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.

Formulation of Biofungicides from Cymbopogon citratus and Tithonia diversifolia: Evaluating Its Antimicrobial Activities against Pythium myriotylum, the Causal Agent of Root Rot of Xanthosoma sagittifolium (L.) Schott

Three fungicide formulations, namely M1, M2 and M3, were prepared from sodium bicarbonate, citronella essential oil and sunflower slurry. The stability of M1, M2 and M3 formulations was determined based on pH, temperature, order of incorporation of the inputs and storage time. The most stable formulations were used for antagonistic tests on Pythium myriotylum. The Minimum Inhibitory Concentration (MIC) was used for the greenhouse tests and the mode of action was determined in vitro. The study showed that the order of incorporation of the inputs “Essential Oil-Tween 80-Bicarbonate-Slurry” (EO-T80-B-S) promotes stability. M1 and M2 are stable at 4°C, 25°C, 37°C and 40°C temperatures and have a pH of 7 and 8 respectively. The Minimum Inhibitory Concentration of M1 and M2 is 1% on P. myriotylum. M1 and M2 act on Pythium by membrane lysis, inhibiting proton pumps and inhibiting protein synthesis. The formulations M1 and M2 reduce the incidence of root rot disease in cocoyam plants growth in the greenhouse. M1 and M2 are potential candidates for improvement of cocoyam seedlings production in Cameroon.

Bacterial extracts and bioformulates as a promising control of fruit body rot and root rot in avocado cv. Hass

At least 20-40% of annual losses of avocado crops are caused by pathogenic fungi.The chemical treatments of these diseases are inefficient,cause environmental pollution and are increasingly restricted by international laws.This work aimed to assess the biocontrol capacity of a bacterial extract to protect avocado fruits and plants from pathogen infections.Extracts from the bacterial isolate Serratia sp.ARP5.1 were obtained from liquid fermentations in a biorreactor.A body rot postharvest infection model with Colletotrichum gloeosporioides on fruits was developed.Moreover,packaging conditions were simulated using the bacterial extract and the commercial fungicide prochloraz as a positive control.Additionally,seedlings infections with Phytophthora cinnamomi were performed on two types of avocado(West Indian race and cv.Hass).The Area Under Disease Progress Curve(AUDPC) was recorded using the bacterial extract and a commercial product with fosetyl-aluminium as treatments.The bacterial extract significantly reduced infections by C.gloeosporioides on injured avocado fruits at 31.1 μg mL^-1.Intact fruits were also protected against body rot infections at the same concentration and showed no significant differences with the commercial fungicide.On the other hand,AUDPC in the seedlings was significantly reduced with the extract treatment at 3 μg mL^-1 compared to the control.However,a possible phytotoxicity effect of the extract was evidenced in the seedlings and confirmed by pathogen recovery and tests on Raphanus sativus seedlings.Finally,formulations of the extracts(emulsion and emulsifiable concentrate) were prepared,and bioactive stability was assessed for 8 wk.The emulsion formulates demonstrated very stable bioactivity against P.cinnamomi.The extract and the emulsion formulate showed promising results for the control of avocado pathogens.New bioproducts based on this type of active principles could be developed for the benefit of avocado industry.

Enhancement of <i>Theobroma cacao</i>Seedling Growth and Tolerance to <i>Phytophthora megakarya</i>by Heat-Treated Oyster Shell Powder

The aim of this study was to evaluate the ability of oyster shell powder soil amendment to enhance cocoa seedling growth and induce resistance against Phytophthora megakarya in nurseries. The results showed that heat-treated oyster shells powder at 1% (w/w) soil amendment significantly increased plant height, leaf number, leaf area, dry shoot and root weight more than chemical fungicide and control treatment after twelve weeks of growth. The results showed that heat-treated oyster shell powder raised soil pH significantly and reduced P. megakarya load of the soil suspension by 82%. Assessment of resistance stimulation by leaf inoculation showed the highest level of resistance recorded in plants treated either with heat-treated or non-treated oyster shell powder. Furthermore, total phenolic compounds contents, total soluble proteins contents, polyphenoloxidase, chitinase, peroxidase and β-1,3-glucanases activities increased in both healthy or infected leaves from cacao plants treated with oyster shell powder more than those treated with chemical fungicide. These findings demonstrated that heat-treated oyster shell powder could be used as biofertilizer and biofungicide to improve the quality of cocoa seedling production and protect the plant against P. megakarya.

Situation of Biofungicides Reconnaissance, a Case of Anthracnose Disease of Cowpea

Plant extracts have long been used in commercial agriculture as anti-microbial tools in food safety applications. These offer growers and agrobiologists many unique benefits which include their eco-friendliness. This work reviews the situation of Biofungicides reconnaissance in reference to fungal disease of cowpea. Twenty different pathogens were associated with various fungal diseases of cowpea and, only the species of Colletotrichum was found to have the virulence and propensity of afflicting a 100% infection on a single susceptible cowpea crop. Plant families under the affliction of Colletotrichum were analyzed. The different forms of botanicals so far availed for use as potential biofungicidal were identified. Eighteen plant families were found to represent the entire plants and plant materials agrobiologically screened within a range of thirteen years and found to habour large spectra of species containing substances of biofungicidal potentials. Current position in the use of Botanicals to combat agricultural pests and disease is 7% of the total cowpea disease management options.

In Vitro Hyphal Growth Inhibition of Plant Pathogenic Fungi by Corrigiola Telephiifolia Extracts

The sugar beet root rot and Bayoud disease, respectively caused by Sclerotium rolfsii and Fusarium oxysporum albedinis, are major agricultural problems in Morocco, affecting its economical and social conditions. As of now, no effective control method of these phytopathogens is available. Therefore the search for new efficient and ecologically undamaging fungicides was essential. The present study reports the antifungal activity of five organic extracts of Corrigiola telephiifolia Pourr., a Moroccan medicinal plant, against these fungi using mycelial growth inhibition assays （in vitro）. The extracts concentration varied from 0.01 to 1 mg.mlt. Also, preliminary information on the chemical composition of the extracts is included. The results showed a difference in sensitivity of both fungi toward the plant extracts. The mycelia growth of Sclerotium rolfsii was concentration and time-dependant. It was markedly inhibited by the polar extracts especially at high dose （p〈 0.001）. While Fusarium oxysporum f. sp. albedinis was much less sensitive.