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.

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.

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.