Issue link: https://read.dmtmag.com/i/275392
www.goodfruit.com GOOD FRUIT GROWER MARCH 15, 2014 21 to do that. However, the time required depends on temperature, and the length of the pollen tube varies by variety. Timing Growers want to know when the king bloom has been fertilized, and then they need to know when to prevent new fl ow- ers, especially side bloom, from being fer- tilized. Two or three sprays after the king bloom sets are usually needed. "In the past, the application timing has been subjective," Peck said. "More pre- cise application timing can be achieved through modeling the fertilization of the desired percent of king bloom needed to achieve a full crop at the desired fruit size. When this target is achieved, a bloom thinner can be applied so that later-blooming flowers are prevented from setting fruit." Stopping fertilization depends on blossom injury. Fish or horticultural oil, combined with liquid lime sulfur, will kill pollen tubes and thus prevent fertilization, but does not affect already fertilized fl owers. An advantage of thinning with liquid lime sulfur and oil is that these materials are effective against the diseases apple scab and powdery mildew, so other fungi- cides need not be applied during bloom. On the minus side, lime sulfur increases the amount of fruit with russet. Additionally, growers outside Washing- ton State are limited in their use of lime sulfur products for thinning due to label restrictions. Peck and Yoder are testing other blos- som thinning materials that are not yet labeled for use. • Gregory Peck Keith Yoder "In the past, the application timing has been subjective." —Dr. Gregory Peck