Seed pathology

Seeds provide an efficient method for disseminating pathogenic organisms to different locations; more than 50 percent of the major bean diseases are seed borne. Mechanical damage, which may occur during harvesting, threshing and/or planting can affect seed viability, germination, and result in contamination by microorganisms. Seed pathogens can be controlled with protectant fungicides that penetrate the seed coat but not the cotyledons. Systemic fungicides, which penetrate the seed coat and cotyledons, provide some degree of control. The date of harvest is very important in the production of high-quality, pathogen-free seed. Leaving plants for prolonged periods in the field after plant maturity increases the percentage of seed infection by fungi and decreases the percentage of seed germination. Various species of bacteria and viruses are seed borne, but no treatment controls them satisfactorily. The seed-borne and seed-contaminating organisms associated with dry beans are given in table form. Color illustrations are given. (AS)La semilla constituye un metodo eficiente de diseminacion de organismos fitopatogenos a diversas localidades; mas de 50 por ciento de las principales enfermedades del frijol son transmitidas por la semilla. El dano mecanico que ocurre durante la cosecha, trilla y/o siembra tambien puede afectar la viabilidad, la germinacion y resultar en contaminacion de la semilla por microorganismos. Los patogenos de la semilla se pueden controlar con fungicidas protectores que penetran en la testa de la semilla pero no en el interior de los cotiledones. Los fungicidas sistemicos, que penetran en la testa y en los cotiledones, brindan cierto grado de control. La fecha de cosecha es muy importante en la produccion de semilla de alta calidad, libre de agentes patogenos. Dejar las plantas en el campo por periodos prolongados despues de que han madurado hace que el porcentaje de infeccion por hongos aumente y que el porcentaje de germinacion de la semilla disminuya. Varias especies de bacterias y virus son portadas por la semilla, pero ningun tratamiento las controla satisfactoriamente. Se presentan en forma de cuadro los organismos portados por las semillas y contaminantes de ellas asociados con el frijol. Se presentan ilustraciones a color. (RA

Seed pathology

Seeds provide an efficient method for disseminating pathogenic organisms to different locations; more than 50 percent of the major bean diseases are seed borne. Mechanical damage, which may occur during harvesting, threshing and/or planting, can affect seed viability, germination and contamination by microorganisms. Seed pathogens can be controlled with protectant fungicides that penetrate the seed coat but not the cotyledons. Systemic fungicides, which penetrate that seed coat and cotyledons, provide some degree of control. The date of harvest is very important in the production of high-quality, pathogen-free seed. Leaving plants for prolonged periods in the field after plant maturity increases the percentage of seed infection by fungi and decreases the percentage of seed germination. Various species of bacteria and viruses are seed borne, but no treatment controls them satisfactorily. The seed-borne and seed-contaminating organisms associated with dry beans are given in table form. Color illustrations are given. (AS)La semilla constituye un metodo eficiente de diseminacion de organismos fitopatogenos entre distintas localidades; mas del 50 por ciento de las principales enfermedades del frijol son transmitidas por semilla. El dano mecanico que ocurre durante la cosecha, trilla y/o siembra tambien puede afectar la viabilidad, germinacion y contaminacion de la semilla por parte de microorganismos. Los patogenos de la semilla se pueden controlar con fungicidas protectores que penetran en la testa de la semilla pero no en el interior de los cotiledones. Los fungicidas sistemicos, que penetran en la testa y en los cotiledones, brindan cierto grado de control. La fecha de cosecha es muy importante en la produccion de semilla de alta calidad, libre de agentes patogenos. El dejar las plantas por periodos prolongados en el campo despues de que estas han madurado, hace que el porcentaje de infeccion por hongos aumente y que el porcentaje de germinacion de la semilla disminuya. Varias especies de bacterias y virus son portadas por la semilla, pero ningun tratamiento las controla satisfactoriamente. En forma de cuadro se presentan los organismos portados por las semillas y contaminantes de ellos asociados con el frijol. Se presentan ilustraciones a color. (R

Opportunities in Tajikistan to breed wheat varieties resistant to seed-borne diseases and improved baking quality

Wheat seed-borne diseases and options for improving baking quality of wheat, as well as the role of genotypes for breeding to achieve high yield and quality are the key issues discussed in this introductory paper. The importance of wheat for Tajikistan and how to achieve food security goals in the country is also elucidated. Wheat seed-borne diseases are caused mostly by fungi. Loose Smut (Ustilago tritici), Common Bunt (Tilletia laevis and T.caries), Karnal Bunt (T.indica), Dwarf Bunt (T.controversa) and Black point (Alternaria spp., Bipolaris sorokiniana etc.) are all seed-borne diseases that are economically and regulatory important for Tajikistan, and these are therefore discussed in detail. The peculiarities of Tajik bread and requirements to the grain quality are also highlighted

Screening for resistance to leaf stripe (Pyrenophora graminea) in barley

Resistance against leaf stripe (Pyrenophora graminea ) have been described in the literature, but only little is known about the resistance in modern varieties. Investigations have been started in co-operation with Danish breeders with the objective to ensure availability of healthy seed for pesticide-free and organic growing of cereals. The results so far show great variation in susceptibility to leaf stripe. Most of the tested varieties or lines were susceptible, but some varieties had a moderate level of resistance and a few were highly resistant. The test have been made with different populations collected from Denmark but only little is known about the virulence pattern in leaf stripe

Antifungal effects of pawpaw seed extracts and papain on post harvest Carica papaya L. fruit rot

Increasingly, public debate on ban of use of synthetic chemicals for pest control has been unabated, due basically to the hazards posed by such chemicals to the ecosystem and environment. Biological control using natural products presents as alternative and a viable means of control of pests. Effects of extracts from Carica papaya. L (seed and papain) on mycelial reduction of the most occurring fungal pathogen causing pawpaw fruit rot were investigated. Different fungi isolated were Rhizopus spp, Aspergillus spp and Mucor spp. The aqueous seed extract and papain exhibited remarkable mycelial inhibition with mean zones of inhibitions between (0.23 - 1.73 mm). Using ANOVA at 5% (P < 0.05) there seem to be no significant difference in activity between the extracts (aqueous seed extract and papain).The importance of these findings is hinged on non- chemical means of shelf life elongation of harvested pawpaw fruit in Africa

Mycoflora and Aflatoxin Contamination of Some Foodstuffs

Analysis was made of the mycoflora and aflatoxin contamination of Rice (Oryza sativa), Beans (Phaseolus vulgaris), Corn (Zea mays), and Groundnut (Arachis hypogaea) sold in four different markets in Sango-Ota, Ogun state, Nigeria. Sixty four samples comprising of four samples of each foodstuff from four food vendors in four different markets was assayed. The samples were contaminated with different species of fungi to include Aspergillus flavus, Aspergillus tamarii, Aspergillus niger, Rhizopus nigricans, Rhizopus oryzae, Saccharomyces cerevisiae, Aspergillus parasiticus, Fusarium moniliforme, Fusarium verticilliodes, Aspergillus ochraceus, Cladosporium cladosporioide, Mucor spp, Trichodema spp, Rhizopus arrhizus and Aspergillus fumigates. Aspergillus flavus and Fusarium spp had the highest rate of occurrence among the isolated fungi. Aflatoxins B1, B2, G1 and G2 were found associated with the samples at concentration ranging from 9 - 25 ppb, 8 - 12 ppb, 6 - 21 ppb, 4 - 8 ppb respectively. The fungal counts were between 6.3 x 102 to 7.0 x 103 cfu/g. The moisture content and the pH of samples were between 10.9 to 28.0% and 6.20 to 6.66 respectively. Effective storage and adherence to HACCP principles will help prevent contamination of foodstuffs with aflatoxigenic fungi

Economic and agronomic feasibility of organic vegetable seed production in the UK, and subsequent seed quality (OF0166)

This is the final report of Defra project OF0166. There is a longer summary at the start of the attached main report. For many farmers and growers, a move to organic production presents major challenges. Among these, the issues regarding the use of organic seeds could yet be a stumbling block, as growers and the seed trade have reservations about using and producing them for four major reasons: 1) The availability of a wide range of organic varieties appropriate to all year round crop scheduling, and differing production techniques and markets 2) The impact of derogation on managing the supply and demand for organic seed 3) The technical issues of organic seed production 4) Maintaining high standards of seed quality, hygiene and vigour. Three biennial vegetable crops: parsnips, winter cauliflower, and bulb onions and a small range of annual crops including lettuces, runner beans, spinach, broccoli were grown for seed production. All the crops were grown under a Spanish “Haygrove” tunnel. These relatively cheap structures allow good ventilation whilst offering protection against wet weather. All the crops were grown following organic protocols. Seed yields were recorded, and comparisons with disease contamination, germination and vigour were made against seed of the same variety produced conventionally by the collaborating seed company. Yields were unpredictable for some crops in the early stages of the project, but this problem was overcome as techniques were better understood and more experience gained. Seed quality was generally very good for most crops, and few problems were encountered with seed borne diseases for most crops. High levels of seed surface contamination with saprophytic fungi (Penicillium and Cladosporium) may have masked the presence of other fungi. Where equivalent comparisons with conventional seedlots could be tested for disease and vigour differences were small. However, major problems were encountered with bulb onion seed production as neck rot resulted in loss of stock material (around 50% of bulbs were lost). Hot water treatments were used in this project and were found to be successful against a range of pathogens on infected onion seed. More research into organic seed treating is advocated. The project has shown that on a small scale at least, good quality organic seed can be produced under relatively inexpensive polythene tunnels. The yields attained can be as good as those from conventional production, but there are without doubt greater risks involved. It is suggested that should diseases or pests become rampant then their control will be difficult. This project has shown that crops like onions are extremely difficult to produce, and that neck rot in particular will be a problem for the seed producer and grower. The use of tunnels is strongly supported; they can keep crops dry at harvest, they do not necessarily encourage disease build up and natural predator populations can be built up in and around them. It can be summed up that 1) Organic seed production was found to feasible, but higher risk than conventional production 2) Seed quality differences were small 3) Costs in terms of management input were high 4) Neck rot ( Botrytis allii) on bulb onions was, and is likely to remain, a persistent problem 5) Hot water treatment was found to be satisfactory for the small volumes of seed treated. Urgent attention is needed to identify other more consistent methods than this which will satisfy Organic protocols

The role of Seed Associations on crop production: how to globalize Brazil in the world seed market?

ABRATES (Brazilian Association of Seed Technology) is a scientific non-profit organization, founded in 1970. Its members consist of research scientists, professors, students and other professionals related to the seed sector, and seed producing companies. The major objectives of ABRATES are: support and stimulate scientific work and teaching on seed technology; disseminate results of scientific and technical papers of interest to the seed sector; cooperate with individuals or entities, public or private, on issues related to seed technology; suggest methods and uniform practices, aimed at improving seed technology in the country. These objectives are achieved by implementing various actions. Three Brazilian Seed Seminars and 17 editions of the Brazilian Seed Congress have been offered. In these events, 7,797 papers were delivered. Eleven editions of the Brazilian Symposium on Seed Pathology, five of the Brazilian Symposium of Forest Seeds, and three of the Brazilian Workshop on Seed Quality Control have been offered by ABRATES. The association edits the Brazilian Seed Journal (Revista Brasileira de Sementes), first published in 1979. A total of 1,722 research papers have been published so far. Since 1990, ABRATES has edited the ABRATES Newsletter (Informativo ABRATES), containing more practical technical articles, news and the abstracts of the Brazilian Seed Congress and other scientific events promoted by the association. In 2012, a new electronic publication was implemented: ABRATES in Focus (ABRATES em Foco), which is a monthly newsletter delivering technical news, interviews, and other information by e-mail. All these three publications can be accessed by the association site (www.abrates.org.br). The association is also in the social network, using Facebook and Twitter. ABRATES edits books and handbooks related to the seed area, dealing with subjects such as seed vigor procedures, sampling, analysis, seed processing, seed pathology and forest seeds. Since 2011, it has been involved in offering training courses to the seed sector, dealing with the specialization of Seed Physiology, Seed Sampling, Seed Analysis, and Seed and Seedling Image Analysis. Basically, all this effort is devoted to the seed production sector, aiming the production of high quality seeds and seedlings of several species

Determination of Toxicity of some Fungal Metabolites on Seed Germination and Pigment Leaching

In present investigation, eighteen fungi were isolated on Potato Dextrose Agar and Rose Bengal Agar medium from abnormal soybean seeds. Out of these eighteen fungi, ten dominant fungi were selected to study the toxic potentialities of culture filtrate of these ten fungi on oilseeds germination, pigment leaching i.e. chlorophyll of spinach and betalain of beet root.  Maximum loss of chlorophylls was caused due to toxins of Aspergillus niger, Aspergillus flavus and Penicillium notatum. Fusarium oxysporum caused minimum loss of chlorophylls. Aspergillus niger and Alternaria dianthicola was responsible for maximum leaching of betalain pigment while Curvularia lunata causes minimum leaching of pigment.---Seed Pathology and Fungal Biotechnology Laboratory, Department of Botany, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad- 431004(M.S.) India  ---Please Cite This Article As: Rajendra B. Kakde and Ashok M. Chavan. 2010. Determination of Toxicity of some Fungal Metabolites on Seed Germination and Pigment Leaching. J. Ecobiotechnol. 2(6):46-55.Â

Sorghum diseases prevalent in Ghana

Field survey, screening trials and laboratory investigation were used to determine the prevalence of sorghum diseases in the major sorghum-growing climatic zones (Sudan, northern and southern Guinea savanna). Farmers\' fields were surveyed in 1997. Ten sorghum entries were evaluated under natural field conditions in 1997 and 1998 at Damongo for their reaction to foliar and panicle diseases while seed samples of field-harvested sorghum were assessed for fungal infection using the blotter method. Two main types of sorghum, viz. the early-maturing, brown-seeded, guinea or guinea-caudatum type and the late-maturing, photoperiod-sensitive, white-seeded, guinea or guinea-caudatum type were found in the sorghum-growing areas. The survey showed that sorghum was cultivated under a range of cropping systems in all possible crop mixtures. Grey leaf spot (Cercospora sorghi), oval leaf spot (Ramulispora sorghicola), zonate leaf spot (Gloeocercospora sorghi) and covered smut (Sporisorium sorghi) were prevalent in all the sorghumgrowing areas. Other diseases recorded were leaf blight (Exserohilum turcicum), sooty stripe (Ramulispora sorghi), grain mould (caused by a complex group of fungi), long smut (Sporisorium ehrenbergii), head smut (Sporisorium reiliana), rust (Puccinia purpurea) and rough leaf spot (Ascochyta sorghi). Anthracnose (Colletotrichum graminicola) occurred infrequently across the regions. Striga hermonthica was more prevalent in the two Upper regions than in the Northern Region. The sorghum entries varied considerably in their susceptibility to the field diseases, with severity mean scores ranging from 2.5 to 3.6. Eight species of fungi were recorded from seed samples. The occurrence of these varied with the sorghum entries, with the genera Fusarium and Phoma dominating, followed by Curvularia.Enquête sur le terrain, essais de dépistage et investigation de laboratoire étaient faites pour déterminer la prévalence de maladies de sorgho dans les zones climatiques principales (soudano-savane et savane guinéenne du nord et du sud) cultivant le sorgho. L\'enquête était menée en 1997 aux champs d\'agriculteurs. Dix variétés cultivées de sorgho étaient évaluées sous les conditions naturelles au champ en 1997 et 1998 à Damongo pour leur réactions aux maladies foliaires et aux maladies de panicules alors que les échantillons de graine de sorgho moissonnée de champ étaient évalués pour infection fongique en employant la méthode de buvard. Deux types principaux de sorgho à savoir la maturation tôt: graine-brune, guinée ou le type caudatum guinéen et la maturation tardive: sensible à la photopériode, graine-blanche, guinée ou le type caudatum guinéen étaient rencontrés dans les zones cultivant le sorgho. L\'enquête révélait que le sorgho est cultivé sous les systèmes de culture divers dans toutes les associations des cultures possibles. La tache à feuille grise (Cercospora sorghi), la tache à feuille ovale (Ramulispora sorghicola), la tache à feuille zonée (Gloeocercospora sorghi) et le couvert de charbon des céréales (Sporisorium sorghi) étaient en prévalence dans toutes les zones cultivant le sorgho. D\'autres maladies observées étaient la rouille des feuilles (Exserohilum turcicum) la rayure de suie (Ramulispora sorghi) la moisissure de grain (causée par un groupe complexe de fongus), le charbon long des céréales (Sporisorium ehrenbergii), le charbon de tête (Sporisorium reiliana), la rouille (Puccinia purpurea) et la tache à feuille rugueuse (Ascochyta sorghi). Anthracnose (Colletotrichum graminicola) se produit peu souvent à travers les régions. Striga hermonthica était la plus en prévalence dans les deux Hautes régions que dans la Région du Nord. Les variétés cultivées de sorgho variaient considérablement en leur prédisposition aux maladies du champ avec les résultats moyens de sévérité variant entre 2.5 et 3.6. Huit espèces de fongus étaient observées d\'ehantillons de graine. L\'apparition de ceux-ci variait avec les genres Fusarium et Phoma dominant, suivi par Curvularia. Ghana Journal of Agricultural Science Vol. 40 (2) 2008: pp. 119-12