Effect of Integrated Management of Anthracnose (Colletotrichum lindemuthianum) on Plant and Seed Health of Common Bean in Hararghe Highlands, Ethiopia
Amin Mohammed, Amare Ayalew, Nigussie Dechassa, Mulugeta Negeri
Bean anthracnose, caused by Colletotricum lindemuthianum (Sacc. & Magn.) is an important disease affecting common bean (Phaseolus vulgaris L.). Information on yield losses and management options addressing both seed and soil-borne inoculum sources of this disease is lacking in Hararghe highlands which produces common bean in large areas. The present study was undertaken to evaluate the effect of integrated management of bean anthracnose through soil solarization and fungicide applications on disease development, seed health and seed yield of common bean variety Mexican-142. Field experiments were conducted at Haramaya University main campus and Hirna Research Sub-Station in 2010 main cropping season. Soil solarization was integrated with mancozeb and carbendazim seed treatments, with foliar sprays of carbendazim at the rate of 0.5 kg/ha at 10 and 20 days intervals. The experiment was arranged in 2 x 3 x 3 split-split plot design with three replications. A total of 18 treatments were evaluated. There was significant difference in the anthracnose incidence, severity, infected pods per plant, infected seeds and AUDPC among treatments. Combined effect of mancozeb seed treatment with carbendazim spray at 10 day intervals and carbendazim seed treatment and carbendazim spray at 10 day intervals have reduced severity by 46.5% and 41%, respectively at Haramaya. Interactions of solarized soil with carbendazim foliar spray frequencies at 10 days interval reduced the number of infected pods per plant by 58% at Haramaya and 38.9% at Hirna. Seed treatments, foliar sprays and soil solarization alone as well as their interactions did not significantly affect pods per plant and seeds per pod at both locations. The combinations of solarized soil + mancozeb seed treatment + carbendazim foliar spray at 10 day intervals produced seed yield of 3.8 t h-1 at Haramaya and 3.6 t h-1 at Hirna over the control. In the results concluded that, the integration of soil solarization, seed treatments and foliar spray were found to be effective in reducing bean anthracnose epidemics and increasing yield. Extensive studies are recommended for detection of seed health and management options to enhance high quality of common bean production in these regions.
Efficacy of Entomopathogenic Fungi against Red Tef Worm, Mentaxya Ignicollis (Walker) (Lepdoptera: Noctuidae)
Tariku Tesfaye, Mulugeta Negeri, Mohammed Dawd
Red tef worm (M. ignicollis) is a serious pest of tef (Eragrostics tef (Zucc.), Trotter: Poaceae) grown on black soils. Hence the present study was conducted to identify the effective isolate and conidial concentration of the entomopathogenic fungi (Beauveria bassiana and Metarhizium anisopliea isolates) and to measure the larval mortality of M. ignicollis caused by the entomopathogenic fungi and, thereby controlling RTW to increase the production of tef on black soils. Laboratory studies were carried out in completely randomized design of with four fungal isolates at four conidial concentrations against 3rd instar larvae of red tef worm. The green house study were carried out in randomized complete block design with the four isolates at the concentration of 1x109 spores/ml. Percent mortality increased from 46.67 to 83.33% and 43.33 to 73.33% when larvae were treated with M. anisopliae isolate, MM and PPRC-2, respectively, whereas, B. bassiana isolates PPRC-56 and PPRC-9609 caused mortality ranging from 43.33 to 66.67% and 43.33 to 50%, respectively when applied at the conidial concentration of 1x106 to 1x109spores/ml under laboratory condition. Percent mortality under greenhouse condition showed that MM (70%) was the most virulent isolate; however, PPRC-2, PPRC-56 and PPRC-9609 caused larval mortality of 60%, 53.33% and 46.67% respectively. It was concluded that all tested isolates can cause infection on 3rd instar larvae of red tef worm and able to cause delayed effect to the next stages after application; however, in both laboratory and greenhouse studies, isolate MM was the most effective at conidial concentration of 1x109 spores/ml. In general, MM (1x109spores/ml) isolate was found to be effective and potency against 3rd instar larvae of red tef worm under laboratory and greenhouse conditions. Therefore, since this agent is safe to the environment and other beneficial organisms and it is recommended to be verified for usage under open and large field conditions for the control of red tef worm.
Effect of Vetiver Grass Headges in Maintaining Soil Fertility and Productivity at Anno Agro Industry Farm, Gobu Sayo District, Oromiya Region, Ethiopia
Abdisa Gesesse, Tesfaye Balemi, P. Natarajan, Yosef Ameha
Inappropriate farming system and utilization of natural resources are among the major causes for the current land degradation in Ethiopia. To control soil erosion cheap, replicable and sustainable conservation measures need to be implemented. The use of vetiver grass (Vetiveria zizanioides L.) makes a better option for soil erosion and sediment control and nutrient trapping in a wide range of environments. This study was undertaken to investigate the effects of using vetiver grass in improving soil fertility and productivity through nutrient trapping. The study was conducted at Anno agro-industry where vetivar grass was being used for soil conservation purpose for more than one and half decade. Sample top soils (0-30 cm) from with and without vetiver grass adjacent area were collected in six replicates and important soil parameters such as bulk density, moisture content, CEC, soil organic matter, total nitrogen, available phosphorous and available potassium were determined. The study also involved growing maize crop for two months in plastic pots filled with soil sample from with and without vetiver to compare their productivity. Plant growth parameters such as days to emergence, plant height, leaf length, leaf numbers per plant, root and shoot dry and fresh weights and root to shoot ratio were used to evaluate the difference in the productivity of with and without vetiver grass soil. Soil bulk density, CEC, Organic Matter, Total Nitrogen, Available Phosphorous, and Potassium contents, were significantly higher for soil with vetiver than for without vetiver grass soil. The results revealed that the use of vetiver grass as a soil conservation practice improved soil fertility and productivity.