POLLINATION COMPATIBILITY OF SUNDROP APRICOT AND ITS PROGENY IN THE CLUTHA SERIES

Flowers of the apricot (Prunus armeniaca L.) cultivar, 'Sundrop' produ ced low fruitset when self-pollinated or caged to exclude bees during bloom. The level of fruit set improved when 'Sundrop' flowers were pol linated with another cultivar, even when the pollen came from trees of its own progeny(the 'Clutha' series). Levels of self-compatibility va ried within the 'Clutha' series; seven selections were as self-compati ble as one of their parents 'Moorpark' whereas six showed low self-com patibility, similar to that of their other parent, 'Sundrop'. Comparis on of tile flowering dates of these and other commercial cultivars whi ch could be used as pollenisers showed that in four of the five years 'CluthaGold', 'CluthaStar', 'CluthaSun', and 'CluthaGem' all flowered with 'Sundrop'. However, one year demonstrated the need to include an earlier flowering polleniser for 'Sundrop'. Five of the six named 'Clu tha' selections were compatible with 'Sundrop'; only lack of synchrony of flowering will affect their value as potential pollenisers for thi s cultivar. Three of the more commonly planted newer cultivars had low self-compatibility-'Sundrop', 'CluthaGold', and 'Valleygold'-thus rev ising the pollination status of apricot from a crop that does not requ ire cross-pollination to one which generally does; care will be necess ary in the planning of new plantings.