Honeycrisp Fruit Maturity Report - Sept 25

In this week's Honeycrisp fruit maturity update you will notice that values from our example regions have moved more quickly and are near or nearing optimum maturity. 

Table 1: Maturity indices for regular Honeycrisp fruit sampled in the current year on Sept 25, 2023 and compared with last year's samples where applicable from Sept 27, 2022. The rate of change since last week's measurement is shown in brackets beside the current measurement.

The average starch values for Honeycrisp fruit measured in all regions is nearing the target of 5 especially in Lakeville and North Medford (no ReTain). Maturity continues to be a few days delayed relative to last year. Maturity values are noticeably different between the most mature and least mature fruit on a tree, so actual values would vary depending on what percentage of the fruit is included in the first pick.

The average DA value for Honeycrisp fruit measured in all regions is at or near the target of 0.60. The most mature fruit on the tree are within the harvest window. 

Please note that use of the DA meter on fruit treated with ReTain has not been verified. The DA meter reading on the treated fruit is 0.60 suggesting near-maturity however the starch index values suggest otherwise. Starch index is a more reliable indicator in this case.

Figure 1: Ten-fruit samples across all four locations. The ground/shade colour (left) on the Sept 25 sampled fruit. The visual results of starch-iodine tests on Sept 18/19 (middle) and the change toward more sugars on Sept 25 (right). Average starch ratings are summarized in Table 1.

Important Note - This maturity report is for general industry purposes only. Growers are encouraged to use their own discretion to harvest trees that are exhibiting delayed colour development or exhibiting maturity indices that disagree with what is being reported here. Values were measured on an average of fruit that were representative of the block's crop load and tree vigour. Fruit representative of size and colour were taken from all sides but not from the interior where maturity is expected to be delayed and is most likely targeted for a second pick timing.

About each measurement:

Starch Index - Starch is converted to sugars as ripening progresses. The starch-iodine test is used because iodine binds to starch molecules turning them blue/black, whereas sugars are not stained and remain clear. The Cornell chart on a scale of 1 to 8 was used above and values are an average of ten representative samples from each block.

Soluble Solids - Approximates the percentage of sugar content of the fruit. Measured using a handheld refractometer. Values are an average of ten representative samples from each block.

DA Meter - The delta absorbance (DA) value is related to the chlorophyll content of the peel. AAFC researchers in Kentville developed a protocol for Honeycrisp. Values above 0.60 are immature, values 0.6 to 0.36 are ideal for long term storage, and values below 0.35 are best for short term storage because they are more prone to storage disorders. Values shown above are the average of twenty fruit taken throughout a block, with readings taken on the transition area between the sun and shade exposed sides. DA values will be noticeably different between the most mature and least mature fruit on a tree. 

Orchard Outlook Newsletter Vol. 23, No 16 & Maturity Update

Today's newsletter includes an update on degree day accumulations, mean temperatures, and precipitation from Jeff Franklin (AAFC). Following hurricane Lee, I provide an industry update to connect you with what others have experienced in the industry including an overall sense of relief. There is some loss of fruit, trees, and trellis and the extent of bruising is unclear at this time. Also included is the second update on Honeycrisp fruit maturity that is nearing harvest maturity.

Table of Contents:

Weather

• 2023 Degree Day Accumulations
• Precipitation

Storm Update

Honeycrisp Fruit Maturity Report

Other Notes

Weather

2023 Degree Day Accumulations

The cumulative degree days for the entire season are essentially equal to the 5- and 10-year averages for base 5°C heat units (Figure 1). Industry members are reporting that fruit maturity is lagging a couple of days behind harvest dates in recent years.

Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to Sept 18 for the past 17 seasons. Provided by Jeff Franklin (AAFC).

• Approximately equal plant development heat units compared to the 5-year average, and 1% more compared with the 10-year average.
• Approximately 3% less plant development heat units compared to 2022, and 3% less compared with 2021.
• Approximately 1% more insect development heat units compared to the 5-year average, and 2% more compared to the 10-year average.

Mean Temperatures

Fruit colouring has been a challenge. Likely the slow colouring is related to the warm temperatures that we have experienced so far in September. Jeff Franklin explains, "Currently, mean daily temperatures are running 2.8 °C ahead of the 25-year average and the average minimum temperatures are approximately 4°C ahead of the historical values."

Table 1. Mean temperatures for the first 18 days of September, current year (2023), 10-year, and 25-year averages. Provided by Jeff Franklin (AAFC).

Precipitation

The precipitation total for the growing season has now even exceeded the very wet year of 2019 (Figure 1). The surplus of water has happened from July onward. This is a good time to take note of wet areas in the orchard to see if areas prone to standing water also correlate with specific areas of poor tree health. Surprisingly, soil temperatures are above-average. 

Figure 2: Precipitation recorded in Kentville for the 2023 season (red line) compared with the 10-year average (black line). Provided by Jeff Franklin (AAFC).

Storm Update

Summary:

• Wind gusts appeared highest near the Minas Basin, Windsor, and on the South Mountain. However, wind gusts throughout the Valley were relatively similar in the range of 70-84 km/hr.
• Estimates of fruit drop are lower than expected and are lower than recent events of Dorian and Fiona. Ambrosia is one of the worst-affected varieties with it's long and brittle stem. The extent of the cut and bruised fruit is to be determined.
  
• There is occasional tree loss. Also, part or full rows of trellis with high density trees have collapsed where crop loads were heavy, post spacing was greater than 25 ft, or there was a knot in the centre of the end post. Failure has happened within blocks or on the eastern side.
  
• Leaves are tattered and could have allowed entry of fire blight bacteria, especially during an already high-risk year. 

  

Honeycrisp Fruit Maturity Report

Table 2: Maturity indices for regular Honeycrisp fruit sampled in the current year on Sept 18, 2023 (Rockland)/Sept 19, 2023 (Lakeville and North Medford) and compared with last year's samples from Sept 20 (Rockland)/ Sept 21, 2022 (Lakeville and North Medford). The rate of change since last week's measurement is shown in brackets beside the current measurement.

The average starch values for Honeycrisp fruit measured in all regions has not reached the target of 5. Maturity continues to be delayed relative to last year. Maturity values are becoming more noticeably different between the most mature and least mature fruit on a tree, distinguishing the first pick from later picks. 

The average DA value for Honeycrisp fruit measured in all regions has not reached the target of 0.60 but is progressing as expected by losing about 0.1 units each week. 

Please note that the use of the DA meter on fruit treated with ReTain has not been verified. The DA meter reading on the treated fruit is 0.69 suggesting near-maturity however the starch index values suggest otherwise. Starch index is a more reliable indicator in this case.

Figure 1: Ten-fruit samples across all four locations. The ground colour (left) on the sampled fruit. The visual results of starch-iodine tests on Sept 12 (middle) and the change toward more sugars on Sept 18/19 (right). Starch ratings are reported in Table 1.

Important Note - This maturity report is for general industry purposes only. Growers are encouraged to use their own discretion to harvest trees that are exhibiting delayed colour development or exhibiting maturity indices that disagree with what is being reported here. Values were measured on an average of fruit that were representative of the block's crop load and tree vigour. Fruit representative of size and colour were taken from all sides but not from the interior where maturity is expected to be delayed and is most likely targeted for a second pick timing.

About each measurement:

Starch Index - Starch is converted to sugars as ripening progresses. The starch-iodine test is used because iodine binds to starch molecules turning them blue/black, whereas sugars are not stained and remain clear. The Cornell chart on a scale of 1 to 8 was used above and values are an average of ten representative samples from each block.

Soluble Solids - Approximates the percentage of sugar content of the fruit. Measured using a handheld refractometer. Values are an average of ten representative samples from each block.

DA Meter - The delta absorbance (DA) value is related to the chlorophyll content of the peel. AAFC researchers in Kentville developed a protocol for Honeycrisp. Values above 0.60 are immature, values 0.6 to 0.36 are ideal for long term storage, and values below 0.35 are best for short term storage because they are more prone to storage disorders. Values shown above are the average of twenty fruit taken throughout a block, with readings taken on the transition area between the sun and shade exposed sides. DA values will be noticeably different between the most mature and least mature fruit on a tree. 

Other Notes

Ambassadors for Temporary Foreign Worker Program

An article in The Grower on September 13 brings to light recent criticisms of the Temporary Foreign Worker Program. As everyone who works within the program is an ambassador of it, this article is being shared here to bring it to your attention. The workers through this program are an essential part of the local industry.

This Orchard Outlook has been published with the input of the Orchard Outlook Committee including this week's contributors: Larry Lutz, Joan Hebb, Kari Brown, Jeff Franklin, Bob Prange, Dustin MacLean and Heather Rand.

Perennia Food and Agriculture Corp.
Edited by Michelle Cortens, Tree Fruit Specialist

Recommendations for Storm Preparation - Hurricane Lee

This update includes suggestions to prepare for possible high wind gusts this weekend. I'm crossing my fingers that we do not see damaging winds. Hopefully this is all in the name of being over-prepared!

Prepare Young Trees and Nurseries

• Tie young trees and nursery trees with rubber tree tie. Max tape does not hold up to high winds. Tie with rubber ties as soon as trees get to the top of the stake in the nursery to be prepared for high winds. 
• Check on support for trees that are known to be brittle at the union, including many of the new Geneva rootstocks (G.11, G.41, G.16 etc).

Prepare Mature Plantings

• Pick fruit from trees with a heavy crop load if desired to lighten the load on trellis systems that are already exhibiting strain. However, a lot of varieties are not yet ready for harvest. If there is good colour in the tops of Honeycrisp trees, check their maturity and it may be possible to harvest a spot pick on tree tops.
• Speak with your packer as they may have a preferred way to handle fruit prior to the storm… for example, they may suggest stripping the trees of fruit for varieties that are ready for harvest and have a processing market. Don’t assume this is the case though. It could be variety specific.
  
• Old, weak, end-posts on trellises could be shored up if possible. Focus on improving supports for trellised high-density orchard. The old, unsupported, dwarf and semi-dwarf trees appear to tolerate high winds better than trellised orchard in some situations.
• A preharvest fungicide like Pristine/Merivon could be applied before or after the storm depending on your priorities.
• Preharvest fungicide is your only protection in storage so having residue on the fruit is desirable. Based on local reports, the residue and associated benefits in storage may last if the products are applied up to two weeks before harvest. Pristine/Merivon ingredients are locally systemic so they are absorbed by tissues on which they are sprayed. The products are rapidly absorbed into plant tissue if allowed to dry. Theoretically the products should have a benefit in storage if applied before the storm.
• You may have other priorities before the storm. Spraying after the storm would ensure that residue is present for storage. But waiting runs the risk of the laneway being obstructed for spraying or crews not having time to spray.
• Apply the preharvest fungicide if possible whether it is before or after the storm.

After the Storm

• Be prepared to brace weakened trellis systems where a breach has the potential to weaken entire rows.
• Have generators and fuel available to support cold storage in case of power outages.
• If applicable, contact crop insurance soon after you observe damage.
• Treat nonbearing orchards exhibiting tissue damage with streptomycin within 24 hours of injury to prevent fire blight trauma infections. More information in Q&A below.

Figure 1: Weakened trellis system with a heavy crop load was braced after hurricane Fiona in fall of 2022.

Fire Blight Q&A:

What's the bacterial risk? High.

This year there is plenty of fire blight bacteria established in infections throughout the Valley. A rotating storm system with wind and rain moves bacteria around and between orchards with the potential to spread infections to new blocks.

It's late in the season so are trauma infections still a concern? Yes.

Remember, bacteria can still be delivered to wounds in cool temperatures. Temperature matters for blossom blight risk because bacteria rely on heat to grow on the floral stigma. For trauma blight, the source of the bacteria is active infections that already have excessive bacterial populations contained in ooze. Trauma events are always cause for concern because bacteria are transported from active infections to open wounds.

Should I use Streptomycin preventatively before the storm? No.

Streptomycin should NOT be used as a preventative treatment in the case of a tropical storm and should be saved for post-infection activity. If applied before trauma, streptomycin can be washed off leaves, degraded by sunlight, and will not provide protective activity if bacteria are moved in from outside your own orchard.

When should I use streptomycin?

Have streptomycin available to treat nonbearing orchards exhibiting tissue damage within 24 hours of injury to foliage or limbs. Note the preharvest interval of 50 days for apples and 30 days for pears.

Can I use Kasumin instead of streptomycin? No.

Do not rely on Kasumin for a trauma event because this antibiotic is not systemic and will only kill cells on the surface of leaves and shoots. Meaning, any bacteria that moves into tissues will not be affected by Kasumin or copper.

Other Recommendations

• The best thing to do is to get ready before the hurricane is even forecasted by season-long maintenance. 
• Check culverts and ditches to make sure they are not collapsed or blocked.
• Store or secure items that could become wind-borne.
• We cannot compare Lee's potential impact with the outcomes seen during Elsa and Fiona. The storms are unique with different direction, rainfall amounts, and wind speeds. And the weakest trellis systems were already tested recently in the previous two storms.
• If you wish to monitor Valley-wide wind gusts and rainfall accumulation on a map, visit capebretonweather.ca and from the panel called 'Layer' select 'Storm Rain' or under 'Extremes' select 'high' and 'wind gust'.
• The province recently submitted a news release stating that AgriStability is still available to the Ag sector with late application up until Dec 31, 2023. Here is a link to the full release: https://novascotia.ca/news/release/?id=20230908001
• We have had no shortage of difficult growing conditions but I hope that you are proud of the good work you have done on everything that you can control.
• If you are feeling overwhelmed and need to talk to someone please know that everyone has access to the Farm Family Support Centre and other resources through We Talk We Grow.

This Orchard Outlook resource has been published with the input of the Orchard Outlook Committee including this week's contributors: Larry Lutz, Keith Fuller, Harrison Wright, Bob Prange, Joan Hebb and Danny Davison.

Perennia Food and Agriculture Corp.
Edited by Michelle Cortens, Tree Fruit Specialist

Honeycrisp Fruit Maturity Report - Sept 12

Similar to last year, I will give short weekly updates on indicators of Honeycrisp maturity from a few example regions. This information is meant to indicate the rate of change of ripening each week and also how this year's maturity compares to past years.

Table 1: Maturity indices for regular Honeycrisp fruit sampled in the current year on Sept 12, 2023 and compared with last year's samples from Sept 13, 2022.

The average starch values for Honeycrisp fruit measured in all regions has not reached the target of 5. Relative to last year, this year's starch values are generally lower meaning that maturity is slightly delayed because starch has not converted to sugars.

The average DA value for Honeycrisp fruit measured in all regions has not reached the target of 0.60. Relative to last year, this year's DA values are generally higher meaning that more chlorophyll is present and ripening is not as far progressed. 

Last year was a year with above-average heat so it is not surprising that maturity is not as far progressed this year. Next week's measurements will report the rate of change to show how maturity is progressing.

Figure 1: Ten-fruit samples across all four locations. The blush (left) and ground colour (middle) on the sampled fruit. Ground colour is still an immature green tone. The visual results of starch-iodine tests (right) and starch ratings are reported in Table 1.

Important Note - This maturity report is for general industry purposes only. Growers are encouraged to use their own discretion to harvest trees that are exhibiting delayed colour development or exhibiting maturity indices that disagree with what is being reported here. Values were measured on an average of fruit that were representative of the block's crop load and tree vigour. Fruit representative of size and colour were taken from all sides but not from the interior where maturity is expected to be delayed and is most likely targeted for a second pick timing.

About each measurement:

Starch Index - Starch is converted to sugars as ripening progresses. The starch-iodine test is used because iodine binds to starch molecules turning them blue/black, whereas sugars are not stained and remain clear. The Cornell chart on a scale of 1 to 8 was used above and values are an average of ten representative samples from each block.

Soluble Solids - Approximates the percentage of sugar content of the fruit. Measured using a handheld refractometer. Values are an average of ten representative samples from each block.

DA Meter - The delta absorbance (DA) value is related to the chlorophyll content of the peel. AAFC researchers in Kentville developed a protocol for Honeycrisp. Values above 0.60 are immature, values 0.6 to 0.36 are ideal for long term storage, and values below 0.35 are best for short term storage because they are more prone to storage disorders. Values shown above are the average of twenty fruit taken throughout a block, with readings taken on the transition area between the sun and shade exposed sides. DA values will be noticeably different between the most mature and least mature fruit on a tree. 

Orchard Outlook Newsletter Vol. 23, No 15

Today's newsletter includes new sections on preharvest fruit quality. Many of you are using DA meters for the first time so we offer tips on what you need to know and how to use and interpret the tool. Next is a refresher on the ripening hormone ethylene to set the stage for the products ReTain and Harvista that influence ethylene. We review highlights on ReTain and Harvista from the discussion at last week's Perennia tailgate meeting. We also share information on diagnosing lenticel injury versus bitter pit, and that Apogee is not expected to influence bitter pit incidence. Finally, remember the importance of preharvest fungicide because it is your only protection in storage.

Table of Contents:

Weather

• 2023 Degree Day Accumulations
• Precipitation

Late Season Diseases

• Reminders about Fungicide Preharvest Intervals (PHI)
• Preharvest Management of Apple Storage Rots and Fungi
• Fire Blight Management

Insects

• Apple maggot

Horticulture

• Calcium Nutrition
• Site Preparation

Harvest Fruit Quality

• Using a Delta Absorbance (DA) Meter
• Delaying or Synchronizing Maturity with ReTain and Harvista
• Estimating Bin Requirements
• Reducing Bruising
• Considering Watercore
• Avoiding Internal Browning
• What's that? Lenticel Injury?
• Ever Wondered about Apogee and Bitter Pit Incidence?
• Consequences of Harvesting too Early

Pest Management Guides 2023

Weather

2023 Degree Day Accumulations

The cumulative degree days as of Sept 1 for the entire season are slightly behind the 5- and 10-year averages for base 5°C heat units (Figure 1). Industry members are reporting that fruit maturity is around 3 days later than last year's harvest dates.

Fruit colouring has improved with recent cool nights that were followed by warm, sunny days. Colouring can continue to improve when nighttime temperatures are below 15°C (or 21°C in the case of McIntosh) followed by daytime temperatures around 20-25°C.

Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to Sept 1 for the past 17 seasons. Provided by Jeff Franklin (AAFC).

• Approximately 3% less plant development heat units compared to the 5-year average, and 2% less compared with the 10-year average.
• Approximately 7% less plant development heat units compared to 2022, and 7% less compared with 2021.
• Approximately 5% less insect development heat units compared to the 5-year average, and 3% less compared to the 10-year average.

Precipitation

The precipitation total for the growing season is now well above the 10-year average. The current year is tracking similar to the total precipitation received in the wet years of 2019 and 2021 when plenty of rainfall was recorded during the preharvest and harvest period. During recently wet years, the storage losses were relatively high but seemed better off when fruit had received a fungicide near to harvest (as close as PHI allows).

Figure 2: Precipitation recorded in Kentville for the 2023 season (red line) compared with the 10-year average (black line). Provided by Jeff Franklin (AAFC).

 

Late Season Diseases

Reminders about Fungicide Preharvest Intervals (PHI)

Table 1: Fungicide products for control of summer diseases listed from longest preharvest interval to shortest preharvest interval. Includes notes about diseases controlled and re-entry intervals (REIs). (Updated on Sept 26 to include Cevya.)

Preharvest Management of Apple Storage Rots and Fungi

A well-timed preharvest chemical control can go a long way to prevent storage rots. Fungal spores that land on unprotected fruit can germinate and symptoms show up as infections in storage. Preharvest fungicide is your only protection in storage.

Recommendations:

• Don't put away the sprayer too early! Late varieties benefit from a preharvest spray too. Please note that more rot has been reported in storage in 2021 and 2022 than in prior years and may be related to changes in the Captan use pattern. Growers who stopped their fungicide program early saw early symptoms of diseases in storage.
• The group 7 & 11 products Pristine and Merivon can be applied up to 5 days before harvest. They are labelled for the control of scab, black rot, flyspeck, and sooty blotch. The short PHI and good activity are especially helpful for protecting apples being placed in long-term storage.
• Monitor precipitation during harvest, especially for late-season varieties. Cumulative rainfall of 25-50 mm washes off fungicide protection. The risk of fungicides being washed off is minimized if applied as close to harvest as possible.
• Of course, avoid bruising or wounding to prevent infections of blue and gray moulds. Take the time to educate staff on the proper way to handle fruit.

Fire Blight Management

Fire blight disease is very prevalent this year. Whether it is because late bloom sprays were not applied, there were carryover infections from last year, it was too wet for timely management, hail damage went unnoticed, or the risk was underestimated. 

Recommendations:

• Summer pruning other than for the purposes of removing fire blight strikes should be avoided during an outbreak of the disease to prevent further spread.
• Monitor nursery trees and young trees to quickly remove trees with infections. Deer are spreading infections where they graze on young tissue.
• Do not break off branches with fire blight infections as you navigate the orchard. Research shows that the bacteria becomes systemic in the tree because branches are not adequately removed. There are then a high number of new infections and significantly more canker tissue and cankers on structural wood. 
• Prune out fire blight infections on young trees in the current year as soon as you notice infections - don't wait for winter. Trees 8 years old and younger are at the greatest risk of rootstock blight.
• Remove fire blight strikes at least 2-4 ft below active infections to remove the leading edge of the bacteria. The younger the tree, the deeper the cut. Being aggressive at the first sign of symptoms will help prevent the re-occurrence of symptoms and the need for continuous cutting back. Repeat tree inspections at least weekly.
• Cut out infections when a period of 2 dry days are in the forecast. Leave prunings in orchard laneways to let dry thoroughly for several weeks. If cutting a whole tree consider letting it dry while attached to the trellis. Don’t make piles that will prevent the wood from drying. 
• Do not cut root suckers during an outbreak because the wounds are susceptible to infection. Instead, remove suckers during the dormant season.
• Potato leafhoppers can transmit fire blight. Their presence in young plantings and nurseries is concerning, especially in areas of active fire blight infections.

Insects

Insect management programs should be based on grower monitoring and/or scouting reports.

• Apple Maggot
• Table 2 provides a list of insecticide products for apple maggot control with their respective preharvest and re-entry intervals.
• Even if your orchard has already been inspected for apple maggot, do not stop spraying prematurely as flies will continue laying into September. 
• Clean maggot traps 7 to 10 days after treating a block for maggot and monitor for new trap captures. Re-treat if new maggot flies are caught. Flies emerge over a period of time so for satisfactory maggot control, monitor the presence of apple maggot flies to inform treatment programs. Remember, a single female can lay hundreds of eggs.
• Significant rainfall will wash off insecticide residues that are needed to ward off apple maggot flies. Re-treatment is required after 10-14 days or cumulative rainfall of 12.5-25 mm (0.5-1 inch). Danitol and products registered for suppression are expected to have a relatively shorter field residual life of 7-10 days.
• Apple maggot flies are weak flyers so a border/perimeter spray of Imidan near known hotspots may be an approach to help kill adult flies from the source.
• Apple maggots pupate in the soil and may not emerge until up to four years later. Therefore, several years of diligent management are required to reduce the resident insect population.
• Remember, apple maggot is a neighbourhood problem and last year had higher than normal fruit damage.

Table 2: Insecticide products for control of apple maggot listed from longest preharvest interval to shortest preharvest interval. Includes re-entry intervals (REIs) and additional information.

Horticulture

Calcium Nutrition

• This year the wet weather is encouraging plenty of vegetative growth. The leaves compete with the fruit for calcium so the lush growth may dilute the calcium in fruit. Therefore, calcium applications are highly recommended this year.
• The recommended rate is 4 to 14 pounds of elemental calcium per acre in a season spread over six to eight cover sprays. 
• Low rates will not cause leaf burn but will likely lead to only minor control of bitter pit and likely will not enhance storage life of the fruit. 
• High rates may lead to some leaf burn, give good control of bitter pit, and may also enhance storage life of the fruit. High rates are recommended for Honeycrisp.
• Calcium applied at two-week intervals is better than occasional, high-rate applications.
• For help calculating the amount of elemental calcium you are applying in each spray, visit Penn State Extension to download a calcium rate calculator. The percentage of elemental calcium will be listed on the label of your product of choice. Check formulated calcium products because they may not contain as much calcium as you expect.
• Ca has very low movement within the tree and needs to be applied directly to the fruit surface to be absorbed. Therefore, thorough coverage is important to cover developing fruit.
• Calcium chloride flake (77% Ca) is the most economical Ca material to use but also the highest risk for foliar burn. Calcium chloride flake is safe when applied at 4.5 kg per 1000 L of spray solution. The risk of leaf or fruit damage from calcium is highest in hot weather. Susceptible varieties can develop lenticel spotting if damaged.
• Calcium chloride flake can be rough on equipment. Use a pressure washer to clean equipment. Consider spraying your spray equipment with superior oil before beginning and the calcium will wash off more easily.
• Calcium chloride is a worthwhile management strategy for bitter pit, even if it has to be applied alone. Waiting for a tank mix partner may mean that ideal application timings are missed.
• Note that nutrient product formulations with calcium may contain boron that would interact poorly with water soluble packaging.

Site Preparation

• Getting ready to plant trees in the spring of 2024? This season is a good time to incorporate limestone, nutrient additions, rip, level the surface, lay out the rows, or plant an overwintering cover crop to hold the soil.
• The Limestone Trucking Assistance Program is accepting applications until September 30, 2023. The application and guidelines are available online here or contact your local Agricultural Office for assistance.

Harvest Fruit Quality

Using a Delta Absorbance (DA) Meter

Many new DA meters are being used in the industry this year so it might be time for a refresher on the topic. What is a delta absorbance (DA) meter, how does it work, and how is it used in the field? 

The DA meter is a handheld device used to monitor the chlorophyll content of the apple peel as an indication of fruit maturity. Chlorophyll degrades as the fruit matures so the reading correlates with other changes that happen during the ripening process. The device works by shining LED lights onto the apple skin and records a value from the light-based reading.

What you need to know:

• Varieties have a unique set of DA meter values associated with them that are the boundaries of when to begin and end harvest, based on local research by AAFC. This means that you cannot test a McIntosh or Cortland and expect it to match values set for Honeycrisp.
• DA meter values become smaller as fruit matures. Typically the readings will change by 0.1 units in one week (ex. from 0.6 to 0.5).
• The late Dr. John DeLong who spearheaded local research on the topic recorded a podcast with us in 2019 on 'Sensing Fruit Maturity'.

Using the DA meter:

• Years ago Joan Hebb created a handy Quickstart Guide. Follow the instructions for calibrating and clearing the mean values. 
• Leave the fruit on the tree but ensure that leaves are not caught between the LED sensors and the fruit surface.
• Take a reading on the average sides of each apple (imagine an apple has four sides, ignore the sun-exposed and shade-exposed sides and use the remaining two sides). 
• Test a minimum of 20 apple samples randomly from each block by measuring 10 apples from one side of the row and 10 apples from the other side (10 apples x 2 fruit sides x 2 row sides = 40 readings). 
• Record the average result calculated by the device then clear the mean value to start over in the next block. Keep your records because it will be valuable to compare blocks within a year and between years. Record the block name and successive dates of measurement.
• Honeycrisp with a DA meter reading above 0.59 is too immature to harvest, 0.59-0.36 is optimally mature and best for storage, and below 0.36 is over mature and susceptible to storage disorders so is best sold immediately (DeLong and others, 2014).
• The DA meter boundaries for Ambrosia destined for long term storage are 0.47 to 0.28 (DeLong and others, 2016).

Recommendations:

• Start taking sample readings 2-3 weeks before the predicted harvest date to anticipate the rate of change and the approaching start time. One of the major benefits of the DA meter is using the readings to chart the progression of maturity and to compare blocks so that more mature blocks can be harvested before others.
• The DA meter values for optimum harvest may vary each year so it is still important to regularly do a taste test and starch test. The DA meter helps to increase the frequency of sample testing and the sample size.
• DA meter values may not be representative of fruit maturity on fruit treated with ReTain or Harvista so consider other maturity indicators. The chlorophyll degradation might be affected by ReTain and Harvista and could be misaligned with typical DA meter values.

Figure 3: The DA meter is a handheld device to monitor apple fruit maturity on varieties with known DA meter harvest protocols. A minimum of 20 fruit in each block should be sampled with readings on the sun and shade exposed sides of each fruit.

Delaying or Synchronizing Maturity with ReTain and Harvista

The Ripening Hormone Ethylene

ReTain and Harivsta products delay fruit maturity through their impact on the plant hormone ethylene, so let's take a step back and review how ethylene production occurs in apple fruit.

• Ethylene is a gaseous hormone produced by the apple fruit that accelerates the ripening process.
• When fruit reach a certain stage of development, ethylene production begins to escalate. When the escalation begins the ethylene production is analogous to an unstoppable freight train. The internal ethylene concentration rises, the hormone is recognized within the fruit and then processes are signalled to quicken fruit maturity.
• The capacity for ethylene production varies between apple varieties. Honeycrisp and Gala have less capacity to produce ethylene than McIntosh.
• Research has discovered products that manage ethylene in plants:
• ReTain stops ethylene production. If ethylene production is stopped early in the process then the internal fruit concentration stays low. Application 3 to 4 weeks before harvest is expected to keep the internal ethylene low. In our analogy, using ReTain means that the freight train coasts but does not gain speed until the ReTain wears off.
• Harvista stops ethylene action within the fruit. The ethylene is present but it isn't recognized within the fruit so ethylene does not quicken fruit maturity. The freight train freezes until Harvista wears off.

Summary of Discussion at the Perennia Tailgate Meeting

Thank you to Stirlings Mountainside Farm for hosting us for a discussion on Sept 1!

• There are many remaining questions and there will be more on-farm experimentation this year so we plan to meet again next year to revisit this topic.
• The main concern with ReTain on Honeycrisp appears to be the colour delay and for that reason there is hesitation to apply it more than 2 weeks before harvest.
• Don't apply ReTain if the block already struggles to get good colour development or if it has a heavy crop load and will have trouble gaining colour.
• In general there is comfort using ReTain on Gala at 2 weeks before harvest, especially to prevent greasiness and cracking.
• We discussed interest in the flexibly offered by Harvista. Harvista can be applied up to 3 days before harvest meaning that red colour is allowed to develop first and harvest dates are predictable. Harvista has an increased cost but several growers argue that an extra bin or two can make up the cost.
• There is interest in using a program of ReTain followed by Harvista for even greater harvest delay. There is limited local experience but experience with Gala suggests positive results using 1/2 rate ReTain on Sept 1 and 1 gal/ac Harvista on Sept 26. Gala harvest was extended until Oct 17 using this combination of ReTain and Harvista.
• DA meter readings after Harvista/ReTain might not actually represent maturity. Changes to chlorophyll content caused by these products might not be synchronous with other maturity indicators.
• If you are testing a rate or timing, leave a small untreated area within the block for comparison.

The Preharvest Management Strategy:

• As even more new plantings come into bearing, consider the advantages of harvest management tools to help slow fruit maturity as you manage labour resources. 
• Both ReTain and Harvista can help reduce the incidence of watercore and internal browning by delaying maturity. 
• Consider testing ReTain or Harvista on a small block and talk to others who have experience using them. Do not give up after one attempt with these products, especially if last year was your first test. Last year was an anomaly with conditions that did not support colour development. Also experiment with different rates, timings, and varieties.
• These products are not expected to prevent the structural stem damage that is associated with windfalls from high winds. 

ReTain

Recommendations:

• Note that the amount of ethylene produced differs by apple variety and so the variety’s response to ReTain will also differ. McIntosh is a high ethylene-producing variety and the full rate is often needed 3 weeks before harvest to slow its maturity. Sensitive varieties like Gala, Jonagold and Honeycrisp produce low ethylene and are more sensitive and thus greatly delayed by full rates of ReTain. For Honeycrisp, local success is achieved with the half rate at 14 or 7 days prior to harvest.
• ReTain applied 3-4 weeks before harvest will delay the harvest period up to 7 to 10 days.
• The effectiveness of ReTain is dose-dependent and time-dependent. Later applications and smaller doses have less effect on maturity and colour development.
• For a multi-pick harvest, ReTain applied 7 to 14 days prior to the anticipated start of the 1st harvest can improve the quality and storage potential of 2nd and later picked apples. First picks will not be affected but later picks will be delayed. Note the PHI of 7 days.
• Xiameter surfactant is recommended at a concentration of 0.05 to 0.1% (v/v) in the spray tank. To prevent possible spotting on fruit, use the 0.05% (v/v) concentration.
• ReTain is not a systemic product. Good coverage of both fruit and leaves is important to response.
• On the label, there is a caution stating that the fruit on heat- and water-stressed trees may not respond to the product.

Harvista

Recommendations:

• Harvista can be applied 3 to 21 days before the anticipated harvest and at a higher rate for fruit that are more advanced in maturity and producing plenty of ethylene.
• Harvista will delay the harvest period up to 7 to 14 days.
• Typically the product will reduce the number of harvest picks because it helps to synchronize the maturation rate.
• Lower rates are recommended for biocoloured apple varieties to allow colour development to progress. It can delay red colour development on Gala and Ambrosia so apply after colour has developed at close to 3 days before harvest. It also reduces stem splits on Gala.
• A customized sprayer system is required for Harvista applications.
• A calibration video is available on the AgroFresh YouTube page. 
• The Harvista Calibration Tool is available on Google Play and the Apple Store.

Estimating Bin Requirements

Large apples fill bins a lot quicker than small apples. If fruit in a block are a relatively uniform size, then a little math can help you estimate bin requirements. The crop volume is determined by the number of trees, number of fruit, and fruit size.

To approximate the number of bins required:

1. Calculate the number of apples per acre (# trees per acre x avg # apples per tree)
2. Refer to table 4 for the # of apples per 17 bu bin of a selected average count size
3. Bins/acre = # of apples per acre / # apples per bin for selected count size

Table 3: Number of apples of a selected count size to fill a 17 bu bin.

Example 1: 125 count size

1. 1000 trees per acre x 60 apples/tree = 60,000 apples/acre
2. There are 2125 apples per bin of 125 count size.
3. Bins/acre = 60,000 apples per acre/2125 apples per bin = 28.2 bins/acre

Example 2: 113 count size

1. 1000 trees per acre x 60 apples/tree = 60,000 apples/acre
2. There are 1921 apples per bin of 113 count size.
3. Bins/acre = 60,000 apples per acre/1921 apples per bin = 31.2 bins

Reducing Bruising

Recommendations:

• Apples picked after significant rain will bruise more easily than if they’re picked when the soil has a lower moisture capacity. This information might be helpful for varieties especially sensitive to bruising.
• Let fruit warm up before harvesting. Apples picked in the cool weather of early morning bruise more easily than those picked in the day’s warmth. Generally, susceptibility to bruising decreases gradually from 0 to 15°C.
• Take the time to educate staff about the proper way to perform harvest activities that reduce bruising. For example, pick the bottom of the tree first, don’t overfill the picking bag, avoid long harnesses that let the bag bump against knees when walking, explain the difference between varieties etc.
• Re-grade orchard roads prior to harvest to lessen bumps that would jostle fruit being transported in bins.
• Have an inspector sample fruit from various positions in the bin two times each week and leave at room temperature for 24 hours to check for signs of bruise development.
• If bins of fruit will sit in the orchard during overnight freezing temperatures, place the bins where they will be shaded from direct morning sun. Direct sun will warm the fruit too quickly and can lead to deep and lasting bruises.

Considering Watercore

Watercore is a fruit disorder closely associated with over-mature apples along with several other factors. It happens most frequently in years with high sunshine and lack of cloudy, rainy days. Also, highly coloured and large fruit are most prone to the disorder. Fruit with the disorder have an appearance of water-soaked flesh because the spaces between the cells become concentrated with sugars instead of air. Small signs of watercore can disappear in storage and add sweetness to fruit. However, more serious watercore can reduce gas exchange in the fruit and lead to internal breakdown.

Recommendations:

• Mature fruit are more likely to develop the disorder because as fruit mature the starches are converted to sugars. The sugar solution builds up in the fruit. Blocks that have a history of watercore should be harvested before other blocks.
• Consider products to delay harvest maturity. Both ReTain and Harvista labels state delayed onset and incidence of watercore.

Avoiding Internal Browning

Internal browning is likely related to carbon dioxide injury. The disorder frequently occurs in overmature and large fruit that have high carbon dioxide concentrations. In particular, fruit harvested late in the harvest window are most susceptible because as fruit mature their ability to diffuse internal carbon dioxide concentrations decreases. The internal carbon dioxide builds up and increases the chance of injury. Consider using products that delay harvest maturity.

What's that? Lenticel Injury?

If fruit have symptoms that don't quite resemble bitter pit, it could be because the issue is actually lenticel injury. Lenticels function as pores in the fruit skin to exchange gases from the inner fruit and the outer atmosphere. The cells that make up these pores are susceptible to cracking if they are damaged by environmental factors or chemicals. Too much or too little water can damage cells by causing them to grow or shrink too quickly, and sun and heat stress can also interfere with normal functioning.

The spots caused by lenticel injury versus bitter pit can be difficult to differentiate. Lenticel injury originates at a lenticel and symptoms surround the lenticel with a distinct edge. Cutting off the skin can reveal corky tissue in the flesh that sits directly against the fruit skin. The early symptoms of lenticel injury are small dimples that can become wider and deeper as fruit firmness decreases. The symptoms can expand and evolve if weak fungi invade the wounds and cause secondary infections.

On the other hand, bitter pit is not associated with a lenticel and is sunken with irregular and diffuse edges. Cutting into the skin will reveal several cell layers of healthy tissue between the fruit skin and the appearance of corky tissue more deeply in the flesh.

Figure 4: The spots caused by lenticel injury versus bitter pit can be difficult to differentiate. Photos A & C by Dr. Paul Hildebrand in 2017.

Ever Wondered about Apogee and Bitter Pit Incidence?

The question of Apogee's influence on bitter pit has come up and there was a study published in 2018 by Lee Kalcsits lab that explored this very question. The work was done in Washington so it may not be directly applicable to our region but what they conclude leads me to be unconcerned about the use of Apogee.

The study by Serban and Kalcsits investigated the influence of shoot extension growth on bitter pit incidence. They did so by testing several rates of Apogee that inhibited shoot growth and the opposite treatments of stimulating shoot growth using the plant hormone gibberellic acid. The study was done using Honeycrisp and bitter pit was assessed after 4 months of storage. In the two-year study, none of the treatments significantly affected the amount of calcium in the fruit or the incidence of bitter pit. Good to know!

The researchers suggest that although Apogee controls shoot extension it doesn’t affect the vigour in terms of mineral balance. Apogee reduces shoot length but the number of internodes stays the same.

Consequences of Harvesting too Early

While trying to avoid overmature fruit, avoid the other extreme as well – immature fruit. Picking fruit too early has penalties. Fruit continue to grow as they mature so a 1/4 inch increase in size from 2 3/8 to 2 5/8 can translate into a 35% increase in fruit volume. It takes just as long to pick one large (88 count) apple as it does to pick one small apple (160 count). But it will take half as long to make up a bushel of large apples than small. So picking cost and time required are less for larger fruit. Picking too early can also sacrifice fruit colour and reduce pack out. Immature fruit bruises easily and is subject to scald, shriveling in storage, and poor flavour.

Pest Management Guides 2023

All changes new to 2023 are made in red text directly on the guides. The information on all expected changes was summarized in a blog post on March 7. 

Decision Tables

• Download the 2023 Petal Fall Insecticide Decision Table
• Download the 2023 Prebloom Insecticide Decision Table
• Download the 2023 Fungicide Decision Table

Guides

• Download the 2023 Pome Fruit Management Guide
• Download the 2023 Organic Apple Management Guide
• Download the 2023 Stone Fruit Management Guide
• Download the 2023 Thinners and Growth Regulators Guide
• Download the 2023 Tree Fruit Weed Management Guide

This Orchard Outlook has been published with the input of the Orchard Outlook Committee including this week's contributors: Joan Hebb, Danny Davison, Kari Brown, Jeff Franklin, and Heather Rand.

Perennia Food and Agriculture Corp.
Edited by Michelle Cortens, Tree Fruit Specialist