Or­chard Man­age­ment

More fine tun­ing

The Orchardist - - Contents - By John Wil­ton

This month I will cover other very im­por­tant pre­har­vest hus­bandry prac­tices nec­es­sary to op­ti­mise fruit qual­ity.

Colour, flavour and tex­ture are the most im­por­tant con­sumer re­quire­ments. Ac­cord­ing to mar­ket re­search re­ports, high fruit colour’s main role is to en­tice newer con­sumers to buy the prod­uct. Re­peat sales are more de­pen­dant on the eat­ing ex­pe­ri­ence. This is flavour and tex­ture, with the lat­ter tend­ing to over­ride flavour. Fruit, when it gets to the con­sumer, must be crunchy and juicy. Any hint of mealy­ness is a big neg­a­tive and likely to stop fur­ther buy­ing.

Har­vest­ing, at op­ti­mum ma­tu­rity for stor­age is the key to main­tain­ing crisp­ness and juici­ness.

The crop has to be set up so this can be achieved. For most va­ri­eties the op­ti­mum har­vest win­dow is no more than two to three weeks.

Last sea­son ex­pe­ri­enced shock­ing weather over har­vest due to fre­quent rain. This in­ter­rupted har­vest, made meet­ing op­ti­mum har­vest ma­tu­rity dif­fi­cult and due to the de­lays fruit was softer and much more prone to in­jury by bruis­ing and stem punc­tures. Also, due to the rain, pre-har­vest fungi­cide cover was thin, so there have been is­sues with post-har­vest rots. All of these prob­lems have re­sulted in ex­pen­sive repack­ing off­shore. Avoid­ing these prob­lems is an easy way to im­prove grower re­turns, and much more ef­fec­tive than try­ing to re­duce costs by thin­ning down the spray pro­gramme.


Last sea­son in­ci­dences of these dis­or­ders were above nor­mal, partly due to the warm grow­ing sea­son we ex­pe­ri­enced. Pit and blotch is al­ways a big­ger prob­lem on ap­ples grown in warm cli­mates com­pared to cooler cli­mates.

Main­tain­ing the cor­rect nu­tri­ent bal­ance will help colour de­vel­op­ment.

As har­vest ap­proaches ni­tro­gen lev­els need to be al­most in the de­fi­ciency range. Leaves need to be pale, rather than dark green. Rel­a­tive to fruit, leaf is a rel­a­tively poor sink for ni­tro­gen, so once fo­liar ni­tro­gen lev­els move past min­i­mum ac­cept­able lev­els a small in­crease in leaf ni­tro­gen may in­di­cate a big lift in fruit ni­tro­gen con­tent. It’s the fruit ni­tro­gen level that de­ter­mines fruit colour de­vel­op­ment.

There is also some ev­i­dence to sug­gest that high phos­pho­rus lev­els rel­a­tive to ni­tro­gen will re­sult in good fruit colour.

Last sea­son, which was a rel­a­tively poor one for fruit colour de­vel­op­ment, I car­ried out some com­par­a­tive leaf and soil test­ing in a block of Scilate on M9 root­stock which was show­ing large dif­fer­ences in colour across it. These sam­ples were taken at the end of March.

The ta­ble be­low shows leaf anal­y­sis lev­els.

In these soils, phos­pho­rus lev­els were sim­i­lar, as were potas­sium and mag­ne­sium.

As with pH, soil cal­cium lev­els were very much higher where colour was good.

Where colour was good, soil was also less dense, and CEC sig­nif­i­cantly higher in­di­cat­ing a more fer­tile soil with a bet­ter root en­vi­ron­ment.

The ev­i­dence points to­wards the need or higher phos­pho­rus sta­tus but how you achieve higher phos­pho­rus lev­els is rather un­clear. Data out of Bri­tish Columbia re­ports in­creased yields in young or­chards from ap­ply­ing sol­u­ble phos­pho­rus through fer­ti­ga­tion over the flow­er­ing pe­riod. This has also been shown to lift tree phos­pho­rus lev­els sig­nif­i­cantly.

A few years ago, fer­tiliser com­pa­nies here used to sell mono-am­mo­nium phos­phate in liq­uid form. Used as fer­ti­ga­tion this would be ideal for lift­ing plant phos­pho­rus sta­tus.

Good leaf health is im­por­tant for colour de­vel­op­ment. Heav­ily cropped trees are very prone to mag­ne­sium de­fi­ciency as har­vest ap­proaches. The rea­son for this is that ripen­ing seed has a high mag­ne­sium re­quire­ment, so to sat­isfy this, leaf mag­ne­sium is mo­bilised and moves from leaves to seed. When se­vere, low mag­ne­sium can lead to leaf break­down.

The an­tho­cyanins re­spon­si­ble for fruit colour have a very high pho­to­syn­thate re­quire­ment so to get good fruit colour leaves must be healthy, there­fore a good fo­liar mag­ne­sium pro­gramme is nec­es­sary.

Ir­ri­ga­tion man­age­ment can play a key role in fruit qual­ity.

From left:

Fig 1. Last year we saw more pit and blotch than nor­mal in­clud­ing va­ri­eties not gen­er­ally prone to the dis­or­der such as this Scilate.

Fig 2. These Sciros were thinned to sin­gles, then pre­har­vest re­flec­tive mulch en­abled al­most all the crop to be pricked as soon as the fruit reached har­vest ma­tu­rity.

From left: Fig 3. Sciros trees in the same block as the tree in Fig­ure 2 af­ter the first pick. Fig 4. Har­vested fruit from the trees in fig­ure 2 and 3 in the bins. This line packed out at 78% whereas later picked fruit man­aged only 60% grade 1.

From left: Fig 5. This young Scilate tree was thinned to 10 fruit per cm² TCA. Note good fruit colour com­pared to fig­ure 6. Fig 6. Crop load here was 16 fruit per cm² TCA. Note poorer colour de­vel­op­ment com­pared to the lighter crop tree in fig­ure 5. Fi

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