Sa Bound

The thinning effect of benzyladenine on red ‘Fuji’ apple trees

SummaryA trial, at the Grove Research Station in southern Tasmania, studied the thinning effect of benzyladenine (BA) on five year old red ‘Fuji’ apple trees. Untreated control trees were compared with trees treated at four timings, from full bloom (FB) to 30 d after full bloom (AFB), with four concentrations of BA (50, 100, 200 or 400 mg I-1). The most effective time of thinning was 20 d AFB, when increasing concentration also increased thinning. Further advantages of this successful thinning were reflected in better fruit size and weight. At 30 d AFB high concentrations of BA depressed fruit weight. Return bloom was improved significantly by both 20 and 30 d. AFB sprays with a concentration effect at 20 d AFB. Timing of sprays had no effect on the incidence of russet which was increased only by applications of 400 mg l-1. Both the higher concentrations and later timings resulted in an increase in shoot numbers and total growth. Reduction in mean shoot length was related more to the concentration of BA u...

Hydrogen cyanamide impacts on flowering, crop load, and fruit quality of red 'Fuji' apple (Malus domestica)

Abstract The extended flowering period of many apple (Malus domestica) cultivars often causes problems in the management of crop load. Hydrogen cyanamide (Dormex®) was examined over a 2‐year period for its effect on flowering, crop load, fruit size, and quality of ‘Fuji’ apple. In Year 1, hydrogen cyanamide was applied at 5 application times (40, 30, 20, 10, or 0 days before estimated budburst (dBEB)) at 3% v/v. These treatments were compared with an untreated control. In Year 2, hydrogen cyanamide was applied at 1%, 2%, or 3% v/v at either 40 or 30 dBEB. The blossom thinner ethephon was applied to all hydrogen cyanamide treated trees at full bloom. An untreated control, a hand‐thinned treatment, and a chemically thinned control were also included. Hydrogen cyanamide advanced flowering in both years when applied at 40 or 30 dBEB. In Year 1, full bloom was advanced by more than 1 week and the flowering period from pink bud to full bloom compressed by the 40 dBEB application, resulting in a very clearly defined full bloom date. Application of hydrogen cyanamide at budburst or 10 dBEB resulted in extended flower development and some bud scorching. Unseasonally warm spring weather conditions in the second year resulted in an abnormally short flowering period. It would appear that under these conditions hydrogen cyanamide can still be used to advance flowering but is not necessary to compress the flowering period. Hydrogen cyanamide reduced fruit set in the first year but not the second. Most treatments showed no detrimental effect on fruit quality. There was no evidence of any negative interactions between HCN and ethephon.

Investigating the efficacy of endothal as a chemical thinner of red 'Delicious' apple

SummaryThe aquatic herbicide, endothal (7, oxabicyclo (2,2,1) heptane-2-3 dicarboxylic acid), was examined for its effectiveness as a blossom thinner of spur red ‘Delicious’ at the Grove Research Station in southern Tasmania. Endothal was applied as a single application at 80% bloom at a range of concentrations from 0.75 ml l−1 to 3.0 ml l−1. These chemical treatments were compared with an unthinned control and a hand thinned treatment. Crop load was reduced linearly with increasing concentrations of endothal. The increase in fruit weight and size corresponded to the level of thinning achieved. Leaf damage was proportional to the concentration applied. Endothal had a flattening effect on the fruit. There was minimal effect on pip numbers. Fruit firmness and soluble solids were improved by most endothal treatments. Return bloom was increased by the higher concentrations of endothal which achieved greater thinning. Endothal shows distinct promise as a blossom thinner of red ‘Delicious’. More work is needed ...

Thinning 'Red Fuji' apples using ethephon at two timings.

A trial was conducted on five-year-old ‘Red Fuji’ apple trees on MM. 106 rootstocks at the Grove Research Station in southern Tasmania in the season of 1988-89. Ethephon was used to thin the fruit at 0,50,100,200,400 or 800 ppm at either full bloom (FB) or 14 days after full bloom (14 days AFB). The thinning response was described by fitting curves. Ethephon was a more effective thinner at FB than 14 days AFB, which contrasts with a previous finding. Mean fruit weight reflected thinning success with the most effective treatment being ethephon at 800 ppm at FB, achieving the target of 200 g per apple.

MODELLING THE EFFECTS OF TIMING AND RATES OF APPLICATION OF BENZYLADENINE AS A SECONDARY THINNER OF FUJI APPLE AFTER ETHEPHON

A trial on ‘Fuji’ apples at the Grove Research Station in southern Tasmania during the 1991/92 season studied the thinning effect and interactions between ethephon and benzyladenine (BA) when BA was applied as a secondary thinner after a full bloom (FB) application of ethephon. The spray treatments were a factorial combination of eight application times of BA (11,13,15,17,19, 21, 23 or 25 days after full bloom (AFB)) with ten concentrations (20,40,60,80,100,120,140,160,180 or 200 mg I“1). An unsprayed control and an ethephon control were included. Target thinning results were achieved 19- 23 d AFB with concentrations of 140-160 mg I“1. A corollary of this successful thinning was an increase in fruit weight and size. Return bloom was improved significantly where thinning was successful. There was no effect on fruit firmness, soluble solids or lateral branching. Drawbacks were an increase in the incidence of russet and a reduction in pip number at the optimum thinning times and concentrations.

The interaction of Cytolin and NAA on cropping red ‘Delicious’ apple

SummaryA trial, at Spreyton in north-western Tasmania, studied the effects of Cytolin and NAA sprays on the thinning and shape of ‘Delicious’ apples. Untreated control and hand thinned trees were compared with trees treated with Cytolin or NAA alone, or in combination. Cytolin was applied at 25 mg 1~‘ at the king petal (KP) stage. NAA was applied at 8 mg I“1 at full bloom (FB) and 7,10, or 15 days after full bloom (AFB). Cytolin alone had no effect on thinning, fruit weight or on pip numbers but it did improve fruit shape. The combination of cytolin and NAA at FB overthinned. Cytolin and NAA combinations applied at all times after FB significantly decreased both mean fruit weight and pip numbers and reduced the percentage of fruit > 70 mm. All Cytolin-NAA combinations and the NAA treatments applied at 10 and 15 days AFB resulted in unacceptably high percentages of apples < 45 mm in diameter (pygmy fruit). It is recommended that Cytolin and NAA should not be used in the same spray programme. NAA alone is a...

Modelling thinning of Pome fruits

K.M. Jones1, S.A. Bound1, M.J. Oakford2 & P. Gillard3 1 Tasmanian Institute of Agricultural Science, University of Tasmania, New Town Research Laboratories, 13 St Johns Avenue, New Town, Tasmania 7008, Australia; 2 Department of Primary Industries, Water & Environment, Grove Research Station, Pages Road, Huonville, Tasmania 7109, Australia; 3 Department of Primary Industries, Water & Environment, Mount Pleasant Laboraties, Launceston, Tasmania 7249, Australia

Effect of biochar on nutrient leaching in a young apple orchard

Nutrient leaching from agricultural soils is a worldwide problem that has been implicated in deleterious impacts on the environment. Application of biochar to soil has been proposed as a means to reduce nutrient leaching and improve fertilizer use efficiency. The potential for biochar to reduce nutrient leaching and increase fertilizer use efficiency was tested by applying 47 Mg ha hardwood biochar before replanting a commercial apple () orchard, in the Huon Valley, Tasmania. Passive wick flux meters were installed at the base of the A1 horizon at a depth of 25 cm to monitor leachate volume and the concentration of nutrients leached below the A1 soil horizon over a 38 mo period. Biochar application significantly increased the concentration of phosphorous in the leachate, while having no significant effect on nitrate or potassium concentration. The volume of leachate collected in the flux meters was significantly higher in the biochar treatment, which resulted in significantly higher amounts of potassium and phosphorous being leaching from the biochar treatment than the control. Biochar application had no significant effect on either the concentration or the flux of nitrate leached from the A1 horizon. Nonetheless, nutrient application was well in excess of tree requirements, such that between 53 to 78% of the applied nitrogen, 5 to 11% of the applied phosphate, and 69 to 112% of the applied potassium were leached below the A1 horizon.

Assessing interactive effects between Cytolin and ethephon on cropping red 'Delicious'

A trial in north-western Tasmania studied the effects of Cytolin and ethephon sprays on the thinning and shape of ‘Delicious’ apples. Untreated control and hand-thinned treatments and trees sprayed with Cytolin alone were compared with trees treated with a full thinning programme (FP). This consisted of ethephon at full bloom (FB) and seven days after full bloom (AFB) or combinations of the FP missing out either the FB or the seven days AFB ethephon sprays, with or without Cytolin. Cytolin was applied at 25 mg l-1 at the king petal (KP) stage. Ethephon was applied at 100 mg I-1 at FB and/or seven days AFB. Cytolin alone had no effect on thinning. Omitting the FB ethephon spray from the programme resulted in underthinning and lower fruit weights. Adding Cytolin to the programme did not cause extra thinning or changes in fruit weight or pip numbers. There was evidence that ethephon thinning sprays reduce the length/diameter (LD) ratio of fruit but the addition of Cytolin to the successful programmes can res...

Thinning ‘Red Fuji’ apples with ethephon or NAA

SummaryA series of trials in Tasmania examined the thinning effects of ethephon and NAA on ‘Red Fuji’ apple. In the ethephon trials, concentrations from 25 to 600 ppm were applied at full bloom (FB) or 14 days after full bloom (AFB) to trees on either seedling or M.M.106 rootstocks. The NAA trial involved spraying concentrations of 5, 10 or 15 ppm at FB or 14 days AFB to trees on seedling rootstocks. Ethephon thinning of ‘Red Fuji’ was similar at FB and 14 days AFB. The dependence of fruit thinning on ethephon concentration was described by fitting non-linear response curves. These relationships were stronger and less variable for M.M.106 than seedling trees. Ethephon proved a satisfactory thinner for trees on both rootstocks. At the high spray volume used, the preferred concentrations at both FB and 14 days AFB would be 25 or 50 ppm for seedling and 100 or 200 ppm for M.M.106 rootstocks. NAA under-thinned at 5 ppm and over-thinned at 10 and 15 ppm at both FB and 14 days AFB. No firm recommendation can be...