Half-baked research: Honeycrisp bitter pit and rootstocks, 2019 & 2020

 

Is this bitter pit?

Yea, this is pretty half-baked all right, but meaning to look and summarize it for quite some time now, recently pushed by colleague Win Cowgill to look at B.10 in this data set based on a recent publication suggesting B.10 was really good at NOT having bitter pit with Honeycrisp as the scion. Humph...

OK, so this work was part of a much larger NC-140 sub-trial honchoed by Cornell's Terence Robinson and WSU's Lee Kalcsits to assess the incidence of bitter pit on Honeycrisp as affected by (many) rootstocks in two NC-140 Honeycrisp plantings, 2010 and 2014. In addition to percent bitter pit in the apples as I will line out below, apple peels were also sent off to Lee for nutrient analysis and Lee and his/our team are working on a real scientific publication (not half-baked) which I will try to update here when it comes out.

For the purposes of my results presented below, basically, 50 Honeycrisp apples (or less if there were not that many on the trees) were evaluated for bitter pit at harvest and after three months regular cold storage. These apples were on trees in the 2010 and 2014 NC-140 plantings at the UMass Orchard in Belchertown. And this was done in 2019 and 2020, although in 2019 the crop was light and there were not enough apples in the 2014 planting to evaluate for bitter pit. You will see what the rootstocks are included in the results. When evaluating the apples for bitter pit incidence, no evaluation was made for severity of bitter pit, apples either had bitter pit (1 or more pits) or not (zero pits). Got it?

OK, so here are the results, pretty self-explanatory, but then I will bullet-list caveats and my take-homes after. 😉 Note you can click on any of the tables/graphs to get a larger image if these are difficult to read (too small) or blurry...

% Bitter Pit (BP) at harvest in 2019 in the 2010 NC-140 Honeycrisp apple rootstock planting. Capital letters (A, B, etc.) mean there is a siginificant difference when %BP is not followed by the same capital letter(s).

% Bitter Pit (BP) after 3 months cold storage in 2019 in the 2010 NC-140 Honeycrisp apple rootstock planting. 

% Bitter Pit (BP) at harvest in 2020 in the 2010 NC-140 Honeycrisp apple rootstock planting. 

% Bitter Pit (BP) after 3 months cold storage in 2020 in the 2010 NC-140 Honeycrisp apple rootstock planting. 

% Bitter Pit (BP) at harvest in 2020 in the 2014 NC-140 Honeycrisp apple rootstock planting. Capital letters (A, B, etc.) mean there is a siginificant difference when %BP is not followed by the same capital letter(s).

% Bitter Pit (BP) after 3 months cold storage in  2020 in the 2014 NC-140 Honeycrisp apple rootstock planting. Capital letters (A, B, etc.) mean there is a siginificant difference when %BP is not followed by the same capital letter(s).

OK, let's unpack this:

• Although some general and obvious conclusions about rootstock effect on bitter pit incidence can be drawn here, there was missing data and different numbers of apples evaluated, i.e. not always 50 apples were available, so don't take these results to the bank. What follows though, I am pretty confident about saying.
• In the 2010 planting, in both 2019 and 2020, the only time there was a significant difference in % BP by rootstock was at harvest in 2019. There G.41 had significantly more BP than B.9, G.214, and the two M.9 clones. G.41, got that?
• I have been trained to not go here, but may we conclude a few things on the non-significant results in the 2010 planting in both years, 2019 and 2020? Yes, I have my reasons. G.41 is generally in or near the top of the list in % BP. B.9 is generally low or near the bottom of the list in % BP. Hmmm... B.10 exhibits more BP than B.9 but generally expressed less BP than most of the Geneva rootstocks. (Sorry Win and Sherif.) G.214 among the Geneva rootstocks seems less bitter pit prone and comparable to B.9 and M.9. I don't know what to say about M.26 but I don't generally recommend that rootstock for Honeycrisp. My theory on all this is the Geneva rootstocks are generally more vigorous than B.9 and M.9, set a lighter crop, and thus are more likely to have BP'd apples? Plus I understand research has shown some issues with various ratios of nutrient (Ca, Mg, and K in particular) uptake among the rootstocks.
• In the 2014 planting, there were significant differences in % BP vs. the rootstocks both at harvest and after 3 months cold storage. After cold storage, G.11 and G.41 were the worse but technically did not significantly differ from many of the other rootstocks. How come I did not have B.9 or B.10 in this planting? Good question. I clearly remember technician Jim (I miss him now) commenting when evaluating the bitter pit how bad the bitter pit was in the apples from the 11's and 41's. Also in terms of severity (how much bitter pit) he said which was not taken into account here. The vigorous V. (Vineland) rootstocks were generally pretty bad, and once again, among the Geneva rootstocks G.214 (4214) did not have that much bitter pit. I really like that rootstock, however, have been recently made aware of some winter hardiness issues with it.

So, my/your take homes?:

• Bitter pit research is so very hard to do, there are so many factors that contribute to bitter pit development it is not even funny. See Dan Donahue's Honeycrisp Playbook (to mitigate bitter pit risk).
• For the reason mentioned above, Geneva rootstocks -- with maybe the exception of 214 -- are more pre-disposed compared to the less vigorous and heavy cropping (which has it's own downside) B.9. M.9's are in there with B.9 but might be more prone to bitter pit. The slightly more vigorous (than B.9) B.10 might be a better choice than G.11 or 41 with Honeycrisp (or any other bitter pit prone variety, Jonagold?) as the scion.
• I have a saying "friends don't let friends plant Honeycrisp on G.41" largely based on my overall experience, including in a significant commerical planting of Royal Red Honeycrisp on G.41 where the bitter pit therein has just been untenable (to date). And this is a good grower, the planting otherwise looks spectacular, although the crops have been lighter than desired. Oh wait, until 2023. Which has looked a lot better, very little bitter pit in that block. But a heavier crop and a very wet summer? And I understand the grower really threw the calcium at them this year after last years ugly look. I also have noted that my NC-140 Honecyrisp trees seem to have a lot less bitter pit than last year. This year's weather effect and a heavier crop? Or maybe as the trees get older they are settling down more? Although this is the 10th leaf, BP was bad last year in the 9th leaf. So I will temper a bit my saying above going forward. And there are obvious benefits to using Geneva rootstocks.

Seems to me I had some other things on my mind regarding this BP issue, but that is enough and this is about as half-baked as it gets, but it also is what it is, and my field observations kind of align with the numbers which don't lie? You just have to question the procedures 🤣 and do some of your own unpacking... 😎

#ifruittree 2023 IFTA Summer Study Tour

To Nova Scotia, July 23-25. Oh yea, maybe I am getting older or just think I have seen it all, I was not particulary inspired to report on my attendance at this IFTA event, but I suppose I need to earn my keep. It was also kind of hot and sunny, which does not particulalry motivate me either, but once I get going it jogs my memory and kind of enjoy documenting it. Although glad when I finish it!

The 2023 IFTA Summer Study Tour was based in Wolfville, Nova Scotia at the Old Orchard Inn where we were treated Sunday July 23 with a hearty reception on arrival -- food that is, otherwise a cash bar, but I have always enjoyed an (or 2 or 3) Alexander Keith's IPA. Monday morning the 24th we (approximately 120 of us) boarded three buses at 7:30 AM (6:30 EDT) for orchard visits in the Annapolis Valley. What fun!

First orchard stop was Birchleigh Farms in Berwick where our host was owner Waldo Walsh. Waldo grows for Scotian Gold where he "farms 100 acres of orchard (apples and pears) with apples representing over 95% of the production. The predominant apple varieties grown on the farm are Honeycrisp, Minneiska (SweeTango), Gala and Ambrosia." Focus of this stop however was Keith Fuller, research scientist for Agriculture and Agri-Food Canada (AAFC) out of Kentville. A project here in collaboration with Nova Scotia Federation of Agriculture "Living Lab" Agriculture Climate Solutions was using Pic Plus Fumigant as a replacement for Telone C-17 in apple replant situations. Fuller's results to-date suggest Pic Plus is useful to improve tree growth in true replant disease situations, but still not as effective as if Telone C-17 was used.

AAFC's Keith Fuller at Birchleigh Farms talk replant disease treatment

Replant disease at Birchley Farms? Looks pretty good to me...

Next up CAP Farms where Andy Parker (the "P" in CAP?), son-in-law Eric Chappel, and Scotian Gold's Danny Davison discussed management of a hi-density Ambrosia planting including their homemade over-the-row sprayer. C Andrew Parker Farm grows for Give Them aWink, "Wink" being a brand of Van Meekeren Farms, also home of Pazazz apples in Canada. Of particular note is the fact their over-the-row sprayer had no fan assist which apparently is not necessarily in their well-sculpted (hedged) rows of apples. No complaints here.

Fanless custom-built over-the-row sprayer at CAP Farms

Nicely sculpted (heged?) apple trees at CAP Farms

Very healthy-looking Ambrosia at CAP Farms

After a chicken BBQ lunch (yum) at the Northville Farm Heritage Centre we walked (literally) to a bi-axe  (Honeycrisp?) block at Van Meekeren Farms being shepherded (babied?) by Harrison VanMeekeren. Unfortunately cropping has been light to date on these Geneva rootstocks. (Which one?, I really should be taking notes!). I was not surprised. Also a hot and sunny equipment demonstration, most notably an autonomously equipped/operated GOtrack tractor. Among other toys by ProduceTech.

Multi-leader Honeycrisp at VanMeekeren Farms

Last (not really) afternoon stop was at Vermeulen Farms looking at raised bed strawberries (not really into it) and a lively farm labor discussion. Not even a picture for you here. Really the LAST afternoon stop was the mandatory group picture from "The Lookoff," overlooking the Annapolis Valley and Minas Basin. Shameless self-promotion picture here but the real group picture here. Second mandatory IFTA Nova Scotia stop was a lobster supper (chicken optional, eh?) at the Louis Millet Community Complex in New Minas. For some reason can't help but think about Evangeline here.

Selfie from "The Lookoff" overlooking Minas Basin 

Tuesday, the 25th of July. Lutz Family Farm Ltd. first on the agenda, our hosts being Larry Lutz, son-in-law Cassian Ferlatte, son Sam, and their Jamaican farm crew. Lutz Family Farm owns over 1,000 acres of land with only 140 acres of orchard, Larry equally likes his winter work of land clearing/logging. Apple rootstocks and Ambrosia pruning were the focus here, but also a thinning trial with Accede was highlighted by Michelle Cortens of Perennia. Take homes? M.26 still in favor in Nova Scotia, although Geneva rootstocks are being planted with some trepidation. Lutz is using Supporter 4 too, and has an on-farm nursery producing ten to twenty thousand trees annually. Prune Ambrosia hard using longish stubb cuts to prevent growth from becoming upright, long and lanky away from the central leader. Accede has promise as a thinner at larger fruitlet sizes, but like all chemical thinning, it's a bit variable in efficacy. If you have eleven minutes, check out my video interview with Larry here, it's a pretty good story.

At Lutz Family Farm Ltd, Sam, Larry, and Cassian field attendee questions

Lutz nursery, 'Rave' bench grafts on G.935 (Larry Lutz photo)

Valent crew and Perennia's Michelle Cortens discuss thinning with Accede

I'd say Accede worked pretty good on these Honeycrisp!

Second morning stop was Crisp Growers Inc. owned Scotian Gold and their fourteen apple growing families. Kind of an interesting (but slightly dated) story here. But we were only here to see the H.S.S AgBot sprayer and Vivid Machines crop load management vision technology (aka camera mounted on an ATV). That AgBot is kind of scary, check out the video, what could go wrong? 😑 

After a Jamaican food truck lunch (yum) and cider tasting (double yum) at Spurr Brothers Farm Market, we followed Lisa Jenereaux to Spurr Brothers Farm to look at V pears (sorry Lisa, I was not really into it) and another replant experiment being honchoed by Keith Fuller, this one being mulching (with and without fumigation) to improve newly planted tree growth. To date results are lackluster explained Keith, as tree growth in general in the first two seasons was poor, and compost and fumigaiton with Pic Plus did not improve tree growth. But pre-plant compost addition suppressed root leasion nematodes and compost presisted for 4+ years after planting as measured by soil C content. Oh well.

Lisa Jenereaux at Spurr Brothers Farms talking about her pears.

Final IFTA Nova Scotia 2023 Summer Tour stop was the impecably manicured Wohlgemuth Farms where pre-harvest leaf removal to improve red color and NC-140 rootstock trials (2019 Buckeye Gala) were showcased by AAFC Kentville personnel. Also some of their research on effect of anti-ethylene products ReTain and Harvista and optimum harvest window of Ambrosia and Honeycrisp apples. Nice orchard, good research, overall a fitting Tour finale. Did I mention they are a hog farmer also?

Pneumatic leaf removal experiment to improve red fruit color at Wohlgemuth Farms 

I have come to the conclusion that hog farmers have the nicest orchard! 

Suzanne Blatt, AAFC Kenville entomologist, does double duty as a horticulturist
while discussing the 2019 Buckeye Gala NC-140 planting at Wohlgemuth Farms

The 2019 Buckeye Gala NC-140 planting (on left)

That's about all I got, maybe all apple trees are starting to look alike, but I have to say, the longer I am in this business the more confused I get (about some things). I can confidently say though that Nova Scotia is a pretty darn good place to grow quality apples -- particularly Honeycrisp, they are absolutely the best there -- but they do have these tropical storms that in recent years have caused them some headaches! Thanks to all who planned and hosted us, best of luck to you during the upcoming harvest!

I think there is Scotian Gold at the end of the rainbow
as seen from the Old Orchard (note foreground apple trees) Inn 

Apple blossom density mapping using a UAV (aka drone)

Precision Apple Cropload MANagement (PACMAN) -- in whatever form it takes -- is "the topic of our time." Unmanned Aerial Vehicles-- UAV's, more commonly known as drones -- likely have a role. In fact, at least one company, Outfield already provides a low cost, turn-key (more or less) solution using drones to map apple blossom and crop density. To that end I acquired a sub-$1,000 "consumer" drone in the spring of 2023 and worked with U.K. based Outfield to get a feel for what this technology could provide?

After getting my FAA Part 107 Remote Pilot Certificate allowing me to legally fly "my" drone -- a DJI Air 2S -- while on the job at UMass, the helpful folks at Outfield (Oli and Andrew) provided me with a cloud based "dashboard" wherein I initially mapped my apple orchard blocks of interest -- five at the UMass Orchard in Belchertown, MA and three at Tougas Family Farm in Northboro, MA. The blocks totaled 3.5 hectares (8.6 acres). Outfield returned to me "flight plan" files that were imported into Litchi. Once the orchard blocks were in full bloom in early May, 2023, and I was ready to fly following all the standard flight safety planning practices, using the Litchi app the drone took off, flew the zig-zag-across the row flight plan while taking (many) high resolution pictures of the trees from about 10 meters (30 feet) above the canopy. All done automatically, including landing in the exact spot the drone took off. Cool! No crashes or wayward drone (yet)! Now, it sounds pretty easy, and it was, but not without some nail biting and making sure everything was in order prior to flying. After flying the block the images are uploaded into the Outfield dashboard and were processed withing 24 hours resulting in a colored blossom density "heat" map.

Litchi zig-zag block flight plan with picture locations

Honeycrisp block blossom density map in Outfield dashboard

Low-high Honeycrisp blossom density example

OK, so what? Is it an "actionable, holy grail" component of PACMAN? Well, I did do a bit of visual ground truthing, but found it kind of difficult to figure out exactly where I was in the block in relation to the "heat' map. (I have put in a feature request to Outfield to make the overlay more "transparent" so the individual rows can be seen.) It seems to me, and I think Outfield is headed in this direction, is the map needs to be synced with a variable rate sprayer so that, for example, bloom thinning sprays could be adjusted accordingly to where bloom density is higher (or lesser)?

Once the apples reach golf-ball size Outfield tells me I can repeat the flyovers and they will give me a yield estimate for the block (and fruit sizes on the horizon). I have not seen that yet, TBD. Drone use in agriculture is evolutionary, I suspect some aspect of this tool to better manage crop load -- or do pest scouting? -- is in my and your future. Stay tuned...

Dan Donahue's Honeycrisp Playbook (to mitigate bitter pit risk)

I attended the Eastern New York Fruit & Vegetable Conference February 22-23, 2023 in Albany NY. Hosted by the Cornell Cooperative Extension (CCE) Eastern New York Commercial Horticulture Program (ENYCHP). A day and a half of tree fruit talks, mostly featuring speakers from Cornell University and on many pest management (insect & disease) and production (horticulture) management issues. Check out my @jmcextman Twitter hashtag #ENYFVC for a bunch of picts and comment on their presentations.

One presentation worth bringing to you here was by Dan Donahue, tree fruit specialist with CCE's ENYCHP. Dan has always been quite inventive, so his talk was excerpts from his 'Honeycrisp Playbook,' a series of specific recommendations to mitigate bitter pit risk when growing Honeycrisp apples. So without further adieu, here is Dan's most recent and comprehensive 'Playbook' (in bold) with some comments by yours truly (in italics)...

Avoid replant sites - yea, Honeycrisp are tough enough to grow as it is, give them a break and grow on virgin ground and/or follow BMP's for replant sites (fumigation, cover-cropping, etc.).

Soil pH should be adjusted to about 7.0 - start a little high on pH with addition of lime to bring pH close to 7, that lime has calcium in it (don't use dolomitic-high mag limestone), and that slightly higher pH than the normal recommendation of 5.9 to 6.5 will enhance nutrient availability.

Use 30% less ground potassium (K) than other varieties - K is antagonistic to calcium uptake and movement in the plant, don't ignore the need to have some K (as dictated by soil/foliar nutrient tests), just don't use as much as you might, say with Gala?

Moderate nitrogen (N), shoot for 2.2% in the leaf analysis, no foliar N - high nitrogen = high bitter pit, enough said? Feed the roots N using calcium nitrate as dictated by leaf analysis, just err on the short side vs. lots of N.

Use B.9 or B.10 rootstocks, avoid Geneva rootstocks - pretty straight forward, M.9 rootstocks fall somewhere between B.'s and G.'s in bitter pit prevalence. B.10 is a bit more vigorous than B.9. Friends don't let friends plant Honeycrisp on G.41. Good tree spacing for Honeycrisp on B.9 are app. 2.5 feet between trees by 10-11 feet between rows. A bit more in Dan's study Bitter Pit Response to Rootstock and Region in Eastern New York State.

No apple crop in 2nd leaf - yup, grow your trees (with moderate nitrogen!) for years 1-3 in the orchard. Apples off young trees will be bitter pit prone anyways. Do de-fruit them when young, only start cropping when they are as tall and wide as you want, as they will stop growing (much) when they start fruiting.

Light to moderate tree vigor, pruning - a "calm" tree is what you want to mitigate bitter pit risk. Use thinning (vs. heading) cuts as much as possible while pruning.

Avoid precision pruning to a bud load < 2.5 buds per target crop load - yea, leave more buds than you might otherwise with say, Gala? You don't want to fall too far short of your target crop load in the end. Good insurance here. But I might go down to 2 buds per target crop load 😎.

Avoid aggressive, early crop reduction, aggravates bitter pit - normally we recommend thinning early and often. Not so much here, but there is a fine line. More below...

Prohexadione-calcium (Apogee/Kudos) at pink, do not apply post-bloom - Dan's work that has been field tested indicates Prohex-Cal applied post boom results in more bitter pit than when it is applied at pink. And actually, that pink application gives pretty effective growth control too. More here from Dan. And his own words "I recommend avoiding conventionally-timed Prohex if at all possible."

10 ppm NAA at bloom, avoid bloom thinning with ATS or lime sulfur - that NAA at bloom nudges the thinning start (but not aggressively) and also promote return bloom (well, at least it is a start). Bloom thinning with caustic thinners typically and aggressively thins early (what did he say above?) and leaves the king bloom typically, especially when using the Pollen Tube Growth Model. King bloom = larger apples = more bitter pit? Maybe, maybe not, this may not always be true. But you might get away with using caustic bloom thinners with B.9/10 rootstocks? If bloom thinning with caustics, you should be using the pollen tube growth model.

Calcium (Ca) at petal fall, continue through 5 weekly applications - I'd be using the formulated liquid calciun products (Sysstem-Cal, etc.) at this timing and then switch to calcium chloride mid-summer until harvest? More here from Dan.

Target chemical thinning at 8-12 mm stage - is this all starting to come together? Besides, particularly when following the carbohydrate model to determine rate and timing of chemical thinner applications, this is when THE most effective chemical thinning often happens, at 8-12 mm. Still, NAA 10 ppm at bloom! And don't forget to use the apple carbohydrate thinning model when chemical thinning at this time.

Hand thin to target fruit load at 35 days post-bloom - Honeycrisp initiates flower bud development early, as soon as 30 days after bloom. Too many apples on the trees thereafter will inhibit flower bud formation = biennial bearing. Get it? So hand thin Honeycrisp first!

3 sprays NAA at 5 ppm - that's 2 oz. per 100 gallons dilute tree row volume per acre, beginning no later 30 days post-bloom, then 45, then 60 -- for return bloom enhancement AND research has shown that the auxin factor of NAA reduces bitter pit. I recommend 2 oz. per acre, period. Some return bloom recommendations use ethephon, might be OK in addition to those NAA sprays.

Limit irrigation (deficit?) late June through harvest - yup, you don't need to be blowing those Honeycrisp apples up and diluting calcium (and promoting calcium sink shoot growth) = more bitter pit risk. More on deficit irrigation of Honeycrisp (where practicable LOL) here from Washington State University.

Use EMR model or passive bitter pit prediction protocol on M.9 rootstocks destined for long term storage - No need to test B.9 or Geneva rootstocks as they will have less or more bitter pit respectively Dan says. If you want to know more, here is the reference for EMR (Environment, Minerals, Rootstock): Daniel J. Donahue, Gemma Reig, Michael Rutzke, Anna Wallis, Michael Basedow, Sarah E. Elone.  2021. A Predictive Model for Malus × pumila Borkh c.v. ‘Honeycrisp’ to Reduce Storage Risk in Eastern New York State, U.S.A.  Acta Horticulturae 1314. Proceedings of the International Symposium on Precision Management of Orchards and Vineyards, October 2019. https://doi.org/10.17660/ActaHortic.2021.1314.51 And, a bit more about the passive bitter pit prediction model here: https://www.goodfruit.com/to-predict-bitter-pit-let-it-sit/

Weigh pros/cons of using ReTain/Harvista sprays, may increase bitter pit - bitter pit risk increases with earlier harvested apples, might increase with later harvested apples, but not really sure here? Apples will get bigger = more bitter pit? There is a sweet spot for less bitter pit with intermediate harvest dates? Just something to keep in mind when using these harvest management tools.

M.9 rootstock, third pick for long term storage = less storage bitter pit - has shown to be the case for that third pick, might represent optiumum maturity?

That is the most current Honeycrisp Playbook (for mitigating bitter pit risk) according to Dan Donahue. But hey, check out It's the Calcium Stupid, some recommendations from the recently deceased Jeff Alicandro/agri.assistance, RIP Jeff.

#ifruittree 2023 annual conference Grand Rapids, MI

Carrying on tradition of posting about my International Fruit Tree Association  (#ifruittree) trips, this time Grand Rapids, MI. I tweeted a bit about the Conference speakers over two days, there were - how should I say politely? - the good talks and the not so good talks, but that is OK. Here I will post a bit about the orchard tour stops, again, a mixed bag IMHO, I'm just calling it as I see it! So here goes...

First stop, Riveridge Land Company "a vertically-integrated company that operates over 860 acres of orchards." Apples and cherries, both metallic V-trellis a la what you see a lot of in Washington. It was OK, but those things cost a lot of money to establish. All things being equal, V-trellis intercepts a lot of sunlight per acre, hence can lead to maximum production per acre. But there are a lot of "gotcha's" IMHO, including training trees (to tie or not to tie?), and in the case of cherries, canker issues. I thought, especially with the cherries, a lot going on here. Cherry variety was "Skeena," apples were Honey's and Fuji's? But the main attraction were the Voen "rain" covers also serving as frost protection with "included" Voen gravity-fed pellet heaters at 20 per acre. Got the impression was both quite effective at preventing frost/freeze damage and preventing rain cracking. Apparently Riverridge has a good wholesale packing and marketing strategy, however, exactly how profitable the whole thing -- covered, hi-density sweet cherries in a humid/lower light environment such as Michigan -- is remains elusive? On the side, I was told they (Riveridge) may be moving to a UFO-style narrow canopy sweet cherry orchard, higher quality cherries and simpler management in that planar canopy? Did I mention we looked at apples on the V-trellis too, likely a better bet, unless organic? 😅

V-trellis cherries at Riveridge with 'Voen' rain/frost/freeze prevention covers

Gravity-fed wood pellet heater to further prevent frost/freeze damage, part of the Voen system

V-trellis apple orchard at Riveridge Land Company

Yup, organic apples at Riveridge. 80 acres. Major issues? Lack of tree growth/vigor compared to conventional, organic fertility (particularly nitrogen) always being a bugaboo. Weed control using landscape fabric leading to vole damage. I had to ask, what about mechanical cultivation as is so common in Europe? (No particularly good answer.) Pest control challenges (plum curculio, scab) such that much of the fruit goes to processing. But apparently demand exceeds supply, and there is a premium paid for organic processing apples, baby food? I got the impression Riveridge was doing it to broaden their portfolio as a supplier so they could offer organic as well as conventional to their customers? A bit of greenwashing? Maybe. Although there was some discussion about the larger organic ideals of soil health, organic pest control, etc. by guest Kyle Rasch of Tom Rasch & Son Orchards.

80-acre organic apple block at Riveridge

Vole damage exacerbated by fabric landscape cloth for weed control in organic orchard (photo courtesy Andre Tougas)

On to Rasch Family Orchards. (Yea, there are a lot of Rasch's out there on the "ridge." And Dietrich's 😂.) Hosted by "characters wanted" Jake Rasch in their hi-density peach block. I couldn't help myself thinking they've been drinking the Greg Lang Kool-Aid! Walking up the hill I saw some pretty nice looking perpendicular-V peaches, but we were looking at a planar V-system with wires, tying, etc. Rationale, according to Jake was better peach quality (mostly red color), labor efficiencies (platforms), and it did not take that much more work than the Perp-V's? Maybe, I could buy that, and am generally an advocate of hi-density tree fruit production, but I worry about within-the-row shading and -- as with all peach systems -- maintaining a properly sufficient light environment in the bottom of the trees. Remember, no really proven dwarfing rootstocks for peaches yet, so it's pretty hard to make a big tree "small." I already saw some pruning messes? Might be better off dispersing the vigor more into Upright-Fruiting-Offshoots, UFO? That can continually be renewed? But I will give Jake the benefit of the doubt for now...mostly because he was just good-humored about the whole thing!

Pruning and training demo by Jake Rasch in planar 'V' peach system.

Ugh! What now Jake Rasch?

After BBQ lunch at a Riveridge pack house we re-assembled in an apple orchard newly aquired by LTI (Let's Try It) Ag Research. Hosted by LTI founder Tye Wittenbach and his righ-hand person Dan Zemaitis. LTI "was founded in 2021 by a group of like-minded industry professionals who identified a need for on-farm research in the apple industry. LTI will focus on membership-driven research of industry problems that face growers each season." The focus here at LTI was a just-planted "apple rootstock evaluation in a replant scenario." Two things stuck out to me: first, lots of replication but absolutely no randomization in terms of experimental design; and second, pretty lousy trees with very few branches. After the fact it's easy to criticise, but either at the nursery or when planted some effort should have been made to promote braching in these young apple trees. Now they are in a situation where they got to get some branches growing on older (2 or three years) wood, which is not easy. Much discusssion about ensued. Maybe it was exacerbated by the replant effect too? Whatever, I would not be happy if it was MY orchard...

LTI's 'Let's Try It' apple replant 'experiment.'

"Where's the branches?" These trees at LTI were somewhat neglected in the nursery and in the first year in the orchard where some intervention (PGR's) could have helped prevent the blind wood seen here. 

Last stop of our day was J. Engelsma Orchard at Engelsma's Apple Cider Barn, Michigan's best "blue ribbon" cider pressed fresh daily. Bridget Engelsma gave us a quick tour of the cidery, but then we followed Jim Engelsma out to a young block of Honeycrisp/B.9 trained to two leaders. I remember these "whip" trees were headed low at planting to get the two leaders, and now the struggle is to get to the top wire (at 9-10 feet) on that weak rootstock. Getting there, but not quite, and Jim admitted, might never happen. Jim's proposed pruning on these trees was done in a couple rows, mostly shortening "click" style pruning of last year's shoot growth to keep the trees planar and set flower buds closer to the trunk? At least that is what I took home, I think Jim's ultimate solution will be using a mechanical hedger with some annual dormant hand-pruning of bigger wood. Should be easy 😎

It was a cold, frosty morning when Andre Tougas took this picture (thanks Andre!) of Jim Engelsma's bi-leader Honeycrisp/B.9 block

OK, enought of me being "negative Nancy" (or so I am told), thanks to IFTA Education Director Greg Lang, the local Michigan State University crew (Amy Irish-Brown, Anna Wallis, Emily Lavely, Derek Plotkowski, Phil Schwallier [retired], and Todd Einhorn), and Ag Association Management (Shane, Shari, Bethany) for hosting, educating, and humoring all 300 or so of us IFTA'rs. Lest me not forget the couple of freeloaders on my tour bus looking for free food and a warm place to spend the day, they succeeded in pulling the wool over my eyes! 👻

PACMAN: Malusim vs. Fruit Growth model app vs. Farm Vision

Precision Apple Crop load MANagement (PACMAN) is the topic of our time. Seriously, it is. Although I have to be a jack of all trades (pest management included) my heart lies in horticulture. And technology. (Although I am no computer geek like some people think I am!) So, I have been interested in the fruitlet growth rate model per Duane Greene et al for quite some time including onerous measuring of fruitlets for quite a few years.

The fruitlet growth rate model is one part of PACMAN which also includes precision pruning, blossom thinning with caustics, chemical fruitlet thinning, and finally – if necessary – hand thinning. Why? Because, particularly when growing high value varieties like Honeycrisp – or where size matters even more, like Gala – it’s money you are otherwise leaving on the table. (Thanks Rod Farrow for that bit of wisdom).

So, carry on, here is what I did for PACMAN in 2022. My main objective was to compare the fruitlet growth rate model when measurements were put into Malusim (MS app) vs. the Ferri-Fruit Growth model ‘FG’ app. In addition, and to make it more complicated of course, Farm Vision (FV) was in the mix. (And I later realized it’s a bit like comparing apples to oranges though. More on that later.) I’m going to lay it out here pretty tersely for you to digest and form your own opinion on the value of using the fruitlet growth rate model as part of your PACMAN strategy going forward. Which I do recommend, with caveats as you will see.

METHOD

At the UMass Orchard (UMO) I chose Gala, Fuji, and Honeycrisp. Per my RECIPE for predicting fruit set, five representative trees were selected at bloom, number of flower clusters counted on each tree (for potential fruit set), fourteen flower clusters tagged per each of the five trees for fruitlet measurements beginning when fruitlets were app. 6-7 mm in size on 23-May and continuing subsequently on 26-May, 29-May, and lastly on 3-June, 2022. Unfortunately, although chemical thinners were applied, the details are sketchy and date of application(s) not included here for UMO.

Ditto for Tougas Family Farm (TFF) Northboro, MA for Gala and Honeycrisp, although over only three measurement dates: 21-May, 25-May, and 27-May, 2022. Here, chemical thinner application dates are noted in the results.

At both UMO and TFF, sometime between August and harvest the number of apples left on each tree were counted for the final fruit set. All make sense so far? Oh wait, on each measurement date I also did a Farm Vision (FV) scan using their provided equipment: smart phone, stereo video camera, and enhanced GPS location. And also did a final FV fruit scan to determine the fruit set in August.

FV scan on 3-Jun, 2022 at UMO, Fuji

There, now the results are presented in both tabular and chart form (Figures 1. through 5.). Ought to be self-explanatory, but we will see 🙂 and more explanation will be included as it’s not always really pretty…

RESULTS

Figure 1. - Predicted fruit set Gala at UMO

A bit of explanation here which applies to all the Figures. There was one measurement date previous to all the initial measurement date(s) noted in Figure 1. (and Figures 2. through 5.). But that is not included because in Malusim there is no prediction. (No growth rate calculated on first measurement.) Otherwise, on the dates noted, those numbers in the tables are predicted fruit set (number of apples per tree) based on Malusim, the FGM app, and Farm Vision. Actual (count) in the Table was the number of apples hand counted (per tree) in mid-August. (Except for UMO Honeycrisp in mid-September.) Actual (FV scan) was what FV 'saw' on the trees mid-August. So you can compare that Actual fruit set to the Predicted fruit set on the last date of fruitlet measurements. Charts are table data visualized. All make sense now?

Gala-specific at UMO (Figure 1.), these trees are on M.9 rootstock, fully mature, tall-spindle. Bloom was spotty but five trees with approximate equal (and good) bloom density were selected. The overall objective here was to compare Malusim and FGM app when the same numbers were used. You can see they differed a bit. Why? Measurements were made by different people (on at least one date), and that could have accounted for some 'increased' predicted fruit set noted on 29-May. (That should not happen!) Advice: same person should measure on each date to keep that source of measurement error down with more consistent measurement technique (hopefully). Farm Vision here was in the ball park.  Oh, one more thing, not sure I am using the trend line appropriately, but I like it here...😉

OK, onward with the rest of the RESULTS (Figures 2. through 5.), with brief variety-location-specific comments.

Figure 2. - Predicted fruit set Fuji at UMO

Same story as Gala here with these Fuji (M.9 rootstock), with that uptick of predicted fruit set on 29-May, different measurement people, student interns? Malusim and FGM app were quite different at the end (3-Jun), FGM being right on compared to Actual (count). I should note that Malusim has instituted some error correction and will exclude measurements deemed to be outside specific error limits (too large, too fast growth rate). Not sure I like it because I think at least here it might have been discarding measurements that were indeed valid? Not sure, but perception is reality? Again, Farm Vision, at least on the last measurement date, predicted more fruit setting than Actual. Is this necessarily a bad thing as some fruit will continue to fall off, June drop, etc. I told you it was a bit ugly, but I am not casting any shadows yet after just one season of evaluation of Farm Vision. (BTW, they are now part of Meter Group/Pometa.) 

Figure 3. - Predicted fruit set Honeycrisp at UMO

At least Malusim, FGM app, and FV align pretty good here with these Honeycrisp on G.11 rootstock in their 9th-leaf. Actual (count) may be an underestimate as there were some drops which were not counted. But not so many to skew the results too badly IMHO.

Figure 4. Predicted fruit set Gala at TFF

At TFF there were only three (total) measurement dates for both Gala (Figure 4.) and Honeycrisp (Figure 5.). Hence only two dates of Predicted fruit set. These Gala were mature tall-spindles on G. 41. I do have some thinning information here, thinners were applied to these trees on 12-May (Promalin + AmidThin, bloom) and 20-May (Maxcel). But I was not worried about using the Predicted fruit set to help with thinning times and rates, at least here, where the objective was to just compare what the three tools were doing in predicting the fruit set. Got it?

Figure 5. Predicted fruit set Honeycrisp at TFF

Thinning regimen here on these Honeycrisp/G.41 was NAA (4 oz.) on 12-May, NAA (4 oz.) plus carbaryl (one pint) on 18-May, and NAA (2 oz.) on 27-May. No Farm Vision here, the equipment was not behaving properly. (Except for the Actual FVT scan.) Malusim and FGM app were close, but not close enough. As an aside, bitter pit was really bad in this light cropped block of Honeycrisp on G.41. Did I say G.41? (Friends don’t let friends plant Honeycrisp on G.41.)  

I have to say that 2022 was overall just plain weird, I mean the weather during the post-bloom period made chemical thinning applications a nail biting experience. What we saw and what happened kind of defied expectation. It was not a 'normal' year. (As if we ever have one?) Can't wait to see what 2023 brings... 😱

RECOMMENDATION

There you go, make of it what you will, there is lots more to dive into. But, I do know this is what I would do: follow the RECIPE using the FGM app. iPhone only unfortunately. Malusim has issues, although I do like the website interface. The app, not so much. But it does more than predict fruit set, and I hear it is being updated to include fixed voice input recognition in 2023. After the initial set up, it takes less than an hour (easily) to do the measurements (per variety per block) using the RECIPE instructions. Preferably with two people. And you get instant results via the FGM app, i.e. predicted fruit set to better inform further chemical thinning decisions. Period. One side effect often observed, is the actual physical process of measuring fruitlets gives better insight over time as to what is going on -- what is growing, and what is not -- that you otherwise get from simple observation from the truck window!

But, Farm Vision (now Meter Group/Pometa) has merits in its early stages. Plus it gives you a crop estimate later in the season for better harvest management. Lots of potential there, and it – or similar tools (FruitScout?) – are the future of precision apple crop load management. Well, then there are rovers and drones, but I don't go there, I let others. Flip-flop, check out Orchard Robotics. And here's a couple videos from Farm Vision you might get a kick out of. I did, reviewing them here in January 2023 when it is otherwise pretty bleak outside. Good luck in 2023...

UMass Orchard Gala - Farm Vision fruitlet scan on 26-May, 2022

https://youtu.be/CGzkWH6PUDE

Tougas Family Farm Gala - Farm Vision fruitlet scan on 25-May, 2022

https://youtu.be/-rKWAHVqusY

The FRUIT GROWTH (FG) app

 The FRUIT GROWTH (FG) app by Joe Ferri – and mentored by his grower brother Tom of TK Ferri Orchard, The Blue Mountains, Ontario, CANADA – is an iPhone/iPad (only, no Android) app that does just what it says: predict apple fruit set based on the apple fruitlet growth rate model. Per the description on the App Store (https://apps.apple.com/us/app/fruit-growth/id1604255929), the FG app features:

• Easy fruitlet size and cluster count input screens.

• Quick apple set prediction results screen.

• Full results easily shared to email addresses and Mac computers.

• The Fruit Growth app accepts fruitlet sizes and cluster counts data to calculate the predicted number of apples that will be set.

• The results are summarized in the calculated results screen. The full results Summary file (.csv) can be shared to an email address, internal device storage or air dropped to a Mac computer.

• The fruitlet size Data file (.csv) can be shared for cut and paste to the Excel Fruit Growth Model (Ferri version).

I used the FG app in 2022 to predict fruit set in two Gala blocks, two Honeycrisp blocks, and one Fuji block. (Across two orchards, results forthcoming in a pending Fruit Notes article.) I found it generally easy to use and once fruitlet growth measurements are made on a given date it gives instant results predicted fruit set so further chemical thinning decisions can be made. One feature of the FG app allows you to do a split tree (top and bottom) calculation predicting fruit set. As you probably know, fruit set is often better in the tops of trees vs. the bottom. Thus you can target and be more effective with your thinning sprays. Below are a few screenshots from my FG app in 2022 (Figs. 1 - 3), and there are a set of excellent screenshots on the App Store (https://apps.apple.com/us/app/fruit-growth/id1604255929) so you can better understand how it works. For reference, per the Ferri’s, here are their specific notes on how to use the FG app once you download and install:

Fruit Growth Model Notes (Rev 3.0.0)

Select a Variety - to input the fruitlet sizes (Fig. 2)

• Input the fruitlet size and Enter button

• For fruitlet size measurement accuracy of 0.5 mm (e.g. if 12 is entered 12.0 is stored, if 12. is entered 12.5 is stored)

Note: Once all current measurements are completed, to advance for the next  sample date and measurements push the blue right arrow next to the date

When each tree fruitlet measurements are completed:

• Enter Clusters button - to input the number of clusters per tree

• Input the cluster count and Enter button

• If two people are counting the clusters, use the + button to add the counts

Note: To delete all the last sample fruitlet sizes and cluster counts push the Trash button

Add Variety button (Fig. 1)

• Enter the variety name

• Choose the number of trees to measure

• Choose the split or full tree option

• (Clusters: Tree Bottom 1-6, Tree Top 7-14)

• Save button - save the file name and settings

Manage Files button (Fig. 1)

• Select a Variety

• Results button - generate the results summary (Fig. 3)

• Share Summary button- generate the full results summary .csv file

• Delete button - permanently deleted the file

• Import Data button - import a fruitlet size Data.csv file

• Share Data button - generate the fruitlet size data .csv file

• (used to cut / paste into the Excel Fruit Growth Model (Ferri) version)

Joe Ferri is actively updating the FG app, it is up to version 3.0.0. You can download from the App Store, it costs $17.99 but is money well spent. Alone, once set up (see my RECIPE for setting up your trees for using the FG app: https://ag.umass.edu/fruit/fact-sheets/hrt-recipe-predicting-fruit-set-using-fruitlet-growth-rate-model) I can complete a set of measurements per variety/block on a given date in less than an hour. It would go quicker with two people, and you get instant results predicting the fruit set. How good is that?

Fig. 1 - FG app iPhone screen “Add Variety/Manage Files”

Fig. 2 - FG app iPhone screen “Enter measurements”

Fig 3. - FG app iPhone screen “Results”