Evaluation of Soybean Entries in the Pan-African Trials for Response to Coniothyrium glycines, the Cause of Red Leaf Blotch (original) (raw)
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The objective of this project was to compile estimates of yield loss in soybean [Glycine max (L.) Merr] to diseases in the top eight soybean-producing countries in 2006. The purpose was to provide information needed by local and world agencies to allocate funds for research and to help scientists focus and coordinate research efforts. Methods used by plant pathologists to estimate yield loss to diseases in these countries included systematic field surveys, cultivar trials, diagnostic clinic records, personal observations, and questionnaires sent to crop consultants and extension staff. The 2006 harvest of soybeans in the top eight soybean-producing countries was reduced an estimated 59.9 million metric tonnes (t) by diseases according to results of the current study. Soybean rust, caused by Phakopsora pachyrhizi, reduced yield in all these countries except Canada in 2006, and the total was more than any other. Next in decreasing order of total yield loss were soybean cyst nematode, brown spot, seedling diseases, anthracnose, and charcoal rot.
Rhizoctonia Aerial Blight of Soybean, its Prevalence and Epidemiology: A Review
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Soybean [Glycine max (L.) Merrill] is high value oilseed crop grown throughout the world as well as in few soybean growing pockets in India. The hot and humid weather conditions during the soybean cropping season favours the attack by various fungal, bacterial and viral diseases, thereby lowering the crop productivity. Rhizoctonia aerial blight or web blight disease, caused by Rhizoctonia solani is considered one of the most economically important disease of soybean in India. It causes yields losses ranging from 35-60% which might reach a devastating level of 80% under favourable environmental conditions. In India, the disease has been reported from most of the soybean growing states of Uttrakhand, Rajasthan, Sikkim, Haryana, Punjab, Uttar Pradesh, Bihar, Madhya Pradesh, Chhattisgarh and Assam. Epidemiological studies prove to be very important in managing the disease as the disease severity highly depends on the weather variables prevailing in the growing season. The present review...
Evaluation of Foliar Diseases for Soybean Entries in the Pan-African Trials in Malawi and Zambia
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Soybean production has expanded worldwide including countries in sub-Saharan Africa. Several national and international agencies and research groups have partnered to improve overall performance of soybean breeding stocks and have introduced new germplasm from Brazil and the United States with the goal of developing new high-yielding cultivars. Part of this effort has been to test improved soybean lines/cultivars accumulated from private and public sources in multilocational trials in sub-Saharan Africa. These trials are known as the Pan-African Soybean Variety Trials, and the entries come from both private and public breeding programs. The objective of this research was to evaluate entries in the trials that include commercial cultivars or advanced experimental lines for the incidence and severity of foliar diseases. All trials were planted in December 2018 with six located in Zambia and one in Malawi. Plants were evaluated during the reproductive growth stages using a visual pretr...
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Soybean [Glycine max (L.) Merrill] is an important crop known to improve population nutritional status and increase soil fertility and its productivity through biological nitrogen fixation. In Côte d'Ivoire, the introduced Bradyrhizobium japonicum used as inoculum had slight compatibility to several soybean varieties compromising their vulgarization. Therefore, the present study was conducted to examine the infectiveness and the effectiveness of indigenous rhizobial isolates on three soybean varieties (Canarana, Doko and Piramana) cultivated in Côte d'Ivoire. The experiment was conducted with potted plant filled with sterilized sand and was statistically laid in Completely Randomized Design (CRD) with sixteen (16) natives rhizobia, one (01) reference strain and uninoculated control (with or without nitrogen) with three replications. The results showed that inoculation significantly improved nodule number, nodule dry weight, plant height and total dry matter of soybean over the negative control treatment. Among the inoculated treatments, five indigenous rhizobia RSC119, RSC324, RSC502, RSC504 and RSC508 significantly (P < 0.05) increased the nodulation and plant growth parameters than B. japonicum (IRAT FA3) with Doko and Piramana. RSC502 produced highest nodule number (64) on Piramama, nodule dry weight was most promoted with RSC504 (321 mg•plant −1) compared to IRAT FA3 strain (95 mg•plant −1) on Doko. The higher effectiveness was recorded with RSC119, RSC504 and RSC502 with 206.73%; 201.79% and 200.
Agronomía Mesoamericana
Introduction. Cercospora leaf blight (CLB) caused by Cercospora kikuchii is an endemic soybean crop disease in Argentina. Objective. To develop and validate a scale to quantify the severity of CLB in leaflets of soybean (Glycine max) for the evaluation of foliar fungicides and cultivar trials. Materials and methods. A diagrammatic scale to assess the severity of CLB on soybean leaflets (Glycine max) was developed. The scale was based on the evaluation of 50 leaflets. The different severity levels of the leaflets were determined according to Weber-Fechner’s stimulus-response law. The proposed scale included severity levels of 1, 4.5, 17.5, 50, 82.2, 95, and 99 %. The validation of the scale was performed by 23 raters (3 experienced and 20 inexperienced) who assessed the severity of CLB on 50 leaflets with and without the use of the scale. Results. The results from the three experienced raters were more precise than those obtained by the inexperienced raters. The scale improved the vi...
Soybean (Glycine max L.) Response to Fungicides in the Absence of Disease Pressure
International Journal of Agronomy, 2013
Field studies were conducted during the 2010 and 2011 growing seasons along the Texas Upper Gulf Coast region to study the effects of fungicides on soybean disease development and to evaluate the response of four soybean cultivars to prothioconazole plus trifloxystrobin and pyraclostrobin. In neither year did any soybean diseases develop enough to be an issue. Only NKS 51-T8 responded to a fungicide treatment in 2010 while HBK 5025 responded in 2011. Prothioconazole plus trifloxystrobin increased NKS 51-T8 yield by 23% in 2010 while in 2011 the yield of HBK 5025 was increased 14% over the unsprayed check. No yield response was noted with pyraclostrobin on any soybean cultivar. Only prothioconazole + trifloxystrobin applied to either NKS 51-T8 or DP5335 in 2010 resulted in a net increase in dollars per hectare over the unsprayed check of the respective cultivar. In 2011, under extremely dry conditions, all fungicides with the exception of prothioconazole + trifloxystrobin applied to HBK 5025 resulted in a net decrease in returns over the unsprayed check.
International Journal of Economic Plants, 2022
Majority of the leaf spot diseases on soybean crop is caused by different pathogenic fungi. Under favourable conditions and severe infection, it may result in heavy defoliation. It decreases the production efficiency of the crop by reducing the surface area available on leaves for photosynthesis. With less photosynthetic activity, the yield may be reduced significantly. Thus, making it a production constraint by reducing the economic viability of the infected soybean crop. Cercospora leaf spot, Target leaf spot, Alternaria leaf spot, Brown Spot, Phyllosticta leaf spot are the major leaf spots caused due to fungus in the soybean crop worldwide. In this review, we are discussing about economic importance, symptomatology, causal organism, disease cycle, epidemiology and integrated management of leaf spots caused due to fungal infection in the soybean crop.
Journal of Plant Breeding and Crop Science, 2018
Groundnut leaf miner (GLM) [Aproaerema modicella (Deventer)] is a serious problem for soybean cultivation in Uganda causing yield losses of up to 100%. The use of soybean [Glycine max (L.) Merr.] cultivars resistant to GLM attack is an important strategy in the integrated pest management program. The aim of this study was to determine the environment × genotype interaction influence on the soybean resistance traits to GLM attack. Eighteen soybean genotypes were evaluated for resistance to GLM attack. The experiment was set up using randomized complete block design replicated three times under natural pest infestation in Budaka (Eastern) and Arua (Northern) districts in Uganda. Data were subjected to analysis of variance, Pearson's phenotypic correlation and cluster analysis. Highly significant (p < 0.001) differences among the genotypes were recorded for all the studied traits, except the number of pupae per plant which was significant (p < 0.05). GLM incidence and severity had significant negative correlations with rainfall and relative humidity. However, there were significant positive correlations between minimum temperature and GLM incidence as well as severity for most of the genotypes. Soybean genotypes VI046160 and VI046167 could be used as parents in breeding for resistance to GLM pest. Areas with high rainfall and humidity would be recommended for soybean production to minimize infestation by GLM.
Journal of Pharmacognosy and Phytochemistry, 2020
Aerial blight (RAB) is an important disease of soybean in the warm and humid regions of the world. This study analyses the impact of the different new generation fungicides and biocontrol agents used for the management of the disease on the qualitative parameters and to test the presence of their residues in the harvested soybean seeds. Results revealed that plots treated with strobilurin fungicides viz., azoxystrobin and pyraclostrobin had enhanced oil and protein content, respectively. Among the bio-agents, Trichoderma harzianum treated plots recorded the highest oil content (20.50%); whereas the protein content was maximum in Pseudomonas fluorescens treated plots (37.77%). All the fungicides, except azoxystrobin (0.0071 ppm) and mycobutanil (0.21 ppm), was found to have their residue below the detection level and were safe for consumptions. Hence, these fungicides are safe from the qualitative and ecological point of view and can be recommended for the management of the Rhizocton...