Colletotrichum gloeosporioides (Penz.) stands out as the primary phytopathogenic fungus within the Colletotrichum genus, causing anthracnose, a primary postharvest disease affecting fruits and vegetables ^{(Mudiyanselage et al. 2019)}. The predominant method for anthracnose management involves chemical fungicides; however, this approach has notable drawbacks, including the development of fungal resistance and concerns related to human health and environmental risks ^{(Bussaman et al. 2012)}. Consequently, there is a growing interest in exploring effective and environmentally friendly alternatives, such as the utilization of plant extract and rhizosphere bacteria ^{(Botanelli et al. 2019}, ^{Banaras et al. 2021}, ^{Sharf et al. 2021)}. In this context, the plant extracts from the noxious weeds coco-grass (Cyperus rotundus L.) and castor bean (Ricinus communis L.) inhibit the growth of fungi belonging to the genera Fusarium, Alternaria, Curvularia, and Colletotrichum ^{(Hernández-Albíter et al. 2007}, ^{Singh et al. 2011}, ^{Luque et al. 2014}, ^{Mudiyanselage et al. 2019)}. As a result, these weed plants emerge valuable alternatives to chemical fungicides or even commercial bacterial-based products, given that plant extracts often exhibit a broad spectrum of antifungal activity due to their diverse array of phytochemicals, reducing the likelihood of fungal resistance ^{(Ashwini and Srividya 2014}, ^{Kim et al. 2014}, ^{Ruiz-Sánchez et al. 2014}, ^{Landero-Valenzuela et al. 2016}, ^{Rashmi et al. 2019}, ^{Banaras et al. 2020}, ^{Javaid et al. 2020)}. However, the assessment of the effectiveness of these plants and bacterial-based products against the same phytopathogenic fungi has been limited. Building on the above, the objective of this study was to evaluate the in vitro antifungal activity of ethanolic extracts from C. rotundus and R. communis against C. gloeosporioides. This evaluation was performed in comparison with the commercial bacterial-Bacillus subtilis (Serenade®) and Streptomyces spp. (Blite Free®), with the intention of gauging the potential of these plant extracts relative to their commercial counterparts.

Leaves of R. communis and C. rotundus were collected from Tecoman, Colima, Mexico, and dehydrated (45-50 °C, two days) in a hot-air oven (Felisa®, Model FE-291A, Mexico), and the commercial products Serenade® (ASO, Bayer, Mexico) and Blite Free® (Altus Biopharm, Mexico) were purchased from a local retailer. The ethanolic extracts were obtained from 50 g of dried leaves of R. communis and C. rotundus plants ^{(Bussaman et al. 2012)}. The WSFT and Tainung Colletotrichum gloeosporioides strains, source from the fungi collection unit at the School of Biology and Agricultural Science, Universidad de Colima. These strains were isolated from Carica papaya L. var. “Maradol”, and cultured in potato dextrose agar medium (PDA, Bioxon®, Mexico) at 25 °C and 75 % relative humidity, for seven days. Culture media with different concentrations (0, 0.125, 0.25, 0.50 and 1.0 %, v/v) of the R. communis (EER) and C. rotundus (EEC) extracts and the commercial bacterial-based products were prepared ^{(Bussaman et al. 2012)}. PDA served as a negative control. The dose-response bioassay involved inoculating 5 μL of the spore solution (1 x 10⁷ conidia. mL^-1) at the centre of the plate. Five replications were made for each treatment. The percentage of inhibition of mycelial growth (% IMG) was calculating using the equation % IMG = [(C - T) / C] x 100, where C represents the mycelium area in the Petri dish of the control group (without extracts and commercial bacteria-based products) and T, the mycelium area in the Petri dish with extract and commercial bacteria-based products ^{(Zamora et al. 2008)}. The % IMG underwent one- and two- factor analysis of variance, each with five levels. Means were compared using Student´s t-test with a Least Significant Difference (LSD) of 0.05. The effective concentration (EC₅₀) was determined by a Probit analysis using the Statistical Analysis System ^{(SAS Institute Inc., 2002)} only for treatments in which more than 50 % of IMG was observed.

In the WSFT strain, the highest mycelial inhibition (52.9 %) (P≤0.046) was observed with 1 % Serenade®, followed by the 0.5 % and 1 % of EER with inhibitions of 49 % and 48.7 % respectively. Regarding the Tainung strain, the most significant inhibition (62.7 %) (P<0.0001) was achieved at 1 % EER, surpassing the mycelial inhibition observed at any Serenade® doses (Table 1). Only the EER and Serenade® induced a 50 % inhibition of mycelial growth in both strains. The EC₅₀ values obtained in the WSFT strain were similar between both products, although the confidence interval was wider with Serenade® (P≤0.0015) (Table 2). Concerning the Tainung strain, the EC₅₀ obtained with the EER was approximately three times greater (1.26 %) compared to Serenade® (0.43 %), the latter representing the lowest EC₅₀ value observed in this study. Accordingly, EER and the commercial product celial growth of WSFT strain, but the Serenade® exhidemonstrated a similar efficacy in inhibiting the my- bited greater inhibition in the Tainung strain.

The greater inhibition (62 %) observed in present research was lower compared to a previous report (73 %) from the essential oil of R. communis ^{(Siqueira-Júnior et al. 2012)}. However, it surpassed the inhibition percentage obtained in C. gloeosporioides (19 %) ^{(Mudiyanselage et al. 2019)}, and Colletotrichum musae (0 %) ^{(Bazie et al. 2014)}, both from methanolic extract of leaves of the same plant species. The differences in inhibition values in these studies may be attributed, in part, to the compounds obtained in each solvent used in the extraction process. The polar index of methanol is higher than those of ethanol, therefore, the latter extracts chemical compounds with slightly higher hydrophobicity compared to compounds extracted using methanol ^{(Abarca-Vargas et al. 2016)}. Concerning C. rotundus, ^{Luque et al. (2014)} reported a mycelial inhibition of C. gloeosporioides of 61 % and 74 % from aqueous extracts of corms and leaves of C. rotundus, respectively. These values are higher than the inhibition obtained (39 %) using an ethanolic extract in this research but lower than those observed with R. communis, which may be attributed to the compounds produced by each plant species, and the compounds extracted in the solvents. On the other hand, ^{Ashwini and Srividya (2014)} reported the inhibition of B. subtilis (57 %) against C. gloeosporioides, which was slightly greater than the 54 % obtained with the Bacillus-based commercial product used in our research, but lower than the 62 % observed with the EER. Likewise, ^{Ruiz-Sánchez et al. (2014)} reported an inhibition range between 63 % and 80 % of some B. subtilis strains against C. gloeosporioides by the in vitro direct confrontation method, and from 13 % to 42 % in the in vitro bacterial filtration assay. The difference in the inhibition values may be due to bioassay performed in each study to evaluate the antifungal activity of Bacillus strains. Besides, the strains A1022 and A1022SC of Streptomyces induced inhibitions of 22 % and 56 %, respectively, in a disk diffusion assay against C. gloeosporioides ^{(Lee et al. 2011)}. These values surpass those observed with Blite Free® in the present study but are lower than those obtained with the EER (62 %) and the EEC (39 %) in the Tainung strain. In conclusion, the analysed weed plant species analysed have the potential as environmentally friendly fungicides against C. gloeosporioides, given their abundant presence in agricultural fields. Future studies are needed to identify the key components responsible for the antifungal activities of the plant extracts.