Dear Trevelyan’s kiwifruit grower,

This weeks Kiwifruit TechTip looks at industry fruit development trends, Trevelyan’s monitoring result comparisons, high temperature fruit at harvest, explosive Gold3, Trevelyan’s 2021 Winter Spray Guides, pre-harvest stain removers and drying fruit quickly, thinking about harvest and upcoming events.

Industry fruit development trends

This week Abdul Jabbar (Zespri’s Fruit Optimisation Leader) shared some industry insights from Smart Monitoring data at Week 10. In summary Abdul states:

SM and Monitoring – Gold3 Summary at Week 10

  • Mean fresh weight of GA is tracking around an av. ̴133 g
  • Mean DM is 16.17 % and this is bit lower than last two high DM seasons yet higher than 2016-18 seasons.
  • Mean SSC is 5.40 °Brix and lower fractile is 4.48 °Brix. Both parameters are at relatively lower value compared to last year.
  • GA flesh colour is developing fine with an average °hue at 109.12, green fractile of 113.68 °hue and colour threshold of 112.61. Overall colour is relatively advanced compared to past seasons.
  • GA fruit is setting a comparatively lower firmness trend with an av. firmness 7.28 kgf and soft fractile of 6 kgf. 

SM and Monitoring  – HW Summary at Week 10

  • Mean fresh weight is 93.33 g
  • Mean DM is at 14.67 %
  • Mean SSC is at 4.48 °Brix and lower fractile is 4.0 °Brix
  • Average firmness is 10.56 kgf

Gold3 Week 10 Industry Monitoring Comparison

Hayward Week 10 Industry Monitoring Comparison

For more detail please see the attached document

How do you compare? Trevelyan’s Monitoring Results – 16/03/2021 – 18/03/2021

In the table below I have presented key maturity data collected from Trevelyan’s Gold3 monitoring samples processed in the period between 16/03/2021 – 18/03/2021, enabling those that have had samples taken in this period to compare against other orchards in similar locations.

Row Labels

# of MA’s sampled

Average dry matter

Average Dry Matter Threshold

Average Colour

Average colour threshold

Average brix

Average lower brix fractile

Average Weight

Average Pressure

Athenree | Waihi Beach

3

17.4

16.8

103.1

106.1

7.0

5.5

172.2

7.2

Maketu

7

16.2

15.7

109.2

112.7

5.8

5.0

132.4

7.0

Maniatutu

3

16.3

15.8

108.0

112.0

5.7

4.9

130.3

6.9

Paengaroa

6

16.5

15.9

108.4

112.1

6.1

4.8

129.1

6.8

Pukehina

1

16.2

15.9

108.8

111.4

5.6

4.9

122.2

7.5

Rangiuru

11

16.1

15.6

107.7

110.8

6.1

5.1

138.8

7.2

Te Matai

46

16.3

15.8

108.2

111.6

6.0

5.0

144.0

7.4

Te Puke No.2 – No.1

14

16.4

16.0

107.4

110.5

6.1

5.1

145.1

7.3

Te Puke No.3 Manoeka

2

15.6

15.0

109.1

113.5

5.7

4.7

131.0

7.6

Whakamaramara | Pahoia | Apata

2

16.5

16.1

106.6

110.7

6.7

5.6

126.9

6.9

Whakatane

1

17.3

16.9

106.5

110.8

6.4

5.0

135.5

7.1

Whakatane North West

1

15.2

14.8

110.0

112.8

5.2

4.6

130.6

7.2

Grand Total

97

16.3

15.8

107.9

111.3

6.1

5.0

141.2

7.3

Figure 3. Gold3 maturity monitoring data (16/03/2021 – 18/03/2021) – all growing methods

The headings highlighted yellow represent key Zespri Maturity Clearance Criteria (as per Figure 4 below).

Figure 4.  Courtesy of Zespri GET Need to Know 14: Harvest 2021 Taste Bands and Maturity Clearance Criteria: Gold Varieties document

High temperature fruit at harvest

One of the factors that determines a successful storage outcome for your fruit is managing the cool chain. Science tells us that once harvested, kiwifruit continues to respire, absorbing oxygen while releasing carbon dioxide and ethylene which results in the ripening of the fruit. The rate of which the fruit respires is directly influenced by temperature (as well as fruit maturity and gases in the environment). Our coolstore team do an excellent job of managing these factors when your fruit is on site, but are already on the back foot if the internal temperature of the fruit is high when it arrives. At this time of year our Operations Team constantly monitoring the internal colour of Gold3 fruit and the coolstore environment, lowering temperatures and/or moving product lines to ensure colour protocols are optimised to meet Zespri’s orders. Lines of “hot” fruit make this task more difficult as they affect the performance of other fruit in the coolstore (due to heat and increased respiration rates), or to the line itself as it may not de-green as expected.

Each truckload of fruit arriving at Trevelyan’s is monitored with the temperature of the fruit in the bins recorded. Unsurprisingly we’ve had some high fruit temperatures recorded with the hot weather we’ve been having recently, but what is surprising however is the “degrees above ambient air temperature” that has been recorded on some milder days. For instance, we’ve seen trucks arriving with fruit temperatures of 33°C when the ambient air temperature (in the shade) is only 18°C – that’s a difference of 15°C! This suggests that the bins have been left sitting for some time in the direct sun before being loaded onto the truck, rather than sitting in the shade.

Where possible, try to arrange the layout of your loadpad to allow for full bins to be stacked in the shade through the day, particularly in the afternoon. This way the potential for the fruit to heat up in the bins prior to packing is minimised and helps ensure the best possible outcome for your fruit.

Explosive Gold3 fruit – keep an eye out!

As packing slowly gets underway I am hearing reports of isolated incidents of explosive Gold3 fruit in the BOP. While explosives in Gold3 haven’t been a widespread issue since 2018 hearing these reports in the first week of packing is concerning. The cause of explosive Gold3 fruit is not understood – it could be that drought stress has caused the vine to abort fruit early (by cutting off the supply of nutrients through the fruit stalk) – this fruit would start to soften on the vine before dropping off. Fruit from areas of dense/dark canopy also have a tendency to detach (often with the stalk still attached), so the reports of “explosives” could actually be a symptom of  dense canopies.

Whatever the cause, it’s a timely reminder that explosive/overripe fruit are a problem at harvest as juice from the squashed/exploded fruit contaminates the surrounding sound fruit in the bag, bin or at bin tip. If the contaminated fruit is not removed at packing time, the juice/pulp  that is spread onto the otherwise sound fruit turns black in coolstore, becoming a storage reject known as Non-Pathogenic Fungal Growth (NPFG), often referred to as Alternaria.

NPFG costs the grower money.

If you are observing or suspect there may be explosive fruit in your orchard, please contact me or your grower representative as soon as possible.

Trevelyan’s 2021 Winter Spray Guides – Conventional and Organic

Please click for a copy of the Trevelyan’s 2021 Winter Spray Guides for conventional and organic growers. Please note that the sprays and timings are suggestions only and the unique circumstances on your orchard(s) may require a different approach to spray management. Not all sprays listed in the Zespri Crop Protection Standard (CPS) have been included, so you may like to consider further options by reviewing this document (found here on the Zespri Canopy website).

Organic/organic conversion growers are reminded that all inputs must also be BioGro™ certified (as well as allowed by Zespri) – please check with BioGro™ that organic status of every input before application

If you have any questions regarding the 2021 Winter Spray Guide, please do not hesitate contacting me or your Grower Representative.

Pre-harvest stain removers

Clean-up sprays are often not required during the KiwiStart period as leaf quality is good and the fruit is not stained from tannins produced as leaves deteriorate later in the season. However, if you choose to use a cleanup spray during KiwiStart:

  • Conventional growers – calcium phosphate/phosphoric acid cleaners such as CP Clean™ are good options for early harvested fruit.
    • Cleaning is completed once the product is dry and apply at of 5L/1000L – applied at 1500L water/ha in both directions (total 3000L water/ha minimum).
  • Organic/conventional growers – citric acid is an effective option (and the only option for organic growers), but there are occasional reports of some stains “re-staining” in coolstore.
    • Apply at 5kg/1000L – applied at 1500L water/ha in both directions (total 3000L water/ha minimum)

Struggling to harvest wet fruit? Du-Wett° and Du-Wett° Stainless may speed up conventional fruit drying times

Laboratory trial data I reviewed in 2019 suggests that the Du-Wett° and Du-Wett° Stainless can speed up drying times on wet fruit. Due to the nature of organosilicone superspreaders, water deposited on the surface of the leaf is spread more evenly and as a thinner film compared to what is normally deposited without the use of a superspreader. This can be extremely useful if your fruit is wet and you’ve got pickers on standby!

Data suggests that in the laboratory, Du-Wett° applied at 1L/ha in 500 litres water nearly halved the time for wet fruit to dry. Observations of growers in the field support this lab data.

If a quicker drying time is required, consider using:

  • Du-Wett° when no stain removal is required
  • Du-Wett° Stainless when a stain removal product is being applied

Don’t forget however, if you plan on putting a sprayer through your orchard immediately prior to harvest, first lift your crop to at least 1.5m above the ground as to minimise contact with the fruit.

Thinking about harvest…

Just a few things to think about as harvest is drawing near:

  1. Lift low hanging fruit – anything lower than 1.5m is likely to make contact with sprayers/tractors/harvest bins which can result in cut, split or bruised fruit (affecting your packout, storage and profit).
  2. Check your sprinkler heads – fruit stain caused by irrigation water can be problematic. Irrigation heads that are too high, have been broken and/or knocked sideways can result in water spraying vertically or diagonally, wetting the fruit. Water sources that are high in heavy metals such as iron or manganese may therefore cause staining on fruit. This type of stain can be extremely difficult to remove, with clean-up sprays often being ineffective – so prevention is the best option. Prevent this type of stain from occurring in the first place by ensuring irrigation heads are set level and not too high so water is not making contact with fruit. 

    If you identify stained fruit on the orchard try dipping some fruit in clean-up spray (at label rates) to see how effective it is at removing the stain. Remember, not all clean-up sprays work the same way – calcium phosphate/phosphoric acid cleaners such as CP Clean are good options for early harvested fruit, but are less effective at removing heavy staining. Tougher stains may require a phosphate buffered lactic acid product such as Jewel Clean LF or KiwiLustre LF – these cleaners act over a period of 2-3 days but typically have some negative impact on leaf condition (so are not typically recommended for use in KiwiStart).

    I also suggest you contact your Grower Services Rep so we can make a plan around harvest – knowing that fruit may be suffering from stain prior to packing is going to provide you with the best possible outcome!

  3. Enter your fruitset date  and spray lines in Spray Diary now – this allows you to run spray diary “test” audits to make sure everything is passing well before harvest (and fix any errors!). Remember to run a “test audit” before your “final audit” – this will let you know if there are any issues with what you’ve recorded. Once you’ve submitted your diary for a “final audit”, your diary is locked and no further changes can be made without contacting Zespri.
    Figure 5. Spray Diary audit buttons – make sure you do a “test” audit before submitting a main audit.
    Feel free to contact me or your Grower Services Representative if you need assistance.
  4. Keep your sward low otherwise the maturity clearance/residue samplers may refuse to access your orchard.
  5. Understand the new Zespri Maturity Clearance System (MCS) – attend a Zespri training session (online or in person) on how to use/understand the new Zespri MCS – see the “Upcoming Events” section below for more detail.

    Upcoming events  

    Zespri Maturity Clearance System (MCS) – Grower Training Schedule 2021

    The Zespri MCS Support Team will take you through the new MCS system and key changes to the clearance process this year. Training content includes login, orchard information setup and management, viewing sample results, and troubleshooting.

    Please click the link below to sign up for a session. Online sessions will take place via Microsoft Teams, and in person sessions will be hosted in Zespri’s board room.

    • Online sessions – click  here to register
    • Thursday 15 April 2:00pm – 4:30pm
    • In-person sessions – click here to register
      • Friday 9 April 1:00pm – 3:30pm

    Have a great weekend!

    Cheers

    Gordon