For the final weekly issue of the Orchard Outlook newsletter, we take a closer look at soil moisture management. While dry periods are a normal part of the growing season, last year reminded us that forecasted rain does not always arrive as expected. This article highlights practical strategies for conserving soil moisture, monitoring conditions with sensors and other tools, understanding irrigation triggers, and interpreting recommendations by soil type. We also discuss deficit irrigation as an option when water supplies are limited, balancing mild water stress to manage vegetative growth while avoiding excessive dryness that can affect tree performance. Current soil moisture readings suggest that sandy loam, loam, and silty loam sites have reached irrigation thresholds, although conditions will vary among orchards and should be confirmed with on-farm observations. Thank you so much to the members of the Orchard Outlook Committee!!

*** Please note that this will be the last weekly issue of Orchard Outlook for the summer. Orchard Outlook will continue to be published occasionally for the remainder of the season as necessary. ***

Weather

2026 Degree Day Accumulations

The cumulative degree days are now on par with the 5-year average (Figure 1). The 5-year average represents warm growing seasons on record so this year would also be considered among the warmest growing seasons.

Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to July 7 for the past 17 seasons. Provided by Harrison Wright (AAFC Plant Physiology).

Approximately the same plant development heat units compared to the 5-year average, and 6% more compared to the 10-year average.
Approximately 4% less plant development heat units compared to 2025, and 2% less compared with 2024.
Approximately 1% more insect development heat units compared to the 5-year average, and 7% more compared to the 10-year average.

Soil Moisture

Dry periods are a normal part of the growing season, and typically they are less concerning when rainfall is expected to replenish soil moisture. However, last season reminded us that forecasted rain does not always arrive as anticipated. In recent weeks, forecasted precipitation has fallen short in the Valley.

During last week's heat wave, there were reports of some leaf curling. Trees use leaf curling as a natural response to warm, dry conditions, reducing leaf surface area and helping conserve moisture. While this response does not necessarily indicate a problem, it brings soil moisture to the top of mind again.

Conserve Moisture
Regardless of how the remainder of the season unfolds, moisture conservation practices can help improve water-use efficiency and maintain more consistent soil conditions. Mowing, mulching, and regular soil moisture monitoring are worthwhile investments, particularly in blocks with lighter soils or a history of moisture stress.

Apply mulch early while the soil profile still contains moisture. Mulching is more effective when applied before soils become excessively dry. Apply a herbicide first.
Consider straw mulch, particularly on sandy knolls or lighter-textured soils. A layer only a few centimetres thick can reduce evaporation from the soil surface, moderate soil temperatures, and improve rainfall infiltration by protecting the soil surface.
Practice season-long mow-and-blow by directing laneway grass clippings into the tree row. Even a few centimetres of grass clippings can help conserve soil moisture while contributing organic matter to the soil.

Monitoring Soil Moisture for Irrigation

Soil moisture can be monitored using the hand-feel method, tensiometers, or electrical resistance blocks. Sensors used in the Valley include: G Dot (electrical resistance blocks), and Spot On sensors (tensiometers). (These products are mentioned for general information only and not as endorsements.)
For more information on soil moisture monitoring methods, refer to Chapter 13 of the BC Trickle Irrigation Manual or OMAFA's publication Monitoring Soil Moisture. Irrigation scheduling can also be based on evapotranspiration estimates.

Irrigation Triggers

Drip Irrigation

Drip irrigation is triggered earlier than overhead irrigation. Drip irrigation wets only a portion of the soil profile, so irrigation is initiated early to maintain the soil at a steady moisture level. Drip irrigation is triggered at 80% available soil moisture.

Overhead Irrigation

Overhead irrigation wets a much larger volume of soil, providing roots with access to a larger water reservoir. As a result, overhead irrigation can typically be delayed until soils reach approximately 50% available soil moisture.

Interpreting Centibar Readings

Several Davis weather stations in the Valley are equipped with soil moisture sensors installed at a depth of 16 inches. These sensors use the electrical resistance method and report soil moisture in centibars (cb). On a scale from 0 to 200 cb: 0 cb represents very wet soil and 200 cb represents very dry soil. The interpretation of centibar readings depends heavily on soil texture because different soils hold water differently.

General Irrigation Guidelines by Soil Type

Light soils like sandy loams should be irrigated at 15 to 40 cb.
Loam soils should be irrigated at 40 to 80 cb.
Heavier soils like silt loam should be irrigated at 50 to 100 cb.
These ranges correspond roughly to the soil moisture range between 80% and 50% available soil moisture.

Guidance When Water Supplies are Limited

Where water supplies are limited, growers may consider deficit irrigation, which involves allowing soils to dry to the upper end of the recommended irrigation range before irrigating.

Target thresholds include sandy loam: 40 cb, loam: 80 cb, and silt loam: 100 cb. This level of mild stress can reduce excessive shoot growth while continuing to support fruit development and overall tree health.
Avoid allowing soils to become excessively dry. As a general guideline sandy loam should not exceed 100 cb, loam should not exceed 120 cb, and silt loam should not exceed 140 cb.
Observations from last season also suggest that fruit from orchards irrigated heavily starting late in the season and until harvest time may have had reduced storage performance.

Water Deeply
Deficit irrigation involves extending the time between irrigation events, but each irrigation should still replenish moisture throughout the active root zone. Deep watering encourages deeper rooting and improves the tree's ability to access water reserves. This includes practices for overhead irrigation systems, in which run times should be sufficient to wet the tree root zone rather than only the surface soil or groundcover.

Approximate water requirements for a deep irrigation to 2 ft depth are:

1.4 inches of water for sandy loam
1.7 inches of water in a loam soil
2.3 inches of water in a silty loam

Using your system's application rate, calculate the run time required to deliver the target water volume.

General Davis Weather Station Sensor Observations

Recent observations from Davis weather station sensors installed at a depth of 16 inches on sandy loam, loam, and silt loam soils suggest that irrigation should be considered in many orchards if it has not already begun.

This recommendation is based on the following sensors: North Medford (NSW041) sandy loam, South Berwick (NSW034) sandy loam, Upper Falmouth (NSW007) loam, Avonport (NSW084) loam, and Lower Canard (NSW015) silt loam.

The information shared here is meant to be used for general guidance. Soil moisture measurements within your own orchard remain the best guide for irrigation decisions. I am learning about irrigation alongside you, so please reach out if you have questions that I can try to answer. I hope this information is a helpful starting point to address pressing questions.

Insects

Apple and Pear: Codling Moth

Recommendations:

If trap captures are below the treatment threshold but continue to build over time then treatment should be applied once a threshold is reached. When the time for apple maggot treatments arrives, the chemistries will also treat late codling moth.
The neonicotinoid insecticides (group 4 products) move into plant tissues over a period of about 24 hours. If it rains before the product is absorbed, the product on the surface is susceptible to wash off.
Approximately a week after application of Imidan, clean out the trap and start monitoring the trap. The capture of an additional 10 or more moths would indicate that a second treatment is required.

Apple Maggot

The Apple Efficacy Guide may be used to compare the products that are registered for control or suppression of codling moth and/or apple maggot. Note that high label rates are often needed for activity on apple maggot.
In blocks that are being treated for codling moth, the control is extended to early maggot flies.
The economic threshold is 1 maggot fly per orchard on a yellow sticky board (Figure 3).

Apply a conventional treatment 7-10 days after the first fly is captured on a yellow sticky board or immediately after a female is captured on a red sphere.
In organic orchards, Surround can be used to deter egg laying and GF 120 fruit fly bait can be used for suppression of adult flies. Both Surround and GF 120 should begin to be applied immediately as flies become present in the orchard. The first maggot fly was caught at the Kentville Research Station this year on June 30.
Clean maggot traps 7 to 10 days after treating a block for maggot and monitor for new trap captures. Retreat 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 so do not stop treatment prematurely.
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. Insecticide residue should be maintained through to the end of August.
Chemical groups 5 and 28 target adult flies to prevents stings. Chemical groups 1 and 4 have activity on adults, eggs, and larvae meaning that they prevent stings and if an egg is laid the products also prevent survival of the larvae.
Sanitation through removing wild apple trees can help to prevent the buildup of populations that will migrate into orchards from the orchard perimeter.
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. (Being cognizant of the 22-day PHI and REI restrictions).
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.

Figure 2: An apple maggot fly on a 1 x 1 inch grid of a yellow sticky trap. The fly has a black F-shaped pattern on the wing that mimic's the shape of a spider's legs. It is slightly smaller than a common house fly and has a white dot in the middle of its back.

Apple - Sucking Insects

Aphids:

Green aphids have been building in population recently. Monitor if you are due for re-treatment. Green aphid will move back into orchards that were treated previously.
Monitor for aphids in young trees and nursery plantings where feeding can disrupt shoot growth. If leaves are curling, high water volumes are needed for effectiveness. Assail also has activity on codling moth, apple maggot and leafhoppers. Be cognizant of REIs if installing trellis.

Mites:

European red mite, two spotted spider mite and apple rust mite are the prominent species that affect apple trees. Although not directly damaging to the fruit, these mites in all their motile life stages can drain the nutrients from the trees and dramatically degrade fruit quality.

Scout your orchards or check your scouting reports to see if there is a treatable population. Those growers with a consultant will receive the most accurate information because mite counts are done using a specialized machine for brushing and beneficial predators are noted as well.
In a hot and dry year, mite populations can double in 7-10 days.
Good spray coverage is critical.
Mites have many generations per year and therefore have a high potential to develop resistance. For resistance management, it is critical to rotate miticide classes.
July is the time of year to control rust mite before foliage becomes bronzed in mid to late August.
All miticides are effective on European red mite and two-spotted spider mite but only products Nexter, Envidor, and Magister provide control of rust mite.

Envidor is slow acting so it requires early intervention.
Acramite, Kanemite, Nealta, and Nexter provide quick knockdown.

Potato leafhopper: Feeds on the young leaves of terminal shoots leading to yellowing at leaf edges, and cupping that will eventually turn brown. Adults are pale yellow-green and walk sideways whereas the white apple leafhopper is white and moves forward and back. Monitor your scouting reports or updates.

Potato leafhoppers can transmit fire blight. Their presence in young plantings and nurseries is concerning, especially in areas of active fire blight infections. Insecticides labelled for leafhoppers are the group 4 products and they include Assail/Aceta, Cormoran, and Sivanto Prime.

Scale Crawlers

If you had scale last year at the packout then they should still be monitored even if an oil application was used in spring.
The scale that are under a waxy coating at this time of year are the adults that are about to give birth to live young. Those live young are the crawlers that leave the waxy coating and become susceptible to insecticides. Typically the crawlers are active in July at about 4-6 weeks post-bloom and with the heat this year they could be on the move early.
Monitor for activity by using traps that are made by using black electrical tape (with adhesive side out) around the scaffold limbs of trees, in areas with known infestations. Crawlers yellow bodies will be caught on the tape when they become active.
When the crawlers are active, Movento with a surfactant is one of the most effective products. The neonicotinoid products Assail/Aceta and Closer may also affect crawlers.

Obliquebanded Leafroller

Monitor or check scouting reports for larval populations. The caterpillar feeds on terminal shoot growth and also on apples, leaving a scar.

Pear Insects

Pear Psylla: Refer to the management guide for product options.
Pear rust mite: Pear rust mite can go unnoticed until heavy russeting extending from the base to the top of the fruit. Growers that apply Agri-mek for pear psylla control would also obtain pear rust mite control. Nexter or Envidor would be other options for pear rust mite control.
Codling moth: Refer to the above information for apples.

Horticulture

Follow Up on Pollination

It is possible to see which fruit were fertilized and which fruit were not, depending on the look of the seeds. The fertilized fruit have plump light green seeds. The fruits with failed fertilization have empty seed pockets with seeds that are shrivelled. Anecdotally, early flowering varieties (or regions that flowered early) appear to have fewer seeds, suggesting poor pollination conditions at that time.

Figure 3: Left: Late flowering Honeycrisp fruitlets with full seed cavities (Photo by Joan Hebb). Right: Early flowering Gravenstein with empty seed cavities (Photo by Michelle Cortens).

Scion Rooting as Rescue Option for Weak Plantings

For whatever reason, sometimes a planting can be weak and fail to fill its space. Maybe trees have been exposed to environmental stressors or maybe the dwarfing rootstock was too small to begin with. Maybe frost heaving exposed more of the rootstock shank. In these situations, trees that scion root are generally the healthiest.

Past local experience has shown that scion rooting can be a management option for weak plantings that fail to fill their space or struggle to thrive. Where scion rooting was used in the past on a weak block, the grower says they wouldn't hesitate to do it again.

For some there might be the concern of too much vigour from scion rooting. After covering the graft union, it took the trees about 5 years to set strong scion roots to become vigorous. Given the short lifespan of orchards there isn't much concern about trees in this situation getting too big. If to much vigour result, then management practices like summer pruning, apogee, and root pruning can keep the vigour in check.

On-Farm Nursery

Scion leaders need support. Stakes should be placed on the side opposite from the bud so it pulls the bud toward the rootstock rather than away.
Monitor for green aphids.
Remember the importance of weed control in nurseries. Management practices now will impact the outcome of the final tree. Encourage the growing point to be successful!
Budding

As August approaches, find a source of bud wood that does not have a history of fire blight strikes. Trees that have shown signs of fire blight strikes or that are situated near fire blight infections should be eliminated as a source of bud wood. Cut bud wood fresh every morning if possible.
Occasionally sanitize all tools used for bud wood collection, storage, and budding by washing in detergent and water and disinfecting with sodium hypochlorite bleach. During bud wood collection and budding, frequently spray hand tools with fresh sodium hypochlorite bleach solution, diluted one part to nine of water.

If bleach is too tough on tools, Lysol and Pinesol at one part product to ten parts of water are good alternatives. Do NOT use rubbing alcohol because even at 70% to 99% concentration it allows bacteria to survive (California Agriculture 1991).

It is highly recommended that you water your nursery before and after budding to encourage callus formation and a healthy union.
The vigorous Geneva rootstocks can fail to accept tbuds, and other propagation approaches like chip budding and bench grafting are recommended. In several situations now, tbudding G969 has resulted in failed bud unions. What appears to happen is that the Geneva rootstock overwhelms the tbud with excessive callus formation (Figure 5).

Figure 4: Two different on-farm nursery situations where t-budding Honeycrisp on G969 failed in 2018 and 2025 due to excessive callus formation and an overly vigorous rootstock.

Tree Health

Top dressing is not recommended after the end of June. Late release and uptake will prevent trees from hardening off before the winter.
Around July the trees are storing reserves in the roots for next year’s growth. When they are storing reserves, late glyphosate applications can be damaging if taken up by root suckers and transported to the root system. Avoid the risk by avoiding glyphosate applications after the end of June.

Nutrition

Calcium:

The goal of foliar Ca sprays is to increase the concentration of Ca in the fruit and reduce the incidence of bitter bit. Begin calcium applications at 4 to 6 weeks after petal fall when fruit have reached the golfball stage at around 35 mm. Calcium applied at two-week intervals is better than occasional, high-rate applications.
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.
The recommended rate is 4.5 to 15.5 kg elemental calcium per ha (4 to 14 lbs of elemental calcium per acre) over an entire 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.
Determine how much elemental calcium you would like to apply over a season and then work backwards to determine the required number of sprays.

Calcium chloride flake (77% CaCl2) is the most economical Ca material to use but also the highest risk for foliar burn. Calcium chloride flake has a low risk of leaf burn when applied at the standard rate of 4.5 kg per 1000 L of water/ha (4 lbs/100 gal/ac).

Calcium chloride flake is 77% calcium chloride which is composed of one calcium and two chloride molecules. According to the weight of the molecules the calcium portion represents about 28% of the total weight. Therefore, our calcium chloride flake contains 28% elemental calcium.
For each spray at the standard rate of 4.5 kg per 1000 L/ha, the 28% portion that is elemental calcium is 1.3 kg/ha (1.1 lbs elemental calcium per acre).
The risk of leaf or fruit damage from calcium is highest in hot weather. Susceptible varieties can develop lenticel spotting if damaged. Target fast drying conditions for applications.

Risk of leaf injury may be enhanced by Captan. Incompatibility has been observed with Epsom salts, and liquid or emulsifiable pesticide formulations in some cases. Do not apply calcium with Apogee/Kudos. Note that nutrient product formulations with calcium may contain boron that would interact poorly with water soluble packaging.

Suckers

Remove woody suckers by cutting or ripping to avoid resource competition, the risk of systemic herbicide uptake, harbouring pests like fire blight shoot blight.
If suckers are more prevalent because of exposed roots due to frost heaving, try to hill the soil to cover the roots.

Mowing

As grass becomes long the extra surface area increases transpiration. Keep grass mowed to conserve moisture.
Keeping the orchard floor cover mowed pre-bloom will minimize flowers that attract bees, which increases the safety of post-bloom insecticide applications.
Mowing and herbicide strips help to prevent issues with two-spotted spider mite (John Michael Hardman).

Pruning and Training

Select strong terminals on young trees and remove competing terminals to single the tops if there are no re-entry intervals active and before the shoots get woody.
Ensure that deer fencing is installed as soon as possible to protect new growth on young trees.
Newly planted trees should be pruned for tree structure and supported as early as possible after planting. Prioritize trees that are known to be brittle at the union, including many of the new Geneva rootstocks (G.11, G.41, G.16 etc).

Cover Crops

Perennia has a series of videos about cover crops that can be accessed from our website.
Summer grasses such as pearl millet and sorghum-sudangrass that have been a popular choice can be planted from mid-June until early August.
For August and September plantings of cover crops, check out the factsheet about Fall Cover Crop Species Selection and Management that was written by Sonny Murray and Caitlin Congdon.

Summer Hedging

A local study by Perennia in 2013 evaluated the regrowth on summer hedging using Ambrosia on M.9 and Gala. Results indicate that the last week of June = 6 to 21 cm of regrowth, first week of July = 4 to 12 cm of regrowth, and second week of July = 2 to 3 cm of regrowth. No regrowth is expected after terminal bud set around the first week of August although it was not included in the trial.
On vigorous trees, delay summer pruning until terminal buds have been set on vegetative shoots. Pruning prior to this on vigorous trees can promote bud break and weak shoot growth.

Events and Notices

Growing Good Growers - Thursday, July 9

Time: Thursday, July 9 at 11:00 am

Topic: Interplants and the approach to replace drought stressed trees.

Location: Birchleigh Farms. We will meet at the North side of Hwy 1 across from the Briar Patch. We will be in the Ambrosia on the east side of the block in the last two rows. Watch for the NSFGA and Perennia signs.

Please bring your thoughts, experiences, and questions to join us for this discussion. There is no need to RVSP, and we encourage you to bring your own coffee and snacks. Everyone is welcome to attend!

Save the Date - NSFGA Summer Tour August 5

The 2026 NSFGA Summer Orchard tour will be held on Wednesday, August 5. Events like this are only possible through sponsorship. Contact NSFGA for sponsorship opportunities.

Pest Management Guide

We offer printable PDFs of the guides from our website:

Online pest guides are also available without login (https://www.perennia.ca/pest-guides/) and with login on your Perennia account (https://www.farmdatatools.perennia.ca/). Using the online tool you can filter for organic and conventional options, search for key information, and sort based on information of interest.

This Orchard Outlook has been published with the input of the Orchard Outlook Committee including this week's participants: Harrison Wright, Joan Hebb, Danny Davison, Ian Willick, Suzanne Blatt, and Colin Hirtle.

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

Pages

Orchard Outlook Newsletter Vol. 26, No 13

Tuesday, July 7, 2026

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