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Thinning
As mentioned last time, the main hand thinning should be largely completed by Christmas. Exceptions to this rule are varieties which tend to show russet problems such as Pacific QueenTM where later thinning can be justified because you need to wait for russet expression to become obvious.
In early January a second pass of the hand thinning is often necessary on earlier thinned varieties to take out non-export quality or poor fruit which was missed on the first run through. Fruit growth curve data calibrated back to days after petal fall will identify the fruitlet size by calendar date to thin down to.
With thinning much after mid to late December sunburn to remaining fruit can become a significant risk if the crop is "bunchy". In these situations it is only safe to remove fruitlets which do not shade other fruitlets in the bunch.
By the way ENZAFoods is buying apple thinnings so where there is a substantial thinning job it's well worthwhile harvesting the thinnings. Where upper tree thinning is being done it's necessary to prevent the thinnings dropping down through the tree in order to avoid bruising damage to the lower tree fruit.
Placing these thinnings in a picking bag is a very convenient way to prevent them falling through the tree.
For badly hail damaged crops, taking this fruit off pre-harvest will give better utilization of harvest labour and more importantly take the crop out early so return bloom can be enhanced.
Sunburn Management
Once the hot weather hits, sunburn becomes a significant risk for sensitive varieties such as Pacific BeautyTM, Pacific RoseTM, Braeburn and Fuji.
Early thinning and breaking up bunches well before the hot weather arrives is the first step you can take. Where crops are heavy, preferential removal of exposed fruit in positions where sunburn is a problem is a good first step.
Overhead sprinklers are very effective for sunburn control if they are well managed. The key to success are a clean water supply with little in the way of dissolved calcium salts, or iron; and setting a realistic "turn on" temperature. Experience has shown us that sunburn usually occurs on exceptionally hot days only so it's those exceptionally high temperatures you have to protect against rather than the normal warm summer day. This means you need to set a relatively high turn on temperature, possibly in the region of 28 to 30oC ambient temperature.
Another technique worth investigating is the use of a kaolin based product called "SurroundTM". This product is now widely used in Washington State for sunburn. A programme of three to four sprays extending over the late December to February period is necessary. The first one should be applied at around 50 kg/ha and subsequent sprays at 25 kg/ha. As the white kaolin deposit is still on the fruit at harvest it's important to discuss its use with your fruit packer before applying it to make sure that he is comfortable with its use.
Apple rows planted North-East-South-West direction tend to be more at risk from sunburn than rows orientated so the sun is shining directly down the row during the hottest part of the day which, with our daylight saving, tends to be 2 to 3 o'clock in the afternoon. With these east-west rows, most of the fruit is inclined to set on the north side of the canopy so you also have a much greater proportion of the crop at risk to sunburn. Spraying "SurroundTM" onto the sunny side of these rows is well worth considering.
Be careful with summer pruning. Do not strip too much leaf cover out as the hot weather approaches.
Tree Training
Young trees with flexible branches in need of spreading should be trained between now and harvest.
Often all that is needed is to give the steeper branch a bit of a twist and the weight of the sizing crop load will hold the branch down in the desired position.
Because trees are making active growth, with branch thickening proceeding rapidly it only takes two to three weeks to set the branches in their new position.
This makes spacers or spreaders, eg light pieces of timber with "V" cuts in each end, a very efficient tree training tool. During the tree training period these spreaders can be used several times over which makes them very efficient. If you have a large block to do, training alternative rows first time round, then two to three weeks later when the "trained" branches have set in their new position the spreaders can then be transferred to the adjacent un-trained rows.
Some varieties with very stiff wood such as Pink LadyTM have an optimum branch size for training and once they grow past this size, training becomes very difficult. If you can get them at the right growth stage training is easy, leave it later and it becomes a nightmare.
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