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  • Author or Editor: D. R. Atkin x
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Abstract

Trees of old-line ‘Atwood’ navel sweet orange [Citrus sinensis (L.) Osbeck] on Rubidoux trifoliate orange [Poncirus trifoliata (L.) Raf.] were planted in 1970 at 331 to 801 trees per ha to determine effects of tree spacing on growth, yield, production costs, and fruit quality. Growth measured as trunk circumference and hence fruit-bearing capacity per tree was inversely proportional to tree density but fruit yields per hectare increase with close spacing.

Open Access

Abstract

Herbicides, growth regulators, and polyethylene plastic tarpaulins were applied or covered 14-year-old ‘Frost Valencia’ sweet orange [Citrus sinensis (L.) Osbeck] on Troyer Citrange [Poncirus trifoliata (L.) Raf. × Citrus sinensis (L.) Osbeck] stumps to control sprouts. Ammonium sulfamate (Ammate X), 2,4-D Esteron Ten Ten, 2,4-D Lithate, ammonium ethyl carbamoylphosphonate (Krenite), and polyethylene plastic tarpaulin gave best results for controlling resprouting.

Open Access

Abstract

A previous paper (1) reported yield and trunk circumference data of this experiment. Briefly, trees in this trial are old budline ‘Atwood’ navel orange (Citrus sinensis (L.) osbeck) infected with a mild form of exocartis viroid on Rubidoux trifoliate orange rootstock planted in the spring 1970 on a 3.2 ha plot in Tulare County, California. The soil type is San Joaquin clay loam.

Open Access

Abstract

Trees of old-line ‘Atwood’ navel orange [Citrus sinensis (L.) Osbeck] on Rubidoux trifoliate orange [Poncirus trifoliata (L.) Raf.] rootstock were planted in 1970 at 6 different spacings in 5 replications to determine effects of tree spacing on fruit quality, tree growth, yield, air temperature, light penetration, and production costs. Growth rate was measured by trunk circumference and tree height. Trunk circumference increased as spacing increased. Closely spaced trees were 0.7 m higher than widely spaced trees after 9 years. Fruit quality analyses showed no differences until the trees began to crowd. Fruit colored faster in 1980 on the widely spaced trees than on closely spaced trees. Fruit from trees spaced 5.5 × 5.5 m reached legal maturity (8:1, solids:acid ratio) 12 days ahead of fruit from trees spaced 2.7 × 4.6 m.

Open Access

Abstract

Gibberellic acid (GA3) applied to navel orange [Citrus sinensis (L.) Osbeck] trees in the whitewash spray mixture [15 lb. Ca(OH)2 + 2 lb. CUSO4 · 5H2O + 3 lb. ZnSO4 · H2O/100 gal - pH 12.6], commonly used in the San Joaquin Valley of California, had no effect on rind resistance to puncture or on rind color. Whitewash applied as a separate spray 6 hours prior to, or 1 day after, GA3 yielded full effect of GA3. The full GA3 effect was obtained also when it was applied as a constituent of a neutralized Cu, Mn, Zn mixture. Effectiveness of GA3 was reduced in the laboratory when it was applied in suspensions containing as little as 0.15 g/l (0.125 lb./100 gal) of Ca(OH)2 and no reduction occurred when smaller amounts of Ca(OH)2 were used to produce alkaline water with pH values of 8.0 through 11.0. We propose that the compatibility of GA3 with dry deposits of whitewash was due to conversion of Ca(OH)2 to CaCO3 and that the lack of compatibility with more highly alkaline suspensions of Ca(OH)2 was due to the conversion of GA3 to the 1 → 3-lactone.

Open Access

Abstract

Fruit production and tree size were measured and yield efficiency was computed for 11-year-old trees of ‘Washington’ navel and ‘Olinda Valencia’ oranges [Citrus sinensis (L.) Osbeck], ‘Minneola’ tangelo (C. paradisi Macf. × C. reticulata Blanco), and ‘Lisbon’ lemon (C. limon Burm. f.) on 21 rootstocks in the San Joaquin Valley of California. Performance of most rootstocks was similar over all scions, and several rootstocks produced trees with higher yields than ‘Troyer’ and ‘Carrizo’ citranges [C. sinensis × Poncirus trifoliata (L.) Raf.], the current standard rootstocks. ‘Yuma Ponderosa’ lemon (× C. limon) had the highest yields, but several trees on this rootstock died or were declining. Trees on ‘C-32’ citrange (C. sinensis × P. trifoliata) were largest, and yielded nearly as much as those on ‘Yuma Ponderosa’ lemon. ‘C-35’ citrange (C. sinensis × P. trifoliata) produced smaller trees with excellent yield efficiencies, and should be suitable for higher-density plantings with most scions, except perhaps navel orange, because this combination yielded poorly at other locations. ‘Rangpur’ lime (C. limonia Osbeck) was promising only with lemon scion, and ‘Swingle’ citrumelo (C. paradisi × P. trifoliata) only with ‘Minneola’.

Open Access