The invention relates to the technical field of microorganisms, mainly relating to a hypha extract of a strain of endophyte separated from wild ginseng fibrous roots in the Changbai mountain under artificial culturing conditions and application of the hypha extract in prompting the growth of corns, improving the stress resistance and increasing the yield. The strain is preserved in China general microbiological culture collection center, and the category name of the fungus is Alternaria tenuissima. The invention aims to prompt the growth of the root system of corns, increase the utilization ratio of the fertilizer, improve the drought resistance and increase the yield of corns by the application of related products.