Apple Harvest - Some Comments On Fruit Behaviour

For Royal Gala, the main early/mid season variety, there will be a range of harvest dates depending on site, rootstock, crop load and what if any growth regulator treatments have been applied.

For instance, this year in Gisborne light-cropping, Hicane treated, girdled Galaxy strain of Gala were ready for their first harvest early in the week commencing 21 January.

In Hawke's Bay, Hicane treated, mature dwarf rootstock Royal Gala that had been well thinned and given reflective mulch were ready for a very significant pick on 30 January.

As a general rule, dwarf rootstocks, particularly M26 will be the first to ripen, and then followed about a week later with similar cropping trees on standard rootstocks.

There are also differences in maturity between MM106 and M793 with the latter being about a week behind the MM106. For trees of similar cropping level, it is quite normal to see 10 days to 2 weeks difference maturity date between the dwarf rootstock and M793.

Tree age and wood age can also have quite an impact on fruit maturity. Young trees which carry most of their fruit on lateral bud of one year wood sites will ripen the bulk of their crop up to 10 days later than mature trees, fruiting mainly on spur wood.

In adolescent trees with a lot of 1-year lateral bud fruit in the upper tree, it is not unusual for the upper tree fruit to be about a week behind the lower tree fruit in maturity even though the fruit in the upper tree looks "redder".

For this reason, it is expensive and unnecessary to send pickers into the upper tree at the time of the first pick. However, before making the decision not to pick the tops with the first pick, it is necessary to go to the top and check the maturity up there carefully.

Trees with a light crop will mature their fruit earlier than those with very heavy crops. If you have got mixed cropping levels within a block, keep a careful watch on how the maturity is moving on the lighter trees. This year we are also receiving reports that maturity is advancing very rapidly in the fruit, particularly where the crop level is light. Because the flowering period was compressed this year, we can expect fruit maturity to move very quickly once it starts to move.

Growers have been asking how rapidly objective fruit maturity indices will move. This is a difficult question to answer unless one is familiar with the block, its cropping level and past history. Historical data from scientific sources suggests the following:

Starch

Slow to begin with - maybe a week to ten days to go from 0 to 0.7, then after another week will go to 2.5, then very rapidly up to 4.0.

Firmness

Expressed as kgf - at harvest will drop by about 0.6 a week, sometimes less, sometimes more. Storage data shows that only fruit taken in the first two or three picks will hold up above 6 after storage. So if you are planning to supply an English supermarket with high flesh pressure requirements, then make sure that you give them the earlier picked fruit.

Brix

Unless the starch degradation is well advanced at time of harvest, brix levels during storage can expect to lift by about two degrees.

The way things are shaping up this year, it looks as if harvest will be very rapid. To get the best out of the crop, the interval between picks will need to be somewhat less than a week - maybe even as close as four days. I would not expect much longer than a couple of weeks from the first significant pick in a block to the finish of harvest in the block.

For normal Royal Gala on MM106 wihtout any growth regulator manipulation, I would expect harvest in Hawke's Bay to start around 11 February.

Blocks treated with Retain. three to four weeks from harvest will be delayed by seven to ten days.

Our size monitoring working on days from full bloom indicates that average fruit size in Hawke's Bay this year may be around 110 count. Light crop blocks will be much bigger than this - we expect to see a number to come in with bigger average fruit size than 100 count. Some of the blocks we are monitoring have been showing a significant drop off in sizing rate, so there may be some surprises out there in regard to fruit size.

In general, the fruit is looking very good and well coloured this year. Very different from last season.

Colour Reversion

Over the period just before harvest it is a good time to check red sport varieties for colour reversion. They show up well at this time of the year. While the reduction in colour requirement in Royal Gala and the widespread use of colour sorters makes the colour reversion problem more manageable, it should not be ignored, particularly in younger blocks.

I suspect also there might be a bit of interest in grafting this winter, so if you are planning to graft to any of the red sports of Gala, it is necessary to select for trueness to type just before harvest while you can still see most of the fruit.

By the way, when it comes to collecting graft wood, or budwood for that matter, try and make sure it comes from fruiting branches and has arisen from a normal bud and not from an adventitious bud - eg, a watershoot straight out of the trunk or a heavy branch. Make sure the good and bad colour trees are clearly marked