Gerben Martijn Ten Hoopen

Gerben Martijn Ten Hoopen
Cirad - La recherche agronomique pour le développement | CIRAD · Unité Mixte de Recherche (UMR) Plant Health Institute Montpellier (PHIM)

PhD, Royal Holloway University of London

About

72
Publications
40,567
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1,077
Citations
Additional affiliations
January 2007 - present
Institute of Agricultural Research for Development
Position
  • Senior Researcher
March 2000 - October 2006
CATIE - Centro Agronómico Tropical de Investigación y Enseñanza
Position
  • Research Associate

Publications

Publications (72)
Article
In this paper, we develop an epidemiological model with both environmental (primary infection from the environmental spores reservoir) and direct transmission (secondary infection from an infected host to a susceptible pod). This model simulates the spatiotemporal evolution of cocoa black pod disease caused by Phytophthora megakarya. Since reliable...
Article
Studying spatial and temporal plant disease dynamics helps to understand pathogen dispersal processes and improve disease control recommendations. In this study, three cacao plots devoid of primary inoculum of Phytophthora megakarya (causal agent of cacao black pod rot disease) upon establishment in 2006 were monitored for presence of disease on a...
Article
Full-text available
Penja pepper (Piper nigrum) produced in Cameroon has long been recognized for its exceptional organoleptic quality. The pepper vine is grown using a support tree (Spondias mombin) in Cameroon. A root disease is associated with plant deaths in both plants. The disease symptoms are characterized by collar cracking and gummosis and the disease was ten...
Article
Cacao black pod rot (BPR), caused by Phytophthora megakarya is the most important cacao disease in Cameroon. Biocontrol of this disease using an oil-based formulation of Trichoderma asperellum PR11 provided more consistent and long-lasting protection of cacao pods under laboratory and experimental plot conditions. The objective of this study was to...
Chapter
Full-text available
Régulation des bioagresseurs des cultures dans les systèmes agroforestiers tropicaux, revue des approches bagny beiLhe L., aLLinne c., aveLino J., babin r., brévauLt t., gidoin c., ngo bieng m.a., motisi n., soti v. et ten hooPen g.m. Résumé. Au sein des systèmes agroforestiers tropicaux, de nombreuses interactions se déroulent dans et entre les en...
Chapter
Here we show that spatial tree structure within cacao agroforests influences pest and disease attack intensity of cacao trees. At the plot scale, regular or random spatial organizations of forest trees reduced pest and disease intensity of frosty pod rot in Costa Rica, and mirids in Cameroon. At the individual scale, the number of neighboring cacao...
Article
Full-text available
Perennial export crops such as cocoa (Theobroma cacao L.) and coffee (Coffea spp. L.) contribute indirectly to food security by providing an income that can be used to buy food, household goods and/or supplies for the cultivation of basic food crops. Thus, any perennial crop loss incurred due to the effects of climate change will also negatively im...
Article
Black pod rot, caused by Phytophthora megakarya, is the main cause of cocoa losses in Cameroon. A few studies have focused on describing black pod epidemics in cocoa yet numerous questions remain. Here, an epidemiological model describing the temporal evolution of cocoa black pod, taking into account the development stages of pods, is developed and...
Article
In Cameroon, Phytophthora megakarya is the causal agent of black pod rot of cacao (Theobroma cacao L). Primary inoculum of P. megakarya is located in the soil. With the onset of the rainy season, this primary inoculum is activated and through rain splash cacao pods become infected. From there repeated cycles of pod infection, sporulation, spore dis...
Conference Paper
Full-text available
Cocoa black pod rot, due to several Phytophthora spp., like Phytophthora megakarya, is the most important disease worldwide and the main cocoa disease in Africa, responsible for yield losses up to 50-80% in the absence of control measures. In this paper, we show how the use of Mathematical modelling and analysis can be helpful to better understand...
Conference Paper
Full-text available
Phytophthora megakarya is the most virulent Phytophthora species reported on cacao (Theobroma cacao) in Africa. Previous studies have shown that it disperses mainly through rain splash from soil to pod where infection occurs. However, this mechanism takes place in already infected cacao plantations. How P. megakarya arrives in disease free plantati...
Conference Paper
Full-text available
Many Phytophthora species have a soil borne phase in their natural life cycles even though disease expression often occurs on aerial plant parts. In Cameroon, black pod rot of cacao (Theobroma cacao L.), is caused by P. megakarya. Primary inoculum of P. megakarya is located in the soil and with the onset of the rainy season, through rain splash, ca...
Conference Paper
CIRAD, CATIE, PROMECAFE, CABI, BIOVERSITY Intl, ICRAF e INCAE crearon en 2007 el PCP. El fin del PCP es unir esfuerzos en la búsqueda de recursos para: desarrollar investigaciones y enseñanza (pre y posgrado) sobre agroforestería, incrementar la capacidad de cada institución para desarrollar proyectos agroforestales, y favorecer la comunicación ent...
Article
Full-text available
Phytophthora megakarya (Pmeg) and Phytophthora palmivora (Ppal) are closely related species causing cacao black pod rot. Although Ppal is a cosmopolitan pathogen, cacao is the only known host of economic importance for Pmeg. Pmeg is more virulent on cacao than Ppal. We sequenced and compared the Pmeg and Ppal genomes and identified virulence-relate...
Chapter
In this chapter, we consider some of the “root-infecting” pathogens of Theobroma cacao. Despite sometimes being described as minor pathogens of the crop, they can cause serious losses locally. We have chosen to examine four pathogens-Verticillium dahliae (Verticillium wilt or sudden death), Rigidoporus microporus (white root disease), Rosellinia sp...
Chapter
This chapter discusses the advances in biological control of cacao diseases over the last 15 years. Most attention has been focused on biological control of frosty pod rot (Moniliophthora roreri), witches’ broom (Moniliophthora perniciosa) and black pod disease (Phytophthora spp.). Research on biocontrol of other diseases in the cacao phyllosphere...
Poster
Les pluies sont le principal facteur de déclenchement de la pourriture brune des fruits du cacaoyer, en absence de celles-ci, une humidité relative élevée (>80%) et des basses températures (autour de 20°C) en champ suffiraient à la formation d’eau libre nécessaire à la germination des structures infectieuses de Phytophthora megakarya, l’agent causa...
Poster
Full-text available
L’installation de parcelles cacaoyères en 2006 sur des terrains dépourvus d’auto-inoculum de Phytophthora megakarya, principal agent pathogène du cacaoyer au Cameroun, permet d’étudier les mécanismes d’introduction et d’installation de l’allo-inoculum. Identifier les facteurs qui déterminent l’installation, la répartition et l’évolution de la pourr...
Article
Full-text available
Among the Phytophthora species that cause black pod of cacao, P. megakarya is the most virulent, posing a serious threat to cacao production in Africa. Correct identification of the species causing the black pod and understanding the virulence factors involved are important for developing sustainable disease management strategies. A simple PCR-base...
Conference Paper
Full-text available
Pepper (Piper nigrum) cultivated near the Penja locality in Cameroon, is considered one of the best peppers in the world. Penja pepper (Fig.1) is the first sub-Saharan African product to obtain a Protected Geographical Indication (PGI) due to it’s exceptional aroma and flavor. Its future however, is seriously threatened since the majority of planta...
Article
Full-text available
Knowledge of the diversity and ecology of plant pathogenic fungi in cacao agroforests and surrounding natural ecosystems can inform the development of sustainable management strategies for new cacao disease outbreaks. This study investigated the occurrence of fungi related to the Ceratocystidaceae and their nitidulid beetle vectors in cacao agrofor...
Article
Full-text available
Combining crop plants with other plant species in agro-ecosystems is one way to enhance ecological pest and disease regulation mechanisms. Resource availability and microclimatic variation mechanisms affect processes related to pest and pathogen life cycles. These mechanisms are supported both by empirical research and by epidemiological models, ye...
Article
Full-text available
The chemical control is the widely control method applied in Cameroon for pests and diseases by all the cocoa producers without technical suitable assistance by the State as before 1980'S. However, it is known that farmers have less knowledge on the good pesticides use for the control of a specific pest. The objective of this study was to provide i...
Conference Paper
Full-text available
L’objectif principal de ce travail était d’identifier les contraintes et opportunités à l’adoption des variétés améliorées du maïs et du niébé au Nord Cameroun. A cet effet, une enquête a été réalisée auprès de 160 acteurs intervenant dans l’adoption des variétés améliorées. Les résultats obtenus montrent que le taux d’adoption des variétés amélior...
Article
Cocoa (Theobroma cacao) pod diseases cause tremendous losses, frequently eliminating over 80% of potential yield. Biological control has previously shown promise to supplement cultural control methods practiced by the majority of smallholders. Mixed Clonostachys inocula were most effective against multiple pathogens in Peru, but not in Costa Rica,...
Article
Full-text available
Plantains are among the crops that enhance food security in Cameroon. However, plantain yields remain low because of several constraints of parasites such as Radopholus similis, a nematode that can cause losses up to 75% in fields when no protection measures are taken. In most cases, the sensitivity of local plantain varieties to R. similis is unkn...
Conference Paper
Full-text available
The arrival and subsequent dispersal of Phytophthora megakarya within young cacao plantations, previously free of black pod and containing cacao germplasm that is evaluated for its resistance to P. megakarya, is the subject of an ongoing study in Cameroon. A total of 12 plantations, established in 2006 on lands free of cacao cultivation for at leas...
Conference Paper
Full-text available
La pourriture brune causée par Phytophthora spp. est responsable des pertes de l’ordre de 30% au niveau mondial. Au Cameroun, l’espèce Phytophthora megakarya est la seule responsable de cette maladie et les pertes peuvent atteindre 100% si aucune mesure de contrôle n’est prise. En général, on considère que l’inoculum primaire qui initie l’épidémie...
Conference Paper
Full-text available
Manipulating ant communities to control pests of cocoa has proven to be a promising strategy, especially in Asia. However, concerning African cocoa mirids, the main pests of cocoa in Africa, basic knowledge on mirid-ant relationships is still incomplete. Our study aimed to characterize the spatial relationships between dominant ant species and the...
Conference Paper
Full-text available
Worldwide, crop monocultures have proven to be particularly susceptible to pests and diseases. In Africa, unshaded "pure" cocoa plantations are often highly damaged by mirids and consequently require intensive phytosanitary protection. The aim of this study was to assess the impact of an alternative agronomic practice, a cocoa-fruit intercropping s...
Article
Full-text available
Premise of the study: Phytophthora megakarya is the agent of black pod disease of cacao and is the main pathogen of this crop in Africa. Population genetic studies are required to investigate how this pathogen emerged. To this end, we developed 12 novel polymorphic microsatellite markers for P. megakarya. Methods and results: Microsatellite sequ...
Article
Full-text available
a b s t r a c t Root rot disease caused by Pythium myriotylum is a major threat to cocoyam cultivation in Cameroon. Control methods based on agricultural practices and chemical treatments have limitations. Since biocontrol is an interesting alternative, this study assessed the potential of four Trichoderma asperellum strains to control P. myriotylu...
Article
Full-text available
Cacao trees are affected by diseases that attack either their vegetative parts, their fruits or both. In cacao pod diseases, several factors are involved in disease susceptibility, such as the fruiting cycle, fruit size, age, position on the tree and cacao genotype. To gain a clearer understanding of how these characteristics influence cacao pod di...
Article
Full-text available
The objective of this study was therefore to develop a formulation of conidia of T. asperellum with the aim of improving its efficacy. The formulations developed were oily dispersions. It was a combination of solvents consisting of groundnut oil or palm oil with structural agents and emulsifying-dispersing agents. Emulsification tests were carried...
Article
Full-text available
https://www.agriskmanagementforum.org/content/incorporating-plant-species-diversity-cropping-systems-pest-and-disease-risk-management
Article
Phytoparasitic nematodes of banana and plantain make one of the major constraints to sustainable banana and plantain production. The burrowing nematode, Radopholus similis, common in Cameroon is of particular importance where most smallholder farmers are unaware of this “hidden enemy”. In intensive plantain plantations, nematicides are often used a...
Article
Full-text available
Field trapping experiments were conducted to evaluate the attractiveness of five different pheromone blends as well as the impact of trap design on attractiveness towards cocoa mirids, Sahlbergella singularis Hagl. and Distantiella theobroma (Dist.), in Cameroon. A total of 361 adults of S. singularis (359 males and two females) were caught. The hi...
Article
Frosty pod rot (FPR), caused by Moniliophthora roreri, reduces yields of cocoa (Theobroma cacao) by over 80% within a few years of disease outbreak. Both biological and chemical control approaches are being developed to supplement cultural management. Our objectives were to optimize the agent(s), their formulation and application regime for FPR con...
Article
Full-text available
To aid the development of compatible biocontrol inocula, a prescreening method for the prediction of compatibility of fungal antagonists was developed. Compatibility between 18 Clonostachys isolates with known antagonistic capabilities against Phytophthora palmivora was tested using intra- or interisolate pairings (dual cultures) on water agar plat...
Article
Full-text available
Shade management is commonly considered to be an effective pest management strategy for cocoa mirids, yet shade management recommendations are not based on extensive knowledge of the mirid ecology in traditional cocoa agroforests. The main objectives of the present study were an assessment of the impact of shade on the spatial distribution of mirid...
Conference Paper
Full-text available
Control of Phytophthora megakarya, the causal agent of cocoa black pod in Cameroon is commonly obtained by fungicide spraying of either copper compounds or a mixture of metalaxyl-M with copper compounds. Research on biocontrol of P. megakarya has identified an isolate of Trichoderma asperellum, PR11 as a promising biocontrol agent (BCA) of P. megak...
Conference Paper
Full-text available
Black pod rot of cocoa caused by Phytophthora megakarya causes significant losses in Cameroon. Studying the spatial and temporal disease dynamics of P. megakarya provides useful information on the mechanisms of dispersal and the physiological and biological factors that are important for its spread and ultimately its management. Therefore, we studi...
Conference Paper
Full-text available
An Association mapping study was initiated collaboratively between Cameroon and France in 2005, aiming to identify the genome regions controlling cocoa traits of agronomic interest for cocoa and molecular markers usable for a marker assisted selection programme. This study was conducted on a population composed of 263 cocoa trees planted in a cocoa...
Conference Paper
Full-text available
In Cameroon, cocoa is traditionally grown in thick and multi-strata agroforestry systems. In such highly diversified ecosystems, cocoa production is seriously impacted by insect pests, especially by the cocoa mirid Sahlbergella singularis. Shade regulation is an ordinary management strategy for cocoa mirids, yet very few studies were able to assess...
Article
Full-text available
Coffee wilt disease (CWD) caused by Fusarium xylarioides, considered to be a soil-inhabiting fungus, is endemic in several African countries, affecting commercially important coffee species and causing serious economic losses. Coffee wilt disease development in naturally infected Coffea canephora fields at the Coffee Research Institute in Uganda wa...
Article
Frosty pod rot (FPR), caused by Moniliophthora roreri, and black pod (BP), caused by Phytophthora spp., of cocoa (Theobroma cacao) cause combined pod losses of more than 80% in Panama. Biological control of both diseases appeared promising in Peru and is desired by certiWed organic producers in Panama. We evaluated both local and Peruvian fungal an...
Conference Paper
Full-text available
Moniliophthora roreri, the causal agent of frosty pod rot, infects only meristematic tissue, i.e. cocoa pods actively growing on the tree. Thus, at present, the efficacy of control agents and the resistance of germplasm need to be tested in expensive field trials even at the preliminary stages. The objective of our study was the development of a bi...
Conference Paper
Full-text available
Effectiveness of biological control agents (BCAs) in field trials is often disappointing compared with results from tests carried out in controlled environments. The BCA identification procedures and the lack of ecological considerations on target disease before application have been blamed for these failings. Cocoa pod pH is a physiological proper...
Article
Rosellinia species have been recorded all over the world. Many species occur as saprobes and only a few are well-known root pathogens. Although Rosellinia spp. have been recognized for more than 130 years to cause losses in many economically important crops and trees, the few existing sets of quantitative data have not previously been collated. Our...
Article
This article describes two field trials carried out at La Lola, Costa Rica, to assess control measures against frosty pod rot of cocoa (Theobroma cacao) caused by Moniliophthora (Crinipellis) roreri. In the first, factorial, trial the control agents were applied using motorised mistblowers (MMs) and hydraulic sprayers fitted with a narrow angle con...
Article
Many small (temporary) collections of fungi maintained by plant pathologists during their research receive inadequate attention to ensure stability. Maintaining collections of fungi in pure and viable conditions, minimising physiological and morphological changes is, however, a necessity. The objective of this study was to find preservation techniq...
Article
This paper describes a factorial trial designed to investigate the delivery systems of fungal biological agents (Clonostachys rosea), applied as single strain or as strain mixture, in comparison with copper hydroxide as a chemical standard against Moniliophthora roreri in cocoa. Application techniques compared were motorised mistblowers fitted with...