Articles
ACC use on young, newly established apple orchards
Article number
1443_2
Pages
9 – 16
Language
English
Abstract
The South African apple industry covers an area of ca. 25,500 ha.
This is slowly increasing per year with new orchards replacing old ones.
The newly established orchards are planted with unbranched, whip trees and the first year or two after establishment is used to fill the allotted space in the orchard and develop lateral branches.
As part of the process of combating the basal dominant architecture that typically could develop in mild winter climates, all fruitlets are removed.
This is currently done by hand as little chemical thinners are used as growers are not very happy with results achieved with chemicals such as 6-benzyladenine (6-BA), carbaryl and 1-naphthaleneacetic acid (NAA), applied as a mixture around petal drop or ammonium thiosulphate (ATS) during bloom.
The ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC) effectively thins apples, especially in the later thinning window of 15-20 mm fruitlet diameter.
We evaluated ACC over two seasons on young apple trees in the Elgin region of South Africa.
The cultivars used were ‘Bigbucks’, a Gala strain, ‘Cripps’ Red’ and ‘Lady in Red’. ACC was applied at either 400 or 600 mL Accede® per 100 L water.
ACC has the potential to remove fruitlets from young apple trees.
For all cultivars, the “15-20 mm fruitlet diameter” stage showed the most potential.
In addition, a higher dosage rate of 600 mL 100 L‑1 looks to be effective for “difficult to thin” cultivars, whereas 400 mL 100 L‑1 is sufficient on “moderate or easy to thin” cultivars.
This is slowly increasing per year with new orchards replacing old ones.
The newly established orchards are planted with unbranched, whip trees and the first year or two after establishment is used to fill the allotted space in the orchard and develop lateral branches.
As part of the process of combating the basal dominant architecture that typically could develop in mild winter climates, all fruitlets are removed.
This is currently done by hand as little chemical thinners are used as growers are not very happy with results achieved with chemicals such as 6-benzyladenine (6-BA), carbaryl and 1-naphthaleneacetic acid (NAA), applied as a mixture around petal drop or ammonium thiosulphate (ATS) during bloom.
The ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC) effectively thins apples, especially in the later thinning window of 15-20 mm fruitlet diameter.
We evaluated ACC over two seasons on young apple trees in the Elgin region of South Africa.
The cultivars used were ‘Bigbucks’, a Gala strain, ‘Cripps’ Red’ and ‘Lady in Red’. ACC was applied at either 400 or 600 mL Accede® per 100 L water.
ACC has the potential to remove fruitlets from young apple trees.
For all cultivars, the “15-20 mm fruitlet diameter” stage showed the most potential.
In addition, a higher dosage rate of 600 mL 100 L‑1 looks to be effective for “difficult to thin” cultivars, whereas 400 mL 100 L‑1 is sufficient on “moderate or easy to thin” cultivars.
Publication
Authors
W. Truter, N. Steyn, S.J. Reynolds, K.I. Theron
Keywords
apple production, climate change, endodormancy, low winter chill, mild winter climate
Online Articles (14)