Podcast season two complete and available

Thursday, October 21, 2021

I hope you enjoyed listening to the 10 episodes of the Orchard Outlook Podcast that were published in season two. These episodes are meant to be fun, conversational, timely, and informative! Plug in your headphones and tune in anytime. 

Please also feel free to suggest new topics and send me your wildest questions that I will ask directly to our expert guests. Text or email any time and I'll keep your questions handy.

Did you miss any episodes in season two? Don’t worry, they’re still available! Listen on any podcast streaming service or listen online at AnchorAsk me how to access the episodes directly on your phone. 

EPISODE

TITLE

GUEST

PUBLISH DATE

E1, S2

Rooting for Water Management

Dr. Denise Neilsen, AAFC (retired)

Oct 21, 2020

E2, S2

Confronting Climate

Bernard Soubry

Nov 25, 2020

E3, S2

Bitter and Sweet Sides of Cider

Dr. Gregory Peck, Cornell

Dec 16, 2020

E4, S2

Don't Sneeze at Blossom Thinning

Michael Basedow, Cornell Extension

Jan 28, 2021

E5, S2

Part 1 Speaking of Sprayers

Jason Deveau, OMAFRA

Feb 24, 2021

E6, S2

Part 2 Still Speaking of Sprayers

Jason Deveau, OMAFRA

March 10, 2021

E7, S2

Welcoming Weather Stations

Jonathan Buffet, Cape Breton Mesonet

April 28, 2021

E8, S2

Don't Play with Fire Blight (ENCORE)

Dr. George Sundin, MSU

May 26, 2021 (re-release)

E9, S2

Loving Local Food

Patrick Kelly, Perennia

June 30, 2021

E10, S2

Ghosts and Skeletons of Powdery Mildew

Dr. Kerik Cox and David Strickland, Cornell

August 11, 2021




Orchard Outlook Newsletter Vol 21, No 17

Wednesday, October 20, 2021


Table of Contents:


  • Fall herbicide application
  • Fall soil pH adjustments
  • Orchard rodent control
  • Reducing the risk of apple scab
  • Peach leaf curl
  • Workshops and conferences for the winter season


Winterizing Orchards


Fall Herbicide Application

Fall is prime germination time for winter annuals, and perennials are susceptible to treatment because they’re actively storing reserves in their roots. Refer to this year's special article 'Fall Weed Control for Winter Annuals and Pesky Perennials' for more information.

Takeaways from the article:

  • Winter annuals like common groundsel, common chickweed, and bluegrass can grow past their treatable stage quickly in spring.
  • Summer and winter annual species have populations that germinate in both fall and spring and therefore troublesome weeds may need to be managed at both times.
  • Bluegrass species should be identified by molecular analysis to inform herbicide choice.
  • Products to manage bluegrass species in young orchards are limited so pre-emerge options should be considered and may need to be applied prior to fall grass germination.
  • After harvest, consider using a post-emerge herbicide to clean up weeds along with a residual product to save time early next season. Orchards without fall application of residual herbicides are expected to exceed weed thresholds in early spring before those treated with residuals.
  • Fall pre-emerge herbicides should be applied to bare ground for uniform control.
  • The majority of weed species by abundance in established orchards are perennials including dandelion, vetch, and wood sorrel. Site preparation is an important first step to limit creeping perennials.
  • After harvest there is an opportunity to treat perennials when they are storing reserves in their root systems before a hard freeze.
  • If planning to apply glyphosate, wait until late spring to avoid translocation to fruit tree root systems.
  • Even if you are not set up to perform weed control in the fall, now is a good opportunity to identify what weed species are present to inform herbicide choices for early next year.
Figure 1: An overhead view of weed cover in the tree row of a young planting on May 14, 2021. The weed cover in the photo is mainly the winter annual shepherd's purse that germinated in the fall of 2020.


Fall Soil pH Adjustments

Soils in the valley are naturally acidic, and nitrogen fertilizers will slowly acidify soils over time. As soils acidify, nutrients such as calcium, potassium and phosphorus are less available for uptake by fruit trees. Other nutrients such as manganese and aluminum become more available and uptake by fruit trees can become excessive.

The pH of orchard soil should be between 5.5 and 6.6 (target 6.0) because nutrient availability is best within this range. Fall is the ideal time to make soil pH adjustments because it gives time for limestone to neutralize the acidity before the next growing season. Also in the fall, the dust from limestone applications will not interfere with growth or bloom.

Recommendations:

  • The results of a soil test will give a lime requirement based on your soil type and pH.
  • Apply calcitic limestome unless magnesium is needed from dolomitic limestone.
  • A surface application of no more than 3 tonnes/ha of limestone in any one year is recommended because higher volumes could be washed away and are ineffective.
  • If the lime is being worked into soil then you can follow the recommended rate on your soil report. Incorporating lime into soil will show benefits sooner than a surface application. A surface application moves down at a rate of about 1 inch per year.
  • If you have ongoing issues with lack of calcium in established plantings, consider banding gypsum at a rate of 4 tons per acre under trees. Annual applications have been shown to reduce bitter pit and senescent breakdown. Gypsum can also improve soil structure and improve water infiltration. Be aware that gypsum can reduce magnesium uptake. Gypsum will not replace the need for lime for pH adjustment.

Orchard Rodent Control

Rodents feed on tree bark in the fall and winter when other food supplies are scarce. The most common issue is when rodent feeding girdles the trunk of young trees at or near the ground surface or at the height of snow accumulation.

Recommendations:

  • Mow ground cover and maintain a weed-free strip to expose mice to predators.
  • Clean up drop apples from the tree row and alleyways to remove attractive food sources.
  • Be aware that using straw mulch can harbour mice.
  • If rodent activity is observed (mouse tunnels, droppings and chewed apples), consider the use of rodenticide. Bait stations manage the risk of poisoning other species and the control is long-lasting.
  • Bait stations placed on the perimeter of the orchard target mice moving into the orchard from bordering fields, fence lines or ditches. Pay particular attention to orchard blocks that neighbour corn and soybean fields.
  • Install tree guards, if feasible, on young trees. Remove after snow melt in spring to avoid fungal problems at the base of the trunks.


Diseases


Reducing the Risk of Apple Scab

Scab spores can be reduced for the next growing season by accelerating the decay of infected leaves in the fall of the current season. The benefit is less disease pressure next spring that can help to reduce the risk of primary scab infections. All efforts to reduce primary inoculum for next year will be helpful for scab control under new fungicide restrictions.

Recommendations:

  • Spraying urea (46-0-0) onto leaves on the ground can reduce spores by about 66%. The recommended rate is 50 kg/ha in 1000 L/ha of water. Alternatively, apply the solution to full trees as leaf fall begins. Urea should be dissolved in warm water before putting it in the tank. The 50 kg/ha rate will supply approximately 23 kg/ha of nitrogen to the ground, so nitrogen application next spring should be adjusted accordingly.
  • Flail chopping all plant matter on the orchard floor in November can reduce the number of scab spores by as much as 85%. Flail chopping in only the alleyway can reduce scab spores by as much as 50%. Why does chopping work? Dr. Gordon Braun explained in a year 2000 publication that:
    • "By chopping up leaves finely, they are more easily broken down by bacteria and molds to be consumed by earthworms."
    • "The apple scab fungus needs to mate with the opposite mating type and smaller leaf pieces reduces the likelihood of the two meeting."
    • "The smaller fragments also fall deeper into the grass and have a greater probability of resting in a position which is less than horizontal which reduces the ability of the ascosopres being successfully discharged into the air currents and carried to susceptible leaves."
  • Using both shredding and urea applications can produce the best results.
Figure 2: Scab spores can be reduced for the next growing season by using both leaf shredding and leaf urea application in the current season.


Peach Leaf Curl

Peach leaf curl is a fungal disease of peaches and nectarines that is usually well-controlled by a fungicide application in spring or late fall. Infections occur in the spring at bud swell when overwintering spores are washed from the surfaces of the bark. Therefore, a fungicide application prior to bud swell in the spring is preferred. However, occasionally early warm temperatures combined with extended snow cover can make spring applications challenging.

Recommendations:

  • The spores overwinter on the bark, so fall applications for peach leaf curl should be tailored to provide complete coverage of trunks and branches. Fall application should be made after 75-100% of leaf drop has occurred and when the temperature is above freezing.
  • Unusually wet winter weather with heavy rain can wash off a protectant fungicide applied in fall. If residues are washed off, re-treatment in spring before buds swell is recommended. 
  • Chlorothalonil (Bravo) has been the most effective fungicide in Nova Scotia. Only 1 spray of Bravo may be applied per year, meaning it cannot be applied in both spring and fall. Other products registered for control include Ferbam, fixed copper products and Syllit. Note that Ferbam is being phased out and the last date of use is December 14, 2021.
Figure 3: Peach leaf curl infections occur in the spring and can be protected by a fungicide in the late fall or early spring.


Events and Notices

For an ongoing list of events including workshops and conferences for the winter season, visit the ‘Events’ tab on the NS Tree Fruit Blog. At this time, all of the usual workshops and conferences are being planned for in-person venues while following COVID protocols. Here's a snapshot:


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


Orchard Outlook: Special Issue - Fall Weed Control for Winter Annuals and Pesky Perennials

Friday, October 15, 2021

It seems counterintuitive to apply an herbicide in the fall when everything seems to be shutting down. But even though the summer annuals are petering out, not all weeds are shutting down. In fact, for winter annuals the fall is prime germination time. And perennials? They’re susceptible to treatment because they’re actively storing reserves in their roots. Knowing the weed life cycle can be helpful for managing troublesome weeds.


Winter Annuals in Our Orchards

The life cycle of winter annual weed species is that they germinate in the fall, overwinter, and then produce seeds in spring or early summer. Winter annuals typical in Nova Scotia orchards include common groundsel, common chickweed, bluegrass, daisy fleabane, Pennsylvania bittercress, scentless chamomile, shepherd’s purse, henbit, and deadnettle (Figure 1). In the early days of spring, these winter annuals are the first you’ll see because they restart growth when the weather warms up. By the time weed management fits into your schedule, these weeds can be too large and are therefore past their treatable stage.

 

Figure 1: Winter annuals typical in Nova Scotia orchards from left to right: common groundsel, common chickweed, and bluegrass.

 


For comparison, note that the summer annuals typical in Nova Scotia orchards are lamb’s-quarters, common groundsel, wild carrot, red root pigweed, barnyardgrass, common chickweed, smooth crabgrass, wild buckwheat, witchgrass, wild radish, bluegrass, prostrate knotweed, foxtail, common ragweed, daisy fleabane, and spotted lady’s thumb (Figure 2). The summer annuals are at treatable stages for relatively longer than winter annuals in spring.

Figure 2: Summer annuals typical in Nova Scotia orchards from left to right: lamb's-quarters, red root pigweed, and common ragweed.


Management Strategies in Relation to Weed Biology

I recently listened to a podcast episode of ‘Out Standing in the Field’ that was co-hosted by my colleagues Caitlin Congdon and Sonny Murray with guest Mike Cowbrough. The focus was on weed management in winter wheat but aspects of the conversation are relevant to our tree fruit crops. Similar to winter wheat, our perennial crops can run into issues with pressure from winter annuals.

In the podcast, Mike emphasized how knowing aspects of weed biology can help with management decisions. Some weeds are summer and winter annuals so depending on when the seeds germinate, management might need to target both populations that germinate in fall and spring (Figure 3). Taking scentless chamomile as an example, they found that neither fall nor spring treatment alone was sufficient for control in cereals. He also mentioned the importance of fall management for the winter annual purple deadnettle, as opposed to spring management.

Figure 3: Photos of common groundsel taken on September 17, 2021 at the flowering stage (left) of a summer annual and a newly germinated winter annual (right).

For bluegrasses, knowing the type of species whether annual, Kentucky, or roughstalk is helpful for herbicide selection. But identification is tricky, so molecular analysis is preferred for a cost of about $20. Contact me for more information if you have concerns about bluegrass or need help identifying grassy species.

Bluegrass species that are winter annuals germinate in the fall and can grow quickly in the spring. The trouble is that post-emerge products work best at the 2-4 leaf stage, which could happen as early as May and would make spring bluegrass management a challenge in busy orchards. Also, bluegrass species have been difficult to treat post-emerge in young orchards in particular because options are limited. The seemingly recent occurrence of bluegrass issues could be a result of losing the post-emerge product gramoxone. Also, glyphosate is not very effective on bluegrass.

The pre-emerge options could prove to be a helpful approach. For example, Dual II Magnum provides pre-emerge management of grasses and likely has activity on Kentucky bluegrass although the species is not listed on the Canadian label. First Ignite could be used to burn down the existing weeds and then Dual II Magnum could be applied before new orchard grass germinates. Dual II Magnum applied with Princep would offer a broader range of control for broadleaves resulting in pre-emerge and long-term control.


Weed Control Programs

Most winter and summer annual weed seeds germinate in the top ½ inch of soil, so pre-emergence treatments are most effective when rained in to the ½ depth of soil. The idea with residual herbicides is that if the viable weed seeds are killed by the treatment, then the undisturbed soil surface will be weed free even after the chemical has degraded over time.

Consider the benefits of treating annuals pre-emerge, especially in young orchards to rely less on post-emerge products. Post-emerge products applied late to tall weeds run the risk of damaging the tender young bark of trees. Good weed control is critical in young orchards to maintain access to resources for tree vigour to fill the space.

A fall weed control trial by Cornell Cooperative Extension in 2014 through 2016 showed that, “Untreated weedy checks and plots without residual herbicide in the fall were the first to break through the suggested PWC [percent green weed cover] threshold of 20% by 19 May in the midst of petal fall insecticide, fungicide, and late fire blight sprays.” Refer to the article directly for more information about herbicides and rates used in their 2-year program. Please note that not all products and uses are allowed in Canada and that Canadian pesticide labels should be consulted. Visit the Tree Fruit Weed Management Guide for a summary of available options.

Fall weed control does have its limitations. A major limitation is that the residual herbicide should be distributed evenly on a soil surface to uniformly prevent seed germination. But in the fall the herbicide strip can be covered with dropped apples, root suckers, tall weeds, and leaves. A residual herbicide is best applied to bare ground.


Pesky Perennials

Next, let’s turn our attention to perennial weeds. Soon they’ll be shutting down but in the meantime before a hard frost they’re storing reserves in their roots for next year. Perennials commonly found in Nova Scotia orchards are dandelion, vetch, sorrels, willowherb, buttercups, dock, quackgrass, hawkweed, plantains, perennial sow thistle, goldenrod, mouse-eared chickweed, thistle, horsetail, catchweed bedstraw, yellow toadflax, St. John’s wort, ground ivy, and scentless chamomile (Figure 4). The 2020 survey by the NSDA suggests that established orchards are challenged with control of perennial weed species because perennials rank high in terms of abundance (Table 1).

Figure 4: Perennials typical in Nova Scotia orchards from left to right: vetch, dock, and St. John's wort.


Table 1: A weed survey done by the Nova Scotia Department of Agriculture in 2020 at 37 orchard blocks in Nova Scotia. Species are ranked by relative abundance determined by the survey. Table modified to show the life cycle for the top 25 listed species.


To kill the life-giving roots of perennial weeds, an herbicide applied to the foliage needs to be transported to the roots. In the early spring during rapid leaf growth, the resources are directed away from the roots so an herbicide like 2,4-D that behaves like a food metabolite is not translocated to the roots. Whereas in the late spring and early fall, resources are being stored in the roots and 2,4-D could tag along. Perennial weeds on the label for 2,4-D could be treated post-harvest (because of the 80-day PHI). Just keep in mind that perennial weeds should be treated while they are green and growing, prior to a hard frost.

Also, take note of perennials before tillage practices especially if they have rhizomes or spread vegetatively. Prepare the site with glyphosate and 2,4-D prior to tillage to limit the spread of creeping perennials like sorrels, sow thistle, mouse-eared chickweed, ground ivy, quackgrass and Canada thistle.

However, if you’re planning to use glyphosate for perennial weed control in established orchard, wait until a late spring application timing. Fruit trees are currently storing reserves in the roots for next year’s growth so glyphosate can be damaging if taken up and transported to the tree’s root system.


Takeaways

  • Winter annuals like common groundsel, common chickweed, and bluegrass can grow past their treatable stage quickly in spring.
  • Summer and winter annual species have populations that germinate in both fall and spring and therefore troublesome weeds may need to be managed at both times.
  • Bluegrass species should be identified by molecular analysis to inform herbicide choice.
  • Products to manage bluegrass species in young orchards are limited so pre-emerge options should be considered and may need to be applied prior to fall grass germination.
  • After harvest, consider using a post-emerge herbicide to clean up weeds along with a residual product to save time early next season. Orchards without fall application of residual herbicides are expected to exceed weed thresholds in early spring before those treated with residuals.
  • Fall pre-emerge herbicides should be applied to bare ground for uniform control.
  • The majority of weed species by abundance in established orchards are perennials including dandelion, vetch, and wood sorrel. Site preparation is an important first step to limit creeping perennials.
  • After harvest there is an opportunity to treat perennials when they are storing reserves in their root systems before a hard freeze.
  • If planning to apply glyphosate, wait until late spring to avoid translocation to fruit tree root systems.

Even if you are not set up to perform weed control in the fall, now is a good opportunity to identify what weed species are present to inform herbicide choices for early next year.


References:

  • Congdon, Caitlin. “Out Standing in the Field: Weed Management in Winter Wheat with Mike Cowbrough.” Perennia, September 8, 2021, https://anchor.fm/out-standing-in-the-field/episodes/Out-Standing-in-the-Field-A-Podcast-by-Perennia-e15pd6j.
  • Klingman, Glenn C. 1961. Weed Control: As a Science. John Wiley & Sons, Inc. pp. 1-421.
  • Breth, D., Tee, E., Donahue, D., and Wallis, A. 2016. Managing Apple Orchard Weeds in the Fall. New York Fruit Quarterly. 24 (4), 9-16. https://nyshs.org/wp-content/uploads/2017/03/Breth-Pages-9-16-from-NYFQ-Book-Winter-2016-4.pdf
  • Nova Scotia Department of Agriculture (NSDA) survey of 37 orchard blocks in 2020
  • Bouchard, C.J., and Neron, R. 2003. Identification guide to the weeds of Quebec. Conseil des productions vegetales du Quebec Inc. pp. 1-251.
  • Palfrey, G.D. 1986. Weeds of Nova Scotia. Department of Agriculture and Marketing. Province of Nova Scotia. ISBN 0-88871-063-1. pp.1-95.
  • LeBlanc, L. and McCully, K. Weed Identification Guide. Agriculture Canada, Nova Scotia Department of Agriculture and Marketing, New Brunswick Agriculture. pp.1-51.
  • Cowbrough, M., Tardif, F., and Letarte, J. 2016. Weed ID Guide for Ontario Crops. Grain Farmers of Ontario. pp 1-270. http://fieldcropnews.com/2016/09/weed-id-guide-for-ontario-crops/
  • Private communications with Sonny Murray, and Kristen Obeid for bluegrass management. This post is not a reflection of their views.

Honeycrisp Fruit Maturity Report - Oct 5

Tuesday, October 5, 2021

Important Note - This information 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.


Table 1: Maturity indices for Honeycrisp fruit sampled across four regions on October 5, 2021.

Note that all blocks being monitored are at various stages of spot picking. Where DA values are higher than they were the previous week, the increase in DA value is largely a result of measuring fruit that were left behind during early picks that are by nature less mature.

The average DA value for fruit measured in all regions following spot picking is above 0.35, which is ideal for long term storage. Over the last week, starch conversion to sugars has progressed (Figure 1).

Figure 1: The visual results of starch-iodine tests on a five-fruit sample across all four regions. Photos were converted to black and white to emphasize the pattern of starch (black) staining. Fruit from the three weekly sample dates are shown to compare starch conversion in sampled regions over time. Average starch index ratings are reported in Table 1.

The block with ReTain treated fruit that is being monitored anecdotally has now crossed the threshold for the DA value recommendation by measuring an average of 0.54. Fruit in the block has maintained average starch levels around 5.6. 

Comments on Colouring

Colouring has been slow to develop on certain varieties this year. An article by Penn State notes this varietal difference explaining the different temperature requirements for colouring, "McIntosh requires temperatures below 70 degrees (21.1°C), Fuji requires temperatures in the low 60s (15.5°C), and Redchief Delicious requires temperatures in the low 50s (10°C), but one day at 90 degrees (32.2°C) will negate the effects of several cool nights."

Anthocyanin is the pigment responsible for red colour in apples. Studies on detached apples show that the precursors for anthocyanin development are formed at temperatures below 15°C and the conversion to anthocyanins is completed at higher temperatures around 20-25°C during sunlight hours (Steyn 2005). Warm temperatures earlier this harvest season slowed down the process of colouring by slowing down anthocyanin production.

Anecdotally, it seems that colouring has improved within the last week in the ReTain treated Honeycrisp block that's being reported on, which could be due to the recently cool nights. Typically colouring will noticeably improve after several cool nights followed by warm, sunny days.

About each measurement:

Starch Index - Starch is converted to sugars as ripening progresses. The starch-iodine test is used as a visual indicator 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 (immature) to 8 (most mature) was used above and values are an average of five representative samples from each block.

Soluble Solids - Approximates the percentage of sugar content of the fruit. Measured using a digital refractometer. Values are an average of five 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 0.60 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 both the red and green sides.

Honeycrisp Fruit Maturity Report - Sept 28

Tuesday, September 28, 2021

Important Note - This information 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.


Table 1: Maturity indices for Honeycrisp fruit sampled across four regions on September 28, 2021.

The average DA value for fruit measured in all regions is above 0.35, which is ideal for long term storage. DA values will be noticeably different between the most mature and least mature fruit on a tree. Over the last week, starch conversion to sugars has progressed from last week's range of 3-6 to this week's range of 6-8 (Figure 1). Measurable soluble solids are increasing. 

Figure 1: The visual results of starch-iodine tests on a five-fruit sample across all four regions. Photos were converted to black and white to emphasize the pattern of starch (black) staining. Fruit from the two sample dates are compared to show starch conversion in sampled regions over the last week. Average ratings are reported in Table 1.

The fruit treated with ReTain on an M.111 is an anecdotal report because I am not monitoring untreated trees for comparison on the same tree age, crop load and rootstock. However, the ReTain treatment has an average DA value of 0.65 this week, which is considered immature. Starch conversion is also low.


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 five representative samples from each block.

Soluble Solids - Approximates the percentage of sugar content of the fruit. Measured using a digital refractometer. Values are an average of five 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 both the red and green sides.

Honeycrisp Fruit Maturity Report - Sept 22

Wednesday, September 22, 2021


Revised 6:25 PM Sept 22: In Figure 1 the photo on the left is in fact Rockland fruit, not Lakeville fruit.

Hello folks, I hope harvest is off to a good start! At the last minute this year I've decided to provide you with a weekly update on Honeycrisp fruit maturity at four different regions throughout the Valley. It will be a test run to see if the information is worthwhile. Enjoy!


Honeycrisp Maturity Report - September 22


Important Note - This information 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 (ie. not representative of a first pick prioritizing the most mature fruit).


Figure 1: The results of starch-iodine tests rated on the Cornell chart scale of 1 to 8 on a five-fruit sample in Rockland (left) and North Medford (right).


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 five representative samples from each block.

Soluble Solids - Approximates the percentage of sugar content of the fruit. Measured using a digital refractometer. Values are an average of five 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 both the red and green sides.


Update on 2021 Degree Day Accumulations

Figure 2: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1st to Sept 19th for the past 17 seasons. Provided by Jeff Franklin (AAFC).
  • Approximately 5% more plant development heat units compared to the 5-year average, and 5% more compared to the 10-year average.
  • Approximately 4% more plant development heat units compared to 2020, and 14% more compared with 2019.
  • Approximately 5% more insect development heat units compared to the 5-year average, and 5% more compared to the 10-year average.

Update on Degree Days and precipitation to end of August

Wednesday, September 1, 2021

2021 Degree Day Accumulations

Degree day accumulations up to this point are keeping pace with years such as 2006, 2010, 2013, and 2018. Please note that degree days may not directly correspond with a change in harvest dates but the extra heat this year certainly could advance maturity. Continue to monitor blocks earlier than usual to catch any signs of advanced maturity to be off to a good start.
Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1st to August 31st for the past 17 seasons. Provided by Jeff Franklin (AAFC).
  • Approximately 6% more plant development heat units compared to the 5-year average, and 6% more compared to the 10-year average.
  • Approximately 4% more plant development heat units compared to 2020, and 12% more compared with 2019.
  • Approximately 7% more insect development heat units compared to the 5-year average, and 6% more compared to the 10-year average.

How about a breakdown of temperature by month? According to the Kentville weather station, June was noticeably warmer than average while July and August were close to the 10-year mean temperature (Table 1). Overall, the temperature this summer has been above-average contributing to the lead in degree days shown above.

Table 1: Monthly temperature averages in 2021 compared with the 10-year average. Provided by Jeff Franklin (AAFC) using the Kentville weather station data.


Seasonal Precipitation

Overall, this summer in Kentville there has been above-average precipitation even though there was an early deficit in June (Table 2). The excess in July was largely due to 50 mm of precipitation received in a localized thunderstorm that didn't affect the whole Valley. For regional differences in precipitation, refer to the records in the NSFGA network of weather stations.

Table 2: Monthly precipitation totals in 2021 compared with the 10-year average. Provided by Jeff Franklin (AAFC) using the Kentville weather station data.


It looks like September could be off to an early wet start with tomorrow's forecast for 50 mm of rain from the remnants of hurricane Ida. 

The overall above-average temperature and precipitation this season has made for some fairly good growing conditions.

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