Frequently Asked Questions

 

Botrytis spores are everywhere.

There are 4 stages of botrytis development
1. Spores on Surface (not visible with the eye)
2. Spores attached (not visible with the eye)
3. Spores germinated (needs high humidity) (first spots visible with the eye)
4. Tissue invasion (visible with the eye)

No. Botrytis is one of a range of fungi and other microorganisms (including yeasts and bacteria) that can cause flowers  and foliage rots. These include the fungi Aspergillus spp. (black mould), Rhizopus spp., Penicillium spp. (blue-green mould), Alternaria spp., Cladosporium spp., Colletotrichum spp. (ripe rot), and Greeneria uvicola (bitter rot).

Unfavorable conditions stimulate infection.

    – Frequent temperature changes >>> Condensation

     – High relative  humidity

Botrytis spores are almost always present in farms, greenhouses and packing storage etc and are produced on many different plant species. Spores from decaying floral parts or leaf material within bunches or from bunch remnants in the greenhouse are more likely to cause bunch rots than spores from sources further away. These spores spread in air currents, by rain splash and by insect carriers (vectors) such as light brown apple moth (LBAM) caterpillars. Insects aid the movement of spores within and between bunches.

Basically every cut-flowers, cut-foliage and pot-plant can become infected with the fungus (botrytis).

During growing is the first opportunity for latent infection of flowers, latent infection may occur at any time after that. The frequency of latent infection can vary during a growing season and between seasons and sites, and it may increase after harvest and during transport.

Unfavorable conditions stimulate infection.

    – Frequent temperature changes >>> Condensation

     – High relative  humidity

Wounding increases the risk of botrytis infection. Examples of wounding include loose flowers stalks (pedicels) and split leaf, plus damage from insects, birds, mildew infection, frost, rain, hail, sunburn and machinery.

Temperature determines how fast infection occurs.
The optimum temperature for spore germination is 18–21 Celsius , although some spores still germinate at temperatures below 10 celsius or above 30 Celsius .

A film of free water is essential for spore germination, with longer wetness periods needed to achieve the same level of infection at sub-optimum temperatures. Surface moisture can be created by rain, dew, mist or fog while high humidity may lead to sufficient condensation within the crevices of some tissues such as flowers. Temperature, relative humidity and wind speed determine the duration of surface moisture, and as a result, the level of infection.

Warm to hot and dry weather through summer and autumn can prevent the expression of latent infections in cut-flowers and the development of botrytis and bunch rots.

The proportion of botrytis developing rots after latent infection appears to be correlated to high relative humidity, and possibly high soil water content.

At low humidity spores do not germinate

Fungicide sprays are an effective means for preventing flowerinfection.

Which factors affecting quality loss pre-harvest
– Genetics
– Cultivation Conditions
– Water loss
– Temperature
– Ethylene
– Bacteria
– Botrytis

Solution to Botrytis

Humidity < 70% ? prevents spore germination

    – More problems when flowers are more mature (open )

     – Low temperature slows down fungal growth

     – Fungicides pre-and post harvest >> but creates resistance

     – Losse packaging

     – Sufficient air movement ( lowers humidity around the flower )

     – Cultivar differences

Poor temperature control.

How to transport flowers successfully by Air or  Sea ?

Select suitable species /cultivars

Pay attention to harvest stage

Use proper pre-treatment ( and rehydration treatments )

Use lowest temperature as possible !!!!

Adapt packaging /stacking to allow sufficient air movement

Built up a database to establish relations between species,cultivation and climate factors and final outcome of shipments.

Humidity < 70% ? prevents spore germination

    – More problems when flowers are more mature (open )

     – Low temperature slows down fungal growth

     – Fungicides pre-and post harvest >> but creates resistance

     – Losse packaging

     – Sufficient air movement ( lowers humidity around the flower )

     – Cultivar differences

Bacteria in water and stem restrict water uptake.

Bactericides been add to the water ( wrong and old )

    – Aluminum sulphate.

     – Chloramine-T

     – Hydroxyquinoline sulphate

Solution to vascular blockage :

For sensitive flowers, use proper bactericides for pre-treatment during harvest, packaging,transport and in vase life. Recut flower stems to remove air/bacteria filled vessels. Use detergents ( surfactants )to facilitate water uptake.Use the right flower-food.

Rapid and continuous cooling is important

Slows down respiration ( breathing ), Slows down aging/senescence, Slows down botrytis growth, Slows down bacterial growth, Suppressed ethylene production and sensitivity

Most flowers can be stored at near ZERO temperatures

     – Some exceptions ( orchids, lilies ,anthurium …)

– Water loss

– Temperature

– Ethylene

– Bacteria

– Botrytis

Fertilizer ( nitrogen ) levels ( vase)

Humidity ( botrytis)

Day/night temperatures

Water management

Shading regime

Conditions aimed at maximum production may interfere with the goal of maximum post harvest quality

-Vase life

-Botrytis sensitivity

-Flower opening

-Vascular blockage

-Ethylene sensitivity

Best way to improve quality is selection

Vase life

Desiccation ( water loss)

Lack of flower opening

leaf yellowing / blackening or wilting

Premature senescence /aging

Fungal /mold attack

Due to the change from air transport to container transport. Quality is increasingly becoming an item.

Flowers have to be resistant to long term storage at relatively low temperatures

Needs superior control of water loss ( desiccation)

Needs superior control of botrytis  infection.

Temperature control is excellent.

Pro’s:

Relatively cheap

Lots of capacity

Excellent climate control ( temp, RH, Atmosphere )

    – Also in the case of delays !!

    – Closed cold chain from fram to end user.

More sustainable

Experience with many tropical fruits and,increasingly with flowers/potted plants

Con’s:

Takes long time

Quality of end product often disappointing in past

4 day shipment , vase life determination under optimal conditions:

Product Vase life reduction

Gerbera                        33%

Rose                              29%

Carnation                    15%

Tulip                             47%

Chrysanthemum       25%

Lily                               33%

Iris                               46%

Freesia                        27%

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Average                    32%