Biological control of Fusarium spp. in bell pepper fruit using Gliocladium species

Despite the rising popularity of high quality colored bell peppers, market growth is currently threatened due to internal fruit rot caused mainly by the fungus Fusarium lactis (FLASC), which causes yield losses of 5% with seasonal peaks up to 50%. Although the disease has emerged as a significant threat to bell pepper production, adequate chemical or biological control measures are lacking. Moreover, Belgian pepper production has an overall low impact on the environment with respect to fungicidal use. Therefore, the need for new biocontrol agents (BCA) to tackle internal fruit rot is urgent as bell pepper growers strive to produce low residue fruit. Hence, more than 100 strains of potential antagonistic fungi were screened for mycelial inhibition of FLASC by employment of an adapted dual culture in vitro selection. The main criteria for BCA selection were at least 20% inhibition of mycelial growth after two days of in vitro growth and sporulation quantities exceeding 10(7) spores mL(-1) after one week of growth on potato dextrose medium. After screening, the best candidates were further evaluated in greenhouse trials during three consecutive years. Both screening methods resulted in the selection of two potential isolates of Gliocladium roseum which significantly reduced infections over the three years of field trials. Although these BCAs proved to be effective against internal fruit rot in bell pepper, further screenings should be carried out to investigate safety, environmental risks and ecological characteristics.