Postharvest rotting caused by Penicillium italicum Wermer is
responsible for significant economic losses of orange (Citrus
sinensis (L.) Osbeck) and lemon (C. limon Burm. f.) worldwide,
but until now was not described on lemons (C. aurantifolia
(Chistm.) Swingle) in Mexico. During May 2002, we analyzed 400
fruits of lemon collected in the state of Colima, which is the
most important lemon producer in Mexico. Rotting and softened
areas covered with a white mycelium and blue conidia were
observed on approximately 30% of the fruits. Affected tissue was
plated onto potato dextrose agar (PDA) for fungal isolation and
identification. Following the morphological criteria (1) and the
internal transcribed spacer 1 (ITS1), 5.8S, and ITS2 region of
the ribosomal DNA (2) (GenBank Accession No. DQ991463), the
fungus was identified as P. italicum and deposited in the
Colección Microbiana y de Cultivos Celulares CINVESTAV-IPN,
México. For the pathogenicity test, the fungus was grown on PDA
for 1 week. Four drops (15 μl each