2013 Iron Butt Rally, Leg 1 Cranberry Township, PA, to Cranberry
Frost Tolerances UMass Cranberry Station of Cranberry Fruit · Frost Tolerances UMass Cranberry...
Transcript of Frost Tolerances UMass Cranberry Station of Cranberry Fruit · Frost Tolerances UMass Cranberry...
FrostTolerancesUMassCranberryStation ofCranberryFruit
Inthelatesummerandintothefall,cranberryfrosttoleranceisestimatedbasedonthedevelopmentalstageoftheplantsandthecolorofthefruit.Theseestimatesarebasedonobservationsandcontrolledtemperatureexperimentation.Thephotosinthisfactsheetshowthestagesandfruitcolorassociatedwithvariousdegreesofcoldtolerance.Observationsshouldbemadebylookingintothevinecanopy;donotseparatethevinesorremovethefruitoruprights.
Summer–30°Ftolerance
Flowers,pinheads,andsmallberries,Howesshown.
Pinheadsandsizinggreenfruit,Stevensshown.
Whitetolightblushfruit–28°FtoleranceNote:fruitmayhaveayellowishappearance
EarlyBlack Howes BenLearStevens
Deepblushonexposedfruitsurface–27°Ftolerance
EarlyBlack
Howes
BenLear
Note:approaching26°Ftolerance
Stevens
Deepblushoverentirefruit–26°Ftolerance
EarlyBlack
Howes
BenLear
Stevens
Red–25°Ftolerance
EarlyBlack
Howes
BenLear
Stevens
Coldhardinessofcranberryfruit. Newlyformedgreenfruitaresensitivetotemperaturesbelow30°F.Late in thesummer, the fruit turnwhiteandthendevelopa faintblushontheexposedsurfaces.Thistransitionisassociatedwithincreasedhardiness;thefruitwillnowtolerate28°F.Asthefruitcontinuetocolor,hardinessincreasesandthefruitcantolerateincreasinglylowertemperatures(seethetablebelow).For all varieties studied, tolerance is the same for each color through the red stage (25°F tolerance).However,asthefruitreachdeepredandmaroonstages,theirtolerancesdifferbyvarietyandmaturity.
For each of the varieties, maximum cold hardiness (tolerance) was associated with full mature color(marooninthetablebelow)butasnoted,theactualtolerancetemperaturediffered.Atfullmaturity,95%survivalaftershort(1-2hr)exposurestotemperatureaslowas18°FhasbeenobservedinEarlyBlack,Howes,andStevens,BUTnotconsistentlyfromyeartoyear.BenLearneversurvivedtemperaturesbelow24°F. In someyears, over-ripe fruit (2weeks aftermaximumcolor) showed loss of tolerance,with allvarietiesdamagedby22°Forlower.Thetoleranceslistedinthetablebelowandinthephotocaptionsreflectaconservativerepresentationoftheavailableresearchdata.
The fruit tolerancetable isbasedoncolordevelopment,which isusedasavisualguidetoripening,achemicalandphysiologicalprocess. It isnotthecolorthatconfers increasedtolerancetofreezing,butrathertheinternalchemicalandphysiologicalchangesintheberriesthataccompanytheincreaseincolor.Asnotedonpage1,colorshouldbeassessedinthefieldbylookingdownatthevines,sincethelowestfruitburied in thecanopyoften remainwhite late into the season.Thoseberriesare likely somewhatprotected by the vine canopy and the internal chemical/physiological changes that occur even in theabsenceofcolordevelopment.
FrostTolerancesofCranberryFruit
Maturitylevel*
EarlyBlack
Howes
Stevens
BenLearandnewhybrids
Green 30°F 30°F 30°F 30°F
Whitetolightblush 28°F 28°F 28°F 28°FDeepblushexposedsurface 27°F 27°F 27°F 27°F
Deepblush 26°F 26°F 26°F 26°F
Red 25°F 25°F 25°F 25°F
Darkred 24°F 24°F
Deepred 23°F 23°F 23°F 24°F
Maroon(1-2wk.later) 23°F 23-20°F 22°F 24°F
Lateseason(endOct.) 23°F 23°F** 23°F** 24°F
*Notethateachvarietywillreachagivenstageonadifferentdate.Generally,EarlyBlack,BenLear,andmanyofthenewesthybridswillcolorearlyandHowes,Stevens,andsomenewhybridswillcolorlater.**lossoftolerancewhenover-ripe
DarkRed–24°FtoleranceEarlyBlackandHowesonly
EarlyBlack
Howes
DeepRed–Tolerancevariesbyvariety
EarlyBlack23°F
Howes23°F
BenLear24°F
Stevens23°F
Maroon–Tolerancevariesbyvariety1-2weeksafterDeepRed
EarlyBlack23°F
Howes23°F.
Toaslowas20°Finsomeyears;returnto23°Ftwo
weekslater
BenLear24°F(neverlower)
Stevens22°F
returnto23°Fin1-2weeks.
May2019.UMassAmherstCranberryStation.E.Wareham,MA02538http://ag.umass.edu/cranberryAuthor/Photography:CarolynDeMoranvilleAdditionalphotography:KrystalDeMoranville
Thismaterial is based uponwork supported by theNational Institute ofFoodandAgriculture,U.S.DepartmentofAgriculture, theMassachusettsAgricultural Experiment Station and the UMass Cranberry Station underProject No. MAS00999. Additional funding provided by the Cape CodCranberry Growers Association. The University of Massachusetts is anAffirmativeAction/EqualOpportunityInstitution.