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  • Author or Editor: F. W. Southwick x
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Abstract

Previous season application of succinic acid-2,2-dimethylhydrazide (SADH) increased fruit set on ‘McIntosh’ apple trees but had no influence on the thinning ability of naphthaleneacetic acid (NAA), naphthaleneacetamide (NAAm), carbaryl (Sevin) or the combination of NAA plus carbaryl.

Open Access

Abstract

Red color development of ‘McIntosh’ apples that previously received a mid-July application of succinic acid 2,2-dimethylhydrazide (SADH) and were then treated before harvest with 2-chloroethylphosphonic acid (ethephon) occurred earlier and more extensively than on controls. Fruit receiving 150 or 250 ppm ethephon were less firm within 7 or 8 days than fruit receiving only SADH. The respiratory climacteric was advanced 6 to 10 days by ethephon treatments as low as 25 ppm. Naphthaleneacetic acid (NAA) was less effective than 2,4,5-trichlorophenoxypropionic acid (fenoprop) in preventing preharvest drop, especially at higher ethephon concentrations. Fruit from all treatments kept well in both CA and air storage provided they were in good condition at harvest. Scald developed to a greater extent on stored fruit that had received ethephon than on controls.

Open Access

Abstract

Residual effects of single applications of 1000 and 2000 ppm succinic acid 2,2-dimethylhydrazide (SADH) in mid-July or mid-August, 1969, were determined. Mid-August treatment of 2000 ppm SADH inhibited June drop, depressed fruit size and increased fruit set; but it did not affect flowering, seed content and viability during June drop, preharvest drop, flesh firmness, or yield in 1970. Flowering and yield were often reduced in 1971 where SADH was applied in 1969. The results suggest that under some circumstances the residual effects of SADH may tend to induce biennial bearing of ‘McIntosh’ apple trees.

Open Access