MSU Extension Apples

General harvest comments

In a typical year, this week would have marked the beginning of Gala and McIntosh harvest. A slow start to apples has pushed these start dates ahead another week for most growers. Over two weeks of outstanding weather for color development means fruit look ready for picking in many orchards, but some earlier varieties saw very little advancement in maturity in a week’s time. This is particularly true for Gala, which appears to be maturing slowly this year compared to McIntosh. Honeycrisp color has many growers getting itchy to spot pick it, but even the reddest fruits that were tested this week were 10-plus days out from optimal maturity.

Harvest timing for prominent varieties is starting to be a concern for growers due to the long wait for the earlier varieties. The delay in early apple maturity combined with the incoming heat wave looks like it might be starting to cause the normal span of maturity across varieties to be compressed this year. Varieties that usually ripen in the second half of September seem to be less behind than varieties typically picked in late August and early September, so this could be a tough ride for growers. Strongly consider deploying ReTain this year to delay the maturity if prominent harvest seasons overlap. The next two weeks may start to become very challenging if current maturity trends continue as we may see McIntosh, Gala, Honeycrisp, Jonagold, Early Fuji, Empire, Jonathan and Jonagold all start to test in the mature range for controlled atmosphere (CA) storage within the next 14 days.

We are fortunate to have had the recent weather for good color development as we look at the forecast for the next couple of weeks. The wet, warm, humid conditions on the forecast for at least the next 10 days will not favor color development, so growers waiting for color on varieties are not likely to see much improvement in the days. Harvest early varieties (SweeTango, Zestar!, Ginger Gold, Premier Honeycrisp, Paula Red) as quickly as possible, as development is moving along rapidly and fruit will get soft in the heat. This is already starting to be evident as maturity tests conducted on several early varieties this week show we are already moving in to the over-mature range on varieties like Zestar! and SweeTango.

Insect update

Apple maggot activity is declining and most growers have already put out their last insecticide for this pest. Bait red sphere traps with apple volatile to improve efficacy, and the threshold for these traps is five apple maggot flies. This will be the last update on apple maggot for the season.

Second generation codling moth is declining or over, and cold weather at dusk in the past two weeks likely means very little mating and egglaying occurred even in blocks that had a later flight. This will be the last update on codling moth for the season.

Brown marmorated stink bug pressure continues to be low so far this season in west central Michigan. Areas in the southern part of the state have reported an uptick in brown marmorated stink bug adult activity, but that has not occurred here thus far. We will continue to monitor for brown marmorated stink bug until harvest is concluded, but risk for the west central region looks low at this time.

Individual variety maturity results

The scales used to rate these different metrics on these charts are as follows:

• Background color: scale 1-4, 1 is fully yellow and 4 is fully green.
• Russet: 1-4, 1 is no russet and 4 is severe russet.
• Pressure: always listed in pounds, and two pressure scores are recorded for each apple tested.
• Watercore: 0-4, 1 is no watercore and 4 is severe watercore.
• Bleeding: 0-4, 0 is no bleeding of red color into flesh and 4 is severe bleeding of red color in to flesh.
• Red: listed as a%age of the whole fruit with red color.

Ginger Gold

This is the last test for this variety this season. Sites further south in west central Michigan have already been harvested. Ginger Gold is starting to get soft at locations it is still hanging, and the coming heat will speed that process along further. It was still eating nicely at the location that was sampled this week, but softness was starting to be evident. Experience tells us that delaying the harvest of this variety is not wise, it is prone to getting soft very quickly.

McIntosh

This variety took a significant jump ahead in development in a week’s time and is running ahead of Gala this year. McIntosh is considered ready for CA storage at a starch index of 5 with suggested firmness between 14 and 16 pounds. Firmness is starting to drop on the variety but is generally within the acceptable range, and the starch index should be in the low end of the suggested range within the week. Significant fruit drop was observed in some blocks this week. The ‘RubyMac’ strain from Ludington, Michigan, showed outstanding color this week, as tends to be true for this high-color Mac strain throughout the region.

Early Fuji

Early Fuji are about one week away from maturity for CA storage. It moved ahead nicely in a week and picked up much improved color. Fuji is considered ready for harvest for CA storage at a starch index of 3 with suggested firmness at 16-18 pounds. Fruits will likely be right in this range within a week, especially with the incoming heat.

Gala

In most seasons, growers would be getting in to Galas this week. This is not one of those seasons. Gala are moving slowly right now and showed very little progress in maturity from last week. Gala are tempting to pick right now because color is outstanding, but biting into one right now will tell you everything you need to know. They are still extremely hard and starchy, they likely need seven to 10 days at even the earliest sites before they will be mature for CA storage. Gala is considered mature for CA storage at a starch index of 3 and firmness of 16-18 pounds.

Jonathan

This variety was sampled for the first time this week and should be very close to or ready for CA storage harvest around next week this time. Jonathan are considered mature for CA storage at a starch index of 3.5 with suggested firmness at 16-18 pounds. Fruit size is small on Jonathan this year, so growers will hope that the variety picks up a little more size in the next several days.

Honeycrisp

This variety is not as far along as the color in many locations suggests, it likely needs 10-14 days at most locations before it reaches early maturity for CA. Honeycrisp is considered ready for CA storage at a starch index of 3.5 with suggested firmness between 15-17 pounds, but it has a wide range of acceptable starch index scores as it is not considered over-mature until a starch index of 7. Bitterpit has not been high so far this year, which comes as something of a surprise given that many orchards are carrying a lighter crop of larger sized fruits.

Many growers will be spot picking some of the most colorful fruits to sell at fresh markets as soon as possible but should be aware that the fruits are still not eating well. While there are several redder strains on the market now (Firestorm, Royal Red), the only newer strain that actually matures faster than a standard season strain is Premier. The others may look redder, but they aren’t actually any further along. This is really important to remember because most growers are newer to the redder Honeycrisp strains and are used to advanced color being synonymous with maturity. The redder Honeycrisp strains on the market change that narrative, so make sure you don’t get fooled by color and pick too soon.

If you are concerned about the harvest timing of Honeycrisp compared to others, consider using reduced rates of ReTain with NAA to stagger harvest and reduce drops. Also, consider picking once for color and then using a reduced ReTain rate to stop maturation for a few days to allow the second pick to pick up more red.

Empire

This variety was sampled for the first time this week and is likely about two weeks away from maturity for CA storage. Size on Empire is small this year, so growers will hope the variety picks up some size in the next couple of weeks. The variety is considered mature for CA storage at a starch index of 3.5 and suggested firmness of 14-16 pounds.

Jonagold

Size on this variety generally looks good this year, but there are sites where crop is lighter where size is pushing a little on the large side. Early maturity for CA storage is likely 10-14 days out for this variety at this time. Jonagold is considered mature for CA storage at a starch index of 3.5 with suggested firmness of 15-17 pounds. Fruits tested this week will need at least another 10-14 days before they test in the mature range for CA storage.

*Firmness is measured with a mechanical 11-mm wide probe inserted into the pared flesh of a fruit to a distance of 8 mm. Starch index is measured on equatorial cross section of an apple stained with iodine solution and rated using the Cornell University starch-iodine index chart for apples on a 1-8 scale (Predicting Harvest Date Window for Apples by Blanpied and Silsbey, Cornell Extension Bulletin 221.)