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- Author or Editor: Heinz K. Wutscher x
- HortScience x
Abstract
Grapefruit trees (Citrus paradisi Macf.) budded on Kama Khatta and sour orange were most productive in a test including 10 rootstocks. Karna Khatta, sour orange, and Yuzu were tolerant, ‘Orlando’ tangelo and ‘Ortanique’ tangor were intolerant of calcareous soil. Trees on Karna Khatta were more susceptible to foot rot than trees on sour orange.
Abstract
Leaf samples from 7-year-old avocado trees (Persea americana Mill. cv. Lula) grown with drip and flood irrigation were collected every 2 months for 2 years (2 leaf cycles) and analyzed for N, P, K, Ca, Mg, Na, Fe, Mn, Zn, Cu, Cl-, and B. Mn and Cl- levels were significantly higher with drip irrigation; levels of the other 10 elements were not affected by irrigation method. Levels of 11 elements did not differ from year to year; only Fe was higher in leaf-cycle 1972-1973 than in leaf-cycle 1973-1974. There were seasonal changes in 10 elements; Na and Zn did not vary significantly with sampling date. Ca, Mg, Fe, Mn, and Cl- increased with leaf age; P, K, Cu, and B declined.
Abstract
Rootstocks affected decay of grapefruit (Citrus paradisi Macf. cv. Redbush) stored for 9 weeks at 10°C plus 1 week at 21°. Fruit from trees on ‘Smooth Seville’ (Australian sour orange) was least susceptible to decay, 3.3%. Fruit from trees on the hybrid C61-253 (‘Shekwasha’ × ‘Chinotto’) was the most susceptible, 27.7%. Postharvest decay was statistically related to rootstocks but not to standard fruit quality characteristics.
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
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.