Thinning ‘Loring’ Peaches with CGA 15281

Abstract

Adequate fruit thinning of ‘Loring’ peach [Prunus persia (L.) Batsch] was achieved with single applications of (2-chloroethyl)-methylbis (phenylmethoxy) silane (CGA 15281) at concentrations of 240, 360, and 480 ppm applied at seed length of 8.8 mm and 2 applications at 240 and 360 ppm applied 7 days apart at 8.8 and 10.8 mm seed lengths in 1978. Additional hand thinning following treatment was required. In 1979 adequate thinning was achieved with 1 application of 240 ppm applied at seed length of 13.9 mm or 480 ppm applied at an 8.5-mm seed length. Yields from these treatments were reduced but did not differ from the control treatment. Multiple applications and higher rates resulted in over-thinning and reduced yields. The sensitivity of fruit to thinning appeared to increase with increased seed length. In 1978, foliage injury occurred at all rates and the severity of injury increased at higher concentrations and multiple applications. However, no foliage injury was observed in 1979.

Peach Fruit and Leaf Tissue Sensitivity to CGA 152811

“…Leaf abscission with CGA 15281 tends to be slight in most cases (3). Some leaf abscis sion was noted in the present study when higher concentrations were applied to the foliage but leaf abscission was not severe at any concentration in these tests.…”

“…Successful peach chemical thinning with ethylene-generating chemicals at ovule length of 7 to 12 mm is well documented (2, 4 ,7 ). Data have shown that the sensitivity of peaches to thinning increases as the peach develops during stage I (the initial period of rapid fruit growth) to early stage II (pit har dening) (3,4,7).…”

Peach Blossom Thinning with CGA 152811

“…Thus, the differences in stem tissue respiration de tected in this study may be related to differ ences in carbohydrate metabolism, which may directly or indirectly influence suscepti bility to cold injury. 4,5). Although (2-chloroethyl)phosphonic acid (ethephon), an ethylene-generating ma terial, has considerable blossom-thinning ef fect (2,7,8), the successful use of CGA as a blossom thinner has not been reported.…”