Anthracnose Citrus disease has been associated with several symptoms worldwide and it is recently compromising Citrus production in the Mediterranean area. Four species complexes are mainly involved: Colletotrichum boninense, C. acutatum, C. gloeosporioides and C. truncatum. In this study, we investigated the genetic diversity of Colletotrichum spp. in Tunisia associated with wither‐tip of twigs on Citrus. Specific primers ITS4‐CgInt allowed the identification of C. gloeosporioides species complex in all the 54 isolates, sampled from three regions and four Citrus species. Overall, our genotypic analysis using 10 SSR markers showed a moderate diversity level in Tunisian C. gloeosporioides population and highlighted that C. gloeosporioides reproduce mainly clonally. In addition, heterothallic isolates were present in our population, suggesting that the pathogen population may undergo parasexual recombinations. The highest genetic diversity in C. gloeosporioides was recorded in Nabeul and on orange, which likely constitutes the area and the host of origin for the Citrus anthracnose disease in Tunisia. In addition, no population subdivision was detected at the geographic, host species or cultivars’ origin levels. However, our study identified two genetic subpopulations and indicated a rapid C. gloeosporioides population change at temporal scale that should be further examined over several consecutive growing seasons in order to understand its population dynamics.

Blue mold rot, caused by Penicillium expansum, is one of the most economically important post-harvest diseases of apple worldwide. The goals of this study were threefold: to evaluate the diversity of P. expansum isolates for mycelial growth, spore production and lesion diameter on apples; to estimate the effects of cold-storage facility conditions on P. expansum population structure; and to investigate the efficacy of three essential oils against P. expansum. The results showed that storage facilities applying fungicides and storing diverse fruit species selected for P. expansum isolates with a larger lesion diameter on apples. In addition, application of fungicides and diversification in stored fruit species significantly select for P. expansum isolates with higher levels of mycelial growth and spore production, respectively. Moreover, the diversity of host species of stored fruit accounted for 38% of the variability observed between storage facilities for the measured fitness parameters in P. expansum isolates and had a stronger effect on P. expansum population structure than fungicide treatment. Essential oils from Mentha pulegium and Syzygium aromaticum significantly decreased mycelial growth and spore production of P. expansum isolates in vitro. Mentha pulegium essential oil also significantly decreased the size of lesions associated with the blue mold rot of apples. Reducing the diversity of stored host species and applying M. pulegium essential oil may be useful in counter-selecting for aggressive P. expansum isolates and reducing losses due to blue mold rot during fruit storage.