MSU Extension Apples

This is the first Grand Rapids, Michigan, area apple maturity report for the 2024 harvest season. Reports are sent out every week (usually on Wednesdays), following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.

Weather update and IPM impacts

We are expecting cooler temperatures this week with nighttime lows in the 50s and 60s. This will help fruit reddening. Daytime temperatures will increase this weekend with high temperatures predicted at 88 degrees Fahrenheit.  

Crop update

Apple harvest is well underway. Wildfire Galas and Premier Honeycrisp were largely harvested across the region this past week. Keep an eye out for other Honeycrisp sports, like Royal Red this week. Galas and early Fujis are also coming up on their harvest windows.

Please keep in mind that stop-drop materials can be very useful to manage harvest windows during this early season, especially if color is a concern, and the windows to effectively use them are sooner rather than later.

This is a difficult harvest season to balance between harvest metrics and visual quality with reddening. Stop-drop materials, reflective ground covers and summer pruning are being used effectively throughout the region to encourage color. Please keep in mind that waiting to harvest can impact the long-term storage and quality of the crop. Maintaining fruit quality and long-term integrity is crucial this year.

Some of these varieties coming into maturity are even exceeding the early predicted harvest dates by MSU this year. Frequent proactive sampling will be needed to stay on top of harvest. Please let me know if there are other varieties you would like me to sample.

Auvil Early Fuji

This variety was sampled at one location in Kent County this week. These apples are nearing maturity in the next two weeks. Auvil Early Fujis and September Wonder Fujis will be a target for harvest in the next week.

Fuji

This variety was sampled at one location in Kent County this week. The later season Fujis are still a few weeks away from maturity.

Gala

This variety was sampled across four locations in Kent County this week. While Wildfire Galas have been harvested across the region, other Galas are moving into their harvest window as well. They taste excellent. Keep an eye on Galas in the next week. The firmness is still too high for optimal maturity, but the starch index is in line with maturity and sugars are developing well.

Honeycrisp

This variety was sampled across four locations in Kent County this week. Premier Honeycrisp have mostly been harvested in the area and Royal Red Honeycrisp will be mature this week. Note that the average firmness is in line with CA storage recommendations and the starch index is mature. These apples taste excellent and the sugars are developing well.

Premier Honeycrisp

This variety was sampled at one location in Kent County this week. This variety is now moving towards over maturity. 

Ruby Mac

This variety was sampled at one location in Kent County this week. Keep an eye on Ruby Macs in the next week as they move into the maturity window. The average firmness and starch values are already in line with maturity.

See the following helpful resources for more information

• Predicted apple harvest dates for 2024 from MSU Extension.
• More information on harvest management tools and timingsfrom MSU Extension.
• Post harvest treatments to extend apple life.
• Guidelines from MSU Extension to check for apple maturity in your own orchard, including specific pressure and starch recommendations by variety.
• Predicting apple maturity and starch chartfrom Cornell University.

Pest and disease update

This will be the last week of my scouting this season.

OBLR Spike

Of note, there has been a spike in Oblique Banded Leafroller populations in the past two weeks. A similar late season spike occurred in 2019, according to Dr. Julianna Wilson. This is likely due to conducive weather conditions for the insect, not associated with another generation. These high populations are not likely to result in fruit damage. Additionally, keep in mind that OBLR are strong fliers and high numbers in a trap do not necessarily indicate high populations in the immediate area. While it can be alarming to see high numbers in traps at this point in the year, they do not necessarily need to be sprayed for.

Disease

Fruit Rots

Keep up control measures for bitter rot and black rot! Be sure to save a shot of Merivon for directly before harvest.

Sooty Blotch and Fly Speck

If you have sooty blotch and flyspeck developing, their symptoms should now be visible. Please keep control for these fungal diseases in mind! The Enviroweather model can take your recent fungicide applications into account for making management decisions.

Bacterial Canker of Stone Fruits

Bacterial canker of cherry (caused by Pseudomonas sp.) and bacterial canker of peach and plum (caused by Xanthomonas sp.) is popping up across the state this season. Both of these diseases are associated with “shot hole” in the leaves, brown dry lesions on the fruit, and cankers in the trees. This can also be associated with gummosis production, which is a general stress response by the trees. If you are seeing infections now, consider summer pruning to remove developing cankers, copper sprays at leaf drop, and dormant copper next spring.

American Brown Rot

While cherry harvest is over now, peaches are also susceptible to American brown rot infection. As fruit gets closer to harvest, susceptibility to brown rot increases. Growers should consider if brown rot management is needed. The use of Indar may not be effective, even at the highest labeled rate of 12 oz./acre. Previous research and resistance screening of American brown rot isolates in West Central and Northwest regions found that most screened fungal isolates had functional resistance to Indar in cherries. Find more information about this study here. Effective materials for managing American brown rot include Merivon, Miravis, and Cevya. Full coverage of all rows will be important to manage this disease.

Insects

Codling Moth

Populations are strongly declining according to the models. I have had very minimal catches in the past two weeks.

Oblique Banded Leaf Roller

Oblique Banded Leaf Roller populations had a late season spike in the last two weeks. This also occurred in 2019 in the area. They are not necessarily a concern right now. This late spike will most likely not damage fruit. Also keep in mind that this is based on adults in traps. OBLR are strong fliers and can travel quite a distance to reach traps.  

Oriental Fruit Moth

The third generation of Oriental Fruit Moth is strongly declining. Keep an eye out for fruit damage at this time in addition to shoot tip damage.

Other Insects

• Dogwood Borer populations have dropped in this area.
• Apple Maggot is likely in the area still.
• Japanese Beetle and/or Rose Chafer leaf damage is present in the area. As they emerge, keep an eye out for leaf skeletonization. I have not been seeing active adults this week.
• Woolly Apple Aphid colonies are still active and growing in orchards. Keep an eye on controlling colonies as we head into the harvest window! I have been seeing more green lacewings, which can control WAA.

For more information about regional reports, please visit the Michigan State University Extension webpage.