**4.5 Current research on the management of anthracnose disease in mango with botanicals**

Anthracnose an important pre and post-harvest disease of mango infests mango parts such as leaves, twigs, flowers and fruits. The disease can dwindle the productivity of infected mango plants as well as the quality of mango fruits; hence, resulting in economic losses. There is therefore the need to manage mango anthracnose disease in order to enhance the health and productivity of mango plants and also maintain the quality of mango fruits. Several methods such as culture, use of synthetic fungicides, resistant varieties and biological have been employed in the management of mango anthracnose diseases. The use of synthetic fungicides is one of the major methods employed in managing mango anthracnose disease. However, the use of synthetic fungicides is usually accompanied with challenges such as pollution of the

#### *Anthracnose Disease of Mango: Epidemiology, Impact and Management Options DOI: http://dx.doi.org/10.5772/intechopen.105934*

environmental, development of pathogenic resistance, residual toxicity and harmful effects on humans [34, 35]. The excessive and improper use of synthetic fungicides can result in the accumulation of fungicidal residue in plants and plant organs used as food which may pose health risk to consumers. For instance, the residual effects of some synthetic pesticides have been recorded in fruits of melon, guava, orange, peach and mango at levels toxic to human consumption [36]. There is therefore the need to find environmentally friendly alternatives in managing anthracnose disease of mango.

The use of botanical fungicides in plant disease management can help promote sustainable agriculture since botanicals are natural, easily biodegraded into harmless substances; hence do not persist in the environment and plant parts used as food. The antifungal activities of botanicals result from the phytochemical they contain. These phytochemicals which are secondary metabolites produced by plants in nature play an important role in the ability of plant to defend themselves against phytopathogens. Phytochemicals have antimicrobial properties [37]; hence, can prevent or reduce infection when applied on plants or plant parts.

Currently, several studies have documented the use of botanical in the management of anthracnose of mango [38–40]. At the pre-harvest of mango anthracnose disease, studies has showed that aqueous extracts leave of *Eucalyptus camaldulensis* and *Azadirachta indica* inhibited the mycelia growth of *C. gloeosporioides in vitro* and also under field conditions, the foliar application of the extracts reduced the incidence and severity of anthracnose on mango plants [38]. Furthermore, literature has also reported that mango fruits treated by dipping in aqueous extracts of *Ruta chalepensis* at concentration of 50 grams of the powdered plant material in 100 ml of distilled water before storage remarkably reduced the occurrence of anthracnose disease, maintained the quality and marketability of the fruits [41]. Some botanicals in comparison to synthetic fungicides have exhibited an equivalent level of antifungal activity against *Colletotrichum* spp. For instance, studies has showed that essential oil of basil leaves inhibited the mycelia growth of *C. acutatum* that caused anthracnose disease in fruits of mango cat hoc variety, and also significantly reduced the incidence and severity of anthracnose on the mango fruits comparable to those treated with the synthetic fungicide Tolent 50 WP (Prochloraz) [40].

Botanicals can be used for the eco-friendly management of both the pre- and post-harvest anthracnose disease of mango [39]. Their studies reported that the pre-harvest anthracnose disease of mango was effectively controlled by the foliar application of aqueous extracts of *Azadirachta indica, Eucalyptus camaldulensis, Allium sativum, Zingiber ofcinale* and *Calotropis procera,* and at the post-harvest stage, mango fruits sprayed with the botanicals reduced the anthracnose infection of the fruits and improved their quality. Although many botanicals have exhibited some potential to be used in managing anthracnose disease of mango, the main challenge is that most of these findings have not moved beyond the research stage and as such not readily available to mango growers and marketers. To encourage the use of botanical in the management of mango anthracnose disease, there is the need to develop and register botanicals which have exhibited the potential to manage the disease into commercial botanical fungicides products which can easily be assessed by mango growers and marketers.
