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- Author or Editor: Heinz K. Wutscher x
Abstract
‘Orlando’ tangelo (Citrus paradisi Macf. × C. reticulata Blanco) on 16 rootstocks was most productive on Swingle citrumelo, Morton citrange, Rangpur lime, and Cleopatra mandarin when the trees were 3 to 10 years old. Fruit quality was superior on Sun Chu Sha Kat, Keraji, and Kinokuni mandarins, hybrid C61-253 (‘Shekwasha’ × ‘Koethen’), Texas and Iwaikan sour orange, and Morton citrange rootstocks. Trees on Swingle citrumelo, Iwaikan sour orange, ‘Precoce de Valence’ sweet orange, Morton citrange, and Sun Chu Sha Kat mandarin had the largest canopies. Leaf levels of N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, Na, Cl-, and B varied significantly with rootstock.
Abstract
Mature ‘Lula’ avocado fruits (Persea americana Miller) were exposed to temp ranging from -2.2 to -8.9°C for 4 hr in a freeze chamber. No off-flavors or discoloration developed during a 7-day ripening period (25°C) after temp of -5.6° and above. Temp of -6.7° and -7.8° caused discoloration and decay of the outer part of the mesocarp; the inner region remained hard, green, and unpalatable. Following the -8.9° treatment, the entire mesocarp decayed. Insertion of thermocouples into the fruits decreased cold tolerance 1°. Seed germination was reduced to less than 50% of normal in the -4.4° to -6.7° range, then decreased to 0 at -8.9°. Tissue temp curves showed heat release coincident with tissue damage, indicating internal ice formation.
Abstract
Thirty-one of 104 ‘Pineapple’ orange [Citrus sinensis (L.) Osbeck] trees on rough lemon [C. iimon (L.) Burm. f.] rootstock in a test in southeastern Florida developed blight between 1974 and 1980, when the trees were 5 to 11 years old. Visual rating of symptoms and sampling of trunk wood in April each year showed that development of elevated wood Zn (>5 ppm) and visual symptoms were simultaneous in 42% of the 31 blighted trees; 29% had high Zn in the wood 12 months before visual symptoms, 10% at 24 months, and 13% at 36 months before blight was detected visually. All blighted trees had higher wood Zn levels (7-25 ppm) than the healthy trees (1-6 ppm).
Abstract
Virus-free nucellar budlines of red grapefruit and an old budline selection carrying exocortis and xyloporosis were grafted on sour orange rootstocks and grown under commercial conditions in the orchard. No differences were found in fruit quality. The old line trees produced the greatest tonnage of fruit for the first 7 years. By the tenth year the old budline trees were only 55-62% as large as the nucellar trees and were producing less fruit. Counting numbers of fruit above and below 96 ring size revealed no distinct differences in fruit size. This information should be vital to those concerned with early returns from citrus groves.
Abstract
Four-year-old nucellar ‘CES No. 3 Redblush’ grapefruit trees on 16 rootstocks, including 8 hybrids, growing on a calcareous soil of pH 8.4 differed in tree size and leaf color. Trees on sour orange, ‘Kunenbo’ mandarin and ‘Cleopatra’ mandarin rootstock were considerably larger and their foliage was greener than those of trees on other rootstocks. Trees on ‘Changsha’ mandarin, C61-250 (‘Shekwasha’ mandarin × ‘Koethen’ sweet orange) also were chlorosis-resistant but they were smaller than the trees on the other tolerant rootstocks. Rootstock effects on 10 mineral element levels in the leaves are discussed.
Abstract
Water injection tests and analysis of the outer trunk wood for Zn, K, Mg, CI, and water-soluble phenolics of trees declining of declinamiento or fruta bolita (Argentina), marchit-amiento repentino (Uruguay), declinio (Brazil), and an unnamed decline in South Africa showed that these trees behave like blight-affected trees in Florida. Water uptake of declining trees is reduced, and Zn, K, Mg, and CI levels in the wood are usually higher than in healthy trees. Trees of ‘Valencia’, ‘Westin’, ‘Tarocco’, ‘Calderon’, ‘Natal’, ‘Alidjan’, and ‘Washington navel’ sweet oranges (Citrus sinensis (L.) Osbeck), ‘Eureka’ and ‘Lisbon’ lemons (C. limon (L.) Burm. f.), ‘Marsh’ grapefruit (C paradisi Macf.), and ‘Comun’ mandarin (C. reticulata Blanco) on trifoliate orange (Poncirus trifoliata (L.) Raf.), rough lemon (C. limon), Cleopatra mandarin (C. reticulata), and Rangpur (C. reticulata hybrid) rootstocks were used in this study.