Influence of Altitudes on Sporangia Size and Aggressiveness of Phytophthoracolocasiae Isolates in Cameroon

A study was carried out in four altitudes in Cameroon to assess the size of the sporangia and the aggressiveness of Phytophthoracolocasiae isolates on taro cultivars. The study was conducted in the West and Littoral regions, which include high, medium and low altitude. Sporangia sizes were measured with the microscope on 50 sporangia collected from each isolate and the cross infectivity of the isolates was assessed on leaf fragments of four cultivars; namely Green Purplish Petiole (GPP), Pink Petiole (PP)

Analyse temporelle des épidemies du mildiou de la pomme de terre au Cameroun

(J. de la Recherche Scientifique de l'Université de Lomé, 1999, 3(2): 89-95

Evaluating Post Harvest Opportunities And Constraints To Utilization And Marketing Of African Leafy Vegetables In Cameroon

A rapid production and market appraisal was undertaken to target important markets, commodities, producers and traders of vegetables (exotic and indigenous) in three regions of Cameroon. For each vegetable, post harvest losses were estimated and gross marketing margins were calculated and then used to estimate daily earnings. The main actors were women of between 17 and 50 years old with an average daily earning of less than 1 000 FCFA (US$1 = 495 FCFA). The typical market woman sold 2.5 different products with a mean daily earning of 525 FCFA per product and a total daily earning of 893 FCFA. By groups, sellers of exotic vegetables, such as tomato and cabbage, earned significantly (p<0.001) more than those of indigenous vegetables. Although earnings from huckleberry were comparable with those from exotic vegetables, its production was still traditional, based on indigenous knowledge or on knowledge borrowed from other staple crops and used little or no external inputs. There were no commercial indigenous vegetable seed producers. The diffusion and effectiveness of the indigenous vegetable seed system depended largely on the quality of the variety to be diffused, kinship relationships, and the existence of a culture for agricultural experimentation. Post harvest systems for all vegetables were rudimentary leading to heavy losses (11% and higher) as most vegetables were sold fresh. No storage facilities were available but opportunities exist in drying vegetables using available low cost solar technology thereby offering a chance to increase the value of the seasonal surplus and earning extra income. Complex and stable trading networks existed for selling vegetables, especially for more commercial crops such as huckleberry. The study indicated that indigenous vegetables can be a viable source of income for rural women and can contribute to poverty alleviation, but post harvest procedures need to be established for the handling and marketing of leafy vegetables

Impact of Fungicide Applications for Late Blight Management on Huckleberry Yields in Cameroon

The influence of late blight infections, caused by Phytophthora infestans, was evaluated on thirteen huckleberry ( Solanum scabrum ) varieties during the 2000 and 2001 cropping seasons in Dschang, Cameroon. A randomised split block design was used. Plants were sprayed four times with Ridomil Plus® (12% metalaxyl + 60% cuprous oxide) at 2.5 kg ha-1 on a 21-day schedule while control plots were not sprayed. Late blight intensity was recorded weekly and fresh shoot yields were evaluated six times at 14-day intervals. Fungicide applications significantly reduced late blight intensity and consequently increased huckleberry yields. Cumulative shoot yields varied with the variety and fungicide treatment, from 54.14 to 238.33 t ha-1. Yield losses due to late blight infection were estimated at up to 46%. Economic analyses indicated that fungicide sprays are necessary for a late blight protection programme in huckleberry. This spray regime based on fungicide application resulted in net profits of US$694 to$ 8,467 ha-1, depending on the variety used and the trial period. The results show that late blight infections if not controlled, decrease huckleberry yields, and consequently net farm incomes. High yielding resistant varieties or foliar applications of Ridomil Plus® may be incorporated in integrated pathogen management schemes against late blight in huckleberries with a view to minimise use of fungicides.L&apos;influence du mildiou, causé par Phytophthora infestans, était évalué sur treize variétés de la morelle noire ( Solanum scabrum ) pendant les saisons culturalles de l&apos;an 2000 et 2001 à Dschang, Cameroun. Les éssais étaient réalisés en split-blocs pris au hazard. Les plantes étaient traitées quatre fois avec Ridomil Plus (12% de métalaxyl + 60% oxyde cuivreux) à 21 jours d&apos;intervalle à la dose de 2.5 kg ha-1. L&apos;intensité du mildiou a été évalué hebdomadairement et les pousses fraiches ont été récoltées six fois à l&apos;intervalle de 14 jours. Des traitements fongicides ont significativement réduit l&apos;intensité du mildiou et par conséquent augmenté le rendement en pousses. Le rendement total en pousses fraiches a été variable. De 54, 14 à 238,33 t ha-1, selon la variété et le traitement fongicide. Des pertes en rendements associées aux attaques du mildiou ont atteint 46%. Des analyses économiques indiquent que quatre traitements au Ridomil plus"sont nécessaires dans un bon programme de protection de la morelle noire contre le mildiou. Ce régime de traitement a poduit des augmentations en revenu net de USS 694 à 8.467 ha-1, selon la variété utilisée et la période d&apos;essai. Des résultats indiquent que le mildiou peut baisser le rendement de la morelle noire et par conséquent le bénéfice net des planteurs de la morelle noire si les actions appropriées ne sont pas menées pour rayer les effets néfastes de cette maladie. En outre, l&apos;utilisation des variétés résistantes ou des traitements foliaires au Ridomil plus" peut etre incorporée dans des programmes de lutte intégrée contre le mildiou de la morelle noire

High efficacy of extracts of Cameroon plants against tomato late blight disease

The classical protection of tomato plants against the late blight disease caused by the fungi Phytophthora infestans involves the use of synthetic fungicides. However, such a practice raises two major issues. First, synthetic fungicides are toxic substances that are a threat to the ecosystem. Second, the efficiency of synthetic fungicides is decreasing due to the development of fungicide resistance by the fungi. In addition, there is growing concern from consumers about food contamination due to heavy reliance on toxic and persistent chemicals in plant protection strategies. Therefore, there is a necessity to evaluate the efficacy of alternative compounds. Biologically active products occur in plants for protection against pests, pathogens and other plants. Such compounds could be valuable as biopesticides for controlling plant diseases because they are biodegradable and selective in their activities. In that context, we conducted laboratory and greenhouse experiments to assess the efficacy of nine extracts of native plants of Cameroon in controlling P. infestans. Sporangial germination was determined after 24 h of incubation on 1.5% water agar medium at 18 °C in the dark. Lesion size, and late blight latency and severity were assessed on 7-8-week-old detached leaflets and whole tomato plants incubated in the greenhouse for 7 days. Our results showed that Cupressus benthamii and Vetiveria zizanioides extracts were the most effective preparations, leading to 23% and 35% inhibition of sporangial germination, respectively, and to 86% and 77% disease reduction. A clear relationship between disease latency and disease severity was established. The identification of C. benthamii and V. zizanioides extracts as potential alternate compounds for late blight control is a major step in the process of replacing harmful pesticides. Using these biopesticides in combination with other established disease management practices could help control late blight in a more sustainable and environmentally friendly way

Relative susceptibility of Musa genotypes to banana bunchy top disease in Cameroon and implication for disease management

Banana bunchy top disease (BBTD) is a serious threat to banana and plantain (Musa spp.) production. BBTD is caused by the Banana bunchy top virus (BBTV, genus Babuvirus) which is spread through infected plant propagules and banana aphid, Pentalonia nigronervosa. A high level of resistance to BBTD in Musa spp. has not been yet discovered, but there is a wide range of susceptibility among Musa genotypes. In this study, performance of 16 Musa genotypes to BBTD infection was studied during 37 months in two replicated field experiments planted in a BBTD-endemic location in the South region of Cameroon. BBTD expression varied among genotypes without any specific patterns related to their genomic composition. In Abang Minko'o, highest BBTD incidence was observed in Cavendish Williams (100%) and in the plantain hybrid variety PITA 23 (91.6%). A larger group of 11 genotypes including 4 plantain landraces, 3 hybrid plantains, 3 hybrid bananas and a Cavendish Grande Nain were susceptible with incidence between 40 and 80%. The disease incidence was least in Gros Michel and Fougamou which after 37 months had less than 20% symptomatic plants. In Kou'ou-si, 60% BBTD incidence was observed on PITA 23 while two plantain landraces (Asung Mbele, Big Essong) and Gros Michel remained uninfected at 37 months after planting. The banana aphid was present on all genotypes; but excepting PITA 23 and Williams in Abang Minko'o and PITA 14 and PITA 23 in Kou'ou-si, the occurrence of infection was not correlated to aphid abundance. BBTD expression on the same genotype planted in different areas reveals that BBTD expression is not only related to the varietal characteristic but also to the epidemiological situation of the area