Soil nematode population studies of some selected plantation crops and uncultivated coastal thicket

The study was conducted on citrus, plantain and pineapple plantations on the Teaching and Research Farm of the School of Agriculture, University of Cape Coast. The survey also covered undisturbed coastal thicket near the site of the study. The aim of the survey was to identify types and population levels of plant parasitic nematodes in soils of the different plantation crops and to find out whether the populations and nematode species differed from those in soils of undisturbed vegetation. The investigations were carried out from April to July 1993. Nematodes were extracted from 100 ml soil samples by an improvised Baerman’s Tray technique and the mean recorded. Nematode counts were determined from 1ml aliquots repeated tree times. Three genera, namely Rotylenchulus, Meloidogyne and Pratylenchus as endo-parasites, Tylenchus (semi-endoparasitic) and eight ecto-parasitics forms which included Xiphimena, a known virus vector, were identified. Meloidogyne, Pratylenchus, Helicotylenchus and Tylenchus occurred in all the plots studied. Hemicyclophora and Xiphimena were the least genera and occurred in low numbers. Plantain supported the greatest number of genera and also the highest nematode populations. There were positive correlations between crop types, soil pH, soil moisture and nematode numbers. Similarly, significant differences were observed between means of initial nematodes numbers at the beginning and end of the season

Response of tomato cultivars to different inoculum concentrations of root-knot nematode (Meloidogyne incognita, Kafoid & White, 1919)

No Abstract Available Ghana Jnl agric. Sci, Vol.36 2003: 87-9

Survey of the incidence and severity of root-knot and Fusarium wilt diseases in some tomato-growing areas in the Central Region of Ghana

No Abstract Available Ghana Jnl agric. Sci, Vol.36 2003: 79-8

Effect of different landforms with water application on the yield of sweet potatoes (Ipomaea batats)

No Abstract. Journal of the Ghana Science Association Vol. 2 (2) 1999: pp.73-7

Influence of weather and soil factors on the incidence and severity of damage by cassava green mite and performance of a released phytoseiid in Gomoa district of the Central Region of Ghana

The main objective of the study was to investigate how weather and soil factors in Gomoa district of the Central Region of Ghana affected the incidence and severity of damage of the cassava green mite (CGM) and also the performance of a phytoseiid – a biocontrol agent against the green spider mite. The study was carried out on 10 cassava farms along a major from Accra to Cape Coast within the area where a phytoseiid, Typhlodromalus manihoti, had earlier been released. Data collected were on: incidence and severity of cassava green mite and phytoseiid; weather and soil physical and chemical properties. The paired comparison design was employed with the sprayed and unsprayed (presence or absence of phytoseiid) as treatments and sampling sites as replicates. Subplots measured 25 x 15 meters with a minimum of 250 cassava plants. The incidence, severity and population of the cassava green mite were observed to be highest in the dry season or short dry spell in the rainy (wet) season. Rainfall and severe drought acting indirectly on food availability to cassava plant were noted to be important mortality factors of the pest. Available phosphorus and organic matter were observed to hinder development and attack of the cassava green mite. However, soil nitrogen, available phosphorus and organic matter significantly promoted the development of phytoseiids. Temperature on the other hand had detrimental effect on the general development of phytoseiids. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 1 Number 3, July (1999) pp. 11-3

Effect of some land clearing practices on plant parasitic nematode populations in soils of farmed lands in the moist semi-decidous rain forest zone of Ghana

No Abstract. Journal of the Ghana Association Vol. 2 (3) 1999: pp.53-6

Repeatability of leaf disc test for assessing resistance levels of international clone trial selections of phytophthora megakarya and phytophthora palmivora infection in Ghana

Developing efficient and reliable screening tests to assess the level of resistance of a perennial crop such as cocoa to diseases is essential to reduce the length of the breeding cycle. The resistance of cacao (Theobroma cacao L.) leaves to two species of Phytophthora wasinvestigated in 25 genotypes of cacao using the leaf disc test. Repeatability of the tests was estimated by calculating the correlation (r) between resistance scores of clones in different inoculation trials of the leaf disc test. Correlations were generally significant (

Influence of the position of detached cocoa pod inoculated with phytophthora palmivora on the development of lesion number and lesion size

An experiment was conducted at the Cocoa Research Institute of Ghana (CRIG) to determine if there were any interactions between Phytophthora infection at the distal, proximal and mid-region positions of cocoa pods. The number and size of lesions in nine different cocoa clones were counted and measured at the three different positions of the pod. There were significant differences (

Incidence of cassava root rot in the central region of Ghana

A survey of the incidence of Cassava root rot in the Central Region of Ghana was conducted from August to November, 1995. The main objective of the survey was to evaluate the economic importance of cassava root rot diseases in cassava production. All the twelve districts in the region were covered by the survey. From each district twenty cassava farmers were randomly selected out of forty farmers and they were interviewed using a questionnaire. The questionnaire was designed to find out the knowledge of farmers on the cassava root rot. The results indicated that 68.4% of cassava farmers in the region were aware of the occurrence of cassava root rot on their farms while 31.6 had not encountered it. The survey revealed that both soft and dry cassava root rot were well established in the Central Region except in one district, Dunkwa-On-Offin. The average incidence of soft cassava root rot in the various zones studied were: coastal districts (Komenda-Edina-Eguafo-Abrem, Mfantsiman, Awutu-Efutu-Senya and Gomoa) 36%; the penultimate coastal districts (Abura-Asiefu -Kwaman Kese, Ajumako-Enyan-Esiam and Agona Swedru) 30%; mid-region districts (Assin Foso and Asikuma-Odoben-Brakera), 21% and Forest District (Upper Denkyira and Lower Denkyira), 15%. For the dry root rot the incidences by zones at dry root rot were: Coastal District, 47%; the penultimate coastal districts, 18%. Mid-region districts, 13% and Forest Districts 27%. Six fungi were found to be associated with cassava root rot in the Central Region. They were Fusarium sp (white and dark colony types), Cunninghamella sp. Mortierella exigua Linnem, Glioclachum fimbricatum Gilman and Abbott, and Polyporus sulphureus Bull. Ex Fr. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 1 Number 1, July (1998) pp. 40-4

Efficacy of screening methods used in breeding for black pod disease resistance varieties in cocoa

Black pod is an important fungal disease of cocoa ( Theobroma cacao L.) that causes severe yield losses. The disease affects the pods, beans, flower cushions, leaves, stems and roots. The objective of this study was to evaluate the efficacy of resistance screening methods used in breeding black pod disease resistance in cocoa. The resistance of cocoa leaves and pods to Phytophthora palmivora was investigated in twenty five international genotypes of cocoa in five laboratory experiments and a field observation at the Cocoa Research Institute of Ghana. A significant clonal difference for leaf and pod resistance was observed at penetration and post-penetration stages of infection. Correlation between resistance of leaves and pods was positive and significant at both penetration and post-penetration stages of infection. The occurrence of such a characteristic of cocoa leaf suggests the value of use of leaves of cocoa seedlings for the prediction of pod resistance to black pod disease. The reliability of the tests was evaluated by correlating results of the inoculation tests with the level of field infection. These correlations were generally positive and significant, both for detached pod and leaf tests. The high positive correlation between detached leaves and pods and natural Phytophthora pod rot infection in the field showed that detached organs can be used for prediction of resistance in the field. Overall, for the convenience of operations and reliability of results, leaf disc test was the best screening method and was also time saving. Clones SCA 6, T85/799, LAF1, ICS 1 and GU 225V were noted to be promising for breeding against black pod disease. The susceptible clones were MO 20, T79/501, VENC 4-4, PA 120 and MOCORONGO.La gousse noire est une maladie fongique importante du cacao ( Theobroma cacao L.) qui cause des pertes de rendement énormes. La maladie affecte les cabosses, des fèves, des coussins de fleurs, feuilles, les tiges et les racines. L'objectif de cette étude était d'évaluer l'efficacité des méthodes de sélection utilisées dans la résistance aux maladies de gousse noir dans le processus d'amélioration du cacao. La résistance des feuilles et gousses du cacao au Phytophthora palmivora avait fait l'objet d'une investigation sur vingt-cinq génotypes internationaux du cacao dans cinq expériences de laboratoire et dans une observation de champ à l'Institut de Recherche sur le Cacao au Ghana. Une différence clonale significative pour la résistance de la feuille et de la gousse avait été observée aux stades de pénétration et post-pénétration de l'infection. La corrélation entre la résistance des feuilles et les gousses était positive et significative aussi bien au stade de pénétration qu'au stade de post-pénétration au cours de l'infection. L'apparition d'une telle caractéristique de la feuille du cacao suggère la valeur de l'utilisation des feuilles de plantules du cacao dans la prédiction de la résistance de gousse aux maladies de gousse noire. La fiabilité des tests avait été évaluée par la corrélation des résultats des tests d'inoculation avec le degrée d'infection du champ. Ces corrélations étaient généralement positives et significatives, tant pour la gousse détachée que pour les tests de la feuille. La haute corrélation positive entre les feuilles détachées et les gousses, ainsi que l'infection de la pourriture naturelle des gousses par Phytophthora dans le champ avaient montré que les organes détachés peuvent être utilisés pour la prédiction de la résistance au champ. En général, pour la commodité des opérations et la fiabilité des résultats, le test de disque de feuille a été la meilleure méthode de sélection et avait été également économiser du temps. Clones SCA 6, T85/799, LAF1, ICS 1 et GU 225V s'étaient révéles être les clones prometteuses pour l'hybridation contre la maladie de la gousse noire. Les clones sensibles étaient MO 20, T79/501, VENC 4-4, PA 120 et MOCORONGO