Utilisation des extraits de plantes contre les maladies de post-récolte des fruits

Currently, the agricultural sector has become an intensive production system, which poses many environmental and health problems and led to the development of  pathogens resistant strains to  chemical molecules used. To reduce the risk of pesticides secondary effects, there is the emergence of alterntaive control methods. These techniques meet several constraints in the orchard for example: humidity, excessive temperatures and ultra violet radiations. Therefore the use of biopesticides in storage conditions can be an effective alternative to fight against postharvest fruit diseases. In Morocco, problems with fruit decays in storage conditions are a major constraint for the development of fruit sectors such as the citrus fruit sector which is threatened by Penicillium rots (Penicillium italicum and  P. digitatum) and the apple sector threatened by Penicillium and Botrytis rots. This situation encourages citrus growers to intensively use synthetic pesticides (benzimidazole, imazalil, and thiabendazole). This review aims to evaluate the antifungal potential of pesticidal plants as an alternative control strategy to the use of synthetic pesticides and the possibility of using them in combination with other eco-friendly control methods. It shows that pesticide-based plants are a promising alternative. Indeed, various species of pesticidal plants can be used as plant extracts for the control of post-harvest fruit diseases. Keywords: Penicillium italicum, Penicillium digitatum, Botrytis, Plant extracts, post-harvest, fruitsActuellement, le secteur agricole est devenu un système de production intensif. Cette situation a posé de nombreux problèmes environnementaux et de santé humaine et a conduit au développement de la résistance des agents pathogènes aux molècules chimiques utilisés. Parmi les mesures envisagées pour atténuer les effets seconaidres des pesticides, il y avait l’émergence des méthodes de lutte alternatives. Ces techniques rencontrent plusieurs contraintes dans le verger par exemple: l’humidité, les températures excessives, et les rayons Ultra Violets. De ce fait, l’utilisation des Biopesticides dans les conditions de stockage peut s’avérer une alternative efficace pour lutter contre les maladies des fruits. Au Maroc, les problèmes à pourritures dans les conditions de stockage présentent une contrainte majeur pour le développement des secteurs des fruits tel que le secteur des agrumes qui est menacé par les pourritures à Penicillium (Penicillium italicum et Penicillium digitatum) et le secteur des pommes qui lui aussi menacé par les pourritures à Penicillium et Botrytis.  Cette situation incite les les agriculteurs à l’utilisation intensive des  pesticides de synthèse (benzimidazole, l’imazalil et thiabendazole….). Cette article de synthèse a pour objectif d’évaluer le potentiel antifongique des plantes comme alternative à l’usage des pesticides de synthèse afin de lutter contre des  maladies post-récolte des fruits ainsi qu’à l’évaluation des combinaison des extraits de palntes avec d’autres méthodes respectueuse de l’environnement. Il ressort que les plantes se présentent comme une alternative prometteuse. En effet, diverses espèces de plantes peuvent être utilisées comme extraits de plantes pour le contrôle des maladies post-récolte des fruits. Mots clés: Penicillium italicum, Penicillium digitatum, Botrytis, Extraits de plantes, post-récolte, fruit

In Vitro and In Vivo Antifungal Activities of Nine Commercial Essential Oils against Brown Rot in Apples

International audienceThis article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BYAfter harvest, numerous plant pathogenic fungi can infect fresh fruits during transit and storage. Although synthetic fungicides are often used to manage postharvest fruit diseases, their application may lead to problems such as the development of fungicide resistance and residueson fruits. In the present study, the antifungal potential of nine commercial essential oils (EOs) extracted from Eucalyptus radiata ssp. radiata, Mentha pulegium, Rosmarinus officinalis, Origanum compactum, Lavandula angustifolia, Syzygium aromaticum, Thymus vulgaris, Citrus aurantium, and Citrus sinensis were tested against the apple brown rot fungi Monilinia laxa and Monilinia fructigena at different concentrations in vitro (against mycelial growth and spore germination) and in vivo (on detached apple fruit and in semi-commercial postharvest conditions). In addition, fruit quality parameters were evaluated and the composition of the EOs was characterized by Fourier transform infrared (FT-IR) spectroscopy. In vitro results showed significant antifungal activity of all tested EOs on both fungal species. EOs from S. aromaticum were the most effective, whereby inhibition percentages ranged from 64.0 to 94.7% against M. laxa and from 63.9 to 94.4% against M. fructigena for the concentrations 12.5 and 100 L/mL, respectively, with an EC50 of 6.74 L/mL for M. laxa and 10.1 L/mL for M. fructigena. The higher concentrations tested of S. aromaticum, T. vulgaris, C. aurantium, and C. sinensis EOs significantly reduced spore germination, brown rot incidence, and lesion diameter. Evaluation of the treatments during storage for 20 days at 4 C on apple fruit quality parameters demonstrated the preservation of the fruit quality characteristics studied (weight loss, total soluble solids, titratable acidity, firmness, and maturity index). FT-IR spectra obtained from all tested EO samples presented characteristic peaks and a high diversity of functional groups such as O–H groups, C–H bonds, and C–C stretching. The EOs examined here may have the potential for controlling postharvest fungal diseases of fruit such as brown rot.

Combination of Sodium Bicarbonate (SBC) with Bacterial Antagonists for the Control of Brown Rot Disease of Fruit

Simultaneous treatment with antagonistic bacteria Bacillus amylolquefaciens (SF14), Alcaligenes faecalis (ACBC1), and the food additive sodium bicarbonate (SBC) to control post-harvest brown rot disease caused by Monilinia fructigena, and their effect on the post-harvest quality of nectarines were evaluated. Four concentrations of SBC (0.5, 2, 3.5, and 5%) were tested. Results showed that bacterial antagonists displayed remarkable compatibility with different concentrations of SBC and that their viability was not affected. The results obtained in vitro and in vivo bioassays showed a strong inhibitory effect of all treatments. The combination of each bacterial antagonist with SBC revealed a significant improvement in their biocontrol efficacies. The inhibition rates of mycelial growth ranged from 60.97 to 100%. These results also indicated that bacterial antagonists (SF14 or ACBC1) used at 1 × 108 CFU/ mL in combination with 2, 3.5, or 5% SBC significantly improved the control of M. fructigina by inhibiting the germination of spores. Interestingly, disease incidence and lesion diameter in fruits treated with SF14, ACBC1 alone, or in combination with SBC were significantly lower than those in the untreated fruits. In vivo results showed a significant reduction in disease severity ranging from 9.27 to 64.83% compared to the untreated control, while maintaining the appearance, firmness, total soluble solids (TSS), and titratable acidity (TA) of fruits. These results suggested that the improved disease control by the two antagonistic bacteria was more likely due to the additional inhibitory effects of SBC on the mycelial growth and spore germination of the pathogenic fungus. Overall, the combination of both bacteria with SBC provided better control of brown rot disease. Therefore, a mixture of different management strategies can effectively control brown rot decay on fruits