250 and Bumper) showed high AUDPC value as compared to the other fungicides. Ridomil Gold reduced the AUDPC value by 75% and 40% on susceptible and moderately resistant varieties, respectively. Grain yield loss was estimated to be 35 to 40 % and 74 to 85 % in moderately resistant and susceptible variety, respectively. There was not significance difference (p

Fungicide Rotation Programs for Managing Phytophthora Fruit Rot of Watermelon in Southeastern United States

About 50% of the watermelons in the United States are produced in the southeastern states, where optimal conditions for development of Phytophthora fruit rot prevail. Phytophthora fruit rot significantly limits watermelon production by causing serious yield losses before and after fruit harvest. Efficacy of fungicide rotation programs and Melcast-scheduled sprays for managing Phytophthora fruit rot was determined by conducting experiments in Phytophthora capsici-infested fields at three locations in southeastern United States (North Carolina, South Carolina, and Georgia). The mini seedless cultivar Wonder and seeded cultivar Mickey Lee (pollenizer) were used. Five weekly applications of fungicides were made at all locations. Significant fruit rot (53 to 91%, mean 68%) was observed in the nontreated control plots in all three years (2013 to 2015) and across locations. All fungicide rotation programs significantly reduced Phytophthora fruit rot compared with nontreated controls. Overall, the rotation of Zampro alternated with Orondis was highly effective across three locations and two years. Rotations of Actigard followed by Ranman+Ridomil Gold, Presidio, V-10208, and Orondis, or rotation of Revus alternated with Presidio were similarly effective. Use of Melcast, a melon disease-forecasting tool, may occasionally enable savings of one spray application without significantly impacting control. Although many fungicides are available for use in rotations, under very heavy rain and pathogen pressure, the fungicides alone may not offer adequate protection; therefore, an integrated approach should be used with other management options including well-drained fields.

Evaluation of Selected Bacterial Endophytes for Biocontrol Potential against Phytophthora Blight of Bell Pepper (Capsicum annuum L.)

Phytophthora blight, caused by Phytophthora capsici, is the most destructive disease of bell pepper in the United States. The effectiveness of current management strategies is limited by the long-term survival of oospores, wide host range, aggressive fungicide-resistant isolates, and lack of resistant cultivars with acceptable agronomic traits. Biological control is a viable alternative, and the use of endophytic microorganisms as biological control agents (BCA) has attracted widespread attention because they colonize the same ecological niches as plant pathogens. Seven isolates of bacterial endophytes in three genera Serratia (B17B), Enterobacter (E), and Bacillus (IMC8, Y, Ps, Psl and Prt), isolated from papaya, snap bean and flowering dogwood were evaluated for effects on P. capsici mycelial growth in vitro, and on disease severity and plant growth in greenhouse environment. All isolates significantly inhibited the mycelial growth of P. capsici with Ps, Psl and Prt having superior inhibitory effects. Seed treatments with Ps, Psl and Prt followed by plant inoculation with P. capsici reduced disease severity, and significantly increased plant shoot height, fresh weight, and fruit yield (number and weight) with Ps and Prt being slightly superior to Psl. Compatibility tests between isolates showed that only B17B and Y were compatible with each other. Sensitivity tests to different levels of mefenoxam (Ridomil Gold SL) showed that Ps, Psl and Prt were tolerant to the fungicide, while P. capsici was highly sensitive. Thus, Ps, Psl and Prt can be used in rotation with mefenoxam to reduce the frequency of fungicide usage for a more environmentally friendly, long lasting, consistent, and effective control of phytophthora blight. Overall, all isolates tested are potential BCAs against P. capsici, but more greenhouse and field studies are required to confirm in vitro results for all isolates that showed good potential in in vitro studies.

Potentiality of Inducer Resistance Chemicals and Bioagents in Managing Lettuce Downy Mildew

The tested inducer resistance chemicals (IRCs) bion (BTH), chitosan and salicylic acid as well as the bacterial bioagents Bacillus pumilus B. subtilis, B. thuringiensis and Pseudomonas fluorescens and the fungal bioagents Trichoderma album, T. harzianum and T. viride resulted in significant reduction to the germinated sporangia (conidia) of the fungus like Bremia lactucae Regel, the causal of lettuce downy mildew. This reduction was gradually increased by increasing the used concentration. The role of the tested IRCs and bioagents on management of the disease under greenhouse was evaluated. Under greenhouse conditions, spraying of lettuce plants artificially inoculted with the causal fungus like resulted in significant reduction to the severity of the disease compared with control treatment. Moreover, the IRC bion as well as P. fluorescens and T. harzianum were the most efficient treatments in this regard. Two field experiments were carried out during 2016/ 2017 growing season under natural infection by the disease to evaluate the efficacy of spraying of lettuce plants with any of the IRC bion and the bioagents P. fluorescens and T. harzianum on plants previously soaked or not in bion just before transplanting on the severity of the disease and weight of the grown plants. Data revealed that there was significant reduction to the severity of the disease with considerable increase to the average weight of each plant compared with control treatment due to sprying of these treatments. However, the fungicide Ridomil Gold MZ was the superior treatment in reducing the disease and increasing the weight of the foliage growth of lettuce plants. In addition, spraying of the IRC bion on plants soaked in bion just before transplanting ranked the second in this regarad followed by spraying of any of the two bioagents. Considerable increase in the activity of the oxidative reductive enzymes, i.e phenylalanine ammonia lyase (PAL), peroxidase (PO) and polyphenol oxidase (PPO), due to spraying of lettuce plants with bion, the bioagents P. fluorescens and T. harzianum as well as the fungicide Ridomil Gold MZ compared with unsprayed plants (control).

Aqueous extracts effects of seeds of <i>Thevetia peruviana</i> and <i>Azadirachta indica</i> on the development of<i> Phytophthora megakarya</i> in locality of Biakoa (Cameroon)

Objective: The objective of this work was to evaluate, the impact of aqueous extracts of seeds of “yellow oleander” Thevetia peruviana (AETP), Azadirachta indica (AEAI) “neem” and Ridomil Gold Plus 66WP in black pod disease in Cameroon during two consecutive years.Methodology and results: A completely randomize bloc device containing four treatments (control, AETP, AEAI and RidomilR and three replications was used in the farm. Extracts were applied twice in a month at the dose of 16.67 g/l while RidomilR was applied one time a month at the dose of 3.33 g/l to the heights H1 and H2. Disease distribution across various pod distribution development stages showed that mature pods were the most susceptible to P. megakarya. A significantly difference is observed between the different treatments on all parameters evaluated. The disease rates were 7.92 %, 5.38 %, 8.94 % and 36.24 % in the plots treated with fungicide, AETP, AEAI and untreated respectively, in 2013, and 10.95 %, 7.85 %, 16.21 % and 37.83 % in the same plots in 2014. The major results obtained compared to the rate of rot showed that AETP was more efficient than RidomilR and AEAI during these campaigns.Conclusion and application of results: This study showed that aqueous extracts are promising and could be an effective and cheap formulation for the biological control of black pod disease. They have to be applied twice in a month at the dose of 16.67 g/l.Keywords: Black pod disease, biological control, plants extracts, RidomilR, neem, yellow oleander.

Effect of pesticides on microorganisms involved in litter decomposition in cacao plantation in Ile-Ife, Nigeria

Wide spread use of pesticides by farmers in agro-ecosystems to control pests may cause the disruption of nutrient cycling by adversely affecting the organisms especially microorganisms, namely bacteria and fungi, involved in decomposition processes thus altering normal nutrient cycling pattern in these ecosystems. This study, therefore, identified and determined the dynamics of bacterial and fungal species involved in cacao leaf litter decomposition and the effect of the pesticide, Ridomil Gold 66WP on the species. This was with a view to understanding the effects of pesticides used to control pests and diseases on litter decomposition rate in cacao plantations. Cacao leaf litter decomposition was studied using litterbag method. Freshly fallen leaf litter was thoroughly mixed and divided into two groups, treated and untreated. The treated was sprayed with Ridomil Gold 66WP at the rate of the recommended field rate of 3.3 g/L and air dried. 20 g of treated and untreated litter were weighed, put in separate 15 cm × 15 cm of 1.0 mm mesh size litter bags and randomly placed on the floor of cacao plantations in Ile-Ife, Nigeria. Three litter bags of each group were randomly retrieved from the plantation on monthly intervals for each month and the content of each litterbag was weighed to determine the rate of decomposition of the litter. The litter contents of each group litter were bulked, ground and microbiological analyses carried out to isolate, characterise and identify the species of bacteria and fungi involved in cacao leaf litter decomposition. The rate of decomposition of pesticide treated cacao leaf litter (0.473) was lower than that of untreated litter (0.582). A total of 31 microbial species consisting of 13 bacterial species and 18 fungal species were isolated from decomposing cacao leaf litter during the sampling period. More fungal species (16) than bacterial species (9) were involved in untreated cacao leaf litter decomposition. Species of the genera Klebsiella, Pseudomonas, Aspergillus, Penicillium and Rhizopus were the most common microorganisms involved in decomposition of cacao leaf litter. Ridomil Gold 66WP did not have significant effect on the total heterotrophic bacterial and fungal counts throughout the sampling period though their counts in treated litter were lower than in untreated litter. There were also no significant monthly variations in both total bacterial and fungal counts. It was concluded that the pesticide, Ridomil Gold 66WP, though had adverse effect on the rate of decomposition of cacao leaf litter, it did not have any adverse effect on the species of bacteria and fungi involved in decomposition of cacao leaf litter.

Evaluation of Some Fungicides and Bio-Agents against Sclerotium rolfsii and Foot and Root Rot Disease of Eggplant (<i>Solanum melongena</i> L.)

Two experiments were conducted in a complete randomized design (CRD) with three replications to evaluate the efficacy of some fungicides and bio-agents against foot and root rot of eggplant. Ten treatments including five fungicides, two plant extracts, one poultry manure and an antagonist were evaluated against the disease and its causal agent. Fungicides and plant extracts were sprayed at the base of each plant and adjacent soil at 40, 50 and 60 days after transplanting (DAT). Poultry manure and bio-agent were applied to the soil before transplanting. The highest reduction of mycelium growth (74.44 %) and sclerotia production (77.13 %) were recorded in Bavistin 50 WP by poison food technique. Topgan 50 WP and Ridomil Gold also had similar effects. The lowest incidence (7.10 %) of foot rot was observed in Bavistin 50 WP at 120 DAT that was similar with Topgan 50 WP and Ridomil Gold. The lowest disease severity (stem lesion area) was also found in each of Bavistin 50 WP (0.71 cm) and Topgan 50 WP which resulted in higher yield (18.07 ton/ha). Application of bio-agent (Trichoderma harzianum) also showed promising effect against foot and root rot disease. Bavistin 50 WP is therefore recommended for controlling the foot and root rot of eggplant.The Agriculturists 2016; 14(1) 92-97

Field management of <i>Phytophthora</i> blight disease of cocoyam <i>Colocasia esculenta</i> L.) With spray regimes of selected fungicides in Nsukka, south eastern Nigeria

Cocoyam ( Colocasia esculenta L). is an important edible tuber crop, but taro leaf blight caused by Phytophthora colocasiae has been the greatest constraint to cocoyam production in Nigeria since 2009. Field trials were conducted to determine the effect of fungicides and the spray regimes on leaf growth, disease incidence, disease severity and tuber yield of cocoyam. The trials were carried out at the Department of Crop Science Research Farm, University of Nigeria, Nsukka for two planting seasons. Treatments with three fungicides (Ridomil Gold Plus, Ridomil+ChampDp 50%:50% mixture and control) and five spray regimes (No spray, weekly spray, 2nd weekly spray, 3rd weekly spray and 4th weekly spray regimes) were laid out in a 3 x 5 factorial in randomized complete block design (RCBD) with three replications. Results showed that fungicide treatments had significant (P 0.05) differences between Ridomil and Ridomil+Champ (50%:50%) mixture) on all measured parameters in both cropping seasons. The fungicides and the spray regimes significantly reduced taro leaf blight, improved growth and yields . Ridomil treated cocoyam plots at weekly spray regimes performed best compared to other fungicides and the spray regime treatment options.. Key words : Colocasia esculenta, Phytophthora colocasiae , Fungicides, Spray regimes, and Nsukka.

In vitro Antifungal Potential of Aqueous Seeds Extracts of Azadirachta indica and Thevetia peruviana against Phytophthora megakarya in Cameroon

This study aims to evaluate the antifungal effects of aqueous extracts of Azadirachta indica (AEAI) and Thevetia peruviana (AETP) seeds taking it from a biological perspective under laboratory conditions. A randomized sample block design containing four treatments ( T-: absolute control, AEAI, EATP and Ridomil Gold Plus at the dose of 3.33 mg/ml) in three repetitions was used. Plant extracts were used in three concentrations: C1: 12.5 µl/ml; C2: 25 µl/ml and C3: 50 µl/ml. The study took place in University of Yaounde 1, Faculty of Sciences, Department of Plant Biology, laboratory Original Research Article

Management of Faba Bean Gall Disease (Kormid) in North Shewa Highlands, Ethiopia

Production of faba bean is inhibited by several yield limiting factors, among which diseases are the main. In Ethiopia more than 17 disease causing pathogens were reported on faba bean. Major diseases recoded in faba bean includes, chocolate spot (Botrytis fabae), rust (Uromyces viciae-fabae), ascochyta blight (Ascochyta fabae), zonate leaf spot (Cercospora zonatae), and black root rot (Fusarium sp.). A new disease, faba bean gall locally called “Kormid in North Shewa was expanded in the highland faba bean growing areas. Studies showed that seed dressing and foliar fungicides have some effects against faba bean diseases. Field experiment was conducted in North shewa highlands to control faba bean gall disease at farmers’ field. The experiment was conducted on farmers’ fields in randomized complete block design in six replications. The treatments were arranged with different fungicides (spray and seed dressing), namely Mancozeb, Ridomil, Chlorotalonil, Bayleton wp 25 (Triadimefon 250 g/ kg), Thiram, Apron star and control. Fungicides were applied as manufacturers’ recommendations. Foliar fungicides were applied three times at seedling, flowering and podding growth stage on local faba bean variety. Disease score and other agronomic data were recorded at different plant growth stage. The highest disease score were recorded in control, Thiram and Apron star in 2013. The highest yield was also recorded in Bayleton and mancozeb sprayed plots respectively. In 2014 the disease prevalence and severity was similar to 2013. Maximum disease score were recorded on Control followed by Thiram and Apron star seed dressing plots. Minimum disease score were also recorded in Baylaton (2.66) and Ridomil gold (2.71) sprayed plots. There was a significant difference between biomass yield and grain yield. The highest grain yield was recorded in Baylaton (3129.8 kg) sprayed plot and followed by Ridomil gold (2708.3 kg) and Mancozeb (2705.7 kg) respectively. There was no significant difference between plots in plant height, pod per plant, seed per pot and seed per plant in both years.

Evaluation of Combined Effect of Micronutrients (ZnSO<sub>4</sub> + Borax) and Fungicides to Control the Purple Blotch Complex of Onion (<i>Allium cepa</i>)

Ten different treatments viz. T0 = Control, T1 = Micronutrients (ZnSO4 + Borax), T2 = Rovral 50 WP + Micronutrients, T3 = Dithane M-45 + Micronutrients, T4 = Ridomil Gold + Micronutrients, T5 = Cupravit + Micronutrients, T6 = Rovral 50 WP, T7 = Dithane M-45, T8 = Ridomil Gold and T9 = Cupravit were evaluated against the purple blotch complex disease of onion caused by Alternaria porri and Stemphylium vesicarium in field condition for bulb yield. In lab condition, all the tested chemical fungicides (Rovral 50 WP, Dithane M-45, Ridomil Gold MZ-72 and Cupravit 50 WP) significantly reduced mycelial growth of both pathogens. Among the fungicides, Rovral 50 WP @ 0.2% reduced the highest radial mycelial growth followed by Dithane M-45 @ 0.45% and Ridomil Gold MZ-72 @ 0.2% compared to control. In field experiment, application of Rovral 50 WP @ 0.2% along with micronutrients showed significant effect in reducing disease incidence and severity which significantly increased bulb yield and yield contributing characters.

PHYTOPHTHORA INFESTANS POPULATIONS FROM THE EUROPEAN PART OF RUSSIA: GENOTYPIC STRUCTURE AND METALAXYL RESISTANCE

Populations of the potato and tomato late blight pathogen from different regions of the European part of Russia were studied for their genotypic structure and metalaxyl resistance. The majority of the studied populations showed a high genotypic diversity, i.e. strains of A1 and A2 mating types, Ia and IIa mitochondrial DNA haplotypes, and different genotypes at Pep1 and Pep2 loci were identified. The highest genotypic diversity was registered among P. infestans populations from the North Caucasus, Mariy El Republic, and the Moscow region. The obtained data confirm a high probability of crossing and hybridization within the most part of the field populations of P. infestans from the European part of Russia. Most of the studied populations included strains with high and low metalaxyl resistance, the incidence of resistant strains depending on the use of metalaxyl-containing fungicides.

Testing Some Fungicides for the Combat of Potato Mildew in the Pedoclimatic Conditions in Seini Town

The aim of this survey was to set the biologic effectiveness of some homologated fungicides, in order to introduce them in the new programs of combating mildew in potato crops. The experimental surveys were carried out at the farm of SC Marmalus SRL of Seini, the Maramures County, during 2013 and 2014. The warning area method was used. The attack was calculated by determining the attack frequency, intensity and degree. In 2013, 8 varieties were tested against the mildew attack, as the Procura variant proved to be the most resistant, and Ostara the most sensible. In 2014, 14 fungicides were tested starting with the outbreaks of the alarm plot; then the appearance of mildew in natural conditions was taken into account. For testing, the sensible Ostara variety and the resistant Procura variety were used. The climatic conditions were favorable to the development of fungi, with high temperatures and atmospheric humidity. The best results were obtained for the Ridomil Gold Plus 42.5WG, for both varieties, with the effectiveness of 86.6% for the resistant variety, respectively, 85% for the sensitive variety. The worst results were obtained by the Dithane M45 product, with an effectiveness of 70.4% for Ostara, as for the Procura variant the Polyram DF product was used with an effectiveness of 73.7%. In the combating of Phythophtora infestans fungi, it is recommended to use with good results the product Ridomil Gold Plus 42.5WG, followed by the products Ridomil Gold X9Z86WG, Infinito 68.7 SC and Consento 450 SC.

Identificación morfológica y molecular de Phytophthora capsici L. en calabaza pipiana y su manejo en invernadero

La calabaza pipiana es importante en la alimentacion de la poblacion en el centro-sur de Mexico. Sus semillas se consumen directamente tostadas y aderezadas con sal; ademas, son el ingrediente principal para elaborar platillos tipicos como el mole verde o pipian, asi como diferentes dulces tradicionales. Algunos microorganismos del suelo causan severos problemas en frutos, lo que afecta el rendimiento. El objetivo del estudio fue identificar morfologica y molecularmente al oomicete causante de la pudricion de frutos de calabaza pipiana, y evaluar opciones de control quimico y biologico en invernadero. Durante agosto y septiembre de 2011, en la zona norte del estado de Guerrero, se colectaron frutos de calabaza pipiana con sintomas de pudricion. La identificacion morfologica se realizo con las claves propuestas por Gallegly y Hong (2008), y la molecular fue mediante la reaccion en cadena de la polimerasa, ITS-PCR. En ambas pruebas se identifico a Phytophthora capsici como el causante de la pudricion de frutos de calabaza pipiana. Las secuencias obtenidas tuvieron 99 % de similitud con P. capsici en sandia de Estados Unidos y en calabaza de Italia, depositadas en el banco de genes (GenBank). Los ingredientes activos, propamocarb+fosetil y metalaxil+clorotalonil, mostraron control al retrasar seis dias la presencia del patogeno en frutos, mientras que los agentes de biocontrol la retardaron cuatro dias

Development of an ecological strategy for the control of downy mildew (Pseudoperonospora cubensis) in cucumber cultivation (Cucumis sativus L.)

Downy mildew is a severe disease of cucumber worldwide. The oomycete Pseudoperonospora cubensis cause it and once it is established in a region, the infection spreads rapidly, causing significant loss of yield and fruit quality. The objective of the research was to develop an ecological strategy for the control of downy mildew in cucumber. The treatments were arranged in a completely randomized experimental design with an alternation of chemical and biological fungicides. The treatments were: T1: systemic fungicide (Ridomil Gold, 2.5 g/l) alternating with a contact fungicide (Bravo 2.5 ml/l), T2: CustomBio 5 (Bacillus-based fungicide, 3ml/l), T3: control (water), T4: Trichoderma sp. (3 ml/l), T5: systemic fungicide (Ridomil Gold 2.5g/l) alternating with CustomBio 5 (3 ml/l), and T6: systemic fungicide (Ridomil Gold 2.5g/l) alternating with Trichoderma sp. (3 ml/l). The following variables were evaluated: stem thickness, plant height, number and weight of fruits, yield, the area under the relative progress curve (AUDPCr), and economic analysis of each treatment. The results showed that the best treatments were T1 and T6, with an AUDPCr of 11.89% and 12.10%, respectively. Treatments T6 and T1 showed the best yield, as well. The profitability analysis showed that all the alternatives were profitable with a Benefit/Cost>1 ratio. However, the treatments T6 and T1 were the most useful. We recommend this control strategy to reduce the use of chemical fungicides and, at the same time, obtain an efficient control of the disease, which guarantees a significant yield of high-quality fruit.

Efficacy of Organic and Conventional Fungicides and Impact of Application Timing on Control of Tomato Late Blight Caused by US-22, US-23, and US-24 Isolates of Phytophthora infestans.

Late blight, caused by Phytophthora infestans, is one of the most economically important diseases of potato and tomato worldwide. Repeated preventative application of fungicides is the primary means of control on susceptible solanaceous host crops. For organic production, fungicide choices are limited, and little efficacy data on noncopper options is available on which to base control recommendations. Twelve fungicides, including organic and conventional selections, were evaluated for both preventative and postinfection control of a single infection cycle of late blight caused by isolates representing three recently identified P. infestans clonal lineages (US-22, US-23, and US-24) using a detached tomato leaf assay. A subset of the most effective fungicides was also tested for preventative control of a single infection cycle of late blight caused by an isolate of US-23 on potted whole tomato plants under laboratory conditions. Fungicide applications made 2 days after inoculation failed to significantly control late blight on detached leaves in all treatments, with the exception of Bravo Ultrex (US-23 only) and Phostrol (US-22 only). Preventative fungicide applications of Bravo Ultrex, Ridomil Gold SL, Revus, Zonix, and low and high rates of EF400 significantly controlled late blight caused by US-22, -23, and -24 isolates. Additionally, preventative application of Phostrol significantly controlled late blight caused by the US-22 isolate; and Phostrol, low rate of Mycostat, and high rate of Champ significantly controlled late blight caused by the US-23 isolate. Late blight caused by the US-24 isolate was significantly reduced compared with US-22 and US-23 isolates for all fungicide treatments applied after inoculation, as well as for all preventative fungicide treatments, with the exception of Bravo, Ridomil, and Revus. In whole-potted-plant assays with the US-23 isolate, late blight was significantly controlled by preventative application of Bravo Ultrex, Ridomil Gold SL, and high rate of EF400; disease was not significantly controlled by Zonix, low rate of EF400, Phostrol, or low and high rates of Champ. Based on these results, it is anticipated that currently available fungicides with suitability to conventional and organic systems can effectively control late blight caused by new clonal lineages of P. infestans when applied preventatively and that late blight caused by the US-24 clonal lineage may require less fungicide use than US-22 or US-23 to mitigate disease.

Identification and control of fungi causing fruits rot in pipiana pumpkin (Cucurbita argyrosperma Huber)

Severe rot symptoms were observed in samples collected during 2012 in a small farm in Cocula, Guerrero, Mexico. One oomycete and two deuteromycetes fungus were isolated from collected symptomatic fruits. In order to carry out the molecular analysis by the amplification of the internal transcribed spacer region (ITS) two representative isolates of each fungus were chosen. The pathogenicity of each isolate was verified with pumpkin fruit inoculation with fungus inoculants and fruits sprinkled only with sterile distilled water as control. The control fruit remained healthy while the fruits which were inoculated with the pathogens were observed to have injuries and rot symptoms five days after inoculation. From the fruits showing injuries and rot symptoms, the oomycete and fungus were re-isolated. Based on the isolation, morphological, and molecular identification, as well as on pathogenicity tests, Phytophthora capsici Leon, Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc., were determined to be the causal agents for rot of the pumpkin fruits. Additionally, five fungicides and the biocontrol agent Trichoderma asperellum were assessed against the above fungus in pumpkin fruits in a greenhouse. The fungicides propamocarb + fosetyl-Al, metalaxyl + Chlorothalonil, quintozene, and the biocontrol agent T. asperellum, delayed the presence of P. capsici, R. solani, and S. rolfsii for 6.00, 4.67, and 5.83 days, respectively. Key words: Cucurbita argyrosperma, soil pathogens, fruit rot, fungicides, Trichoderma asperellum.

Organic Potato Product for Baby Foods and Dietetic Food

The article indicates the relevance of producing organic potato, primarily for children who need special protection from damage caused by pesticides, nitrates and Heavy Metals (HM), as well as for medical nutritional therapy of people suffering from chronic diseases. We have identified tasks and purposes for studying the dynamics and intensity of pesticide accumulation in the potato tubers; revealing the effectiveness of biological insecticides; determining heavy metal contamination level of products near anthropogenic area – the M-4 ‘Don’ federal highway; revealing nitrate accumulation in the tubers at different fertilizer doses; determining duration of various hazardous components accumulated in potato tubers and giving production recommendations for safety interval between pesticide application and harvesting operations. Field experiments were conducted at Educational and Experimental Farm of Bunin Elets State University. Chemical insecticide Actara and biological agents Fitoverm, Acarin, Bitoxybacillin were used for pest control. Antifungals (fungus killers) Profit Gold (TANOS) and Ridomil Gold and herbicides (weed killers) Sencor and Rimus were also applied. Sencor and Rimus remained in potato tubers longer, for 55 and 66 days after processing, respectively. Nitrate threshold limit value (80 mg/ kg) was not exceeded in the experiments with NPK composition options: N30-60P60-90K30-60. Accumulation of heavy metals in tubers increased at a distance of 50m from the highway, but did not exceed TLV. At 100 meters away from the road HM were detected in the tubers, but in smaller concentrations. Lead and cadmium were not discovered in potato tubers grown at a distance 500 meters away from the highway.

A True Endophyte of the Endangered Tree, Cynometra travancorica in the Efficacy and Economics of Fungicides and their Application Schedule for Early Blight (Alternaria solani) Management and Yield of Tomato at South Tigray, Ethiopia

Early blight, caused by Alternaria solani, is the most pressing problem of tomato Production and productivity in Tigray region. However, only limited attempts have been made to tackle this problem in the study area. Therefore, this study was conducted to (1) investigate the efficacy and spray frequencies of fungicides (2) determine yield loss incurred due to early blight and (3) assess cost benefit of the fungicides. Three fungicides (ridomil gold, Agrolaxyl and Mancozeb) each with three spray frequencies (every 7, 14 and 21 days) were evaluated using moderately susceptible variety, Melkashola in a Randomized Complete Block Design (RCBD) with three replications. Significant differences were observed among the treatments in-terms of disease incidence (DI), disease severity (DS), and AUDPC and disease progress rate (DPR) and; yield and yield components. Mancozeb among the fungicides and weekly spray among the spray frequencies were found the most effective in controlling the disease and improving the yield of tomato. Application of Mancozeb every week minimizes the disease by (47.75%) and consequently improves the yield by (112.48%). Weekly application of Mancozeb was found the most effective in controlling the disease with minimum values of DS (10.45%), AUDPC (266.0%-days), and DPR (0.09) and; higher marketable yield of (355.68 q/ha) and most economical with maximum marginal rate of return (MRR) (2,671.3%). Bi-weekly spray of Mancozeb also gave next higher MRR (1,724.3%). Maximum yield loss (52.94%) as compared to the most protected plot was incurred on untreated plots. Therefore, from the findings it can be conclude that application of mancozeb at weekly interval can be considered as the best management strategy to reduce disease epidemics and improve tomato yield.

English

The most effective disease management method for yield reducing diseases affecting tomatoes is the use of fungicides. This study evaluated the efficacy of chemical control on three Phytophthora sp. isolates, pathogenic to tomatoes. The effect of fungicides on mycelial growth of Phytophthora sp. and on tomato wilt was evaluated in vitro and in vivo . Two tests were done in Petri plates, and one on seedlings, in completely randomized design as a 4x3 factorial, with 5 replications. In vitro tests were done in growth chamber, at 25°C. The experimental unit consisted of a 5-mm diameter fungal mycelial plug placed 30 mm away from a filter paper disk, of similar size, soaked in fungicide, over cornmeal agar. The first test evaluated four commercial products registered for the control of potato blight: clorotalonil+metalaxyl (Folio Gold ® 742.5 WP); propamocarb chloridrate (Infinito ® 687.5 CS), metalaxyl-m+mancozeb (Ridomil Gold ® 68 WP), cymoxanil + manconzeb (Curzate ® MZ 72 WG), at the recommended doses. The other assays evaluated three doses of Infinito (0.125%, 0.150% or 0.175%) and Ridomil. In vivo test was done in the greenhouse, and the experimental unit consisted of one pot, containing one tomato seedling, cultivar Alambra F1. Fungicide was drenched on the seedling soil one day prior to inoculation with 50,000 zoospores per pot. Data of mycelia growth inhibition by fungicide were submitted to analysis of variance and the averages compared by the Tukey test at 5% significance; efficacy was determined as a function of Ridomil®, the standard fungicide. In the first test, regardless of isolate, Infinito® presented performance similar to Ridomil ® with efficacy of 98.5%, while Folio Gold ® presented efficacy of 57.3% and Curzate ® had no fungicide effect. Growth of isolate PP3 was smaller in all fungicides. In the second in vitro test, all three doses of Infinito ® had efficacy above 82%. The best control was observed on isolates PP3 and PP4. In the third test, in vivo , no significant differences were observed in root matter among the standard fungicide and the doses of Infinito ® ; however, efficacy of Infinito ® at 0.175% was 14% greater than that obtained with Ridomil ® . It can be concluded that Infinito ® is one more option for the control of tomato wilt.