Bloom timing of almond cultivars in California
Time of bloom and bloom overlap between cultivars is an important consideration when choosing cultivars for new orchards. Self-incompatible cultivars need good bloom overlap between compatible pollenizers for successful cross-pollination and nut set. Cold rain storms in northern California can lengthen bloom or delay a cultivar's bloom, negatively affecting bloom overlap between cultivars in some years. Under varying weather conditions, planting cultivars with the most coincident bloom reduces this risk. Selecting cultivars for pollenizers that bloom slightly earlier and later than an orchard's main cultivar reduces risk related to poor cross-pollination at any one point in time. Conditions reducing honey bee flight can also result in poor cross-pollination. If early or late blooming orchards are planted, selecting cultivars from within the same full bloom group will help ensure good bloom overlap and cross-pollination. Full bloom time for 34 cultivars in the Chico Regional Almond Variety Trial is reported for twelve consecutive years relative to 'Nonpareil' full bloom.
Connell, J.H., Gradziel, T.M., Lampinen, B., Micke, W.C. and Verdegaal, P.S. (2018). Bloom timing of almond cultivars in California. Acta Hortic. 1219, 25-30
Prunus dulcis, pollenizer, bloom overlap, 'Nonpareil', cross-pollination