Effects of Some Plant Extracts, Bioagents, and Organic Compounds on Botrytis and Sclerotinia Molds

Botrytis cinerea and Sclerotinia sclerotiorum are necrotrophic fungi and are closely related pathogenic fungi that infect hundreds of plant species worldwide. In this study, the natural botryticidal/scleroticidal efficacy of some plant extracts, bioagents, and organic compounds known to possess antifungal activity was evaluated. Pathogenicity tests of the fungal molds showed virulence divergence, depending on the isolate and host plant. All B. cinerea isolates, except the BF isolate that infected only broad bean leaves, demonstrated ability to infect detached lettuce and broad bean leaves. Moreover, all Sclerotinia sclerotiorum isolates, except for SSP, demonstrated ability to infect the two plant species, whereas the SSB isolate did not cause any infection in broad bean leaves. The efficacies of Moringa oleifera (Mor), Cinnamomum zeylanicum (Cin), amino acid derivatives (Aad), Trichoderma harzianum (TH), Cactus spp. (Agr), and Bacillus subtilis (BS) were tested either in vitro or in vivo against the highly virulent isolates of the two pathogenic fungi. The efficacy of most potential biofungicides was consistent in vitro as well as in vivo, and the inhibitory efficacy of TH, BS, Cin, Mor, and Aad treatments was significantly high against Botrytis cinerea and Sclerotinia sclerotiorum in vitro and ranged from 62% to 100%, depending on the isolate. In addition, BS, Aad, TH, and Mor treatments had significant inhibitory effects ranging from 53% to 100% against most of the isolates on lettuce leaves. The Agr and Cin treatments exhibited low or no inhibitory effects against many isolates in vivo, and they reduced the mold infection caused by only BCC and SSB isolates. Most of the tested potential biofungicide treatments tended to reduce mold infections, and some of them, such as Cin, exhibited a higher inhibitory effect in vitro than the others. Real-time PCR was conducted for some symptomatic/asymptomatic samples, and the results showed either consistent molecular/symptomatic patterns or latency of B. cinerea. The results confirmed the suitability of the studied natural compounds as effective biofungicides, and they could be the best choice to safely control the most destructive fungal molds.