Production and pest update brought to you by the OMAFA Apple Team: 

Erika DeBrouwer, Tree Fruit Specialist and Kristy Grigg-McGuffin, IPM Specialist

Grower Grind

Much talk this week across calls has been regarding the heat and the smoke. Growers are irrigating to get the trees through the continued dry period that most regions are experiencing, although we are hopeful that we receive rain in the near future. Some growers are noting that they are seeing more fruit than originally expected, with many finishing up hand thinning and later regions still in the breadth of hand thinning. Early regions anticipate an early harvest compared to average with the spring split staying strong and later regions are noting an average timing, although time will tell.

Growth Stages

Apples across the province are continuing to size, with hand thinning slowly in most regions. We are seeing some reversion of terminal set in Ambrosia at the Simcoe Research Station, which isn’t uncommon but definitely note-worthy when hedging and leaf sampling.

Hazy Days

As many are aware, the air quality the past few days and over the weekend doesn’t look good in many areas. Please monitor your regional air quality utilizing this link: Air Quality Ontario: Map: Ontario’s Air Monitoring Stations, AQHI

The last time an article was written regarding smoke for apples was in June of 2023 (It’s Up in the Air: Concern about the Impacts of Smoke from Wildfire on Horticultural Crops), where most of the material was related to thinner efficacy.

“The impact of the smoke from wildfires on apples has been noted to help apples as they develop… smoke aids apples when the sun gets diffused by aerosols in the atmosphere, allowing for softer light to hit more of the tree canopy. The haze and its shade effect will also contribute to lowering overall temperatures in an orchard, creating more steady average daily temperatures for apples. Lastly, if there continues to be fires or the fires come back closer to harvest, there are reports of the smoke preventing sunburn on apples from harsh direct sunlight.”

Following the 2023 season, it was noted that there was early sun damage on the fruit, which could have been attributed to the sudden dispersal of smoke.

Sunburn Risks

The main crop risk associated with apples at this time would be sunburn. The sudden clearing of smoke could lead to abrasive sunlight on fruit, noted as shock exposure. There has been some sun damage seen on fruit already.

Photo-oxidative sunburn

• Defined as: Shock exposure to visible light due to light intensity, which can occur at low temperatures (17°C).
• How it happens: Risk factors include hand thinning, tree training, selective picking, summer pruning, branch movement and postharvest transit.
  Photo-oxidative sunburn has been seen in the province where areas that have had ‘overcast’ conditions due to the smoke, with a sudden break and intense sunlight could have led to fruit sunburn.  
• What happens to the fruit: Bleaching and eventual darkening of the peel.

For sunburn mitigation please refer to this article: What the Crop?! Apple Update: July 25, 2025 which goes into various strategies for mitigating sun damage such as, moisture, field activity management, nutrient support, evaporative cooling, protective netting, and protection products.

*Most sunburn protectants (kaolin clay, calcium carbonate) have limited compatibility for tank-mixing with other products; consult product labels regarding best practices for product use.

Employee Safety

Most growers are giving employees the option to work while supplying N-95 masks to help mitigate the effects of smoke inhalation and air quality impacts on health. For information on how to reduce exposure, safeguard employee well-being, and keep your workplace prepared during wildfire smoke events:

• 6 ways to protect employees from wildfire smoke
• Wildfire Smoke in Canada | MILTSD shares Q&A for workplaces
• Small Biz Safety Podcast | Episode 29 | Protect employees from wildfire smoke
• Farm Safety Roundup, Ep 19: Weathering the extremes | Farm safety in tough

Stay safe, keep track of the air quality and monitor employee health!

Leaf Sampling

A reminder that this is the time to perform leaf sampling collections for nutrient analysis, as this is when nutrient are most stable given terminal bud set. Best practices for leaf collection and a list of labs are listed below. but more information can be found here: Why You Need a Tissue, a Leaf Tissue Analysis.

Best Practices in Sample Collection

To achieve accurate results in your leaf tissue analysis there are some best practices that are recommended.

• Sample each cultivar, age, rootstock, and block of apple trees separately.
• Sample from the same trees year to year to better interpret leaf analysis reports over the years

Collect fully mature leaves from this season’s growth at shoulder height (Figure 1).

• Collect at least 100 leaves for each sample.
• Do not combine healthy and unhealthy leaves, avoiding damaged or abnormal leaves.
• Collect tissue samples into labelled paper bags as the leaves will rot in plastic bags and deliver right away.
  • If they cannot be delivered immediately, they should be dried to prevent spoilage. Samples may be dried in the sun or in an oven at 65°C or less.
• Plant tissue should be sampled separately from variable areas large enough to sample soil and fertilize separately.
• Plants suspected of nutrient deficiency should be sampled as soon as a problem appears. Take tissue samples from a problem area and submit a separate sample from an adjacent, non-affected part of the orchard. Also collect and submit a soil sample from both affected and non-affected areas to aid diagnosis.
• Take precautions to prevent contamination with dust or soil. Avoid contact of samples with brass, copper or galvanized (zinc-coated) metal.

Remember, plant tissue sampling does not replace soil testing, the results are the most useful with a visual assessment of the crop and current soil conditions and a recent soil test. A list of registered testing facilities can be found at this link: Soil, leaf and petiole tissue, and forages and feed testing labs | ontario.ca

Heat Check

A reminder that with high daytime temperatures predicted, careful consideration needs to be made when applying sprays. See the What the Crop?! Apple Update: July 3, 2026 for tips on spraying during heat waves.

What the Crop?! Apple Update: July 3, 2026

See more

Fly Time

Apple maggot have been caught throughout the province. Emergence is closely linked to soil moisture with flushes in flight often following periods of significant rainfall loosening soil. Those areas that have been seeing good amounts of rain may see that reflected in trap catches. On the other hand, those areas that have seen little to no rain over the last weeks may see a delayed emergence of this pest. Apple maggot has the ability to remain in the soil (for multiple years!) until conditions are right.

With catch on yellow sticky boards, it is important to differentiate between male and female adult flies:

• Both are slightly smaller than a housefly with black bodies, white spot on their back where the thorax joins the abdomen, and distinct F-shaped banding on their wings.
• Males generally begin emerging before the females, but by peak emergence (August), the sex ratio is about 1 to 1.
• Females have a more pointed abdomen with 4 white bands, while the males have a more rounded abdomen with only 3 white bands.

Timing for management depends on the type of trap:

• Sexually immature males and females are attracted to the yellow sticky boards, which mimic nectar sources. Insecticides are not needed until 7-10 days after first fly, particularly a female, is captured.
• Sexually mature females ready to lay their eggs are attracted to red spheres (not as commonly used), which mimic ripe apples and indicate an insecticide should be applied immediately as damage is imminent.

For more information on registered products or those with efficacy against apple maggot, see Apple Maggot on Ontario Crop Protection Hub.

Imidan has worked well for years as a border spray option for many growers. However, all hand thinning activities must be finished before it can be used. The main reason why Imidan can be used effecively as a border spray is its activity as a contact adulticide, killing adults as they fly into the orchard from surrounding areas. Not all alternative products registered for apple maggot have this same activity and therefore are not recommended in a border spray program.

In the table below, adapted from Dr John Wise at Michigan State University, summarizes the characteristics of apple maggot products. Organophosphates (Imidan) and neonicotinoids (Assail, Calypso) are the only insecticide groups that have strong long-lasting activity on the adults as well as a curative effect on the eggs and larvae due to their ability to penetrate into the flesh of the fruit.

Summary of Insecticides Used to Control Apple Maggot

Chemical Group	Life-Stage Activity	Efficacy	Residual Activity	Mite Flaring Potential
OP (1B)	Egg Larva Adult	Excellent	14+ days	Low
Pyrethroid (3)	Adult	Fair-Good	7-10 days	High
Neonicotinoid (4A)	Egg Larva Adult	Good – Excellent	10-14 days	Low-Moderate
Spinosyn (5)	Adult	Fair	7-10 days	Moderate
Diamide (28)	Adult	Fair-Good	10-14 days	Low
Surround	Adult (deterrent)	Fair	7-10 days	Low

Beetlemania Begins

Japanese beetle activity has started in many regions. The characteristic leaf skeletonization is quite distinct. Look for damage and congregations of this pest at the top of the canopy as damage often moves down the tree. Honeycrisp is often the most preferred variety.

Most insecticides applied for oriental fruit moth or codling moth should have good efficacy on Japanese beetle; however, the tendency of these beetles to move in from surrounding areas may make multiple applications necessary. 

For more information on registered products or those with efficacy against Japanese beetle, see the Japanese beetle section on Ontario Crop Protection Hub.

If applying a control product, target timing for early morning while beetles are still relatively inactive on the tree. Once feeding begins, the sex pheromones emitted by females combined with what numerous studies believe to be feeding-induced plant volatiles attract more beetles to congregate in the feeding area. Achieving knockdown before this occurs could help reduce the number of individuals coming into the orchard from surrounding areas.

Good weed control in and around the orchard will also help reduce Japanese beetle pressure. Populations tend to be more abundant in orchards where there is poor control of wild raspberry, blackberry, Virginia creeper and wild grape.

The Second Wave Crawls In

Based on the degree day model, crawler emergence for second generation San Jose scale is predicted to begin shortly in the earliest areas of the province.

Predicted emergence date of second generation San Jose scale, by region (biofix March 1st, base 10C)

Region	Current Degree Day Celsius (DDC)	Predicted Crawler Emergence (806 DDC)
Essex	796 DDC	July 16
Lambton, Middlesex, Elgin	665 DDC	July 27
Norfolk	696 DDC	July 24
Wellington	530 DDC	>14 days
Niagara	665 DDC	July 25
Grey	581 DDC	>14 days
Durham, Northumberland	580 DDC	>14 days
Ottawa	605 DDC	>14 days

Damage from the 1st generation crawler activity can be found. Those that have a history of damage from this pest may want to consider managing the 2nd generation to prevent fruit damage close to harvest, especially since activity can continue well into September.

For more information on registered products or those with efficacy against scale, see San Jose scale on Ontario Crop Protection Hub.

For good resistance management, always rotate to a different chemical group than what was used for the first generation.

As mentioned earlier, crawler activity is typically 4-6 weeks. In previous years, I have seen new scale damage on Ambrosia at the end of September. Applying two consecutive sprays 14-days apart will extend the length of coverage to avoid this late-season damage. However, be aware of the preharvest interval particularly on any early varieties.

If you are planning to make one application only, you may want to consider holding off a week or two from start of predicted emergence timings to target peak crawler activity. There is the possibility of fruit damage occurring during the gap in spray timing, particularly in a year like this where generations may be overlapping.

Degree (Days) of Separation

Adult flight for the second generation of apple leafcurling midge is nearing it’s end in all regions. Emergence predictions for the 2nd generation adults are summarized below. The third generation is predicted to begin at 942DDC. However, once terminal bud set occurs, there is little concern for this pest as they lay eggs in actively unfurling leaves. That said, if root suckering is an issue in your orchard these later populations will continue to be active on these terminals.

For a full list of products with efficacy on leafcurling midge, see Leafcurling Midge on the Ontario Crop Protection Hub.

Predicted emergence date of second generation adult apple leafcurling midge, by region (biofix March 1st, base 9C)

Region	Current Degree Day (DDC)	5% Gen 2 (430 DDC)	50% Gen 2 (556 DDC)	95% Gen 2 (701 DDC)
Essex	883	Passed	Passed	Passed
Lambton, Middlesex, Elgin	752	Passed	Passed	Passed
Norfolk	798	Passed	Passed	Passed
Wellington	623	Passed	Passed	July 23
Niagara	769	Passed	Passed	Passed
Grey	671	Passed	Passed	July 20
Durham, Northumberland	668	Passed	Passed	July 19
Ottawa	695	Passed	Passed	July 17

AgRobotics Demo Day – Simcoe

See AgRobotics in action at the July 21st Demo Day! REGISTER HERE

The AgRobotics Working Group Demo Day brings together the most promising agricultural technologies under one roof — or rather, one sky. Spend a full day at the Simcoe Research Station watching robots, drones, autonomous mowers, and precision tools work the land in real conditions.

• Location: Simcoe Research Station, 1283 Blueline Rd, Simcoe ON
• Date: Tuesday, July 21 from 9 AM – 4 PM
• Parking: Free on-site parking available
• Accessibility: Accessible pathways throughout the demonstration area
• Lunch is provided to those who pre-register, so register today!