Answers to Your Burning Postharvest Questions

Alicain Carlson, John Dole, Iftikhar Ahmad, ,North Carolina State University

Overview of TopicsOverview of Topics

General Postharvest Handling Harvest Time of Dayg

Effects and Control ofWater Quality Effects and Control of Ethylene

Species Evaluations: Celosia, Eremurus, Marigold SnapdragonMarigold, Snapdragon

General Postharvest Handling

Maximizing Postharvest LifeMaximizing Postharvest Life

There are many factorsThere are many factors that effect vase life of cut flowers: Pre‐harvest Harvest General Post‐harvest

QualityQuality

Poor quality declines fasterPoor quality declines faster

CultivarCultivar20 Water

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Developmental stageDevelopmental stage

Harvest at Harvest at optimum stage to 

i imaximize postharvest life Varies with market

– Direct to consumer– Retailers– Wholesalers

CarbohydratesCarbohydrates

Sugars fuel plantsg p Highest levels possible Effects:

– Open buds– Develop, maintain color

Sources:– Made by the leaves, stored in the stemsto ed t e ste

– Provided by the grower in a postharvest solution for cutsfor cuts

TemperatureTemperature

The warmer the The warmer the temperature:– Faster the respiration rate

– Faster bacteria grow

–More stems bend after storageStem bending in Gerbera after storage g

Temperature Drives RespirationTemperature Drives Respiration

For every 10oC increase in temperaturey p– Respiration rate doubles– One day vase life is lost

G t fi ld h t t ASAP Get field heat out ASAP Set cooler at 34 to 38oF

Close to 32oF is optimum for most speciesClose to 32 F is optimum for most species 34‐35oF or 34‐38oF is more practical

A few crops are cold sensitive– Oriental lilies, zinnias, celosia, tropicals– Cool gradually

Storage take home: Short and cold as possibleStorage take home:  Short and cold as possible

BotrytisBotrytis

Botrytis is the main problem on flowers and foliageBotrytis is the main problem on flowers and foliage Often present during production Becomes a major issue during storage and shippingBecomes a major issue during storage and shipping Try to control during production

Botrytis Development

Reducing Botrytis ProblemsReducing  Botrytis Problems

Prevent condensation on the flowers!

Keep cooler and production floors dryproduction floors dry

Give breathing room inGive breathing room in buckets

Avoid mechanical damage Work clean

K fl DRY Keep flowers DRY Keep floors dry

Cut Flower HandlingCut Flower Handling

Decline due to lackDecline due to lack of water uptake St bl k d b Stems blocked by:

–Microorganisms• Bacteria and fungi naturally on plants and in tap waterand in tap water

• Build up in buckets or vase solutions

Cut Flower HandlingCut Flower Handling

Air plugsp g– Form from air drawn into xylemWhen stems cut or– When stems cut or out of water, recut to remove plug

Physiological blockage

Eventual halt of water– Eventual halt of water uptake

– No way to overcome

Sanitation Best PracticesSanitation Best Practices

Use a cleaner with a residual effect

Regularly sanitize tables, tt h dcutters, choppers, and 

coolers Keep trash cans emptied p p

daily– For both botrytis and 

ethylene controlethylene control

Keep hose nozzles off the floor

Minimize Cross‐contaminationMinimize Cross ContaminationMinimize Cross Contamination

High‐polluting FlowersHigh polluting Flowers

Achillea Sunflower Mums Gerbera CelosiaCelosia   Dahlia ZinniaZinnia

Floral PreservativesFloral Preservatives

• Hydrating• Powders• Liquids

Hydrating• Holding• Vase

– Acidifier– Biocide Liquids

• Pills• Buckets

• Vase• Species specific

– Carbohydrate

• Jugs• Packets

specific

• Tea Bags

SummarySummary

Work clean and dryWork clean and dry Store and transport as cold as possible Use proper treatments

Harvest Time of Day

IntroductionIntroduction

M i h t• Morning harvest• Avoid heat• Higher water content• Rest of the day for processingRest of the day for processing

• Afternoon harvest• Increases carbohydrate content • Lower water contentLower water content• Decreases postharvest ethylene sensitivity

• Few studies on when to harvest cut stems for longer vase life

TreatmentsTreatments

• Harvested at three times of the day:

• Morning: 7 – 8 am• Noon: 12 – 1 pmNoon: 12  1 pm• Afternoon: 5 – 6 pm

• Postharvest performance was evaluated after either:

• No storage• No storage• 2 week storage (in water) at 35 ± 3°F

• CultivarsLi i th ‘ABC P l ’• Lisianthus ‘ABC Purple’

• Marigold ‘Double Eagle’ Gold Coin

• Zinnia ‘Deep Red’ Benary’s Giant

Vase LifeVase Life

18

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Storage Harvest time

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07-8 am 12-1 pm 5-6 pm 7-8 am 12-1 pm 5-6 pm

No storage 2 Week StorageNo storage 2 Week Storage

Storage and harvest time

SummarySummary

Aft h t b tt th i h t f• Afternoon harvest was better than morning or noon harvest for vase life extension

• Storage reduced vase life:• Lisianthus and marigold stems harvested in afternoon had smaller reduction than morning and noon harvests

• Carbohydrates were higher in afternoon or noon harvests of lisianthus and marigold, but no clear pattern was observed for zinnia

ConclusionConclusion

Li i th d i ldLisianthus and marigold stems should be harvested in afternoon for longest vase life

Water Quality

Water QualityWater Quality

Hi h lit t t t t k•High quality water promotes water uptake•EC levels vary with species

Target pH 3.0‐4.0

Initial pH 5.0‐7.0

Vase solution pHVase solution pH

Low pH optimum for almost all

20

Low pH optimum for almost all species Tap water usually has too high of pH

12

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03 6.2 7.6

l iVase solution pH

Mum ‘Naru Lavender’

Electrical conductivity (EC)

Zinnia ‘Benary’s Giant Scarlet’

Electrical conductivity (EC)

101112

Zinnia ‘Benary’s Giant Scarlet’

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3456

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Without Holding

0123

0 2 30 1 2 3 4Solution EC (dS/m)

Effects and Control of Ethylene

What is Ethylene?What is Ethylene?

Natural ripening hormoneNatural ripening hormoneProduced internally in flowers and externally by hother sources

• Fruits, veggies, flowers• Mechanical damage ( i d i f(triggers production of internal ethylene)

• Exhaust from combustion enginesengines

• Cigarette smoke, BBQs, fireplaces, space heaters

• Bacteria, yeast, and fungi, y , g• Air pollution 

Signs of Ethylene ExposureSigns of Ethylene Exposure

Leaf, flower and bud abscissionB d b ti

Hydrangea Lily

Bud abortionRapid flower senescencesenescenceEpinasty ‐ distinctive curling, drooping of 

Waxflower

g, p gleaves or bracts

Waxflower

Minimizing Ethylene EffectsMinimizing Ethylene Effects

LLower temperatureApplying anti‐ethylene agentsRemove sources

Anti‐ethylene AgentsAnti‐ethylene Agents

STS (AVB) STS  (AVB) • First solution to use immediately after harvest• Use only once on each batch of flowers• Protects for entire flower life• Protects for entire flower life• Registered in CA, WA, MN, TX• Safe disposal is a major issue

( h lbl ) 1‐MCP (Ethylbloc)• Non‐toxic gas treatment for coolers and trucks • Also available as sachets for packing boxesP i l 10 d• Protection lasts up to 10 days 

• No disposal problems ‐ short re‐entry period• Not as long lasting

Water

STS

1-MCP

Postharvest Evaluation of CutPostharvest Evaluation of Cut Celosia, Eremurus, Marigold, and S dSnapdragon

TreatmentsTreatments

Expt 1: Harvest stageExpt. 1: Harvest stageExpt. 2: Harvest proceduresExpt. 3: Ethylene sensitivityExpt 4: Storage methods &Expt. 4: Storage methods & durationExpt. 5: Grower treatments (Hydrators)Expt. 6: Wholesaler treatments (Hydrator + Holding preservatives, sucrose pulses)Expt 7: Retailer/FloristExpt. 7: Retailer/Florist treatments (Vase preservatives with or without floral foam)

Celosia SummaryCelosia Summary

• Harvest at:• Harvest at:• Early stage (with only <1 in. head size) for longest vase life (10‐14 days longer)

• Later stage (>2 in. head size) for bestLater stage (>2 in. head size) for best  visual quality

• Store only in water, preferably for not more than a weekmore than a week

• Place continuously in FL Clear Professional Flower Food, with or i h fwithout foam

• Celosia stems should not be:• Placed in hydrator and/or holding• Placed in hydrator  and/or holding solutions 

• Pulsed with sucrose

Eremurus SummaryEremurus Summary

• Harvest when no florets are open• Harvest when no florets are open

• Handle in water (‘Line Dance’) or dry (‘Tap Dance’) after harvest

• Store no more than one week• Treat with 0.2 mM STS for 4 h to overcome ethylene effect

• Pulse with 10% sucrose with 7 ppm KathonPulse with 10% sucrose with 7 ppm KathonCG, for 24 h

• Place continuously in commercial floral preservativespreservatives

• Stems should not be:• Placed in hydrator and holding solutions• Placed in floral foam

Marigold SummaryMarigold Summary

• Harvest when ≥ 50% petals have• Harvest when ≥ 50% petals have opened, for visual quality

• Stored dry, but not for more than 2 weeksweeks 

• Hydrate after harvest with either STS, FL Hydraflor 100, or Chrysal Professional 1 for (4h)

• Pulse with FL Hydraflor 100 (4h)Pulse with  FL Hydraflor 100 (4h) followed by FL Clear Professional Flower Food

• Place continuously in FL ClearPlace continuously in FL Clear Professional Flower Food with or without foam

• Stems should not be:Stems should not be:• Pulsed with sucrose• Placed in floral foam

Snapdragon SummarySnapdragon Summary

H t t• Harvest at:• Early stage (when lowermost floret starts expanding) for longer vase life

• Later stage (when 2‐3 florets have• Later stage (when 2‐3 florets have opened) for best visual quality

• Store dry for not more than 2 weeks• Store dry, for not more than 2 weeks• Hydrate with 0.2 mM STS (1 mL.L‐1 Chrysal AVB), or FL Hydraflor 100 for 4h

• Pulse with 5% sucrose for 24h• Pulse with 5% sucrose for 24h

• Place continuously in FL Clear Professional Fl F d Ch l Cl U i lFlower Food or Chrysal Clear Universal Flower Food without foam (foam reduced vase life)

Questions/Comments…..