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

Across the province growers are hand thinning, applying foliar nutrients, irrigating (in certain areas), preparing for harvest and keeping on top of summer time pests.

Growth Stages

Terminal bud set has begun, noting a slowing of terminal growth and an ‘end’ to this season growth. Some rainfall in certain areas has sparked new growth and certain areas seem to have a stop and go terminal ‘set’.

Terminal bud set is also an indicator of floral induction, meaning buds set for next season will be deciding whether to turn into floral buds. Be sure to provide your trees with enough nutrients and water necessary to aid in this process.

At the Simcoe Research Station, fruitlets and terminals are sitting at the following:

	Honeycrisp	Ambrosia	Gala
Fruitlet Size	54.1 mm	44.6 mm	43.7 mm
Terminal Growth	25.6 cm	23.7 cm	26.6 cm

Leaf It to the Lab

Terminal bud set has begun – noting an ideal timing for nutrient leaf sample collections in apple orchards. If you have not done so, but plan to, be sure to take advantage of this timing.

• If you want more details on the how to collect samples check out Why You Need a Tissue, a Leaf Tissue Analysis
• For the impact of drought and humidity on nutrient mobility check out Orchard Leaf Tissue Sampling
• If you want background information on nutrients check out Cornell Nutrient Management

Rain Check, Please?

Rainfall has been sporadic to say the least, some growers experienced significant rainfall over a short period of time, where neighbours had minimal to no significant rainfall (Figure 1). For information on irrigation check out the resources below:

• 3 Secrets of Irrigation Water Taking Permits Revealed
• Using ET Data to Make Irrigation Decisions
• Irrigation Timing in Fruit Trees

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.

To Prune or Not to Prune – That Is The Question

There have been many questions lately on how to manage fire blight. Now that fire blight is present, when should you prune it out? Unfortunately, there is no easy answer, since the severity of the infection and the weather conditions suitable for infection impact the decision.

Be mindful of where your management recommendations are coming from. In the northeast, we experience much more humid and wet conditions than that in the western part of North America. While more arid climates may be able to leave strikes to dry, doing so in our region may result is significant spread to adjacent trees or blocks.

Pruning the trees at this time of year can have two different outcomes:

1. Reduce the inoculum and prevent the spread of disease.
2. Increase shoot growth, making the tree even more susceptible to fire blight.

Blight the Bullet

Older, Vigorous Trees

When dealing with older (especially >10 year old) vigorous trees that have MANY fire blight strikes, avoid pruning out shoot and blossom strikes early in the growing season. Extensive early pruning stimulates trees to produce succulent shoots, making them more susceptible to infections.

When dealing with high vigour trees that have only a FEW fire blight infections, pruning out the fire blight may help to provide complete control of this disease.

Older, Low Vigour Trees

In slow growing, low vigour trees or trees that have been sprayed recently with Apogee/Kudos, the bacteria generally doesn’t move into major limbs or trunks during the growing season. As a result, lesions can be pruned out when the tree is dormant. This may help to save time and money.

Young Trees

In comparison, young (<5 years) vigorous trees are very susceptible to fire blight and the bacteria may move rapidly into the trunk and down to the rootstock, killing the tree. As a result, pruning is recommended on young trees AS SOON AS INFECTION APPEARS to prevent the spread of the disease to adjacent trees.

When Does It Stop?

Keep in mind that once the terminal buds have set on apple trees, fire blight stops spreading within infected trees. Summer pruning to increase fruiting wood in high-density orchards encourages new shoot growth and extends the susceptibility period for shoot blight. However, leaving the disease in the orchard may serve as a source of inoculum, and cause increased infections in the result of hail, severe storm, or high wind damage.

Key Pruning Points

If you decide to prune out fire blight strikes, remember:

• Cut at least 30 cm (12 in) or more beyond the visible infected tissue, preferably into 2nd or 3rd year wood.
  • Look at the cambium after your cut – if it appears brown, you need to cut further (but disinfect your pruner first!)
• Prune out strikes when there are 2-3 consecutive days of low humidity and temperatures below 25°C to allow pruning wound time to heal without conditions conducive to disease spread.
• Disinfect tools between cuts by dipping them in a 65-70% alcohol solution or a solution of 1 part bleach to 5 parts water.
• If time and labour allow, remove pruning cuts from orchard as soon as possible and burn – but be sure not to touch healthy trees along the way!
  • If wet weather is not predicted, pruning clippings could alternatively be tossed into the row middles and allowed to dry before flail mowing.
• Continue monitoring and managing insects in infected blocks that may spread the fire blight bacteria, such as aphids, leafhoppers and beetles.
• Manage excessive succulent growth, where possible.
  • Prohexadione-calcium (Apogee/Kudos) can provide protective benefits when applied now (ie., thickening of cell walls to prevent infection) but this action will take 10 days from application.
• Consider products that:
  • Surface sterilize such as Cueva or Oxidate
  • Boost immunity such as Lifegard, Regalia or Double Nickel
  • Dessicate infection such as Buran or Cyclone Plus

In sections where trees are severely affected or trees are continuously infected year after year, it may be more cost-effective to simply remove the whole tree.

Drop It Like It’s Rot

With hand thinning starting, a reminder that those apples on the ground might seem harmless, but are prime real estate for pathogens like black rot and bitter rot. This means increased risk of fruit infection for the remaining crop later in the season.

The weather lately has been optimal for bitter rot infection – hot, humid and thunderstorms. Fruit on the floor have been known to cause infection of remaining fruit on the tree by splashing spores during rain events. A simple orchard floor clean-up can go a long way in reducing disease pressure and protecting fruit quality. Toss or sweep thinned fruitlets to the row middle and mulch.

Agrobotics Demo Day – Simcoe

See AgRobotics in action at the July 22nd Demo Day! REGISTER HERE

Join the AgRobotics Working Group and Innovation Farms Ontario for in-field demonstrations of robotic technology at the Ontario Crops Research Station – Simcoe (1283 Blueline Rd. Simcoe ON) on July 22, 2025 from 9:30 AM – 3 PM.

Lunch is provided to those who pre-register, so register today.

Confirmed robots in attendance: Vivid Machines, Oz, Finite Farms, HarvestCorp, Burro, Monarch Tractor, Upside Robotics.