Our objective was to increase the percentage of marketable red fruit at harvest time on paprika pepper (Capsicum annuum L.) plants intended for mechanical harvest by using ethephon [(2-chloroethyl)phosphonic acid] to remove late-developing blooms and green fruit. We conducted three experiments on field-grown plants in southwestern Oklahoma. We tested ethephon solutions of 0, 1000, 2000, 3000, and 4000 μl·liter–1 as a one-time foliar application on various dates. Total dry weight of harvested fruit decreased linearly with ethephon rate in all three studies. Marketable fruit as a percentage of total harvested fruit weight increased linearly with ethephon rate in two studies. There was no consistent effect of ethephon on the intensity of red pigment extracted from dehydrated marketable fruit. With proper timing, as little as 1000 μl ethephon/liter was enough to alter the distribution of total harvested fruit weight toward marketable fruit and away from green fruit. A target spray “window” of the last 10 days in September seemed appropriate for southwestern Oklahoma, and the recommended rate of ethephon was between 2000 and 3000 μl·liter–1.
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