Field Efficacy of a Biopesticide Based on <i>Tithonia diversifolia</i>against Black Sigatoka Disease of Plantain (<i>Musa</i>spp., AAB)

Black Sigatoka disease (BSD) is a foliar disease caused by Mycosphaerella fijiensis, responsible of reduction of the photosynthetic area of banana plant and yield at harvest since it has an influence on fruit physiology. The control of BSD relies on the use of chemicals which are not affordable for the small holder farmers and increase the cost of production. Moreover, this chemical control is ineffective, negatively impacting the environment and human health, and is at the origin of strain resistance. Tithonia diversifolia is known as rich in many compounds such as mineral elements, defense metabolites, some phytochemicals;and it is increasingly used in agriculture. Recently, the protective effect of Tithonia diversifolia liquid extract against BSD development on plantain vivoplants in the nursery was highlighted. The aim of our study was to evaluate the efficacy of a biopesticide base on Tithonia diversifolia on the BSD development in a plantain field under high disease pressure. The effect of Tithonia diversifolia biopesticide on Mycosphaerella fijiensis mycelial growth in vitro was evaluated. An experimental field at the flowering stage was selected and treated with the biopesticide base on Tithonia diversifolia at three different concentrations: undiluted (100%), diluted at 1/2 (50%) and diluted at 1/4 (25%) for 17 weeks. The disease severity, the number of functional leaves, the youngest spotted leaf (YSL) and the youngest necrotic leaf (YNL) were evaluated in course of time. The biopesticide treatments significantly (P < 0.001) reduce the BSD severity in course of time, but it is more effective for the most diluted concentration (25%). The number of leaves increases in course of time as well as the rank of the YSL and the YNL confirming the efficiency of BSD control. The efficacy of this biopesticide base on Tithonia diversifolia could be a hopeful ecoresponsible solution for the plantain sector in general and in particular for poor small farmers.

Plantain Bananas PIF Seedlings Treatment with Liquid Extracts of <i>Tithonia diversifolia</i>Induces Resistance to Black Sigatoka Disease

Plantain bananas culture encounters the problems of seedlings quantity and quality unavailability. Black Sigatoka Disease (BSD) is one of the main pathological constraints of banana that can severely reduce the photosynthetic leaf area, leading to the losses of production of about 50% in banana plantation. The use of liquid extracts of Tithonia diversifolia could potentially induced the resistance of the PIF seedlings to BSD during the vegetative stages in the nursery. The aim of this work was to evaluate the effect of Tithonia diversifolia liquid extracts against the development of BSD on the PIF plantain bananas seedlings. The explants in the greenhouse and the seedlings in the shade were watered with liquid extracts of T. diversifolia during the process of PIF seedling production in sterile and non-sterile conditions. The treated seedlings show a more effective enhancement of seedlings quality parameters and also induce resistance against BSD. The vegetative stages parameters (the number of shoots, the diameter and the height of shoots, the foliar area, the length and weight roots) were improved in treated seedlings compared to controls ones. The treated seedlings showed maximum protection against BSD of up to 87% compared to controls. They also exhibited an increase in the accumulation of total proteins and total phenolics, as well as the activity of defense-related enzymes (peroxidase, polyphenol oxidase and glucanase). The treatment seems to acts as a vital stimulator and could therefore be a useful tool for small holder farmers favouring an eco-friendly agriculture using fewer synthetic inputs.

Potential Biostimulant Effect of Clam Shells on Growth Promotion of Plantain PIF Seedlings (<i>var</i>. Big Ebanga &Batard) and Relation to Black Sigatoka Disease Susceptibility

Plantain contributes significantly to income generation and food security for millions of people in the world. However, it faces problems of seedlings quantity, quality and availability. The innovation of the “plants issus de fragments de tiges” (PIF) technique could be a solution to these problems for small holders’ farmers. The aim of this research is to evaluate the effect of clam shells through amendment of Batard and Big Ebanga PIF substrate, on the growth promotion of seedlings and their protection against black Sigatoka disease (BSD). Plantain PIF seedlings of the two varieties were grown in a substrate amended with 1% concentration of the clam shells powder in the presence of negative control in the sterile and non-sterile conditions. Agromorphological characteristics, susceptibility level to BSD, total proteins and polyphenols content were assessed. Because of the presence of clam shells in the substrates, explants germinated quickly, generated high number of shoots, grew taller by 32%, with a diameter of pseudo stems of 30%, and area of leaves of 18% compared to control. In addition, the seedlings were less susceptible to BSD by 73% compared to those of controls. The treatment seems to allow the accumulation of larger amounts of total proteins and polyphenols before inoculation and after inoculation that could participate in the growth promotion and the reduction of plant’s susceptibility level. Clam shells treatment acts as a biofertilizer/biopesticide and could be helpful to boost production of plantain seedlings, the use of the by-products of fishing in agriculture and helps alleviate poverty of small holders’ farmers.

Stimulatory Effect of Tithonya diversifolia-by Products on Plantain Banana Vivoplants in Nursery (A Review)

Plantain banana is an important cash crop that serves as stable food for millions of people around the world and contributes to income generation. Indeed, they provide a major staple food crop for millions of people and play an important role in the social fabric of many rural communities. Plantain banana cultivation encounters major problem of seedlings unavailability that are essential for the creation of new plantations, as well as parasitic constraints. Mycosphaerella fijiensis is the main pathogen attack constraints of banana plant responsible of black Sigatoka disease, and viruses, which can severely reduce the photosynthetic leaf area, leading to banana production losses of more than 80% in plantations with soil fertility problems. The repeated use of synthetic input is the origin of contamination to the environment, different pollution sources of plants and human health, as well as resistance to some strains of pathogens and plant fertilization problems over time. Recent works carried out in nursery have shown that vivoplants of plantains treated with biostimulants based on natural products notably Tithonia diversifolia biopromote good growth and less susceptibility to M. fijiensis. Indeed, an increase in agromorphological characteristics, good accumulation of growth and defense biomarkers was also observed. In this context, Tithonia diversifolia is shown to be involved in the stimulatory effect mechanism of growth promotion and defensive reaction of plantain vivoplants against various pathogens and it is suggested to be acting as a vital stimulator. This article reviews the current state of knowledge on plantain banana cultivation constraints and on the potential of Tithonia diversifolia in relation with its different stimulatory effects on plantain vivoplants.

Assessing New Banana Genotypes for Relevant Traits: Implication for Variety Selection

Understanding the performance of new crop genotypes for traits of relevance is important in selecting potential cultivars to satisfy end-users. The objective of this study was to determine the performance of new banana genotypes for bunch mass (BMS) and BMS-related traits, resistance to black Sigatoka and sensory attributes. Eight cooking banana genotypes consisting of six new hybrid genotypes selected from advanced breeding trials and two control cultivars were evaluated in a randomized complete block design for three crop cycles at three locations in Uganda. Genotype, location, crop cycle and their interaction effects were significantly different for most traits assessed. The overall top two genotypes (“9058K-2” and “8099K-16”) combining high BMS, resistance to black Sigatoka and acceptable sensory attributes were identified. These genotypes are suggested as potential commercial cultivars for release to farmers in Uganda and/or other East African countries with similar environmental conditions to those where the genotypes were tested. It should be noted that high BMS/yield and resistance to diseases are not the only factors to consider when selecting banana genotypes that meet end-user needs. A combination of high BMS/yield, acceptable sensory attributes and resistance to diseases essentially influence the selection process of banana cultivars.