ARS | Publication request: LONG-TERM USE OF APOGEE® FOR 'NITTANY' APPLE ON M.9 ROOTSTOCK

Submitted to: Annual Cumberland Shenandoah Fruit Workers Conference
Publication Type: Proceedings
Publication Acceptance Date: January 5, 2005
Publication Date: March 20, 2005
Citation: Miller, S.S. 2005. Long-term use of apogee® for 'nittany' apple on m.9 rootstock - the second year 1. Proceedings of the 80th Cumberland Shenandoah Fruit Workers Conference. pp. 117-119. 2004

Interpretive Summary: Experiences describing the annual effects of Apogee plant growth regulator have been widely reported, but little is known regarding long-term use on the same trees over many years. Cumulative effects can be more important than annual effects and fruit growers want to know what to expect over many years use of a material. A study was designed to examine the effects of annual Apogee sprays over a five-year period. Apogee sprays reduced shoot growth each year in the first two growing seasons and reduced pruning time about 40% over untreated control trees. In the second growing season when fire blight infection was significant, Apogee reduced the number of fire blight strikes compared to controls. There were no effects of Apogee on return bloom, yield, fruit size, or fruit quality in the second season. Results indicated that Apogee sprays applied in the first season had no effect on growth or fruit variables in the second season. This information is valuable for fruit growers, fruit extension specialist and researchers interested in making annual applications of Apogee plant growth regulator.

Technical Abstract: A study was designed to examine the annual and long-term effects of yearly applications of the vegetative growth regulator Apogee® (prohexadione-calcium) on young bearing 'Nittany' on Malling.9 apple trees. This report describes the effects observed in the second growing season (2004). Apogee was applied in two sprays at recommended dosages (125 mg'l-1 followed by 63 mg'l-1) beginning at petal fall in 2003 and repeated in 2004. Dormant pruning time was reduced by 40% on Apogee-treated trees as a result of the 2003 application, but bloom density was not affected compared to untreated control trees. In 2004, Apogee-treated trees had fewer fire blight strikes compared to untreated trees. Yields per tree and fruit size did not differ between Apogee-treated trees and the untreated control trees and there was no effect on fruit quality variables as a result of Apogee treatment. After two successive yearly applications of Apogee to young bearing apple trees, response to Apogee appears to be the result of the application in the given growing season and not an effect of previous applications.