Malt quality of 4 barley (Hordeum vulgare L.) grain varieties grown under low severity of net blotch at Holetta, west Shewa, Ethiopia

Four malt barley varieties (Beka, HB 120, HB 52 and Holker) and 3 fungicide (propiconazole) spray intervals (7, 14, 21 day) and no spray control were arranged in a RCBD in 4 replications to assess net blotch (Pyrenophora teres) effect on malt quality. The varieties were grown at Holetta agricultural research center in 2005, on 12 m2 plot. Grain flour starch pasting and malt qualities were analyzed. Mash odour and colour were evaluated qualitatively. Significant differences (P < 0.05) in malt qualities were observed among varieties and also due to spray intervals in hot water extract (HWE, mean range = 76.6 to 79.7%). The varieties had a pasting- time and -temperature (Ti) of 4.7 to 5.0 min and 64.7 to 66.3°C, respectively. Peak, hot paste, cold paste, breakdown and setback  viscosities were ranged 276.5 to 314.9, 176.3 to 218.3, 294.1 to 333.2, 86.3 to 99.6 and 102.4 to 116.4 BU, respectively. The pasting curves indicate no amylo- or -waxy starches with evidence of no damage by sprout- induced a-amylase activity and spray intervals. The varieties Ti matches mashing temperature (64 to 65°C) used in malt barley brewing. Malts from these grain varieties were prepared under controlled conditions. Malt aroma and flavor was similar with industry malt of sugary sweet taste. Thousand-kernel malting weight loss (TKMWL) was 11 to 13% and is in the range for desirably modified barley grain on malting. The varieties had a malt protein 6.4 to 7.4% and free amino nitrogen (FAN) 124.4 to 140.0 mg/100 g malt (db). The diastatic tendency assessed using malted barley flour as sources of enzymes and refined wheat flour starch as a substrate (1:29) showed a reduction in peak viscosities (mean) of the substrate starch paste from 678.0 to 168.0 BU. The varieties did not show consistent quality requirements in all parameters. Beka and HB 120 were better than HB 52 and Holker in HWE and diastatic tendency. The FAN level was high among HB 120, HB 52 and Holker. The findings indicate that net blotch incidence and severity influenced HWE and filtration time.Key words: Diastatic tendency, malt extract, FAN, malt barley qualities, net blotch, propiconazole, starch flour pastin

Sources of stem rust resistance in Ethiopian tetraploid wheat accessions

Stem or black rust of wheat caused by the fungus Puccinia graminis f. sp. tritici Ericks and Henn (Pgt) is an important disease on wheat worldwide. Pgt is an obligate biotroph, heteroceous in its life cycle and heterothallic in mating type. Seedlings of 41 emmer (Triticum dicoccum), 56 durum (T. durum) wheat accessions were testedfor their response to stem rust (Puccinia graminis f. sp. trictici) infection under greenhouse condition at Kulumsa Agricultural Research Center, Ethiopia. The test included screening of accessions and multipatotype testing to postulate sr genes. Vigorous screening of accessions was conducted using ten stem rust races, namely TKM/J,SKM/J, TTM/J, STM/J, TTL/K, TKR/J, TKM/J, TTM/H, SKM/J and JKM/G and, 33 stem rust differential lines. Flor’s gene-for-gene theory was applied to postulate Sr genes in the tested accessions. Eighteen emmer and 6 durum accessions were found to be good sources of resistance to stem rust infection. In addition, the presence of Sr 7b, 8b, 9a, 9b, 10, 14, 24, 27, 28, 29, 30, 31, 32 and Tt-3 + 10 genes was postulated in 16 selected emmer and 5 durum wheat accessions. Hence, efforts to exploit these valuable Sr genes in Ethiopian cultivated tetraploidwheats could be rewarding to get stem rust resistant varieties and boost wheat production

Evaluation of pathogenic isolates in Ethiopia for the control of chocolate spot in Faba bean

Faba bean (Vicia faba L.) is one of the earliest domesticated food legumes in Ethiopia and is now cultivated on large areas in many countries. Production of the crop is, however, constrained by several disease infections including fungal diseases. The objectives of this work was to find out natural prevalence of Bacillus isolates on faba bean leaves in Amhara Regional state of Ethiopia; and to identify potential biocontrol agents for the management of chocolate spot (Botrytis fabae). Thirty eight distinct groups of isolates of Bacillus species out ofa total 110 isolates obtained from 12 districts of north-west Ethiopia were found to occur on faba bean leaves. They differed in morphological and cultural characteristics. Thirty isolates of Bacillus spp. were tested for their effects on Botrytis fabae pathogen by dual culture technique on potato dextrose agar. Sixteen isolates produced 5 mm or higher inhibition zone and out of these isolate 43y and 56y were the most effective having inhibition zone of 8 and 7 mm, respectively. Isolates reduced the growth of the pathogen colony in dual culture by 23- 64%. The highest reduction was caused by isolate 115y (64%), followed by 114-3y (52%) and 29y and 67y (50% each). Isolates of Bacillus were placed on actively growing colonies of B. fabae and were found to cause lysis of B. fabae mycelium. Eleven isolates caused 8 mm or higher lytic area of mycelium. Maximum lysis of mycelium was caused by isolates 111-1y (16.8 mm) and 116y (11.3 mm), and they were confirmed from CABI Global Plant Clinic as Bacillus and not pathogenic to plants and animals. Further evaluation of promising antagonistic isolates by thedetached leaf technique showed that most of them reduced the disease development on leaves. However, the degree of disease reduction varied with cultivar. Isolates 108-2y, 20-2y, 47-2y and 36-1y proved most effective in retarding disease development on two susceptible and one tolerant cultivar and can be further explored for commercial use for management of chocolate spot disease of faba bean

Spatial Distribution of Enset Bacterial Wilt (Xanthomonas campestris Pv. musacearum) and its Association with Biophysical Factors in Southwestern Ethiopia

አህፅሮት የእንሰት አጠውልግ በሽታ በዛንቶሞናስ ካምቴስትሪስ ፓቶቫር ሙሳሴረም በሚባል የባክቴሪያ ተህዋስያን አማካኝነት የሚከሰትና በኢትዮጵያ ውስጥ እንሰትን ከሚያጠቁ በሽታዎች ውስጥ ቀዳሚውን ስፍራ የያዘ አደገኛ በሽታ ነው፡፡ የዚህ ጥናት አላማ በደቡብ ምዕራብ እንሰት አብቃይ አካባቢዎች ላይ የዚህን በሽታ ስርጭትንና በሽታው በአካባቢው በሚለዋወጡ ከሥነ-ሕይዎታዊና ሥነ-አካላዊ ነገሮች ጋር ያለውን ዝምድና ለማጥናት ነው፡፡ ለዚህም በ10 ወረዳዎች ውስጥ በሚገኙ የ120 የእንሰት ማሳዎች ውስጥ የዳሰሳ ጥናት ተካሂዷል፡፡ በበሽታው የተጠቁ የእንሰት መጠን (Incidence) በአማካይ በወረዳዎች መካከል 23.67- 31.92 በመቶ ነው፡፡ እንደዚሁም የበሽታው የጥቃት መጠኑን በተመለከተ (Severity) ከፍተኛ የሆነ ጥቃት (62.50 በመቶ) በሰሜን ቤንች ወረዳ የተመዘገበ ሲሆን በአንድራቻ ወረዳ ዝቅተኛ የጥቃት መጠን (49.58 በመቶ) ተመዝግቧል፡፡ ሎጅስቲክ ሪግሬሽን ሞዴል እንደሚያስረዳው የእንሰት አጠውልግ በሽታ ስርጭቱ ከ25 በመቶ በላይ ሆኖ የመገኘት አጋጣሚው የእንሰት ማሳ የአፈሩ pH ከ5.5 - 7 መሆን፣ የእንሰት ሰብል ብቻ በአንድ ማሳ ውስጥ መትከል፣ በሽታ ተቋቋሚ ያልሆነ የእንሰት ዝርያ፣ ዝርያውን ከሌላ አርሶ አደር ማሳ መጠቀም እና ምንም ዓይነት አረም ማረምና የበሽታ መከላከያ ያልተካሄደበት ማሳ ናቸው፡፡ በሌላ በኩል ደግሞ የበሽታ ጥቃት መጠን ከ55በመቶ በላይ የመሆኑ አጋጣሚ የአየር ፀባይ የሰሜን-ቤንችንና የየኪ ወረዳዎችን የሚመስሉ አካባቢዎች፣ አረም በሚታረምበት ወቅት እንሰትን በገጀራ መቁረጥ፣ ተቋቋሚ ዝርያ ያልሆነ የእንሰት ተክል፣ የእንሰቱ ዕድሜ ከመካከለኛው እስከ ምርት ለመስጠት ያለው ጊዜ፣ የአርሶ አደሩ ለበሽታው ያለው ዝቅተኛ ግንዛቤ ናቸው፡፡ የዚህ ዳሰሳ ጥናት ግኝቶች እንደሚያመለክቱት የእንሰት አጠውልግ በሽታ በከፍተኛ ሁኔታ በደቡብ ምዕራብ ኢትዮጵያ አካባቢዎች ላይ የተሰራጨ ሲሆን የስርጭቱን መጠን ለመቀነስ እንሰትን እንደ አንድ አማራጭ የማሳው አፈሩ pH ከ5.5 እስከ 7 መካከል ውጪ መትከል፣ ከሌላ ሰብል ጋር አቀላቅሎ መትከል፣ በእንሰት ማሳ ውስጥ የምንጠቀምባቸውን የመገልገያ መሳሪያዎችን ማፅዳትና መጠቀም፣ በበሽታ የተጠቃውን ከማሳው ነቅሎ ማውጣትና ማቃጠል፣ የባለሙያ ምክር መጠቀም መቻል እና በአርሶ አደሮች መካከል የእንሰት ዝርያ መለዋወጥ እንዳይኖር  ማድረግ ናቸው፡፡             Abstract Enset (Ensete ventricosum) bacterial wilt (EBW), caused by Xanthomonas campestris pv. musacearum, is one of the highly destructive diseases of enset  in Ethiopia. Field survey was conducted to determine the distribution of EBW and its association with biophysical variables in Southwestern Ethiopia. In the survey, 120 enset fields in 10 major enset growing districts were assessed. The mean disease incidence across districts ranged from 23.67 to 31.92%, and significantly different levels of disease severity were recorded among districts. Thus, among districts, the highest mean disease severity of 62.50% was recorded from Semen-bench, whereas Andiracha district showed the lowest (49.58%) mean severity. Logistic regression analysis indicated that EBW incidence of >25% had high probability of association with enset grown on soils with pH of 5.5-7, sole cropped, susceptible clones, using planting materials obtained from other farmers and enset fields with no weeding and EBW management practices. EBW severity of >55% had high probability of association with growing enset in Semen-bench and Yeki districts, weed management through machete slashing, growing local susceptible enset clones, vegetative to maturity growth stages, and low to medium levels of farmer’s awareness about EBW. Findings of this survey indicate that EBW is widely distributed and could be minimized through growing enset preferably on soils out of pH 5.5-7 ranges, intercropping system, proper weeding, access to disease-free planting material, disinfecting farm tools before using, rouging out and burning of infected plants, accessing of advisory services, and limiting free exchange of planting material among enset growers

\u3ci\u3eAspergillus\u3c/i\u3e and aflatoxin in groundnut (\u3ci\u3eArachis hypogaea\u3c/i\u3e L.) and groundnut cake in Eastern Ethiopia

This study was conducted to assess major Aspergillus species and aflatoxins associated with groundnut seeds and cake in Eastern Ethiopia and evaluate growers’ management practices. A total of 160 groundnut seed samples from farmers’ stores and 50 groundnut cake samples from cafe and restaurants were collected. Fungal isolation was done from groundnut seed samples. Aspergillus flavus was the dominant species followed by Aspergillus parasiticus. Aflatoxin analyses of groundnut seed samples were performed using ultra performance liquid chromatography; 22.5% and 41.3% of samples were positive, with total aflatoxin concentrations of 786 and 3135 ng g−1 from 2013/2014 and 2014/2015 samples, respectively. The level of specific aflatoxin concentration varied between 0.1 and 2526 ng g−1 for B2 and B1, respectively. Among contaminated samples of groundnut cake, 68% exhibited aflatoxin concentration below 20 ng g−1, while as high as 158 ng g−1 aflatoxin B1 was recorded. The study confirms high contamination of groundnut products in East Ethiopia

Potential antagonistic fungal species from Ethiopia for biological control of chocolate spot disease of faba bean

Chocolate spot disease ( Botrytis fabae Sard) is one of most yield limiting constraints of faba bean ( Vicia faba ). There is promise in using biological control agents to control chocolate spot diseases, nevertheless, this strategy has not been fully exploited. The objective of this study was to assess the prevalence of different antagonistic fungi on phyloplane of faba bean in Ethiopia and to evaluate their antagonistic potential against the pathogen. A total of 110 isolates of Trichoderma species were obtained from faba bean leaves from 12 districts, which were grouped into 18 distinct groups differing in colony and other characters. Similarly, 26 distinct isolates belonging to species of Penicillium , Aspergillus , Fusarium and Phioalophora were identified from leaves of faba bean. In vitro and in vivo studies revealed strong antagonistic potential of many isolates. Thirteen isolates of Trichoderma produced 4 mm or more inhibition zone and reduced growth of pathogen colony, when grown in dual culture with it. Antagonistic isolates caused lysis of pathogen mycelium more than 6 mm on agar plates. The antagonists significantly reduced pathogen growth in a range of 24.5 to 0.8 mm. The efficacy of the Trichoderma isolates ranged from 47.6 to 98% and that of the other fungal isolates ranged from 13.1 to 34.5%. On detached leaves, isolates 6-1T, 18-3T and 87T of T. ovalisporum and 52-BT, 108-1T and 108-4T of T. longibrachiatum were found to reduce development of chocolate spot on four genotypes of faba bean. The outcome indicates that biocontrol agents, particularly of species Trichoderma are prevalent on faba bean leaves and can be further explored and developed into effective mycofungicides for management of chocolate spot disease of faba bean.La maladie de t\ue2che du chocolat ( Botrytis fabae Sard) est une des contraintes limitatives du rendement du haricot faba ( Vicia faba ). L\u2019utilisation des agents biologiques de contr\uf4le serait promettant, par ailleurs, cette strat\ue9gie n\u2019a jamais \ue9t\ue9 amplement exploit\ue9e. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer la pr\ue9valence de diff\ue9rents champignons anatagonistiques sur la phylloplane du haricot faba en Ethiopie et d\u2019\ue9valuer leur potentiel antagonistique contre le pathog\ue8ne. Un total de 110 isolats d\u2019esp\ue8ces de Trichoderma \ue9tait obtenu des feuilles du haricot faba dans 12 districts, et group\ue9es en 18 groupes diff\ue9rents en colonie et autres caract\ue8res. Similairement, 26 diff\ue9rents isolats appartenant aux esp\ue8ces de Penicillium , Aspergillus , Fusarium et Phioalophora \ue9taient identifi\ue9es des feuilles de haricot faba. Des \ue9tudes in vitro et in vivo ont r\ue9v\ue9l\ue9 un fort potentiel anatagonistique de beaucoup d\u2019isolats.Treize isolats de Trichoderma ont produit 4 mm ou plus de zones d\u2019inhiition et ont r\ue9duit la croissance de colonies pathog\ue9niques lorsque cultiv\ue9s ensemble. Sur plateaux agar, des isolats anatagonistiques ont caus\ue9 plus de 6 mm de lysis des mycelium pathog\ue9niques. Les anatagonistes ont significativement r\ue9duit de 24.5 \ue0 0.8 mm la croissance des pathog\ue8nes. L\u2019efficacit\ue9 des isoltas de Trichoderma variait entre 47.6 et 98% et celle d\u2019autres isolats fongiques variait entre 13.1 et 34.5%. Sur des feuilles d\ue9tach\ue9es, les isolats 6-1T, 18-3T et 87T de T. ovalisporum et 52-BT, 108-1T et 108-4T de T. longibrachiatum \ue9taient trouv\ue9es susceptibles de r\ue9duire le d\ue9veloppement de la t\ue2che du chocolat sur quatre g\ue9notypes du haricot faba. Le r\ue9sultat indique que des agents biocont\uf4les, particuli\ue8rement des esp\ue8ces Trichoderma sont pr\ue9valants sur des feuilles de haricot faba et peuvent \ueatre examin\ue9s et d\ue9velopp\ue9s en mycofungicides efficaces pour la gestion de la maladie de t\ue2che du chocolat du haricot faba

Genetic fingerprinting and aflatoxin production of \u3ci\u3eAspergillus\u3c/i\u3e section Flavi associated with groundnut in eastern Ethiopia

Background: Aspergillus species cause aflatoxin contamination in groundnut kernels, being a health threat in agricultural products and leading to commodity rejection by domestic and international markets. Presence of Aspergillus flavus and A. parasiticus colonizing groundnut in eastern Ethiopia, as well as presence of aflatoxins have been reported, though in this region, no genetic studies have been done of these species in relation to their aflatoxin production. Results: In this study, 145 Aspergillus isolates obtained from groundnut kernels in eastern Ethiopia were genetically fingerprinted using 23 Insertion/Deletion (InDel) markers within the aflatoxin-biosynthesis gene cluster (ABC), identifying 133 ABC genotypes. Eighty-four isolates were analyzed by Ultra-Performance Liquid Chromatography (UPLC) for in vitro aflatoxin production. Analysis of genetic distances based on the approximately 85 kb-ABC by Neighbor Joining (NJ), 3D-Principal Coordinate Analysis (3D-PCoA), and Structure software, clustered the isolates into three main groups as a gradient in their aflatoxin production. Group I, contained 98% A. flavus, including L- and non-producers of sclerotia (NPS), producers of B1 and B2 aflatoxins, and most of them collected from the lowland-dry Babile area. Group II was a genetic admixture population of A. flavus (NPS) and A. flavus S morphotype, both low producers of aflatoxins. Group III was primarily represented by A. parasiticus and A. flavus S morphotype isolates both producers of B1, B2 and G1, G2 aflatoxins, and originated from the regions of Darolabu and Gursum. The highest in vitro producer of aflatoxin B1 was A. flavus NPS N1436 (77.98 μg/mL), and the highest producer of aflatoxin G1 was A. parasiticus N1348 (50.33 μg/mL), these isolates were from Gursum and Darolabu, respectively. Conclusions: To the best of our knowledge, this is the first study that combined the use of InDel fingerprinting of the ABC and corresponding aflatoxin production capability to describe the genetic diversity of Aspergillus isolates from groundnut in eastern Ethiopia. Three InDel markers, AFLC04, AFLC08 and AFLC19, accounted for the main assignment of individuals to the three Groups; their loci corresponded to aflC (pksA), hypC, and aflW (moxY) genes, respectively. Despite InDels within the ABC being often associated to loss of aflatoxin production, the vast InDel polymorphism observed in the Aspergillus isolates did not completely impaired their aflatoxin production in vitro

Integrated management of Aspergillus species and aflatoxin production in groundnut (Arachis hypogaea L.) through application of farm yard manure and seed treatments with fungicides and Trichoderma species

Groundnut (Arachis hypogaea L.) is an important cash crop in the lowland areas of Ethiopia. However, prevalence of Aspergillus invasions and subsequent aflatoxin contamination compromises the quality of groundnut kernels. This study was conducted to evaluate the effect of farm yard manure (FYM) and seed treatments against Aspergillus species pod colonization and aflatoxin accumulation under field conditions. The inhibitory efficacy of Trichoderma species as biocontrol agents was also assessed. A total of 20 treatment combinations including pre-planting applications of FYM at 0, 2.5, 5, and 7.5 tons/ha and seed treatments with carbendazim at 2 g/kg and mancozeb at 3 g kg-1, and Trichoderma harzianum and Trichoderma viride each at 5 g/kg as well as untreated seed as control were used. Treatments were laid out in a randomized complete block design (RCBD) in three replications. The experiment was conducted in two consecutive seasons (2014 and 2015) at Babile Haramaya University sub-Research Station. The highest pod and seed yields (1901.5 and 1281.5 kg/ha, respectively) were recovered from plots treated with T. harzianum at 5 g/kg seed. A. flavus was abundantly recorded in control plots, which could be responsible for the high aflatoxin B1 (5704.4 µg/kg) and B2 (2219.0 µg/kg) contamination. However, plots treated with T. harzianum at 5 g/kg seed and FYM at 5 tons/ha + T. harzianum at 5 g/kg were free from aflatoxin. Integrations of T. harzianum as biocontrol seed treatment and soil amendment with FYM were effective in the pre-harvest management of Aspergillus spp. and aflatoxins contamination

Effects of planting pattern, relative planting date and intra-row spacing on a haricot bean/maize intercrop

(African Crop Science Journal, 1997 5(1): 15-22

Effects of planting pattern, relative planting date and intra-row spacing on a haricot bean/maize intercrop

Performance of five bean (Phaseolus vulgaris L.) genotypes grown in mixed and row intercropping pattern with maize (Zea mays L.) or sole cropping, were evaluated in the Hararghe highlands of Ethiopia. Under intercropping, bean and maize grain yields were reduced on the average by 67% and 24%, respectively. The effects of five relative planting dates of the two crops and three intra-row spacings on bean performance and maize grain yield in mixed intercropping were also evaluated. Delayed maize planting and simultaneous bean and maize planting improved bean seed yield. With simultaneous planting, bean yield was increased by 48.5%. In contrast, delayed bean planting and a 0.10 m bean intra-row spacing increased maize grain yield and reduced bean seed yield. The productivity of the bean/maize intercrop as determined by Land Equivalent Ratio was superior, in all combinations, compared to sole cropping. A maximum of 28% relative yield advantage was obtained with intercropping.La performance de cinq genotypes de haricot eleves en culture mixte et en rangs avec le mais et en monoculture etaient evaluee sur le plateau d' Haraghe en ethiopie. Les recoltes de haricot et du mais variaient significativement selon le systeme de culture. En culture mixte, la recolte de haricot et du mais etait reduite par 67% et 24% respectivement. Les effets de cinq dates relatives de semis de deux plantes et trois distances entre les rangs sur la performance de haricot et la recolte du mais en culture mixte etaient aussi evalues. Un semis tardif du mais et un semis des haricots et du mais simultane augmentent la recolte de haricot. En utilisant la plantation simultanee, la recolte augmentait de 48.5%. Contrairement, un semis tardif de haricot et un espacement au sein des rangs de 0.10 m avec de haricot augmentent la recolte du mais et diminuent la recolte de haricot. La productivite de la culture mixte haricot/mais determinee par le rapport l'equivalent-terre etait superieure dans toutes les combinaisons. Un avantage en recolte relative de 28% au maximum etait obtenu avec la culture mixte