MSU Extension Apples

General comments

A reprieve from the rain has been most welcome and a lot of fruit have found a bin in the last week. It’s estimated that the Ridge and Belding, Michigan, are over 75% harvested. Gala and Honeycrisp are done. Jonathan and Jonagold are mostly done. Quite a few Golden Delicious were harvested in the last few days. Red Delicious harvest is beginning as well. Most varieties in the Grand Rapids, Michigan, area continue to mature about four to five days or more ahead of our 2019 predicted apple harvest dates.

We are hearing of concerns about the potential for fruit drop with the upcoming storm this weekend. Red Delicious in particular might need some help to stay on the trees if the high winds do show up. Michigan State University Extension fruit educator Phil Schwallier recommends 10 parts per million (ppm) NAA as soon as possible, followed up a week later with another 10 ppm if you can’t get them harvested before then. A second application is needed or the first NAA will enhance drop a week out if you can’t get them harvested.

I received several pictures from growers in the past week of San Jose scale on harvested apples. This is likely the third generation of this pest, which has become the norm in the last decade as opposed to the two generations most common in years past. If you find hot spots in blocks for San Jose Scale, take the time to mark the area with flagging tape or by dropping a pin on your phone. This pest moves very slowly and is easy to target with spot treatments next year if you know where the hot spots are.

Brown marmorated stink bug continue to be active in traps, in the orchards and on buildings. We continue to see and hear of less damage in apples than the past few years.

There have been reports of woolly apple aphid in some blocks this fall, but numbers are much lower than this time last year. Perhaps the natural enemies helped take care of it along with targeted sprays over the season.

Variety sampling results

Strains are noted where applicable. We try our best to collect samples from blocks untreated with harvest management products. Samples collected for this report are from the general Grand Rapids area, targeting fruit that seems mature and on the outside of the tree and ready for the next picking.

Individual variety results

Gala

Most Gala blocks have now been harvested. Those left are likely treated with harvest management products (i.e., ReTain, Harvista). Our sample this week is from untreated Buckeye Gala.

Jonagold

Nearly all Jonagold have been harvested. Our sampling block indicates Jonagold is in the mid-term to short-term CA window if treated with 1-MCP. This will likely be the last week to look at Jonagold.

Golden Delicious

The predicted harvest date for Grand Rapids area Golden Delicious is Oct. 8. Many have been coming off in the last few days, so the date was accurate, perhaps more due to being behind from last week’s rain than absolute maturity reasons. The block we sample from has been harvested, so no data for this week. Goldens need to come off soon to be condition for long-term CA storage.

Red Delicious

Red Delicious continue to move slowly as usual. Our predicted harvest date is Oct.11, which will likely be a good target date. There has been some harvest starting in the last day or two. Internal ethylene numbers are still very low, but 20% of fruits tested are now over the 0.2 ppm climacteric. Red color is about the same in our testing block, but there is a noticeable improvement in red color across all Reds on the Ridge in the past week. Fruit firmness is still very good at 17.7 pounds and down from last week’s 20.3 pounds. Starch clearing is similar to last week on average, but there were a few more fruits with readings of 6 to 8 than last week, so they are moving.

Red Delicious are not quite there for long-term CA storage, but harvest on early maturing sites can begin at any time. Thinking back to the very wet weather in May 2019, I have to wonder if moldy core will be more of an issue in Red Delicious this year. I haven’t seen or heard of any yet but do keep an eye on it.

Ida Red

This is the third week for Ida Red samples. Our predicted harvest date is Oct.15, which will be a good target date. Some harvest will begin soon as time allows. Thirty percent of fruits are now over the 0.2 ppm internal ethylene level. Red color is improving and probably the main reason you might wait on harvest. If color is good and there’s a free slot in your picking schedule, it would be OK to go after Idas sooner rather than later.

Rome

Rome continue to move very slowly through maturity per usual. Starch readings are now in the range for long-term CA so they could be harvested if time allows. Our predicted harvest date is Oct. 20, which will likely be on the too late side. They are hard as rocks and don’t eat very well at all. We haven’t seen any bleeding yet but keep an eye on it and harvest ahead of the bleeding if possible to satisfy market demands.

Evercrisp

We added Evercrisp to our sampling this week from two different blocks. This variety tends to look very much like its Fuji parent in its maturity parameters, especially in the starch clearing. It acts more like its Honeycrisp parent when it comes to high internal ethylene readings.

Evercrisp is immature and needs some improvement in the area of background color, which is very green and quite unsightly. Firmness is outstanding and you really have to trust your dental situation to attempt to bite into one. Brix are very good, which I think is typical for this variety. Next week’s samples will give a better target for Evercrisp, but if the background color improves, they could be harvested for long-term storage.

Fuji

Our predicted harvest date for late season Fuji is Oct. 28, which will likely be much too late for long-term CA storage. As we are moving through harvest at a good clip, no one will want to wait too long to go after Fuji. Our second week of sampling shows very little movement in maturity other than internal ethylene. This is very typical of Fuji—fast out of the gate and then it stalls for several weeks with only slight improvements in color and starch clearing. Keep in mind that Fuji often stains oddly for the starch index test and it will look farther along than it is—don’t let this fool you. Evercrisp seems to do the same for starch staining as its Fuji parent.

In years past when sugar levels are high as they seem to be this year, Fuji (and other varieties) can get callus tissue inside the core. This often is mistaken by buyers for moldy core. Just something to watch out for and if you see it and need my confirmation, please let me know (email me at irisha@msu.edu). Buyers have tried to reject loads for this non-defect. Check out “Moldy Core of Apple” from Kari Peters at Penn State University for a good comparison of moldy core and callus tissue with pictures to help with the identification.

Granny Smith

Granny Smith was added to our sampling for this week. They are very immature and likely to really ripen well into November. This is not a common variety on the Ridge and should be the last apple you harvest when there is nothing left to harvest.

Apple maturity sampling parameters

• % fruits with internal ethylene over 0.2 ppm = indicates when ethylene begins to influence fruit ripening and it cannot be held back easily after this is reached.
• Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested
• Background color: 5 = Green, 1 = Yellow; range is of all fruits tested.
• Starch: 1 = all starch, 8 = No starch; range is of all fruits tested. Using Cornell Starch Iodine Index Chart.