scholarly journals Seasonal Variation on the Incidence and Severity of Major Folia Diseases of Cassava in Sierra Leone

2021 ◽  
Author(s):  
Alusaine Edward Samura ◽  
Sahr N. Fomba ◽  
Augustine Mansarsy ◽  
Musa D. Saffa ◽  
Dan D. Quee ◽  
...  
Keyword(s):  
Sierra Leone ◽  
Rainy Season ◽  
Bacterial Blight ◽  
Dry Season ◽  
Mosaic Disease ◽  
Brown Spot ◽  
Cassava Mosaic Disease ◽  
Seasonal Prevalence ◽  
Cassava Bacterial Blight ◽  
Dry Seasons

A diagnostic survey was conducted in the rainy and dry seasons from 2014 to 2015 to determine the incidence and severity of major diseases of cassava in Sierra Leone. At least three chiefdoms and five villages per district were targeted. The survey was carried out in fourteen districts of the country with geo references using a GPS. On the spot assessment was conducted in all fields. Prevalence, severity and incidence were calculated. The most dominant diseases included the cassava mosaic disease and the cassava bacterial blight. The prevalence of cassava mosaic disease was high with 69.1% and 61.5% in the rainy season and dry season, respectively. The prevalence of cassava bacterial blight was 100% and 92% in the rainy season and dry season, respectively. Diseases of less importance included white spot and brown spot diseases as well as cassava anthracnose disease. The study provides bases for the deployment of improved varieties and provides information on the seasonal prevalence, incidence and severity of cassava diseases in Sierra Leone.

Combining ability of cassava genotypes for cassava mosaic disease and cassava bacterial blight, yield and its related components in two ecological zones in Ghana

Euphytica ◽  
2013 ◽  
Vol 194 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Elizabeth Yaa Parkes ◽  
Martin Fregene ◽  
Alfred Dixon ◽  
Bright Boakye-Peprah ◽  
Maryke Tine Labuschagne
Keyword(s):  
Combining Ability ◽  
Bacterial Blight ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Cassava Bacterial Blight ◽  
Ecological Zones

scholarly journals The invertebrate colonization during decomposition of Eichhornia azurea kunth in a lateral lake in the mouth zone of Paranapanema River into Jurumirim Reservoir (São Paulo, Brazil)

2002 ◽  
Vol 62 (2) ◽  
pp. 293-310 ◽  
Author(s):  
N. de L. STRIPARI ◽  
R. HENRY
Keyword(s):  
Decomposition Rate ◽  
Rainy Season ◽  
Dry Season ◽  
Material Loss ◽  
Litter Bags ◽  
Eichhornia Azurea ◽  
Mouth Zone ◽  
Dry Seasons ◽  
Invertebrate Colonization

The invertebrate colonization during decomposition of Eichhornia azurea was observed in a lateral lake in the mouth zone of Paranapanema River into Jurumirim Reservoir in two periods of the year. The litter bags method was used for measuring the decomposition rate as well as to evaluate the invertebrates colonization. Forty-two litter bags, measuring 15 × 20 cm in size and 2 mm mesh net, were incubated "in situ". Six litter bags (three for colonization and three for decomposition measurements) were removed after the 1st, 3rd, 7th, 14th, 28th, 56th and 72nd days of incubation. After each day, the material was carefully cleaned for detritus removal and invertebrate sampling. The biological material was fixed with 4% formaline and then sorted and identified. The remaining plant material was dried in an oven (at 60ºC) and weighed. A fast material loss occurred during the first 24 hours and the decomposition rate was higher during the rainy season than in the dry season. A peak on invertebrate density (110 ind.g.DW--1) on the remaining detritus of Eichhornia azurea was recorded in the 56th day of dry season, when the polyphenol concentration of plant detritus was 0.57 UDO.g.DW--1. In the rainy season, higher density was found in the 28th day of incubation, when the polyphenol concentration was 4.36 UDO.g.DW--1. Apparently, the reduction in the polyphenol concentration was followed by an increase in invertebrate densities. The majority of the species observed in the detritus belongs to the collector group that was dominant after the 7th and 14th days in the rainy and dry seasons, respectively.

Field reaction of cassava genotypes to anthracnose, bacterial blight, cassava mosaic disease and their effects on yield

2000 ◽  
Vol 8 (2) ◽  
Author(s):  
C. N. Fokunang ◽  
T. Ikotun ◽  
A. G.O. Dixon ◽  
C. N. Akem
Keyword(s):  
Bacterial Blight ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Field Reaction

Cassava mosaic disease. [Distribution map].

1998 ◽  
Author(s):  
Keyword(s):  
Sierra Leone ◽  
Tamil Nadu ◽  
Andhra Pradesh ◽  
Central African Republic ◽  
Democratic Republic ◽  
Mosaic Disease ◽  
Equatorial Guinea ◽  
Cassava Mosaic Disease ◽  
Distribution Map ◽  
New Distribution

Abstract A new distribution map is provided for Cassava mosaic disease Viruses: Geminiviridae: Begomovirus Hosts: Cassava (Manihot esculenta). Information is given on the geographical distribution in ASIA, India, Andhra Pradesh, Karnataka, Kerala, Tamil Nadu, Sri Lanka, AFRICA, Angola, Benin, Burkina Faso, Burundi, Cameroon, Cape, Verde, Central African Republic, Chad, Congo, Congo Democratic Republic, Cote d'Ivoire, Equatorial Guinea, Ethiopia, Gabon, Ghana, Guinea, Guinea-Bissau, Kenya, Lesotho, Liberia, Madagascar, Malawi, Mauritania, Mauritius, Mozambique, Nigeria, Rwanda, Sao Tome & Principe, Senegal, Seychelles, Sierra Leone, South Africa, Sudan, Tanzania, Togo, Uganda, Zambia, Zimbabwe.

scholarly journals Seasonal morphological variability in an in situ Cyanobacteria monoculture: example from a persistent Cylindrospermopsis bloom in Lake Catemaco, Veracruz, Mexico

2016 ◽  
Vol 75 (s1) ◽  
Author(s):  
Owen Lind ◽  
Laura Dávalos-Lind ◽  
Carlos López ◽  
Martin López ◽  
Juli Dyble Bressie
Keyword(s):  
Rainy Season ◽  
Morphological Variability ◽  
Morphological Diversity ◽  
Dry Season ◽  
Transient Condition ◽  
Dry Seasons ◽  
Trichome Morphology ◽  
Determining Factor

<p>The phrase <em>cyanobacteria bloom</em> implies a transient condition in which one to few species dominates communities. In this paper we describe a condition in which the <em>bloom</em> is of multi-year duration consisting of different morphologies of a single cyanobacteria species. Lake Catemaco, Veracruz, México maintained a year-round massive (10<sup>8</sup> trichomes L<sup>-1</sup>) population of potentially toxin-producing cyanobacteria, <em>Cylindrospermopsis spp.</em> The trichomes are present as straight and coiled morphotypes.  The relative trichome morphology abundance varied with rainy (June – October) and dry seasons (November – May), but total trichome abundance did not vary.  Coiled trichomes and heterocytes (occurring only on coiled trichomes) were significantly more abundant, both absolutely and relatively, during the dry season. Both coiled trichome and heterocyte mean volumes were significantly smaller during the rainy season than during the dry season.  Biovolumes were largest in January when water temperature was 5º C cooler suggesting buoyancy as a morphology-determining factor. However, with a more than three-fold lower TIN concentration during the dry season, we hypothesized that the coiled morphotype became abundant primarily because it formed heterocytes, which the straight morphotype did not. Spatial trichome and heterocyte abundance differences were small among the 15 lake sites (average CV for all dates = 20%). However, there was a pattern of increased heterocyte and coiled trichome abundance from lake inflow, as a nitrogen source, to outflow during the rainy season. The total volume of heterocytes per litre of lake water increased progressively four-fold from a minimum early in the rainy season to a maximum at the end of the dry season. Morphological diversity, as seen in Lake Catemaco, can partially compensate for the lack of species diversity in determination of community structure.</p>

scholarly journals Seasonal morphological variation of the vas deferens of scorpion mud turtle (Kinosternon scorpioides)

2014 ◽  
Vol 14 (3) ◽  
Author(s):  
Diego Carvalho Viana ◽  
Leandro Almeida Rui ◽  
Amilton Cesar dos Santos ◽  
Maria Angélica Miglino ◽  
Antônio Chaves de Assis Neto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rainy Season ◽  
Vas Deferens ◽  
Microscopic Analysis ◽  
Lipid Vesicles ◽  
Dry Season ◽  
Transmission Electron ◽  
Cellular Debris ◽  
Mud Turtle ◽  
Dry Seasons

This study aimed to characterize the morphology of the vas deferens ofKinosteron scorpioides by macroscopic and microscopic analysis. Were used 20 adult male jurarás collected at regular intervals during the year and divided into four experimental groups in the rainy and dry seasons, being processed for light microscopy, scanning electron microscopy and transmission electron microscopy. Morphometry for tubular and luminal diameters and epithelial height were also performed. On rainy season, vas deferens presented pseudostratified epithelium with cylindrical cells, spermatozoids and milky fluid in the lumen, with cytoplasmic organelles and lipid vesicles. On dry season, epithelium was pseudostratified with cuboid cells, with cellular debris and no spermatozoids. There was significant variation (p<0,05) for morphometry of vas deferens, with lower values of tubular and luminal diameters on rainy season, and higher epithelial height on dry season.

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