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ARS Home » Pacific West Area » Davis, California » Nat'l Clonal Germplasm Rep - Tree Fruit & Nut Crops & Grapes » Research » Publications at this Location » Publication #198744
Title: TRUNK SPROUTING AND GROWTH OF CITRUS AS AFFECTED BY NAA, ALUMINUM FOIL, AND PLASTIC TRUNK WRAPS

Author
item Stover, Eddie
item CILIENTO, SCOTT - UNIV - OF FLORIDA
item MYERS, MONTY - UNIV - OF FLORIDA

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2006
Publication Date: 12/1/2006
Citation: Stover, E.W., Ciliento, S., Myers, M. 2006. Trunk sprouting and growth of citrus as affected by naa, aluminum foil, and plastic trunk wraps. HortScience. Volume 41: pages 1612-1615

Interpretive Summary: Citrus trees in commercial Florida orchards are developed with 0.30 m to as much as 0.75 m of bare trunk before the lowest branch (Brown, 2000). Shoots growing from the trunks of young citrus trees compete with development of the desired scion canopy, and their control is routine. Use of trunk wraps to reduce sprouting is typically combined with removal of any sprouts that form (Jackson, 1994). As the canopy develops and trunks become shaded, trunk sprouting becomes much less common. Shade inhibition of sprouting can be used on young trees through application of opaque wraps (Jackson, 1994). Preparations of 1-naphthaleneacetic acid or its ethyl ester (NAA) have been reported to reduce trunk sprouting in many tree fruits (e.g. Aldritch and Arnold, 1982; Nauer and Boswell, 1978; Raese, 1975) and formulations are labeled for such use in citrus as well as other crops (Amvac Chemical Co, 2006). The purpose of this study was to compare the effects of trunk wraps and NAA on trunk sprouting and tree growth on young citrus plantings representing three scion varieties and three different rootstocks.

Technical Abstract: In spring 1999, a commercial NAA (1-naphthaleneacetic acid) preparation for trunk sprout inhibition was compared to a corrugated plastic trunk wrap, aluminum foil wrap, bimonthly hand-removal of sprouts, use of NAA preparation plus bimonthly hand-removal when sprouts appeared, and a non-treated control. Three recently planted groves on three different rootstocks (‘Midsweet’ orange (Citrus sinensis) on Swingle citrumelo (Citrus paradisi x Poncirus trifoliata), ‘Valencia’ orange on Volkamer lemon (Volk, Citrus limon), and ‘Minneola’ tangelo (Citrus paradisi x C. reticulata) on Smooth Flat Seville (SFS, Citrus hybrid) received each of the treatments in a randomized complete block experimental design, with trees blocked by initial height and circumference. Every two months, sprouts were counted on each tree, and removed from the hand-removal treatments. After one year all sprouts were removed and counted and height and circumference of trees was determined. Across all experiments, 82-100% of non-treated trees produced trunk sprouts and all sprout control methods significantly reduced sprouts per tree. NAA treatments were never significantly less effective at sprout suppression than the wraps at the P=0.05 level, although in two experiments wraps were more effective than NAA at P=0.10. Time of sprout appearance varied between the three experimental blocks. Plastic and foil trunk wraps enhanced development of trunk circumference compared to non-treated controls in ‘Midsweet’/Swingle and ‘Valencia’/Volk. Greater trunk circumference resulted from use of wraps vs. NAA in all three experiments, which appeared unrelated to differential sprout suppression. In these experiments, it appears that either wraps enhanced tree development beyond the suppression of sprouts, or NAA influence on tree metabolism somewhat reduced trunk growth. The economics of the sprout suppression methods are also discussed.