MSU Extension Apples

General harvest comments

We are approaching the final push of harvest as our latest varieties start to ripen up. Most growers feel they are around two weeks from the end of the season at this time, although those estimates always vary some by farm. Golden Delicious is quickly being moved into bins and growers are cleaning up any final picks of Honeycrisp that are still hanging out there. Red Delicious will be the next variety on the docket for many area farms, and harvest is likely going to get underway by the weekend.

Idared is about a week out from testing in the mature range. Fresh market growers have been eyeing Fuji for harvest this week as they run out of other varieties to pick, but this variety is still a good week out from testing in the mature range, even for controlled atmosphere (CA). The same is true for EverCrisp.

Growers were finally gifted some decent harvest weather over the past several days, which helped everyone push along and stay on schedule. More rains on Oct. 15 and 16 continued to make orchards slick, but crews have done a good job of pushing through this inconvenience. West central Michigan has seen night temperatures in the high 30s on a couple of nights in the past week, but no frost has been reported in fruit production areas south of Bear Lake, Michigan. Temperatures are forecasted to drop as low as 35 degrees Fahrenheit on the night of Oct. 17, so we may see our first patches of frost in the low spots of our microclimate-filled region.

Brown marmorated stink bug pressure continues to be very low so far this season in west central Michigan. Once again, no brown marmorated stink bugs were captured in our trap line this week. Trace amounts of feeding damage have been found in isolated fruits here and there, but no reports of damage at an economic level have come in this season. As has been mentioned for several weeks, based on the lack of observed activity, we feel the pest does not pose an economic risk to our crop in the west central region this season.

San Jose scale 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 and Lorsban, as well as an uptick in early applications of oil with Esteem. If you want to deploy late season San Jose scale control, Valent suggests that an application of Esteem at 5 ounces per acre with horticultural mineral oil 1% v/v (summer or winter grade) at 200 gallons per acre with an airblast sprayer or 400 gallons per acre with mist blower can be used post-harvest to smother overwintering scale and get control for next season.

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.

Red Delicious

This variety is in the early range of maturity for harvest for CA storage at most farms in the region. Later sites will still want to give the variety until the end of the week or the beginning of next week, but most sites in the region can get started with it when they finish Golden Delicious. Red Delicious generally have a heavy crop this year. Although it’s moving into the early end of the mature range, some growers will still opt to wait a few extra days before they start this variety to get better color. Some standard sized orchards with a heavy crop and lush growth from all the rain this season aren’t displaying as strong of a red color as growers would have hoped.

We saw some moldy core in the samples we ran last week but did not see any this week, so it’s possible we just got unlucky in our fruit selection last week. 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 spring time. The issue tends to be worse on any variety with an open channel from the calyx in to the core, so we tend to see it frequently on the ‘Delicious’ varieties.

Idared

The second half of next week will likely mark the start of Idared harvest for west central Michigan, it’s not quite ready yet. That’s welcome news for area farms because most growers need at least another week to clean Golden and Red Delicious, as well as other odds and ends.

Idared is considered mature for CA storage harvest at a starch index of 3.5 with suggested firmness of 14 and 16 pounds, and fruits tested this week are still at least a week shy of that mark. Idared have beautiful color development this year, but unfortunately we did see some bleeding of that strong color in to flesh again this week. Be aware that some pink in the flesh may be an issue when running Idas this year.

EverCrisp

This variety was sampled for the third time this week and is still probably 10-14 days out from being mature. Fruits sampled this week were still hard and green, although the red color continues to improve as the background color begins to fade towards yellow.

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 late 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. Prior to this shift, fruits are not aesthetically appealing and would likely not pack very well.

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 comes by this trait honestly from its Fuji parent and is certainly something to monitor in coming years as more of this variety goes into the ground. Watercore that has been seen so far has been light, but harvest is still a couple of weeks out.

Fuji

Fresh market growers who are running out of varieties to pick were eyeing this one this week, but the variety needs another good week to ripen up. Red color development is outstanding in Fuji this year, which is part of the reason some operations are itching to pick it already. Despite appearances, Fuji is solidly a late-season apple in west central Michigan and is unlikely to be ready before the third week of October in a typical year in our area.

Although starch index at a couple of farms was close to the low end of the CA storage maturity mark in this week’s testing, another week should move Fuji in to a more ideal range. Background color is still very green, so another week will allow that color to lighten up a little bit and bring out even better red color. Fuji is considered mature for CA storage harvest at a starch index of 3 with suggested firmness between 16 and 18 pounds. We did not see any watercore in our samples this week.

Winesap

Winesap tested this week looked to be seven to 10 days 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.)