Spatial distribution of roots, nematode populations and root necrosis in highland banana in Uganda

Nematology ◽  
2004 ◽  
Vol 6 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Imelda Kashaija ◽  
Beverley McIntyre ◽  
Henry Ssali ◽  
Fred Kizito
Keyword(s):  
Spatial Distribution ◽  
Damage Assessment ◽  
Root Biomass ◽  
Management Practices ◽  
Nematode Species ◽  
Horizontal Distribution ◽  
Radopholus Similis ◽  
Root Necrosis ◽  
Root Sampling ◽  
Distribution Of Roots

Abstract Banana root distribution, nematodes, and necrosis were assessed in banana (Musa AAA) monoculture and banana-legume intercrops in Uganda, with the aim of establishing their relationship in order to enhance decision making with regard to management practices and sampling for nematode population and damage assessment. The intercrops had no effect on the vertical or the horizontal distribution of banana roots and nematodes. Approximately 90% of the root biomass was in the upper 0.3 m and none was below 0.7 m. Within 0.5 m of the banana mat, the majority of root mass was in the surface 0.15 m, but outside this radius more were found from 0.15-0.3 m. This spatial distribution suggests that fertiliser applications would be most effectively applied within a 0.5 m radius of the banana mat. Nematode species and root necrosis were uniformly distributed horizontally on the roots; vertical distribution differed among species. Significantly larger populations of Radopholus similis were found in the upper 0.3 m; none was present below 0.5 m. Helicotylenchus multicinctus and Pratylenchus goodeyi were found throughout the rooting profile; H. multicinctus density being high in the upper 0.5 m, while P.goodeyi was generally low throughout. More root necrosis was noted in the upper 0.3 m, coinciding with the greatest population density of R. similis and the greatest amount of root biomass. The spatial distribution of nematodes indicates that root sampling and nematicide application should be concentrated within 0.5 m of the banana mat.

Entomopathogenic nematode (Heterorhabditidae and Steinernematidae) spatial distribution in turfgrass

Parasitology ◽  
1996 ◽  
Vol 113 (5) ◽  
pp. 473-482 ◽  
Author(s):  
J. F. Campbell ◽  
E. Lewis ◽  
F. Yoder ◽  
R. Gaugler
Keyword(s):  
Spatial Distribution ◽  
Vertical Distribution ◽  
Entomopathogenic Nematodes ◽  
Entomopathogenic Nematode ◽  
Soil Surface ◽  
Nematode Species ◽  
Horizontal Distribution ◽  
Steinernema Carpocapsae ◽  
Foraging Strategies ◽  
Temporal And Spatial Distribution

SUMMARYUnderstanding the temporal and spatial distribution of entomopathogenic nematodes is essential for determining the role of these insect parasites in soil communities and ultimately for their use in suppression of pest insect populations. We measured the vertical and horizontal distribution of endemic populations of entomopathogenic nematodes (Steinernema carpocapsae and Heterorhabditis bacteriophord) in turfgrass. Vertical distribution was determined by taking soil cores every 3 h from 05.00 to 23.00 h, over 4 days, and dividing the cores into 8, 1 cm deep sections. Steinernema carpocapsae was recovered primarily near the soil surface: 50% of positive sections were recovered in the thatch or first 1 cm of soil. S. carpocapsae recovery was lower during the middle of the day and none were recovered in the upper section. H. bacteriophora was recovered uniformly throughout the top 8 cm of soil and its vertical distribution did not change over the course of the day. Horizontal distribution was measured as the number of nematodes recovered from cores taken from 12 randomly selected 0·3 × 0·8 m sections from within four 15·3 × 15·3 m plots. Samples were collected biweekly over a 9-month period. H. bacteriophora had a patchier distribution than S. carpocapsae and both nematode species had more patchy distributions then their potential hosts. Our results support the hypothesis that these two species of nematode utilize different foraging strategies; S. carpocapsae primarily a surface adapted ambusher and H. bacteriophora as a cruise forager.

The vertical and horizontal distribution of roots in northern hardwood stands of varying age

2006 ◽  
Vol 36 (2) ◽  
pp. 450-459 ◽  
Author(s):  
Ruth D Yanai ◽  
Byung B Park ◽  
Steven P Hamburg
Keyword(s):  
Root Biomass ◽  
Fine Root ◽  
Forest Type ◽  
Soil Depth ◽  
Horizontal Distribution ◽  
Biomass Density ◽  
Coarse Roots ◽  
Northern Hardwood ◽  
Clear Cutting ◽  
Distribution Of Roots

Coring methods cannot reveal the distribution of roots with depth in rocky soil, and fine roots are typically sampled without regard to the location of trees. We used quantitative soil pits to describe rooting patterns with soil depth and distance to trees in northern hardwood stands. We sited three 0.5 m2 quantitative soil pits in each of three young (19–27 years) and three older (56–69 years) stands developed after clear-cutting. Live roots were divided into diameter classes delimited at 0.5, 1, 2, 5, 10, 20, and 100 mm; dead roots were not distinguished by size. Mean total live-root biomass was 2900 ± 500 g·m–2 in older stands and 1500 ± 400 g·m–2 in young stands. The root mass in the 2–20 mm class was 2.7 times greater in the older stands (p = 0.03); fine-root (<2 mm) biomass was 1.5 times greater (p = 0.12), suggesting that fine-root biomass continues to increase past the age of canopy closure in this forest type. Root biomass density declined with soil depth, with the finest roots (<0.5 mm) declining most steeply; roots were found at low densities well into the C horizon. We analyzed root biomass density as a function of the influence of nearby trees (represented as the sum of basal area divided by the distance from the pit) and found that fine as well as coarse roots reflected this influence. In systems where this is the case, root measurements should be made with attention to patterns of tree distribution.

Spatial Distribution of Mealybugs (Hemiptera: Coccomorpha: Coccoidea) in the Root System of Pruned and Non-pruned Coffea arabica Trees

2019 ◽  
Author(s):  
Flor E Acevedo ◽  
Mauricio Jiménez ◽  
Juan P Pimentel ◽  
Pablo Benavides
Keyword(s):  
Spatial Distribution ◽  
Root Biomass ◽  
Developmental Stages ◽  
Control Strategies ◽  
First Year ◽  
In Planta ◽  
Coffee Tree ◽  
Root Death ◽  
Root Sampling ◽  
Tree Pruning

Abstract Root mealybugs are important pests of coffee in many parts of the world. Despite the importance of these insects very little is known about their biology, ecology, and coffee susceptibility at different developmental stages. This study determined the effects of coffee tree pruning on root biomass, the number and within-plant spatial distribution of root-associated mealybugs, and weed-mealybug associations near coffee root systems. We made destructive root sampling of pruned and non-pruned coffee trees every 3 mo during the first-year post-pruning. In each sampling, we quantified coffee root biomass, and the number and spatial distribution of mealybug genera. Mealybugs feeding on weed roots were sampled every 2 wk for the duration of 10 wk. We identified the mealybug genera Puto Signoret (Hemiptera: Putoidae), Dysmicoccus Ferris (Hemiptera: Pseudococcidae), Ripersiella Tinsley (Hemiptera: Rhizoecidae), Rhizoecus Künckel (Hemiptera: Rhizoecidae), and Geococcus Green (Hemiptera: Pseudococcidae) associated with coffee roots. Species from Puto and Ripersiella were the most abundant representing 91% of the total mealybugs found in non-pruned trees, and 75% of the ones found in pruned trees. Coffee tree pruning reduced root biomass by 60% and mealybug numbers during the first 9 mo post-pruning. Mealybugs associated with a variety of weeds growing near coffee roots increased their number during the first 6 wk after coffee pruning. Our results suggest that coffee tree pruning causes a high percentage of root death, which correlates with a decrease of root-associated mealybugs that probably migrate to weed roots. This study provides basic information for designing mealybug control strategies in pruned coffee trees. Las cochinillas de las raíces son plagas importantes del café en varias partes del mundo. A pesar de la importancia de estos insectos se conoce muy poco sobre su biologia, ecología y sobre la susceptibilidad de plantas de café en diferentes etapas de desarrrollo. Este estudio determinó el efecto de la poda de árboles de café en la biomasa de raíces, el número y la distribución espacial in-planta de cochinillas asociadas a las raíces, y asociaciones de cochinillas con arvenses en el plato de los árboles de café. Se realizaron muestreos destructivos de raíces en árboles de café podados y no podados cada tres meses durante el primer año después de la poda. Las cochinillas alimentándose de raíces de arvenses fueron muestreadas cada dos semanas durante diez semanas. En cada muestreo se cuantificó la biomasa de raíces de café, se identificó el género de cochinillas, su cantidad y su distribución espacial. Se identificaron los géneros de cochinillas Puto Signoret (Hemiptera: Putoidae), Dysmicoccus Ferris (Hemiptera: Pseudoccocidae), Ripersiella Tinsley (Hemiptera: Rhizoecidae), Rhizoecus Künckel (Hemiptera: Rhizoecidae), y Geococcus Green (Hemiptera: Pseudococcidae) asociados a raíces de café. Especies de Puto y Ripersiella fueron las más abundantes representando el 91% del total de cochinillas encontradas en árboles no podados y el 75% de aquellas encontradas en árboles podados. La poda de árboles de café redujo la biomasa de raíces en un 60% y el número de cochinillas durante los primeros nueve meses después de la poda. Las cochinillas asociadas a varias especies de arvenses presentes en los platos de los árboles de café incrementaron su número durante las primeras seis semanas después de la poda de los árboles. Los resultados de este estudio sugieren que la poda de árboles de café causa una alta muerte de raíces, lo cual se correlaciona con una reducción en las cochinillas quienes probablemente migran hacia las raíces de las arvenses. Este estudio proporciona información básica para el diseño de estrategias de control de cochinillas en árboles de café podados.

Spatial Distribution of Roots across Three Dryland Ecosystems and Plant Functional Types

2019 ◽  
Vol 79 (2) ◽  
pp. 159 ◽  
Author(s):  
Jessica G. Swindon ◽  
William K. Lauenroth ◽  
Daniel R. Schlaepfer ◽  
Ingrid C. Burke
Keyword(s):  
Spatial Distribution ◽  
Plant Functional Types ◽  
Functional Types ◽  
Dryland Ecosystems ◽  
Distribution Of Roots

Spatial distribution of roots and cracks in soils cultivated with sunflower

2017 ◽  
Vol 64 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Giovanna Cucci ◽  
Giovanni Lacolla ◽  
Gianraffaele Caranfa
Keyword(s):  
Spatial Distribution ◽  
Distribution Of Roots

Spatial variability of the physical-hydric properties of cohesive soils under rainfed and irrigated sugarcane cultivations

2021 ◽  
Author(s):  
Brivaldo Gomes de Almeida ◽  
Bruno Campos Mantovanelli ◽  
Thiago Rodrigo Schossler ◽  
Fernando José Freire ◽  
Edivan Rodrigues de Souza ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spatial Variability ◽  
Structural Changes ◽  
Management Practices ◽  
Geometric Mean ◽  
Soil Layer ◽  
Multivariate Techniques ◽  
Geostatistical Approach ◽  
Physical Attributes ◽  
Soil Spatial Variability

&lt;p&gt;Geostatistical and multivariate techniques have been widely used to identify and characterize the soil spatial variability, as well as to detect possible relationships between soil properties and management. Besides that, these techniques provide information regarding the spatial and temporal structural changes of soils to support better decision-making processes and management practices. Although the Zona da Mata region is a reference for sugarcane production in the northeast of Brazil, only a few studies have been carried out to clarify the effects of different management on soil physical attributes by using geostatistical and multivariate techniques. Thus, the objectives of this study were: (I) to characterize the spatial distribution of soils physical attributes under rainfed and irrigated sugarcane cultivations; (II) to identify the minimum sampling for the determination of soil physical attributes; (III) to detect the effects of the different management on soil physical attributes based on the principal component analysis (PCA). The study was carried out in the agricultural area of the Carpina Sugarcane Experimental Station of the Federal Rural University of Pernambuco, 7&amp;#186;51&amp;#8217;13&amp;#8221;S, 35&amp;#186;14&amp;#8217;10&amp;#8221;W, characterized by a Typic Hapludult with sandy clay loam soil texture. The investigated plot, cultivated with sugarcane, included a rainfed and an irrigated treatment in which a sprinkler system was installed according to a 12x12m grid. The interval between consecutive watering was fixed in two days, whereas irrigation depth was calculated to replace crop evapotranspiration (ETc) and accounting for the effective precipitation of the period. Daily ETc was estimated based on crop coefficient and reference evapotranspiration (ETo) indirectly obtained through a class A evaporation pan. In both treatments, the soil spatial variability was determined according to a 56x32m grid, on 32 soil samples collected in the 0.0-0.1m soil layer, spaced 7x8m, and georeferenced with a global position system. The soil was physically characterized according to the following attributes: bulk density (BD), soil penetration resistance (SPR), macroporosity (Macro), mesoporosity (Meso), microporosity (Micro), total porosity (TP), saturated hydraulic conductivity (Ksat), gravimetric soil water content (SWCg), geometric mean diameter (GMD) and mean weight diameter (MWD). The results of the descriptive statistics showed that among the studied attributes, Ksat, SPR, and Macro presented higher CV values, equal to 63 and 69%, 35 and 40%, and 32 and 44%, under rainfed and irrigated conditions, respectively. The minimum sampling, adequate to characterize the different soil attributes, resulted in general smaller in the rainfed area, characterized by higher homogeneity. Thus, the GMD, SWCg (both with 2 points ha&lt;sup&gt;-1&lt;/sup&gt;), and SPR (with 6 points ha&lt;sup&gt;-1&lt;/sup&gt;) were identified as the soil physical attributes requiring the lowest sample density; on the other hand, MWD and Ksat, with 14 and 15 points ha&lt;sup&gt;-1&lt;/sup&gt;, respectively, required the highest number of samples. Pearson&amp;#8217;s correlation analysis evidenced that soil BD was the most influential physical attribute in the studied areas, with a significant and inverse effect in most of the investigated attributes. The geostatistical approach associated with the multivariate PCA provided to understand the relationships between the spatial distribution patterns associated with irrigated and rainfed management and soil physical properties.&lt;/p&gt;

scholarly journals DIVERSIDADE E DISTRIBUIÇÃO ESPACIAL DE BROMELIÁCEAS EPIFÍTICAS DO ALTÍSSIMO RIO TIBAGI – PARANÁ – BRASIL

FLORESTA ◽  
2010 ◽  
Vol 40 (1) ◽  
Author(s):  
Annete Bonnet ◽  
Gustavo Ribas Curcio ◽  
Franklin Galvão ◽  
Carina Kozera
Keyword(s):  
Spatial Distribution ◽  
River Estuary ◽  
Horizontal Distribution ◽  
Variable Number ◽  
Climatic Factor ◽  
Atmospheric Humidity ◽  
Floristic Survey ◽  
Microclimatic Conditions ◽  
Definition Of ◽  
Epiphytic Bromeliads

O presente estudo teve como objetivo caracterizar a diversidade e a distribuição espacial das bromeliáceas epifíticas na região do altíssimo rio Tibagi, considerando os fatores geomorfológicos, pedológicos, climáticos e vegetacionais. A avaliação fitossociológica das bromeliáceas foi realizada mediante instalação de parcelas em número variável nas três áreas de estudo. O levantamento florístico foi complementado por observações nas áreas adjacentes às parcelas, respeitando a compartimentação geomorfológica, pedológica e vegetacional. Foram registradas onze espécies de bromeliáceas no total, tendo sido sete delas observadas na área da cabeceira do rio Tibagi, oito no cânion e nove na floresta da foz do rio Bugio. A riqueza foi relacionada, principalmente, com as condições macro e microclimáticas. A umidade fornecida pelas nuvens e chuvas formadas na cuesta do segundo planalto, assim como, em microescala, a umidade atmosférica gerada pelas cachoeiras existentes no cânion e originada da evaporação da água dos Organossolos, é o fator climático fundamental na definição dos padrões encontrados. Considerando a distribuição horizontal das espécies, a diminuição de bromeliáceas da porção mais próxima ao canal para a mais distante está atrelada ao gradiente microclimático, formado pela redução em umidade relativa associada à diminuição em luminosidade. Palavras-chave: Bromeliáceas; distribuição espacial; umidade; rio Tibagi.   Abstract Diversity and spatial distribution of epiphytic bromeliads of the high Tibagi river, Paraná, Brazil. The present study aims to characterize the diversity and the spatial distribution of epiphytic bromeliads on the region of the high Tibagi river, considering geomorphologic, pedologic, climatic and vegetacional factors. The phytossociological evaluation was achieved with installation of variable number of plots in the three study areas. The floristic survey was complemented by observations in adjacent areas, respecting the geomorphologic, pedologic and vegetacional compartimentation. Eleven bromeliad species were found in total, being seven species in headwater of Tibagi river area, eight in canyon area and nine in the forest of the Bugio river estuary. The richness was related, mainly, with the macro and microclimatic conditions. The humidity supplied by clouds and rains formed in the cuesta of the second platean, as will as, in microscale, the atmospheric humidity generated by canyons waterfalls and originated of the Organossolos water, is the fundamental climatic factor in the definition of the found standards. Considering the species horizontal distribution, the bromeliads reduction of the closer portion to the stream to the most distant ones is related to the microclimatic gradient, formed by the decreasing of relative humidity associated with luminosity.Keywords: Bromeliads; spatial distribution; humidity; Tibagi river.

Effects of nematode infection and mulching on the yield of plantain (Musa spp., AAB-group) ratoon crops and plantation longevity in southeastern Nigeria

Nematology ◽  
2005 ◽  
Vol 7 (4) ◽  
pp. 531-541 ◽  
Author(s):  
Annemarie Auwerkerken ◽  
Thomas Dubois ◽  
Bart De Schutter ◽  
Paul Speijer ◽  
Omalara Rotimi ◽  
...  
Keyword(s):  
Nematode Infection ◽  
International Institute ◽  
Radopholus Similis ◽  
Population Densities ◽  
Southeastern Nigeria ◽  
Musa Spp ◽  
Root Necrosis ◽  
Meloidogyne Spp ◽  
Crop Cycle ◽  
Plant Crop

AbstractThe effects of nematode infection and mulching on plantain cv. Agbagba (Musa spp., AAB-group, false horn) yield and plantation longevity were examined in a field experiment at the High Rainfall Station of the International Institute of Tropical Agriculture (IITA) at Onne in southeastern Nigeria. The 2nd, 3rd and 4th crop cycles (1st, 2nd and 3rd ratoon, respectively) following the plant crop cycle (mother crop) were examined in nematode inoculated or non-inoculated and mulched or non-mulched treatments. Nematodes (Radopholus similis, Helicotylenchus multicinctus and, to a lesser extent, Helicotylenchus dihystera, Hoplolaimus pararobustus and Meloidogyne spp.) were inoculated at planting of the mother plant, but were also present in relatively high population densities in the non-inoculated treatments at harvest of the 1st crop cycle. Plants inoculated with nematodes failed to reach harvest and neither did plants in the non-inoculated non-mulched treatments in any ratoon. Only non-inoculated mulched plants reached harvest, producing 0.85, 1.22 and 0.2 Mg ha−1, respectively in the 1st, 2nd and 3rd ratoon, taking toppled, broken and dead plants into consideration. Mulched plants were larger, had more suckers, survived longer and had healthier root systems compared with non-mulched plants. Damage to roots was greater in the inoculated plants compared with the non-inoculated plants for the 1st and 2nd ratoons but not for the 3rd ratoon. Radopholus similis was most strongly associated with root damage (percentage root necrosis and dead roots), although H. multicinctus population densities were also positively correlated with percentage root necrosis. At flowering of the 1st ratoon, 71% of the inoculated non-mulched plants were dead compared with only 1% of the non-inoculated mulched plants. Helicotylenchus multicinctus remained the most abundant nematode throughout the experiment. Together with R. similis, it comprised over 95% of the plant-parasitic nematode population.

Spatial and temporal population patterns of Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae) parasitoids (Hymenoptera: Aphelinidae and Encyrtidae) caught on yellow sticky traps in citrus

1986 ◽  
Vol 76 (2) ◽  
pp. 265-274 ◽  
Author(s):  
M. J. Samways
Keyword(s):  
Spatial Distribution ◽  
Management Practices ◽  
Host Density ◽  
Population Level ◽  
Sticky Trap ◽  
Aonidiella Aurantii ◽  
Final Population ◽  
Parasitoid Population ◽  
Yellow Sticky Trap ◽  
Seasonal Population

AbstractParasitoids of Aonidiella aurantii (Maskell) on citrus in South Africa were monitored using two types of yellow sticky trap. One of these traps was highly efficient, being fluorescent with peak reflectance at about 530 nm. Aphytis spp. populations were low before February and high thereafter. Citrus surrounded by natural bush was an isolated reservoir of high host and parasitoid population levels. Aphytis spatial distribution within the orchard was extremely patchy, with over 100-fold differences in population levels over a distance of a few metres. This patchiness mirrored that of its host. This contagious spatial pattern was maintained despite 1000-fold seasonal changes in population levels. These temporal changes were characteristic and general throughout an orchard, and independent of patchiness. Initial Aphytis population levels did not dictate the final population level at the end of the season. Comperiella bifasciata Howard and its hyperparasitoid Marietta javensis (Howard) also showed clear seasonal population trends, but not of the same magnitude as those of Aphytis. There was no statistically significant correlation between the spatial distribution of one parasitoid with that of another, even between C. bifasciata and M. javensis. The patchiness of these two species was not correlated with overall host density. Aphytis and C. bifasciata were partially mutually exclusive. Aphytis was by far the most economically important of the parasitoids. Pest management practices, therefore, should aim at conserving the pool of Aphytis within the orchard as far as practicable.

Nematodes associated with East African Highland cooking bananas and cv. Pisang Awak (Musa spp.) in Central Uganda

Nematology ◽  
2001 ◽  
Vol 3 (6) ◽  
pp. 535-541 ◽  
Author(s):  
Dirk De Waele ◽  
Paul Speijer
Keyword(s):  
Nematode Population ◽  
Frequency Of Occurrence ◽  
Root Damage ◽  
Radopholus Similis ◽  
East African ◽  
Population Densities ◽  
Musa Spp ◽  
Root Necrosis ◽  
Root Death ◽  
Pratylenchus Goodeyi

AbstractA survey was conducted at 17 sites in Central Uganda. Suckers were detached from East African Highland cooking bananas (Musa spp., AAA-group) and the cultivar Pisang Awak (Musa spp., ABB-group), and assessed for nematode population densities and root damage. The frequency of occurrence on both Musa groups was Helicotylenchus multicinctus 88%, Radopholus similis 74% and Pratylenchus goodeyi 50%. Helicotylenchus multicinctus and R. similis densities were higher (P ≤ 0.05) on Highland cooking bananas compared to Pisang Awak, while P. goodeyi densities did not differ significantly between the groups. Helicotylenchus multicinctus and R. similis were observed to be the major pests of Highland cooking bananas in Central Uganda, causing extensive root death. Radopholus similis may be the more important of the two, as it was also highly associated with root necrosis.

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