MSU Extension Apples

General harvest comments

Growers are hustling to finish off second and third picks of Honeycrisp, and most orchards will be completely stripped by the weekend. Jonagold harvest is complete at most farms, and those that are still working on it will be wrapped up by the end of the week. Rome harvest started this week, and Golden Delicious harvest is also getting underway at many farms this week. Red Delicious harvest is about a week out, and Idared harvest is closer to two weeks out. Most growers feel they are past the half-way mark. Although the compression in maturity this year has brought some stress, growers have generally been able to stay on schedule.

There is some concern of fruit drop with heavy rain and storms predicted to move through the state on Friday afternoon and evening. While the severity of the forecast has dialed back somewhat from the original prediction, growers worried about the storm can consider using NAA on some of their later varieties to help stick fruits on trees.

Heavy rains in recent weeks mean that little to no fungicide residue is left on many area orchards. Most processing growers have already boxed orchards, but growers of later fresh market varieties such as Fuji and EverCrisp are strongly advised to consider a preharvest fungicide this year. Sooty blotch, fly speck, pin point scab and various fruit rots such as bitter pit all thrive in a fall as wet as the one we have had. It has been a long time since the last fungicide went out in most area orchards.

Brown marmorated stink bug pressure continues to be very low so far this season in west central Michigan, and activity in hot spots in the southern part of the state was down this week as well. No brown marmorated stink bugs were captured in our trap line this week, but a couple of pictures of them were sent in to me by local growers. Feeding damage has been found in isolated fruits here and there, but no reports of damage at an economic level have come in this season. Based on the lack of observed activity, we feel the pest does not pose an economic risk to our crop in west central Michigan this season, and there is no reason to be using an insecticide to manage it at this time.

San Jose Scale can be seen on the calyx ends of fruits in affected orchards. Generally, there seems to be less this year than last year, thanks in part to many operations targeting the pest early this spring with oil pus Lorsban. No management for this pest is conducted at this time of year, but harvest time is a valuable opportunity to take note of areas on your farm that pressure seems to be building. This pest tends to begin in several localized hot spots within a field and radiate outwards over several years. Flagging affected trees or regions of an orchard can allow for targeted pruning and oil pus Lorsban applications next spring to combat spread.

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 percentage of the whole fruit with red color.

Honeycrisp

Growers did an excellent job of getting second and third picks of this variety into bins in the last week. There is a little bit of second and third pick fruit hanging out there yet, but the majority will be gone by the weekend. We had only two sample sites of Honeycrisp left this week, and both moved into the over-mature range. Fruits sampled were second and third pick fruit from the interior of the canopy of large, mature trees so they had a greener background color and not more than 50% red color. Appearances can be deceiving; these fruits were all testing either at or over the mature range.

Remember that while using a quarter-pouch rate of ReTain plus 10 parts per million (ppm) of NAA on Honeycrisp one to two weeks prior to first pick will delay ripening by about a week; that delay is even less when used at the same rate after first pick—closer to a three- to four-day delay in ripening rather than a full seven days. The NAA at 10 ppm will keep fruits stuck to the tree for 10 or more days, but it will not stop those fruits from becoming over-mature while they hang there.

Jonagold

This variety moved very quickly this year, surprising growers and industry stakeholders alike on that front. It was cleared for harvest by local buyers over a week ago and is already getting hard to find in area orchards. Growers did a great job of getting after this variety in a week’s time. Fruits at the one site we still had this week had moved along some but were not yet over-mature, which is great news for growers still getting through the end of it. Quality on Jonagold this season has generally looked excellent, with good color, firmness, size and brix. This will be the last report on this variety for the season.

Golden Delicious

This variety was in the early range of maturity for controlled atmosphere (CA) storage harvest at most Oceana County locations where ReTain was not used last week and ReTain-treated Goldens along with some late sites in Oceana and Mason counties moved into the early window of maturity this week. Some Golden Delicious orchards will be delayed on harvest to wait for better sugar content in fruit, but we have seen scattered harvest of the variety in a week’s time and the next seven days will see most orchards getting started.

We continue to see a lot of fruit russet on this variety this year. This shouldn’t be too much of an issue for processing growers, but growers trying to sell Goldens on the fresh market may want to weigh their options carefully before sending them for this purpose. Many orchards are looking at russet levels that would make a significant portion of the crop unsuitable for fresh market sales.

Mutsu/Crispin

This variety is ready for CA storage harvest throughout the region. There was a renewed emphasis on harvesting this variety in the optimal range of maturity this season to avoid issues coming out of storage associated with immature fruit, and we could really see the effect of that effort this year in our sampling at the lab. I have never been able to find Mutsu/Crispin to sample after the first week of October in past years in this area despite the fact it tested very immature at that time, but this year it’s all still out there.

The wait has been rewarded, the variety has moved into the acceptable range for CA storage harvest. Mutsu/Crispin is considered ready for CA storage harvest at a starch index of 3 with suggested firmness of 16-18 pounds. Fruits tested this week were right in the early end of that range. This variety will likely be cleared by local buyers for harvest in the second half of this week.

Rome

Harvest of this variety is underway throughout the area. Concern over bleeding of red color in to the flesh of the ‘Law’ strain always leads to this variety being harvested as soon as it tests in the lowest acceptable starch index range for CA storage, and it hit that mark late last week. We started to see some bleeding in the Law Rome we tested this week; red color in fruit this year is so strong that it’s not surprising to anybody that we are seeing it happen as fruits mature. Rome is considered mature for CA storage harvest at a starch index of 3 with suggested firmness of 15-18 pounds. Most of it will be gone in a week’s time.

Red Delicious

This variety could use another week at most farms, even for early CA storage harvests. It moved very little in a week’s time. We saw an uptick in bleeding of red color into flesh this week, so processors should be aware this could be an issue with this variety this season at some sites. Some moldy core was also observed in our samples this week, about 1/10 fruit that were cut this week displayed it at all four sites.

This issue tends to be worse in Reds in years with exceptionally wet spring weather because the fungi that cause the issue colonize the flower parts as soon as the blossoms open up in the spring time. The issue also tends to be worse on any variety with an open channel from the calyx in to the core; we tend to see it most frequently on the ‘Delicious’ varieties. We will continue to keep an eye on the prevalence of moldy core as we approach harvest of this variety.

Idared

This variety is at least two weeks out at most area farms. Red color is very strong on Idared this year, unfortunately so much so that we saw some light bleeding from the peel into flesh in all three of the samples we ran this week. Processors should be aware that this may be something we see at many Idared sites this year. Idared is considered mature for CA storage harvest at a starch index of 3.5 with suggested firmness between 14 and 16 pounds.

EverCrisp

This variety was sampled for the second time this week and still needs a couple more weeks to ripen up. Unlike some of our more established varieties, we do not have specifications defining storage maturity for the variety. Since it has Fuji parentage and its harvest season and appearance can be somewhat reminiscent of that variety, we have used Fuji maturity specs as estimates for EverCrisp in the first couple of years fruits have come onto the market.

Starch index can be a difficult way to determine the maturity of Fuji as it has an uncharacteristic iodine staining pattern due to differences in starch type within flesh. EverCrisp looks to be the same way, typically displaying a “Fuji stain” pattern. This makes using the standard starch scale to determine harvest timing somewhat of a challenge.

Background color may end up being one of the biggest determining factors for maturity of this variety, as EverCrisp tends to display an extremely strong green background color that dulls the red color until the second half of October. As the green color moves into the light green and yellow range, we start to see the color look less like a brown and more like an appealing red, much like we observe with standard strain Fuji.

Watercore seems to be a significant issue for this variety based on what we have seen in our samples over the past three years. It probably comes by this trait honestly from its Fuji parent, but it’s certainly something to monitor in coming years as more of this variety goes in to the ground. Watercore that has been seen so far has been light, but we are still a good two weeks out from harvest.

Fuji

This variety could use at least another week throughout the region at even the earliest sites in Oceana County, closer to two full weeks would be better. Fuji is considered mature for CA storage harvest at a starch index of 3 with suggested firmness of between 16 and 18 pounds. Starch index is a difficult way to monitor maturity on this variety since the staining pattern tends to be atypical, so growers should also be watching background color and red color quality to help guide decisions on harvest.

Winesap

Very little of this variety is left in the area, but I include it because it’s one of the later apple varieties available for testing in our region, so it provides a nice comparison point as we look at how much longer we will be in harvest mode. Winesap tested this week looked to be about two weeks out from early maturity for CA storage harvest. The variety is considered mature for CA storage harvest at a starch index of 2.5 with suggested firmness between 17 and 19 pounds.

*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.)