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  • Author or Editor: F. Zucconi x
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Abstract

Fruit removal force (FRF) of sour cherry, Prunus cerasus L. ‘Montmorency’, was markedly reduced by foliar sprays of 2-chloroethylphosphonic acid (CEPA) applied 3-15 days prior to harvest. The maximum reduction in FRF occurred with CEPA 6 days after treatment for all concentrations (500, 1000, 2000 and 4000 ppm). In addition to a reduction in FRF the dispersion of the individual FRF values was significantly reduced. Fifty per cent fruit removal with the 500 ppm treatment was accomplished by a force of 171 g compared to 434 g for the control. High concentrations (2000 and 4000 ppm) of CEPA caused serious phytotoxicity, such as leaf abscission, terminal dieback, gummosis and enlarged lenticels. Trees of low vigor or the spurs and terminal growth of weak wood were most seriously affected. Fruits on branches treated with CEPA appeared to be advanced in maturity. There was a striking delay in anthesis in the spring following summer application of 4000 ppm CEPA. No significant delay occurred at lower concentrations. Ascorbic acid (20,000 ppm), iodoacetic acid (300 ppm) and salicylic acid (500 ppm) were either not effective or less active than CEPA.

Open Access

Abstract

(2-Chloroethyl)phosphonic acid (ethephon) applied as a foliar spray to sweet cherry trees within 2 weeks of fruit maturity promoted fruit abscission at the lower (fruit:pedicel) zone, as indexed by a reduction in the fruit removal force (FRF). There was no significant effect, at the concn studied, on abscission at the upper (pedicel:peduncle) zone. Promotion of abscission with ethephon was time and concn dependent. Ethephon concn of 100 to 1000 ppm were effective with a greater response from the higher concn. Absorption periods of 4 and 24 hr resulted in responses equal to 73 and 94% of that observed when ethephon was present for the entire experimental period. Of 9 sweet cherry cultivars evaluated, all responded similarly in terms of reduction in FRF. Ethephon enhanced fruit enlargement and pigmentation when applied early in Stage III of fruit growth. The increase in wt was most pronounced in the fleshy pericarp tissue.

Open Access