Preparations for making dura x pisifera crosses involve collecting pollen from male inflorescences of pisifera palms and isolating (bagging) female inflorescences on dura palms.

For large-scale crossing designs it is necessary to complete several hundreds of crosses. An example of a connected crossing design involving 225 dura and 50 pisifera with 9 dura crossed onto one pisifera is given in Table 1.

As germinated seeds should be planted at about the same time, it is crucial to complete a crossing program quickly to avoid differences in the speed of germination rate due to the age of the seeds.

Pollen can easily be stored in ampoules sealed under vacuum for a year, so pollen collection can proceed regardless of whether palms bear anthesizing female inflorescences.

Progress therefore mainly depends on the rate of emergence of female inflorescences on the dura, particularly when female parents are assigned to a specific pisifera before actual crossing work starts. Speed of completing the crossing program can be increased if numbers are assigned to the female parents according to the emergence of inflorescences. For example, in Table 1 the first 9 dura which produce female inflorescences are crossed with pisifera 1 and numbered 1, 26, 51, 76, 101, 126, 151, 176 and 201; pisifera 2 is crossed onto the second set of 9 dura with females inflorescences which are numbered 2, 27, 52, 77, 102, 127, 152, 177 and 202.

The first 25 pisifera are in this way crossed onto the total of 225 dura, the numbers of which are assigned as female inflorescences become available. Pisifera 26 to 50, however, must be crossed with the specific 225 dura for which the numbers were already assigned when crossed onto pisifera 1 to 25.

Once pollen collection has started, initial progress depends thus mainly on the rate of availability of female inflorescences of different dura. On the other hand, availability of male inflorescences from pisifera 26 to 50 tend to become the constraint for completing the final stage of the crossing program. For that reason, a spare set of pisifera should be reserved to ensure that the program can be finalised in time. In the same vein, nominating an additional set of dura will speed up completion of the first part of the crossing program.