During field work it was observed that during days with poor weather conditions, especially cool, overcast and windy days, male phase flowers did open, but the anthers remained closed, and no flowers opened in the female phase. It often happened that when unfavourable conditions commenced while flowers were open, either male or female, they were arrested in that stage for up to 24 hours and did not close until conditions had changed. From Figure 1 it can be seen that there is a major difference between A and B-type cultivars regarding the time of opening and closing of flowers of the two sexual phases. This caused an overlap of the two phases and could have been one of the reasons for exceptionally good fruit set we experienced. Pollination Pollination is the transfer of pollen from the anthers to the receptive stigma.
Avocado pollen is sticky and heavy and therefore suitable for insect-pollination.
Bee activity is related to weather conditions and corresponds to a great extent with the opening and closing of the avocado flowers. It was observed that bees do collect nectar from closed flowers between the female and male phases, but without contributing to the pollination process. In spite of the overlap of male and female phase flowers in the same cultivar, it must be considered that avocados are natural outbreeders and that pollen donors, with an alternate flower-opening cycle should be available for effective pollination. The 'Fuerte' pollen usually out-performed the 'Hass' pollen. There is no doubt that the avocado stigma is receptive at the time the flower opens in the female phase.