Pre-penetration, penetration and colonization events of Colletotrichum gloeosporioides in flowers and fruits of guava (Psidium guajava L.)

Colletotrichum gloeosporioides causes anthracnose on guava fruits and it produces 40% of losses worldwide. The infection process of C. gloeosporioides was determined in guava flowers and fruits. Physiological maturity fruits and flowers were inoculated with the fungus (1x10(6) conidia / mL), the control treatment sterile distilled water was applied, covered with white paper (27.2 degrees C and 74% RH). Samples were taken every 2 hours to 12 hours and every 24 hours up to 120 hours, fixed immediately in FAA (Formaldehyde, alcohol, acetic acid), dehydrated in ethanol (50, 70, 96 and 100%) and observed in the electron microscope scanning. Germination occur 3-4 h after inoculation (hdi) in flowers and fruits, to 24 hdi had germinated over 45% of conidia. The germ tube varied in size (40-70 mu m), with little formation of appressoria. Fungal penetration occurred between 8 and 12 hdi. At 12 hdi tissue colonization starts, 48 hdi appear coarse conidiophores and conidia. At 72 hdi anthracnose symptoms observed at the scanning microscope, 96 hdi stereomicroscope observed in fruits and small lesions 120 hdi; no significant differences (P> 0.005) between the events of pre-penetration, penetration and colonization of flowers and fruits. Not control the fungus was observed. Infection events of C. gloeosporioides, information basic and important epidemiological studies and control.