Effect of temperature on the growth of Geotrichum candidum and chemical control of sour rot on tomatoes

Geotrichum candidum is an important pathogen causing sour rot in fruit and vegetables. In this study, G. candidum was identified as a pathogen causing postharvest tomato fruit rot for the first time in Greece. The effect of temperatures and incubation period on the mycelial growth and conidia germination of G. candidum was investigated. It was also found that the optimum temperature for the mycelial growth and conidia germination of G. candidum was 25 degrees C, while this pathogen was also very active at temperatures between 15 and 30 degrees C. Incubation at 40 degrees C inhibited mycelial growth and conidial germination of G. candidum. Conidia germinated after an 8-h incubation period with a higher percentage after 16h. In addition to the above studies, the effectiveness of fludioxonil and propiconazole against G. candidum was evaluated. EC50 values of G. candidum isolates for propiconazole ranged from 0.050 to 0.250 mu l/ml, while this fungicide inhibited the growth of the fungus on tomatoes. In contrast, the EC50 values for the effect of fludioxonil were 3.057 to 3.891 mu g/ml, while this fungicide was not effective against G. candidum on tomatoes. Generally, this study showed G. candidum as a new threat for tomatoes in Greece. This pathogen can develop in a wide range of temperatures. Propiconazole seems to be an effective fungicide against G. candidum in tomatoes.

Automated summary

Geotrichum candidum was identified as a pathogen causing postharvest tomato fruit rot for the first time in Greece. The optimal temperature for its growth was found to be 25 degrees C, with activity also observed between 15 and 30 degrees C. Propiconazole showed effectiveness in inhibiting the growth of the fungus on tomatoes.