Tomato (Lycopersicon esculentum Miller) early blight caused by Alternaria solani is one of the most destructive diseases that reduce tomato production worldwide. The effect of organic manure, biofertilizer (N₂-fixer's bacteria) as Azotobacter chroococcum and Azospirillum lipoferum and the bioagents Trichoderma harzianum and Bacillus subtilis in controlling early blight of tomato cultivar 935 was evaluated under greenhouse and field conditions during the two successive growing seasons 2018/2019 and 2019/2020 at Abshway county, Fayoum governorate, Egypt. Adding biofertiizer and spraying tomato plants with bioagents or the fungicide Oxyplus (copper oxychloride) reduced the disease incidence and disease severity better than using the mineral fertilizer and spraying with bioagents or Oxyplus in both greenhouse and field experiments.
T. harzianum + B. subtilis with biofertilizer significantly increased the activities of defense-related enzymes i.e., catalase, polyphenoloxidase, peroxidase and the total content of phenols under greenhouse conditions. As well as, this treatment increased plant height, number of branches, chlorophyll content, plants NPK content, number of fruits/ plant and total yield under the field conditions compared to chemical fertilizer.