2016 Michigan peach harvest date prediction

Bill Shane, Michigan State University Extension - May 31, 2016

The harvest of Michigan peaches in 2016 is expected to start early and be somewhat compressed from south to north in the Lower Peninsula.

The Michigan State University peach harvest model is predicting that Redhaven harvest in 2016 will begin approximately July 29 in southern Michigan, about four days before the long-term average and about three days earlier than 2015. The spread of harvest dates are predicted to be from July 29 in the southwest corner of Michigan to Aug. 6 at the Northwest Michigan Horticultural Research Station, northwest of Traverse City, Michigan – a difference of eight days. The predicted spread between north and south harvest dates for the same variety have ranged from four to 12 days, depending on the year.

The peach harvest model is available on the Enviro-weather website under the Fruit section as two tools. One tool provides estimated peach harvest dates for 76 varieties at a single location and the second tool gives regional peach harvest estimates for three representative varieties for all weather stations in a region. These tools are based on 20 years of peach harvest and temperature data.

The model is based on an observed relationship between degree-days and onset of harvest. The predictive equation is D = -0.0386x + 234.9, r2 = 0.752, where x is the cumulative degree-days (DD) base 50 degrees Fahrenheit from Jan. 1 through June 3 and D = the estimated harvest day of year (e.g., Jan. 1 = 1 and Dec. 31 = 365 in a non-leap year). The estimation is for the onset of the main season Redhaven harvest, not including fruit with split pits that typically ripen several days earlier than undamaged peaches.

Factors such as soil type, proximity to Lake Michigan, crop loads and weather shortly before harvest can affect peach ripening and are not accounted for in the model. Also, a heavier crop delays the harvest date in an individual orchard.

Table 1. Estimated Redhaven harvest onset in 2016 and 2015 for six locations based on the MSU peach maturity prediction model.
Enviro-weather station location	Estimated harvest date for 2016	Estimated harvest date for 2015
Benton Harbor (SWMREC)	July 29	Aug.3
Fennville	Aug. 1	Aug.6
Sparta	Aug.2	Aug.6
Romeo	Aug.5	Aug.3
Hart	Aug.8	Aug.8
NWMHRS	Aug.6	Aug.9

For Michigan, the start of significant peach volume is with the Redhaven season, providing a handy benchmark time point. The estimated Redhaven harvest day can also be used to approximate the harvest dates for other varieties by adding or subtracting harvest dates relative to this reference variety (Table 2).

The Michigan peach crop potential for 2016 looks decent to good, with only a few sites so far reporting poor fruit sets.

Table 2. Typical yellow melting flesh peach variety harvest windows for the Michigan climate.
Older peach varieties	Newer varieties with significant production	Newest peach varieties
Harbinger = -33*	PF-1 = -30	Rich May = -28
Harrow Diamond = -25	PF-5B = -25	Desiree = -26 ^^ PF-5D Big = -22 ^^ Earlystar = -18 ^
Garnet Beauty = -10 Early Red Haven = -10 GaLa = -8 Sentry = -8	Glenglo = -13 PF-7 = -10 Summer Serenade = -10 PF 8 Ball = -10 Rising Star = -8	Brightstar = -12 ^ PF Late 8 Ball = -5 ^^
Redhaven = 0 Reliance = 0 Vivid = +2 Bellaire = +3 PF-12A = +3 John Boy = +3	PF 9A-007 = -2 PF 11 Peach = -2 PF 15A = +2 Blazing Star = +2 Starfire = +3 Redstar = +3 PF 14 New Jersey = +4	PF Lucky 13 = +6 ^
Glohaven = +8 Canadian Harmony = +10 Loring = +12 Suncrest = +12	Blaze Prince = +8 Bounty = +10 PF 17 = +12	PF Super Duper = +8^^ John Boy II = +8 ^ SweetStar = +14 ^
Contender = +18	PF 19-007 = +14 Allstar = +16 Coralstar = +16 Beaumont = +19	Messina = +17 ^^
Cresthaven = +24 Redskin = +26	PF 23 = +20 PF 24-007 = +22 Glowingstar = +22 PF 24C Cold Hardy = +24 PF 25 = +26	PF 22-007 = +20 ^^ July Prince = +24 ^^ PF Paramount = +24^^ Gloria = +26 ^^ LA
Madison = +28 Harcrest = +28 Fayette = +28 Encore = +31	PF 27A = +30 PF 28-007 = +32 Autumn Star = +37 ^ PF 35-007 Fat Lady = +40 ^^ Laurol = +41 PF Big George = +50^^	Flame Prince = +38 ^^ PF Legendary = +41^^ Victoria = +47 ^^ PF Fashionably Late = +54^^

* = Estimated harvest days before (-) or after Redhaven. Harvest order can change depending on the warm/cool characteristics of a season. A cooler year will delay harvest dates, a warmer season will compress the harvest dates closer together.
^ = Little experience with this variety to date
^^ = Very little experience to date.
LA = Low acid type. Harvest order numbers are more tentative with newer selections.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).

MSU Extension