Soil-borne and Compost-borne Aspergillus Species for Biologically Controlling Post-harvest Diseases of Potatoes Incited by Fusarium sambucinum and Phytophthora erythroseptica

Abstract

Nine isolates of Aspergillus spp., isolated from soil and compost were tested in vitro and in vivo for their antifungal activity against Fusarium sambucinum and Phytophthora erythroseptica, the causal agents of the Fusarium dry rot and pink rot of potato tubers. Tested using the dual culture method, the pathogen growth of F. sambucinum and P. erythroseptica was inhibited by 27 to 68% and 16 to 25% by all Aspergillus species, respectively. The highest inhibitory activity against both pathogens was induced by the isolate CH12 of A. niger. A significant reduction of the mycelial growth of both pathogens tested using the inverse double culture method involves the presence of volatile antifungal metabolites. Their effectiveness was also evaluated as tuber treatment prior to inoculation with the pathogens. The highest effectiveness in reducing Fusarium dry rot severity was recorded on tubers treated with the isolate CH12 of A. niger. This study also revealed that the efficacy of Aspergillus spp. as biocontrol agents may be enhanced by varying the timing of their application. In fact, the lesion diameter of dry and pink rots was reduced by 54-70 and 52% with preventive application, respectively. However, this parameter decreased by 21-48 and 47% when the Aspergillus spp. were applied simultaneously with pathogens, respectively. Similarly, diseases' severity, estimated based on average penetration of F. sambucinum and P. erythroseptica, was reduced by 57-77 and 55% with preventive treatments and by 29-68 and 44% with simultaneous application, respectively. This study reveals that Aspergillus spp., isolated from compost and soil, exhibits an interesting antifungal activity toward F. sambucinum and P. erythroseptica and may represent a potential source of biopesticide. Testing of their culture filtrates, their organic extracts and their toxicity may give additional information on their safe use as biocontrol agents.

Assessment of the Antifungal Activity of Non-pathogenic Potatoassociated Fungi toward Fusarium Species Causing Tuber Dry Rot Disease

“…In accordance, previous Tunisian studies have shown the effectiveness of Aspergillus and Penicillium genera, originally recovered from compost extracts and solarized soils [18,47], in controlling Pythium spp. [48], Fusarium spp., and Phytophthora erythroseptica the causal agents of watery rot, dry rot and pink rot, respectively [20]. Compost-associated Penicillium spp., Aspergillus spp., and Talaromyces assiutensis were also shown able to suppress black scurf and stem canker potato disease caused by R. solani [49].…”

“…Successful biocontrol of potato postharvest diseases, including Fusarium dry rot, was achieved using Pseudomonas spp., Enterobacter spp., Bacillus spp., Trichoderma spp, Aspergillus spp. [2,[15][16][17][18][19][20]. Furthermore, an interesting approach to post-harvest disease control that has gained attention is the use of biocontrol agents (BCAs) naturally associated to healthy plants or tubers.…”

Antifungal Potential of Extracellular Metabolites from Penicillium spp. and Aspergillus spp. Naturally Associated to Potato against Fusarium species Causing Tuber Dry Rot

“…Various Aspergillus species recovered from solarized soils and/or composts (A. niger, A. flavus, A. terreus, A. nidulans) have successfully suppressed potato postharvest diseases such as Pythium leak incited by Pythium ultimum tuber dry rot induced by F. sambucinum and pink rot caused by Phytophthora sp. [29][30][31][32]. Several studies have also pointed out the usefulness of bioactive metabolites from naturally plant-associated fungi.…”

“…and Aspergillus spp. [27,31,32]. It is interesting to seek for new bioactive compounds exhibiting antifungal activities from plant-associated fungi [39,40].…”

Control of Fusarium Dry Rot Incited by Fusarium oxysporum f. sp. tuberosi Using Sargassum vulgare Aqueous and Organic Extracts

“…were found to be active against Fusarium spp [12][13][14][15]. Biondi et al [16] demonstrated the ability of methanol extracts of the cyanobacterium Nostoc strain to suppress the mycelial growth of F. oxysporum, Penicillium expansum, Phytophthora cinnamomi, Rhizoctonia solani, Sclerotinia sclerotiorum, and Verticillium albo-atrum.…”