WelcomeRecent successes that are already benefitting the pipfruit industry include:
HortResearch acknowledges the significant support that it receives through research contracts from the NZAPMB, from Government through contracts from the Foundation for Research, Science and Technology, and from a wide range of commercial clients.
We invite you to fully participate in the field day programme. Seek answers to your questions, interact fully with our staff and guest speakers, and take advantage of the new opportunities being presented to the fruit industry.
Enjoy the day!
Dr Ian Warrington
Chief Executive Officer
New management strategies for apple black spotThe Integrated Fruit Production (IFP) initiative which has been introduced this season by ENZA has given a sharp focus to disease management research required to cope with stricter requirements for pesticide use in apples.
IFP does not necessarily mean that fewer fungicides will be used for disease control. The philosophy of IFP is that fungicides will only be applied where their use can be justified. This may lead to a reduction in fungicide use in some situations. We need ways to better assess disease risk so that fungicides can be applied more precisely when they are needed, however, any modification of standard spray programmes must ensure that there is no increase in risk of disease control failure.
Current research is developing methods to assess disease risk more accurately. This requires precise monitoring of disease activity in the crop to determine:
1) When weather is suitable for infection (weather stations and Mills' periods)
2) When ascospores are being released in spring (ascospore monitoring service)
3) Threshold disease levels to trigger appropriate fungicide responses, including:
a) black spot and powdery mildew levels at key growth stages
b) assessment of potential ascospore dose at leaf fall in autumn.
Potential Ascospore Dose (PAD)
Correct fungicide management requires information on numbers of ascospores available in spring in individual orchard blocks. This helps to determine whether or not a fungicide is needed in response to a particular infection period. Methods developed by Prof. MacHardy in New Hampshire will be evaluated under New Zealand conditions in a new research programme to be initiated this autumn.
PAD assessment involves determining the amount of black spot on leaves just before leaf fall in autumn and using a formula to calculate the potential number of ascospores that could be released the following spring. Included in the research programme will be a study of the effectiveness of autumn urea treatment in reducing PAD and an evaluation of the possibility of using PAD and sanitation practices to delay or reduce the use of fungicides in spring.
New chemistry for black spot controlStroby WG - a new fungicide for the control of scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha) on apples.
Stroby WG, a fungicide from the strobilurine class, gives excellent control of
Venturia inaequalis and Podosphaera leucotricha on apples. Against V. inaequalis Stroby WG has a preventive effect, by preventing spore germination, and also curative effect in that it prevents further sporulation of the fungus. To achieve these effects, it should be applied as a block treatment consisting of several applications. The preventative and curative effects combined with its good rainfastness provide unusually long-lasting protection against leaf and fruit scab.
Management of silver leaf and virus diseases to maximise profitability on Golden Queen orchardsIntroduction
Imports of cheaper canned peaches are a real threat to the New Zealand process Stonefruit industry. To counter such competition and to grow the export side of the process peach industry it is clear that;
1. The average yields of Golden Queen peaches [currently 25t/ha] must be raised to around 45t/ha so that the crop will continue to return a healthy profit to the orchardist and the processor.
2. The integrity of the Wattie label and NZ’s clean green image [producing pure foods from an unspoilt environment], must be supported by the adoption of integrated fruit production methods .
The Solution
Previous research shows that better tree health is the key to the improved orchard performance required. To achieve such large gains in fruit yields, HortResearch, Rex Graham & Associates Ltd., the Summerfruit Sector of NZ Fruitgrowers Federation and J. Wattie Foods Ltd. linked as partners in a three year Technology for Business Growth Scheme.
This programme addresses limitations to production [hence profitability] and ensures that fruit is produced using environmentally sound growing practices, by;
1. Controlling pests and diseases of Golden Queen peaches - using new disease management technologies and insect monitoring to minimise use of pesticide sprays [integrated fruit production].
2. Producing virus free peach trees - using up-to-date virus detection, elimination and plant propagation technologies.
3. Reducing the impact of silverleaf disease - on the productivity of peach trees in commercial orchards.
1. Integrated fruit production
Objective 1 uses co-operating orchards as models for the rest of the industry to follow an integrated approach to pest and disease management. Significant reductions in pesticide usage have been achieved by threshold spraying from pest monitoring and pre-infection spraying using infection period forecasts. As the integrated fruit production objective has been extensively reported in the No.1 newsletter to Wattie growers and at RGA field days, we will now discuss the other two objectives in more detail.
2. Stone fruit viruses.
The two major viruses, Prunus Necrotic Ringspot and Prune Dwarf, significantly reduce the yield and quality of fruit from infected trees. Prune dwarf also shortens the productive life of peach trees.
Prunus Necrotic Ringspot Virus [PrNRSV] is widespread throughout Prunus species, being rather symptomless in New Zealand. Prune Dwarf Virus [PrDV] also infects apricot, cherry plum peach and nectarine. In New Zealand it has been found only in trees already infected with PrNRSV. The resulting disease, peach rosette (called peach stunt overseas) leads to progressive stunting of shoot growth [moving out from the point of infection]. Such symptoms on lightly infected trees may become obscured by tree growth after December.
HortResearch was contracted over three seasons to determine the rate of spread and effects of virus infection on Golden Queen tree performance in the Hawke’s Bay.
Effects of virus infection on tree performance.
We found that PrNRSV reduced saleable yield by an average of 17%, and PrDV by a further 21%, a combined total of 38% for the peach rosette complex. Virus-infected trees set fewer fruit and had higher levels of fruit splitting than virus-free trees. Over 3 seasons the cumulative gross return was reduced by over $14, 000 per hectare on trees infected with both viruses [see graph].
Of major concern was the fact that production from trees infected with both viruses continued to decline, even though the trees were still approaching maturity [going from year 5 to year 8]. Fortunately, PrNRSV infected trees [without PrDV infection] did not show a continuing decline in tree productivity over time.
These results are supported by similar work in Australia and the US, where a reduction of 30% in yield resulted from peach rosette disease.
Virus spread
1. The use of infected rootstocks and or scion material is the principle means of infection of newly planted orchards. This would certainly be so for PrNRSV as the disease is symptomless hence both rootstock and scion are likely to be infected. PrDV would be expected to be mainly transmitted via rootstock, as the stunted growth of infected trees would not be selected for budding. However in the first year of infection, trees are symptomless.
2. Both viruses can also spread by infected pollen vectored by bees. In our recent survey, where a clean orchard was planted about 300 m from an infected block, by year seven 59% of trees had PrNRSV and 1% had PrDV infection. Another study [DSIR] in the 1970’s using Golden Queen orchards initially planted with virus free trees [near Auckland] found that by year seven, 20% of the trees were infected with PrNRSV.
Management of Virus Diseases
The principle control method is to start with virus-free trees and to avoid infection for the maximum time possible by locating plantings away from infected Prunus and removing PrDV-infected trees. It may also be important to avoid using hives that have been used in stone fruit over the previous two weeks. US virologists have suggested that thrips may assist in the transmission of these pollen borne viruses. This is unproven, and future research may determine the importance of thrip control.
Currently, virus-free trees are being propagated from a DSIR source of Golden Queen. Also a selection from a Hawke’s Bay orchard has been virus-eliminated at Mt Albert Research Centre. This selection is now undergoing bulking up using tissue culture. Also it is anticipated that all future releases from Quarantine, will also be multiplied using virus-free propagation techniques.
It is then planned that this virus-free scheme will be carried through to the production of Summerfruits where the benefits of higher yield and reduced fruit splitting will assist industry profitability.
3. Silverleaf Disease
Silverleaf, caused by the wound pathogen Chondrostereum purpureum, is a major disease of stone fruit as it reduces the productive life of trees and reduces fruit yields.
The characteristic silvering of the foliage is caused by fungal enzymes which cause leaf cells to separate and degrade. This results in reduction of photosynthesis, increased respiration and reduced transpiration. Hence it is common for silverleaf-infected trees to exhibit reduced growth and produce fewer, poorer quality fruit. Silverleaf disease in stone fruit usually leads to premature tree death, further reducing orchard yields.
Effects of silverleaf disease on tree performance.
To assess the effects of silverleaf on yield and fruit size, the total crop from infected trees in 1996 was picked and weighed. Fruit defects were also recorded. The results [Table 1]. showed that;
1. Silverleaf has a marked affect on tree productivity, with a 37% yield reduction in moderately silvered trees and 80% for heavily silvered trees,
2. Fruit from heavily silvered trees were larger - most were over-mature and affected with brown rot,
3. Fruit from moderately silvered trees also exhibited more brown rot than fruit from healthy trees.
Table 1: Effect of Foliage Silvering Intensity on Fruit Size and Weight
|
Tree Health |
Mean Fruit Diameter (mm) |
Mean Fruit Weight (g) |
Yield per Tree (Kg) |
|
Control Moderately Silvered Heavily Silvered |
63.5 a1 66.4 b 65.9 b |
123.5 a 134.0 b 130.0 b |
59 37 12 |
Management of Silverleaf Disease
Silverleaf control is necessary in the nursery to ensure the disease is absent in trees offered for sale. Inspection of nursery blocks during 1995 and 1996 emphasised the need to apply two coats of Garrison to rootstocks following heading back. A single coat is absorbed into the xylem tissues giving poor coverage of the cut surface.
In most orchards it is estimated that 5-10% of new trees are infected each year. Infected trees often die within 2 years leaving gaps in the production block. In orchards with wide plant spacing [350 trees/ha] tree losses have an immediate and significant impact on cash flow. The silverleaf fungus discharges spores and infects pruning wounds during wet periods. Trees are least-susceptible to infection over the autumn period and most-susceptible in late-winter and spring.
It is most important, particularly in young plantings, to;
1. Practice post-harvest (summer) pruning - April to early May.
2. Apply effective wound dressings [such as Garrison] to all wounds on the main stem.
3. Apply preferably two coats to large pruning wounds.
4. Conduct good orchard hygiene by removing dead infected wood that would otherwise produce spores.
5. Make cuts correctly, avoiding ragged and split wounds that allow ideal infection sites.
In Summary
The adoption of the new technologies delivered by this information transfer programme will lead to more productive and longer-lived Golden Queen orchards. Improved disease and pest control will also result, with the benefits of lower chemical residues on the fruit and growing practices that are environmentally sound.
This will lead to higher sales of canned stone fruit and greater, more-sustainable yields; that is, better returns for the grower and processor alike.
Use of apple starch in determining maturity and qualityDefining harvest maturity as the condition at picking that ultimately provides acceptable consumer quality, implies a measurable stage in the development of the apple that consistently relates to storage life and market quality. Starch content is a major compositional factor affecting fruit quality that may be estimated by practical objective measurement. Starch accumulates in the apple during fruit growth and is converted to sugars as fruits mature and ripen. Apples attain commercial quality when harvested after the onset of starch degradation but before excessive depletion of reserves for the intended storage life of the fruit.
The progression of starch degradation is measurable with potassium iodide/iodine solution which stains the amylose component of apple starch a blue/black colour. The relative stage of apple maturity may be judged by comparing the stained apple pattern with a numbered starch pattern index chart and the recommendations provided for the cultivar. This is a most important factor to consider in assessing fruit development as it assists judgments that may be unreliable when based on visual indicators alone such as skin colour.
The practical usefulness of maturity indicators ultimately depends on the extent to which they contribute to the prediction of quality after storage. Seasonal and orchard factors often contribute to variation in quality independently of starch pattern index values. In our recent research, quantitative changes in apple starch are being measured and related to starch pattern indices and other measures of maturity. Both the timing and pattern of quantitative starch losses has been found to differ from that indicated by starch pattern index. This work is exploring opportunities for improving our interpretation of starch changes in relation to fruit quality.
Tree / row / volume spraying made easy• how it works
• when it works
• how you can do it
•and what it might save you
Backgound to TRV spraying
It has always been difficult to decide how much spray/chemical is required for thinning and pest and disease control on different sized trees. The Tree Row Volume (TRV) spraying concept came out of America in the mid eighties when apple growers there experienced variable thinning responses on new plantings of smaller trees on different training systems.
Over the last ten or more years we have seen a widespread trend in NZ toward more intensive plantings with smaller overall tree sizes. The old standard spray volume in the USA was a somewhat arbitrary 3,800 L/ha (400 US gallons per acre) typically applied to globular multileader trees of 7m or more in height and spread, planted on 9 m row spacings. Not so very long ago in New Zealand most people considered 2,500 L/ha the standard dilute spray volume required to spray to the point of runoff on MacKenzie centre leader apples. Most people now consider 2,000 L/ha an appropriate dilute spray volume - but is it really?
The TRV concept and calculation
The American researchers who developed TRV spraying looked at different ways of describing tree canopies in relation to the spray deposits achieved and found that the volume down rows that was potentially occupied by tree canopy was a good predictor of the spray deposits achieved across a wide range of training systems. The Americans calculated Tree-Row-Volumes by multiplying tree height by maximum spread,and dividing this by the row spacing. This is shown in the formula below, where the 10,000 figure is the number of square metres per hectare, which gives the number of cubic metres of Tree-Row-Volume per planted hectare.
| Height (metres) X Spread (metres) X 10,000 | ||
| USA-TRV (m3/ha) | = | |
| Row spacing (metres) |
To work out the spray volume required for any given canopy it is necessary to estimate how many cubic metres of TRV could be covered per litre of dilute spray mix. The American researchers found that one litre of spray mix could cover 7.5 cubic metres of TRV on a dense canopy and as much as 11 cubic metres of TRV on more open canopies.
Thus for any given canopy, the estimated TRV is divided by an appropriate coverage figure to obtain the litres per hectare required to apply a dilute spray to the point of runoff.
This concept and calculation was introduced to New Zealand in the mid to late 1980’s - unfortunately it didn’t work on our trees.
Making TRV work on NZ canopies:
Step 1 =Measurement of TRV
The USA-TRV calculation assumes a rectangular tree profile (looking down the row) and works well when you are dealing with trees that look like that. In NZ most of our trees, including multileader stonefruit, assume more of a triangular profile and fill on average only 40 to 70% of the rectangle estimated by the USA-TRV calculation. It should come as no surprise then that the USA-TRV calculation frequently overestimates the spray volumes required on NZ canopies by up to 60% (see example at the end of these notes).
If you are dealing with truely triangular tree profiles a simple correction for the USA-TRV calculation is to halve the TRV estimated from a rectangular profile. This approach is widely used on dwarf plantings in Europe now, with the modification that tree height is measured there as the crown height (i.e. height from first foliage to the top of the tree) and tree spread is measured at the mid crown height (i.e giving about half the maximum spread). To use this calculation for trees with a triangular profile, just use the half crown spread and crown height instead of the maximum spread and full height figures used in the USA-TRV equation (above).
Figure 1: Measurements used in three different methods for estimating TRV.
In practice few trees assume a true triangular or rectangular profile down the row and we have adopted a calculation system where tree spread is measured at half metre height intervals. This allows TRV to be estimated as a stack of small rectangles, which are simply added together to obtain a Height-Stratified estimate of TRV (HS-TRV).
Figure 1 shows the different measurements used to estimate tree row volumes for the three measurement systems discussed above. An example calculation for HS-TRV measurements is given in Table 1 on the final page.
Making TRV work on NZ canopies:
Step 2 =Choosing A Spray Coverage Volume
Each litre of dilute spray mix has the potential to cover a finite surface area of leaves, fruit and branches. The extent and efficiency of cover is influenced by many factors, including drop size, sprayer air speeds/volumes, weather conditions and canopy density. TRV canopy concerned is currently the most uncertain part of using the TRV system for sprayer calibration. From our experiments comparing coverage on seven different NZ canopies, we have achieved consistent and equivalent spray deposits at full leaf using 11 m3 of TRV covered per litre of dilute spray mix. In those experiments deposits were significantly lower than targetted on only one very dense canopy (over 5 metres tall and planted on 4m row spacings), and was significantly higher on very open dwarf trees. At this stage we believe that the 11 m3/L figure can be used reliably on most canopies for most sprays. For thinning and late dormant mealybug sprays it may be advisable to increase the volume applied by going to the 7.5 m3/L figure used by the Americans for dense canopies.
Making TRV work on NZ canopies:
Step 3 =Seasonal Spray Volume Adjustments
A recent modification in the use of TRV spraying by some American states has been the introduction of a Stage of Growth Factor. This assumes that a full leaf coverage figure can be adjusted to apply less spray early in the season when there is less canopy present to spray and coverage is easier to obtain. An argument against this approach is that, for most diseases at least, there is more pressure early in the season. Therefore the use of a single coverage figure all season will give higher chemical deposits in the spring when they are most needed. Most NZ growers currently make spring spraying adjustments by driving faster early in the season - that sort of practice is not at odds with TRV spraying and there is no reason why it should not continue, provided the spray reaches all parts of the trees. It is worth noting that seasonal growth in mature slender spindle blocks can give a 30% increase in TRV from dormant to full leaf. If HS-TRV measurements on such a canopy indicated that it required 2,200 L/ha at full leaf, this would imply that early season sprays at around 1,550 L/ha should result in an equivalent pesticide dose. The best option in determining seasonal spraying requirements is to measure HS-TRV’s in the spring and again around December.
Making TRV work on NZ canopies:
Step 4 =Concentrate and Dilute Spraying Techniques
Dilute spraying using the TRV approach is undertaken just like any other dilute operation, the only difference being that the sprayer usually needs to be calibrated to provide three or more different spray volumes on a typical orchard. A set of swingover nozzles and some switching of nozzles on or off in different blocks can usually provide three or more appropriate volume application rates for different canopies. However, there will be situations where further nozzle arrangements are required - representing a need for additional nozzle rings, multihead swingovers, or other exotic sprayer nozzling arrangements. Whether such modifications can justify their cost will depend on each orchard situation concerned.
Concentrate TRV spraying can either involve altering spray volumes, or, more simply, use of a fixed volume with changes to the rate of chemical in the tank. In the latter case, a concentrate rate should be selected that allows the greatest possible volume to be applied with spray droplets of an efficient size range [ A rough rule of thumb regarding drop sizes for efficient spray use is that average drop size, or VMD, should be around 120-150 microns, with 90% of the droplets less than about 250 microns in diameter.] , without producing runoff on the smallest TRV canopy to be sprayed (typically 3X concentrate on the smallest canopy). This spray volume is then used for all concentrate applications and the TRV estimates are used to alter the amount of chemical that is added to the tank for blocks with different canopy sizes. This approach to spraying is simple in terms of sprayer calibration, but requires that the blocks of different TRV’s are large enough to justify separate tank mixes. As with all concentrate spraying it is recommended that a flow meter or similar monitor is fitted to the tractor.
For both dilute and concentrate TRV spraying it is essential that block sizes are known and that different blocks are identified as belonging to one of several possible TRV size classes. TRV measurements need to be made for at least one representative block from each identified size class. Note that TRV and spray volume estimates are influenced by row spacing and application volume requirements need to be estimated separately for similar sized trees on different row spacings.
Example: Cost-benefits of TRV spraying
Taking a fairly typical NZ orchard as an example, we have measured HS-TRV’s ranging from 18,000 to 30,000 m3/ha. The smaller HS-TRV figures were for typical slender spindle Red Delicious and Braeburn trees, while the larger figures in this case were for vigorous Fuji trees. Some of the range in HS-TRV figures was also related to different row spacings, which were 4, 4.5 and 5 metres on this particular property. Despite the large variation in HS-TRV estimates, all of the trees were between 4.5 and 5.5 metres tall. The grower therefore had made no spray volume adjustments between the different canopies, all of which were sprayed at the magic 2,000 L/ha (or a 3X concentrate of this) once they were in full leaf. We estimated that a coverage figure of 11 cubic metres per litre of dilute spray mix was appropriate for all of the blocks on the orchard (i.e. non were overly dense). Therefore, our estimated spray volume requirements for this property ranged from 1,600 L/ha up to 2,700 L/ha. In this case there were more blocks with smaller trees and the grower would have been able to reduce both the total orchard spray bill and spraying times. More importantly perhaps, under a Tree-Row-Volume calibration the larger trees were not placed at risk of inadequate pest and disease control through not enough pesticide being applied by the standard 2,000 L/ha application.
Whether TRV spraying represents a potential increase or decrease in chemical and spraying costs depends entirely on the mix of different blocks on the orchard concerned. Either way it allows objective estimation of sprayer calibration and operation requirements.
TRV Refinements
There appears to be potential for early season sprays, or applications to particularly open canopies to use coverage figures in excess of 11 m3/L of dilute spray. We are currently involved in ENZA and Crown funded projects to examine different aspects of TRV spraying. In particular the potential to obtain objective estimates of canopy density that can be used to identify appropriate coverage figures. We also hope to show that HS-TRV figures can be used to describe spray volume requirements in different parts of trees. This will allow improved the calibration and operation of tower sprayers, especially for thinning sprays.
Table 1: Example HS-TRV Calculation and Dilute Spray Volume Estimation
| Date | Jan 1997 | Cultivar | Royal Gala | |||||||||||
| Block | Front | Rows | 5 m | |||||||||||
| LHS | Tree | RHS | Full | TRV for | ||||||||||
| Spread | Height | Spread | Spread1 | Segment2 | ||||||||||
| 6.0 | 0.0 | 0 |
HS-TRV =21,100 m3/ha
Maximum Spread =4.2 m
Assuming one litre dilute spray covers 11 m3 of Tree Row Volume the estimated volumes required to reach runoff in this example are: | |||||||||||
| 5.5 | 0.0 | 0 | ||||||||||||
| 0.2 | 5.0 | 0.2 | 0.4 | 400 | ||||||||||
| 0.3 | 4.5 | 0.4 | 0.7 | 700 | ||||||||||
| 0.6 | 4.0 | 0.8 | 1.4 | 1,400 | ||||||||||
| 1.0 | 3.5 | 1.1 | 2.1 | 2,100 | ||||||||||
| 1.3 | 3.0 | 1.3 | 2.6 | 2,600 | ||||||||||
| 1.5 | 2.5 | 1.6 | 3.2 | 3,100 | ||||||||||
| 1.8 | 2.0 | 1.9 | 3.9 | 3,700 | ||||||||||
| 2.0 | 1.5 | 2.2 | 4.2 | 4,200 | ||||||||||
| 1.3 | 1.0 | 1.4 | 2.7 | 2,700 | ||||||||||
| 0.1 | 0.5 | 0.1 | 0.2 | 200 | ||||||||||
21,100 |
||||||||||||||
1 The sum of the left and right hand spread measurements
|
||||||||||||||
Integrated Fruit Production Presented by: Jim Walker
Co researchers: P.W. Shaw, S.J. Bradley, V.C Murrell & P.L. Lo
HortResearch
Havelock North & Nelson Research Centres
Approximately 80 orchards around the country are involved with the ‘pilot’ Integrated Fruit Production (IFP) programme. These orchards are evaluating the proposed pest management procedures including pest monitoring methods and thresholds. The Hawke’s Bay and Nelson field days present current research into IFP pest management which may be adopted as part of the programme.
Leafroller and codling moth
The basis of leafroller and codling moth control in the IFP programme is tebufenozide (Mimic) but alternative products (eg lufenuron or Match), which are also highly selective, are being assessed for insect control and tools to manage any potential for resistance in these new selective insecticides. Leafroller treatment response thresholds are also being tested against the current threshold of one infested/damaged shoot (or fruit) per 200 against one per 400.
IFP programmes are also being monitored on commercial orchards in Nelson and The Hawke’s Bay. In one sample of seven Hawke’s Bay IFP growers, with a total of 30 separate cultivar blocks, an average of 2.4 insecticides per block had been applied between petal-fall and January 20, 1997. Growers report finding low levels of insect damaged or infested fruit during their regular monitoring programmes.
Woolly apple aphid
Woolly apple aphid (WAA) can be a serious pest of apples but is usually partially suppressed by frequent applications of organophosphate (OP) insecticides. IFP is based on selective pesticides for codling moth and leafroller control so, in the absence of OP sprays, WAA can increase to very damaging levels. IFP research is evaluating control of WAA with new aphicides and biological control with Aphelinus mali, the parasitoid of WAA. Trial results show that once it is established within a block, A. mali can provide effective biological control of WAA provided control is not disrupted by some pesticides.
Many pesticides have been screened for their effect on A. mali. Most have little effect on the parasite but chlorpyrifos, (eg Lorsban), diazinon (eg Basudin) and carbaryl (eg Basudin) are disruptive. Trial results show carbaryl to be highly disruptive to biological control and contributing towards WAA outbreaks. As long as these compounds are used in NZ apple production selective aphicides will be required. Three new aphicides one foliar and two soil applied are also being evaluated for WAA control, one of these pirimicarb (Pirimor) is selective and should be registered for use on apples within the near future.
Leafhoppers
Leafhopper populations are being monitored in IFP trial blocks at Havelock North and Nelson. Buprofezin (Applaud) and chlorpyrifos are being evaluated for early season control.
Beneficial species
Many different species of natural enemies are thought to be important in biological control of key orchard pests. Apart from A. mali and Typhlodromus pyri, other important natural enemies have been identified such as spiders, earwigs, lacewings and predacious mirid bugs.
IFP pest management research trials are being conducted at both Havelock North and Appleby research orchards to identify the important regional differences in pest management. All aspect of these trials will be presented and summary results of graphical presentations will be provided.
Hail: The use of nets, insurance and hail guns in FranceThe pattern of increased hail events over the last six years has also been experienced in Europe. These events have shown that everyone in the ‘fruit value chain’ shares the financial risk of hail damage. Effort and research has been invested by the French industry into determining how best to manage the hail risk.
Current assessment of the main methods of combating hail in France:
Guns and rockets
- Not part of officially recommended risk strategy.
- No explanation for the mechanism of hail guns and if they were 100% effective we would know by now.
- Use of rockets to seed hail clouds is expensive and risky.
Insurance
- Part of risk strategy: cheaper than nets over short term.
- Cost has increased over recent years: Premiums from approx. 6 to 12%, where deductible is 30%. Fruit value insured is limited to $26k/ha. and 260k/orchard.
Nets
- Part of risk strategy: only viable alternative to insurance.
- Efficient but cost, reliability and longevity is questioned.
- Used for 40 years and new systems being developed.
Indicative costs for net systems for high density orchards in France:
|
System |
Year developed |
Cost ($NZk/ha) |
Installation (hrs/ha) |
|
Italian |
1957 |
18-24 |
350-500 |
|
Austrian |
1975 |
13-20 |
250-350 |
|
Single row |
1994 |
7-11 |
50-150 |
|
‘Safety valve’ |
1996 |
7-11 |
100-200 |
Computer software has been developed to assist with risk management decision making i.e. to calculate the best proportion of orchard netted, insured and exposed areas for given grower circumstances and climatic events.
Growers have been advised to consider investment in protection against hail along with other priorities for capital expenditure. i.e. debt reduction, frost protection, orchard redevelopment and expansion.
The French industry intends to further study hail protection methods with the objective of ensuring increased supplies of fruit to the market, every year.
New releases from the pipfruit breeding programmeNew apple and pear selections from the HortResearch Breeding Programme recommended for trialling on commercial orchards since 1994 include:
Apples
A20R02T032: A yellow apple with an orange blush on exposed fruit. Flesh is very crisp, sweet and has long storage potential. Seen as a possible alternative to Orin. Harvest mid-March.
A20R02T273: An attractive orange red stripe with crisp tangy flesh. Very good storage performance. Harvest early March.
GS494: Bright red block colour on cream background. Good flavour and storage. Harvest 10 days before Gala.
Pears
P098R01T045: Round-oval, red skinned, crisp flesh. Full WBC aroma. Long storage potential, good shelf-life. Harvest mid-February.
P037R48T106: Attractively blushed green-yellow pear with crisp juicy flesh. Refreshing flavour, good storage. Harvest mid-January.
P037R48T81: Attractively blushed yellow-green fruit. Sweet crisp flesh, good storage potential. Harvest early February.
Fruitlet thinning of apple with Benzyladenine - an IFP-compatible alternative to CarbarylThe New Zealand apple industry is presently dependent on the use of Carbaryl for fruitlet thinning of most apple cultivars. While the product is usually very effective and economical, there is international pressure to discontinue its use in apple production. With Integrated Fruit Production systems, it is extremely unlikely that the use of Carbaryl will be possible in the long term. These changes have highlighted the vulnerability of the industry to a lack of alternatives for thinning.
6-Benzyladenine (6-BA) is a cytokinin (a naturally occurring plant growth substance) which can induce fruitlet thinning of apples. Efficacy studies have been conducted at HortResearch during the past five years to establish the optimum concentration range for fruitlet thinning, optimum water application rates and to compare thinning effect of 6-BA against current standard commercial thinning practices.
Single applications of 6-BA applied when fruit are between 10-12 mm in diameter have caused significant thinning. This growth stage is also when Carbaryl is most effective. A concentration of 150 ppm of 6-BA was found to be optimum for commercial thinning effect. This concentration gave a thinning response equal to NAA 7.5 ppm (at bloom) followed by Carbaryl at 12 mm fruitlet stage.
Efficacy of 6-BA (150 ppm) has been further tested using reduced water rates, ranging from 550 L to 2,200 L per hectare. Significant thinning was achieved with all water rates but higher water rates improved efficacy. Thinning using 150 ppm 6-BA applied in 1,100L water per hectare gave thinning responses which were as good as Carbaryl (160 mls/100L) or NAA 7.5 ppm at bloom plus Carbaryl (160 mls/100L) at 12 mm fruitlet size. A water rate of 550 L per hectare resulted in insufficient thinning. The use of Regulaid adjuvant also enhanced thinning efficacy.
Most recent studies will determine thinning responses to application of 6-BA at an earlier stage of fruit growth. Presently the efficacy of 6-BA is extremely encouraging to substitute the use of Carbaryl. However thinning responses are highly dependent on applications being timed to coincide with warm temperatures (optimum 18-220 C) as found with both conventional thinners, NAA and Carbaryl.
6-BA will be registered for use in NZ under the trade name CylexR by Abbott Laboratories.
Genetic markers in pest and disease resistance breedingBreeding new cultivars with natural resistances to pests and diseases is one of the major aims of the HortResearch apple breeding programmes. For scion cultivar breeding, resistance to black spot and powdery mildew are most important, while with rootstock breeding the focus is on resistance to woolly apple aphid and Phytophtora.
Natural resistances form an alternative to pesticides to control pests and diseases. However, an approach similar to resistance management with pesticides is necessary to ensure the natural resistances remain durable. To achieve this, the breeders are dependant on the use of genetic markers and molecular biological techniques.
The two disease control strategies and the risks involved for each method are compared, and the progress on the use of genetic markers as breeding aids are described.
Futures for FruitFutures for Fruit is an industry foresight project that aims to improve the profitability of growers through better long term planning. This project was initiated in March 1996 by HortResearch and New Zealand Fruitgrowers Federation and culminated last year in the NZ Fruitgrowers Federation Annual Conference. At this Conference a number of possible scenarios for the future of the NZ fruit industry were studied.
Foresight is imagining the future. Foresight acknowledges that there are sudden market changes and technology leaps which make forecasting unreliable in today’s environment. Foresight looks beyond the normal horizon of 3-5 years to a future 10 to 15 years from now. The aim of the Futures for Fruit Foresight project is to build the most accurate picture of the future and thereby be in a position to feed this into the various planning processes across the whole industry. Our project goal is:
To identify and secure long term sustainable competitive advantage for the New Zealand Fruit Industry.
Industry Foresight ensures future competitive advantage by helping to answer the questions;
• what new types of customer benefits will be desired
• what new skills, technologies, resources and capabilities will be needed to offer those benefits;
• how will we need to reconfigure the customer interace to meet future needs.
The New Zealand Fruit Industry faces incredible challenges over the next 10 years. Grower responsibility and accountability for product quality will increase. However, it will not be sufficient to just produce high quality fruit at the packhouse. All parts of the industry will need to predict shifts in the market place and thereby plan changes in production practices to meet future market requirements. Likewise the impacts of the market place will be felt both directly and indirectly by all related service, research and marketing businesses.
There is a limit to what can be achieved by either incremental quality and efficiency improvement or by focusing on removing costs from the industry. Future success will come from bold strategy initiatives that focus on value added and market leadership. Foresight enables an industry to get to the future first and to help create that future.
Increasing global competition in our industry poses great threats to those who are not prepared. Whilst New Zealand has a number of unique advantages, success in the marketplace will only come from creating new competitive space. Much of the success in doing this will depend on good industry foresight and effective investment. The project team is planning to hold a workshop with a few key industry people in order to develop a five year Strategic Plan for the fruit industry. This Plan will be a bold visionary document that will illustrate what can be achieved by industry-wide planning. This will be a key document for the fruit industry in New Zealand to improve its competitive position over the next 5 years and to increase returns to growers.
Sponsors of the Futures for Fruit foresight project in 1996 were;
HortResearch
NZ Fruitgrowers Federation
NZ Kiwifruit Marketing Board
ENZA New Zealand (International) Ltd
Pipfruit Growers of NZ Inc.