Chaetomium species for plant disease control are reported to be antagonize many plant pathogens. It is a new broad spectrum biological fungicide from Chaetomium species which firstly discovered and patented No. 6266, International Code: AO 1 N 25/12, and registered as Ketomium® mycofungicide for plant disease control in Thailand, Laos, Vietnam, Cambodia and China. Chaetoimum biofungicide and biostimulants are applied to implement integrated plant disease control. It showed protective and curative effects in controlling plant disease and promoting plant growth. It has been successfully applied to the infested soils with integrated cultural control for the long-term protection against rice blast (Magnaporte oryzae), durian and black Pepper rot (Piper nigram L.) (Phytophthora palmivora), citrus rot (Phytophthora parasitica) and strawberry rot (Fragaria spp.) caused by Phytophthora cactorum, wilt of tomato (Fusarium oxysporum f. sp. lycopersici), basal rot of corn (Sclerotium rolfsii) and anthracnose (Colletotrichum spp.) etc. Further research is reported on the other bioactive compounds from active strains of Chaetomium spp. We have discovered various new compounds from Ch. globosum, Ch. cupreum, Ch. elatum, Ch. cochliodes, Ch. brasiliense, Ch. lucknowense, Ch. longirostre and Ch. siamense. These new compounds are not only inhibiting human pathogens (anti-malaria, anti-tuberculosis, anti-cancer cell lines and anti-C. albicans etc) but also plant pathogens as well. These active natural products from different strains of Chaetomium spp. are further developed to be biodegradable nanoparticles from active metabolites as a new discovery of scientific investigation which used to induce plant immunity, namely microbial degradable nano-elicitors for inducing immunity through phytoalexin production in plants e.g. inducing tomato to produce alpha-tomaline against Fusarium wilt of tomato, capsidiol against chili anthracnose, sakuranitin and oryzalexin B against rice blast, scopletin and anthrocyaidin against Phytophthora or Pythium rot Durian and scoparone against Phytophthora or Pythium rot of citrus. Chaetomium biofungicide can be applied instead of toxic chemical fungicides to control plant diseases.