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High ethylene levels were associated with flower abscission in apple (Malus sylvestris) and cherry (Prunus avium and Prunus cerasus), "June drop" of immature cherries, and harvest drop of apple and red raspberry (Rubus idaeus). However, an increase in ethylene content was not associated with June drop of apples and harvest drop of cherries. During the period of fruit ripening on the plant, the largest increases in ethylene occurred in apple flesh and red raspberry receptacular tissue. Ethylene remained low throughout the period of sweet and tart cherry ripening. The data obtained indicated marked ethylene gradients between adjacent tissues. Increases of ethylene in some tissues may have resulted from ethylene diffusion from adjacent tissues containing high levels of ethylene.Ethylene has been associated with the initiation and termination of many physiological processes in plants (16). The purpose of this research was to measure the amount of endogenous ethylene in developing fruits and in tissues adjacent to the fruits to determine if there was a relationship between the amount of ethylene in the tissue and the stage of fruit development. Three types of fruit were selected for study:apple. a climacteric fruit (12); cherry, a nonclimacteric fruit (15. 17); red raspberry, a fruit whose ripening physiology has not been reported. MATERIALS AND METHODSAt the Cornell Orchard in Ithaca samples were collected from several cultivars of apple (Malus sylvestris), several cultivars of red raspberry (Rubus idaeus), as well as one cultivar each of sweet cherry (Prunus avium) and tart cherry (Prunus cerasus). Ethylene extractions were completed in less than 60 min after collection. The method of ethylene extraction has been described (2). Subsequent to that communication ethylene contamination by the extraction apparatus was eliminated by: turning the balloons inside-out and storing them in a vacuum for 24 to 48 hr before use; attaching the balloons directly to the arms of the capillary stopcock; limiting the use of the balloons to a single extraction. Syringe contamination with ethylene was eliminated by using plastic disposable syringes and storing the syringes with the plunger removed from the bore.Ethylene extractions were made in triplicate. The data represent averages for the three replicates except when, in a few extractions, the value (nl C,H4/g) for the highest replicate exceeded by 150% the value for the lowest replicate. When this occurred, the value for the unrepresentative replicate was discarded. Therefore, when comparing ethylene values in the tables and figures. significant differences usually exist when the larger of the two values exceeds the smaller by more than 150%, e.g., a value of 0.160 nl CMH/g is probably significantly higher than a value of 0.100 nl C2Hl/g.

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Field observations in 8 growing seasons indicated that maturity dates for ‘Delicious’ apples (Malus domestica Borkh.) could be reliably predicted 1 week in advance, by using the average firmness-total soluble solids value for a geographic region. When the average firmness-total soluble solids values were close to the maturity index line, apples matured within 1 week.

Diphenylamine (DPA) is an antioxidant which is widely used on apples for scald control during fruit storage. Since appreciable residues of DPA remain on apples when sold, it was of interest to study the extent of possible transfer of the compound to cider. Cider was expressed f r o m j v e cultivars of DPA-treated apples following their storage and the original fruit, the pomace and cider was analyzed for DPA residues. Only traces of the compound were found in cider with virtually all of the DPA found concentrated in the pomace. The toxicologic signijcance of the results are discussed.

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