Key to productivity in 2018
A high proportion of kiwifruit flowers survive through the season to harvest. This makes it relatively easy to quantify the amount of fruiting wood you need to bear your target crop.
Fruit is carried on ‘current’ seasons wood, that grows from wood that grew during the past season. In winter, you are laying down the wood that will produce new shoots next spring that carry the fruit.
Wood that grew for the full previous season tends to produce the most flowers. Only the first flush of shoots each season carries flowers, so seeing stalks from recently picked fruit is a good indicator of mature wood. The less suitable late-grown wood tends to be stalk-less and greener in colour.
Good sun exposure is another indicator of quality fruiting wood, which will depend on how open the canopy was through the last season.
Lower vigour wood has the buds closer together. Moderate vigour wood is usually most suitable at winter pruning as it has a reasonable length, helping you to fill the canopy, and plenty of prominent buds, close together, encouraging good flower production.
Use information from harvest and previous seasons to guide
Set a realistic yield target and allow for losses through the season including spring flower abortion and thinning off rejects. Figures from previous seasons monitoring are a useful guide. You can work back from your targeted yield to numbers of flowers required in spring. To convert those to quantity of wood at winter pruning, a key ratio
is flowers per winter bud. In a poor season this can be 0.8-1 on Hayward; whereas in a good season there may be around 2 flowers per winter bud. Knowing typical figures for your variety and orchard is a great help when setting up your winter pruning. Target fruit size is an important factor as large fruit size increases trays produced and vice versa. Because we are pruning before we know key factors like how cold the winter will be and how warm or ‘decisive’ the spring will be we need to build in a margin for variability.
It's a compromise! Assuming everything will go well for the rest of the season means you're at risk of producing below potential from normal seasonal variations. If you are too conservative, you can tip beyond having good control of production to potentially having a difficult vine canopy and high production costs.
As the winter progresses, you can refine targets a bit as you gauge what the winter chilling has been like. Remember though that winter chilling is not the whole picture for flower production.
If you have covered blocks in your orchard, you will be building up information about the flower to winter bud results and further losses during the season. Being significantly warmer
through the winter will reduce winter chill but a warm spring is hugely beneficial and should result in better retention of the flowers produced. You need to be conservative while you build up your information about the impact of covers but can fine-tune pruning as you develop records from a range of different winter and spring conditions.
Work your production targets back to winter buds required per square metre of female orchard canopy, by taking off the proportion of the orchard in male-vine canopy. When it comes to doing the actual pruning, you'll need a simple working version such as 'canes every 30cm on the third wire' or '15 canes per side per bay' to work with. Working to buds
per square metre is more appropriate when using lots of older wood where the winter buds are borne on spurs and short canes.
Fruit payment incentives reward good performance and reduced variability. Having the canopy more even across the orchard starts with even winter pruning.
When translating your targets to winter buds per square metre or canes per bay, the target needs to be adjusted if bays differ. Male vine layout can create a key difference between bays. Some male vine arrangements create 2 types of bays – those with some of the area occupied by male vines and those that are all female canopy. Bays with only female canopy need a little more fruiting wood to offset the reduced fruiting canopy in bays part-occupied by male vines. Otherwise, you may be creating un-evenness within the orchard or limiting your overall crop if the targets were worked out for the female bays then just less wood tied down in the male bays.
Spreading fruiting wood well across each bay helps production and quality. Every bay with below-target quantities of wood reduces your potential crop and ability to adjust to seasonal conditions. Unevenness between bays reduces the efficiency of your sunlight capture by crowding some bays and under filling others.
If you have vine restructuring to do, don't do it all in one season and reduce your production. Time and time again, I see vines where there have been significant cuts made that have reduced the crop below target potential. People say: “Vines have been given a good tidy up”; “it had to be done and vines will be in better order for next season”. They will be tidier but you may be rueing the lower yields driving your income over the next two years! Restructuring can be successfully spread over 2-4 years whilst maintaining potential productivity and income.
You can fill in gaps with temporary fixes: train an occasional cane parallel to the vine leader if you are short of fruiting wood close to the leader; bring a cane across from the other side of the vine to fill a gap; keep older wood where there are some good spurs on it that will fruit the next season. You can’t take these measures too far or you have chaos, unmanageable summer growth and potential issues with dense canopy, disease and poor pollination.
Review male vine size and positioning before you start pruning so you can benefit from any changes as soon as possible. You may be able to reduce the size of existing male vines and tie female wood into their place. Keeping the male rows narrow is especially important in a strip male orchard with narrow row spacing. Broad male vines can be occupying 20-25% of the orchard area with no gain in pollination– just reduced production.
Consider whether a hanging curtain opposite male vines is worthwhile for you. These miss out on a bit on sunlight so may be lower dry matter fruit but can be a significant production boost if you can keep the males well-trimmed and don’t bash all the fruit driving through the block.
Similarly, skirts at the edges of blocks provide useful production if there is room for them and the fruit is well pollinated. Having male vines in the outside row helps or timing supplementary pollination for these rows if they are a little later to flower.
Sick vines need to be tracked and dealt with. Training in a longer leader from a neighbouring healthy vine is a useful way to fill in a gap. If replacing the vine, add a generous amount of compost to the planting hole, especially if the block isn't irrigated. If you have Armillaria, sluicing is a successful treatment although you may want to do this later in the autumn or winter when the soil has cleared the excessive April rainfall.
If you’ve carried much of the crop on weak spurs on twoyear old wood, you may be having trouble filling up your orchard canopy. First check if there is some underlying issue like roots being water-logged, wind exposure or Armillaria that is holding back these vines. Fix that if you can.
In a canopy that isn’t strung, consider setting up strings just for the areas where canopy development is lagging. This exploits the vines natural growth habit of strongly growing upwards and it will be close to the leader so make good fruiting wood for you in future seasons.
Otherwise, ensure you make most cuts where you want to stimulate regrowth and not where you don’t want it. You don’t want to get into a situation where each year your best wood grows so far from the leader that you mostly remove it. You are likely best leaving winter wood with new growth some distance from the leader and cutting a neighbouring cane near to the leader to stimulate regrowth there.
Time spent training young vines is seldom wasted – this can include selecting a better trunk or leader than the one trained in already. Watch for tapes or ties strangling permanent wood – the trunks or leaders – and remove them.
How do you make the transition from a young-vine canopy where you ‘keep everything and just arrange it as best you can’ to an orderly canopy where there is enough fruiting wood to renew a good proportion of it each year? Compromise! Make some of the hard cuts but leave enough wood to make your target even if it is not the wood you really want.
All pruning creates a disease entry site so ensure coverage with preventative sprays fits around your pruning and aim to prune dry vines in fine weather as much as practical. Larger cuts should be protected, with smaller sizes treated if you have to work in less favourable weather. Clean pruning equipment regularly and mark disease cankers for hygienic removal.
Tying down is a big part of the success of the whole winter pruning job. Vines left with the right quantity of wood and cuts made in the right places need to be tied down with the cane as evenly spaced as possible to make best advantage of the sunlight that will be captured by the leaves.
Breakages may well occur at tying down – made worse if there is cicada-damage to canes or when tying down on frosty mornings. Tying as you go helps to assess whether you are getting the intended numbers actually tied into bays – you may need to leave 1-2 canes more per bay at pruning if there's a significant number of breakages. Watch also that any cuts made to the ends of canes at tying down are appropriate as shortening each cane can put your bud numbers behind target and it often removes closely-spaced buds.
Where you just don’t have the numbers you want, still space canes further apart even if they radiate from the leader rather than being arranged at right angles to it. They will capture
more sunlight, need less summer work and may help to lift wind above the canopy too.
It’s the tying down that also makes your ‘fixes’ work – those canes left to fill in the area around the leader only do that if they’re tied into the right place! Otherwise, they just clutter and don’t capture the additional light and space you intended.
If you are grafting to a new variety this winter you’ve probably already decided your strategy. You need to create light and space for the new graft to grow and tend it well through the season. Some growers have had good success notch-grafting so producing one more crop while the new variety gets established. However, done badly, both crops can suffer.
If you are notch grafting, I'd aim to graft quite high on the trunk so you have more mature rootstock trunk available for girdling or future variety changes. The exception to this is if you are removing Hort 16A and need the graft low enough to remove all that variety.
Also don’t neglect the parts of the orchard staying as they are – they are the areas providing the cash flow while you get back to full production! There will be flow-on impacts from the wet autumn in 2017. The most severe effects are on those orchard areas where the vine root systems were flooded for several days. Even where vines and support structures have come through the flooding intact, these vines will have suffered from lack of air in their root zone. Kiwifruit are especially sensitive to this.
There will also be effects on small areas in many orchards like where vines in a dip suffered root zone waterlogging. Some of the vines I’ve seen had browned leaves on their replacement canes within a couple of weeks as a result of the waterlogging. Impacts are likely to continue to show up in the spring, as poor or delayed budbreak, poor spring growth and small fruit size. Strategies you can use to help vines recover include:
Avoid sending heavy machinery through affected areas, especially while the soil is still wet. This weight will further compact the soil while it is in a sensitive state, reducing soil aeration for longer. If you have to take gear in there, stick to existing wheel tracks and reduce weight where possible – such as by doing that area towards the end of a tank of spray when there is less weight.
• Omit ActigardTM on these vines as the defensive-response
it generates in the vines may further stress them.
Clear silt from around the vine trunks so it doesn’t create a crust that further blocks air from getting into the soil.
• Add a generous amount of organic matter around the vines in the affected area – but not touching the trunks - this provides good material for new roots to grow in which will help the vine to recover.
If water collected from ponding or run-off, adding local drainage or clearing existing drainage pathways can help. Where possible divert run-off from areas like tracks away from the vines into tolerant areas.
Restrict the cropload on vines in affected areas for the 2017/18 season. The vines need leaf area to help the roots to recover so don’t do this by harshly winter pruning the vines. They have reduced cropping capacity while they recover, so thin flowerbuds early in spring back to a low or moderate crop load.
If you have strings, train shoots onto them early in spring and keep going back to direct growth up the strings – you might need to do this as often as weekly during rapid periods of growth.
Make flower counts in spring as soon as you can be confident the buds you will count are unlikely to abort.
If you have excessive flower numbers so a big thinning job – you can help contain costs and still improve the relative leaf area by tweaking off whole shoots that have weak growth and many flowers.
In summary, winter pruning by choosing enough suitable wood to accommodate a range of growing season conditions, tied down well, is key to good kiwifruit orchard productivity in 2018.
In most situations, fruit packing will not be finished for another couple of months and the prices received for the crop maybe four to six months away. Gross production, usually expressed as bins harvested, should already be known on a variety by block basis so it is possible to rank block and variety performance.
While not all of the fruit is packed, a substantial proportion of most varieties will have already been packed, so this should
give a reasonable indication of how well the crop is likely to pack out. Bay. This delayed bud break and probably also compressed it. There was further heavy rain in the preflowering period which meant that by the fruitset period some blocks on heavier soils or adjacent to rivers, had rather wet soils. We believe these wet soils adversely affected fruitset in some places.
From the end of September until the second week in February, very little rain occurred giving ideal weather conditions for growing high quality fruit. Temperatures during the first 50 days after full bloom were above normal so conditions were ideal for fruitlet growth. High temperatures above 30°C around the end of November caused some sunburn which later turned to russet. Later high temperatures during December and January, when there were a number of days with maximum temperatures above 30°C had less effect on sunburn than we would normally expect from these temperatures. High temperatures generally came with a lot of wind which we think maintained fruit surface temperatures near ambient air temperature and this as well as the long period of sunny weather that preceded this hot weather conditioned the fruit to the heat and was probably responsible for the relative lack of sunburn issues.
Although the summer was warm and dry, there were good diurnal temperature regimes as we ran into harvest so fruit colour on the early varieties was very good. With this good colour packouts have been very good with many lines packing 90% or more Grade 1 export.
Since it started raining in early February, some parts of Hawke’s Bay will have had over 300mm, almost twice the normal rainfall for this period making for very challenging harvesting conditions. It has also meant a lot of cloudy weather with warm nights so getting colour into the later varieties has been a challenge.
As with the wind earlier on in the season, the wet conditions have lead to further instances of trellis failure, so as mentioned last month, support trellis repair and maintenance will take fairly high priority once the crop is off.
Harvesting in wet conditions creates a lot of mud through the orchard. With high yields, many orchard blocks are harvesting between 200 and 250 bins per hectare.
This represents between seven and nine bins per 100m of row length for orchards planted at 3.5m between rows.
Most orchards use heavy tractors with bin forks to shift bins which means double handling of the bins, so you are looking at something like 14 to 18 tractor trips in and out of each 100m of row. This does not take long to create a quagmire, not to mention the compaction problems this level of heavy traffic will cause on wet soils.
Several large orchard properties here have begun harvesting into bins carried on a train of trailers pulled by light weight tractors. As the “bin train” usually consists of four or five bins this means only a couple of trips down each row so there is hardly any significant damage to the orchard floor compared to bins handled individually by tractors with forks. Another major advantage of the trailers is that the bins do not come in contact with the orchard floor so are free of mud.
Mud can become a real problem when bins are being moved around by tractors and forks. Muddy bins also represent serious risk factors for post harvest rots.
The wet autumn has been ideal for rampant weed growth. Aggressive grasses such as paspalum, as well as similar broadleaf weeds, eg mallow, have flourished this autumn. Some mallow have taken on the appearance of small shrubs with woody stems. Once weeds of this type get out of control, they are no longer easy to control.
Generally, I am not keen on post harvest herbicide clean up sprays because I like to maintain good soil cover over the winter. Also, where orchards are being grazed by sheep, these animals do a pretty good job of dealing to the weeds.
Grazing recently planted orchards is not advisable due to the potential damage they may do to trees unless the grazing is very well supervised. With the amount of hard to control weeds that are thriving in orchards this year, applying a good post harvest herbicide is probably a good idea. It is much easier to control these difficult weeds in the autumn because there is better translocation of herbicides down into the root system.
Activated Amitrol is a good herbicide for autumn clean up weed control because it is generally not used during the growing season and covers a different weed spectrum to glyphosate. Where mallow is the dominant weed, it may be necessary to use fluroxypyr.
be certain of their effectiveness. These are hydrated lime at 1kg per square metre cultivated into the soil along the planting row. Width of the treated strip is unknown but I would think probably 1 to 1.5m width with the trees in the centre of the strip. This treatment has performed as well as Basamid® in Tasmanian studies. Here, I have seen it perform well in an apple nursery situation.
Formalin is also reported to be an effective SARD treatment when applied to wet soils and is much less temperature dependent than other soil fumigants. Growers who have tried it report that there are application problems due to the large amount of water needed to drench it into the soil.
Where replanting is planned, life is a lot easier if the new trees can be planted well before bud break. This minimises the fireblight risk by avoiding late flowering which can be a major problem with late planted trees and also gives tree growth a full growing season to maximise early tree development.
It is very important to make sure newly planted trees grow well right from planting. Where there has been good tree development in the first year, it is possible to carry a significant crop of good quality exportable fruit in the second year. The ultimate success of any new orchard planting depends on rapid canopy establishment. This is largely determined by how rapidly the trees grow in the first couple of seasons. Making young trees grow well is much more important than tree planting density and usually much less expensive than planting trees closer.
Assess soil quality before planting to identify limiting factors to tree growth. This means both a physical examination of the soil to determine soil depth, texture and drainage and soil testing to determine soil organic matter level, pH and nutrient levels.
The benefit of early planting cannot be over emphasised in regard to young tree establishment and growth. A ready supply of soluble phosphorus has been shown to markedly improve young tree growth, even in soils with what appears to be adequate phosphorus levels. Mono-ammonium phosphate (MAP) is often used around young trees to stimulate growth. About 100g per tree is the application rate. The best way to apply this fertiliser for intensive plantings is to broadcast it along the row. Do not be tempted to put it in the planting hole. I have seen too many trees killed with fertiliser in contact with the roots.
Drainage to avoid soil waterlogging is much more important than irrigation for young tree growth unless the soil is very light and sandy with low moisture holding capacity. On soils with good moisture holding capacity and a favourable environment for root growth, it is possible to grow young trees well without the need for irrigation as long as their root systems are well established before hot weather with wind and high evaportranspiration rates arrive.
Generally, irrigation is recommended for maximising young tree growth in intensive orchards on precocious dwarfing rootstocks. They key is knowing when and how to use it properly. For intensive plantings, I prefer drip systems rather than sprinklers unless the latter are required for frost protection.
Because we are pushing orchard performance to its upper limits and dwarfing, precocious rootstocks tend to have limited rooting volume, the irrigation system needs to have fertigation capability.