Field observations indicate that conjunctive use of ethephon (Ethrel) and NAA (Fruitone-N) can induce early pecan [Carya illinoensis (Wangenh.) C. Koch] shuck (involucre) dehiscence, while greatly reducing undesirable leaflet abscission. Comparisons of the efficacy of 2,4-D and NAA in preventing undesirable leaflet abscission revealed that the comparative molar protective activity of 2,4-D greatly exceeds that of NAA, providing leaflets absolute protection against ethephon-induced abscission, but it was functionally inferior to NAA due to the induction of leaflet necrosis. Single ethephon treatments accelerated shuck dehiscence 3 to 6 weeks for several cultivars. Treatment of ‘Stuart’ and ‘Moneymaker’ pecan fruit and foliage, several weeks prior to the completion of natural shuck dehiscence, with a NAA-ethephon mixture accelerated shuck dehiscence by 5 and 3 weeks, respectively, without severe leaflet abscission or loss of nut quality. These data indicate possible development of harvest-aid technology for early harvesting of pecan without severe leaflet abscission. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon); (2,4-dichlorophenoxy)acetic acid (2,4-D); and 1-naphthaleneacetic acid (NAA).
The discovery of auxins provided the basis for current chemical fruit thinning of apples. The promotion of postbloom fruit abscission was first reported over 60 years ago ( Davidson et al., 1945 ), and since then, synthetic auxins, NAA and its
-naphthaleneacetic acid (NAA) has been successfully used to control basal sprouts in several crops ( Boswell and McCarty, 1974 ; Eynard et al., 1986 ; Holt and Chism, 1988 ; Stover et al., 2006 ) and has shown some success in sucker control in hazelnut in Europe
and Palmer, 1982 ; Yuan and Greene, 2000b ). Some researchers reported that the primary mechanism of fruit thinning by chemical thinners such as naphthaleneacetic acid (NAA) and 6-benzylaminopurine (6-BA) is the result of reduced carbohydrates
preharvest fruit drop can occur independently of fruit ethylene production ( Sun et al., 2009 ). Losses resulting from preharvest fruit drop can be mitigated by applying either naphthaleneacetic acid (NAA; Fruitone L; AMVAC Chemical, Newport Beach, CA) or
efficacy. Various growth regulators have been shown to promote flower bud formation in apple. Harley et al. (1958) reported that flowering in apple was increased by NAA to a greater extent than could be accounted for by fruit removal alone, providing
Leaves of ‘Mountain Snow’ chrysanthemums (Chrysanthemum morifolium Ramat.), sprayed with 10 mm NAA or 10 mm NAAEE, exhibited severe epinasty after 24 hr, while leaves sprayed with 5 mm ethephon did not. Treatment with 100 μm AOA 24 hr before application reduced ethylene production rate of leaves, but not epinasty. Localized application of NAA to adaxial, abaxial, or both leaf surfaces resulted in similar amounts of leaf epinasty. Epinastic leaves had enlarged adaxial epidermal cells. Size of abaxial epidermal cells was unchanged. This study provides evidence that leaf epinasty of chrysanthemum following NAA application is not the result of auxin-induced ethylene production. Chemical names used: (aminooxy)acetic acid (AOA); 1-naphthaleneacetic acid (NAA); 1-naphthaleneacetic acid ethyl ester (NAAEE); and (2-chloroethyl)phosphonic acid (ethephon).
synthetic auxins reduced preharvest fruit drop of apples ( Gardner et al., 1940 ; Marini et al., 1993 ) and oranges ( Gardner et al., 1950 ; Zur and Goren, 1977 ). One application of naphthalene acidic acid (NAA) may delay apple fruit drop for ≈10 to 14 d
, color, and cro p value by as much as 20% while maintaining fruit quality ( Byers and Eno, 2002 ). Naphthaleneacetic acid (NAA), a synthetic auxin, and aminoethoxyvinylglycine (AVG), an inhibitor of ethylene biosynthesis are two compounds that
). Increased abscission of young apple fruit caused by the chemical thinner naphthaleneacetic acid (NAA) is linked with increased ethylene production; hence, NAA may act in part through ethylene signaling ( Curry, 1991 ; Zhu et al., 2008 ). The pathway of