Low Pollen Production as a Cause of Fruit Malformation in Strawberry

The differential tendency to form misshapen fruit and anther quality and pollen production were determined in ‘Benton’, ‘Totem’, ‘Olympus’, and ‘Tyee’ strawberries ( Fragaria × ananassa Duch.) in field trials in 1983 and 1984. All flowers had a full set of anthers; however, the proportion of anthers that appeared unhealthy (dull yellow, brown, or black) varied. Usually the proportion of unhealthy anthers was higher in primary than in secondary or tertiary flowers of an inflorescence. Primary flowers often contained only unhealthy anthers. This condition was found in 90% of the primaries of ‘Benton’ in 1983 and in all those of ‘Tyee’ in both years. ‘Tyee’ released ≤6000 pollen grains per flower. When 75% or more of the flowers at a ranking had at least some healthy anthers, pollen production averaged ≥240,000 grains per flower. ‘Tyee’ had the highest incidence of misshapen fruit (18–19%) in both years. Comparable values were ‘Benton’, 14–17%; ‘Olympus’, 10–11%; and ‘Totem’, 7%. From 42% to 70% of the primary fruit of both ‘Tyee’ and ‘Benton’ were malformed each season. Low pollen production in ‘Tyee’ and ‘Benton’, a result of anther failure, likely contributed to the high incidence of malformation in primary fruit.