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Stop the Rot in Flower ShipmentsC. W. Fischer, Jr. and J. R. Keller *

Cornell University, Ithaca, N. Y.

Rot in flower shipments can be prevented by the use of brominated activated charcoal suspended over the flowers. Flowerspacked in tight enclosures for ease and cheapness of handling develop a high humidity whichfavors rot. It is usually impossible to lower the temperature of flowers sufficiently toovercome rot in shipment. This combinationof high humidity and favorable temperatureprovides ideal conditions for the growth offungi and the subsequent damage to flowers.

Similar problems occur in handling fruitsand vegetables. Rotting of berries and someof the fleshy vegetables is common.

Such molding is not readily controlledon flowers, probably because blooms may beeasily damaged or discolored by the use ofconventional fungicides. Remedial measuressuggested at present consist of sanitation,and temperature and humidity control. Obviously, there are many uncertainties in sucha program.

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Petri plate enclosure showing agar (a),Plasteline seal (b), fungus colony (c)charcoal (d).

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A new approach to the problem was suggested by some studies made in connectionwith the control of ethylene production byplant material. You will recall that theproduct known as brominated activated charcoal (referred to as BAC) seemed especiallyeffective in neutralizing the effects ofethylene gas produced by the plant material.At the same time, it appeared In some instances that the secondary molding often accompanying ethylene injury was greatly reducedwhen the charcoal was used. This was especially apparent in trials with orchidflowers. BAC stopped the injury due to self-produced ethylene and also prevented moldinvasion of the flower.

To further investigate these aspects ofmold control, pure cultures of fungi wereconfined with BAC. The mere presence of thecharcoal caused considerable inhibition ofthe fungus colony. Further, spores of Botry-tis, when "dusted" on agar in culture plates,were killed by the action of the brominated

charcoal. These experiments indicated clearly that BAC actually had the fungicidalproperties.

Carnation flowers, sprayed with Botry-tis spores, were used in the first trialswith plant materials. Flowers were enclosedunder bell jars and BAC, pasted between layers of Kraft paper with Carters Rubber Cement, was suspended on chicken wire over theflowers. We observed that flowers so treated remained free of mold after several days'confinement at room temperature. Flowers enclosed without charcoal or with plain activated charcoal lacking the bromine decomposedrapidly in a comparable period due to theaction of mold. Apparently bromine from thecharcoal was released slowly. This gas acteddirectly as a fungicide in a fumigation action.A solution of bromine water introduced into abell jar enclosure with carnation flowers gave-control of the rotting but was harmful to theflowers.

Pompon chrysanthemums were next inoculated with a suspension of Ascochyta ray blightfungus. This organism causes much damage toflowers during shipment from the South.Again, the charcoal was applied by suspensionabove the inoculated plant material and againthe material gave complete control of rotting,

aic

Enclosure of flowers showing wire neeting (a)for support of BAC pasted between Kraftpaper (b) inside bell Jar (c). .^

* The authors express their thanks to Drs. Kenneth Post and L. H. MacDaniels, Department ofFloriculture; and to Dr. A. W. Dlmock, Department of Plant Pathology, for their indispensable cooperation in this program.

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while untreated flowers broke down rapidly inconfinement.

Another trial was made with gladiolusflowers inoculated with Botrytis. BAC seemedeffective in controlling the growth of thefungus in this instance, too.

In an effort to simulate practical shipping conditions BAC was applied to smallboxes containing carnation flowers that hadbeen previously inoculated with the fungussuspension. The flowers were first wrappedin waxed paper, next in the paper containingthe BAC. They were then placed in a waxedflorists' cut flower box and put at 50°F fortwo weeks. At the end of this period, thetreated flowers showed absolutely no sign ofmold Invasion, while comparable flowers packed without the BAC were completely worthlessbecause of mold damage.

A preliminary trial with the materialwas made on raspberries and strawberries byDr. R. M. Smock, of the Cornell Pomology Department. Dr. Smock observed that BAC merelysuspended above quart veneer containers ofthese fruits, which had been placed in largermetal cans, definitely reduced molding. Atrial in our laboratory indicated that molding of tomatoes was reduced by use of theBAC.

Thus, the brominated charcoal used withplant materials in confinement appeared tocontrol, or even kill, mold on a wide varietyof products. Essentially, the treatment seemed to affect a sterilization of the plantmaterials.

The inevitable difficulties naturallyenough have appeared. Complications observedwere as follows. The charcoal had to be heldin rather close proximity to the material tobe protected in order to be effective. Whenthe charcoal was merely spread on the bottomof an enclosure rather than suspended overthe flowers, It was far less effective in the

Appearance of Alternaria colonies followingconfinement with BAC (A) and ordinary activated charcoal (B). (c) plate served ascontrol.

Appearance of carnation flowers sprayed witha Botrytis suspension following enclosureunder bell Jars with (left to right) BAC,bromine water, no amendment.

control of molding. Secondly, the treatedcharcoal was actually toxic to flowers if itcame in direct contact. If the flowers werewet, BAC also seemed toxic, not because ofdirect contact, but rather, we think, becausethe bromine, liberated from the charcoal, apparently dissolved in the water on the surface of the flowers and formed the strong andtoxic hydrobromic acid. Finally, in atmospheres of high relative humidity (above about90 per cent), the charcoal absorbed largeamounts of water, became noticeably wet andlost effectiveness. However, this actionwas sufficiently slow so that the BAC seemedto accomplish most of the protective fumigation.

Thus, despite the difficulties involved,the brominated activated charcoal seems to

Appearance of pompon chrysanthemum flowerssprayed with an Ascochyta suspension following enclosure under a bell jar withBAC (L). Control (R). „—,_, , _ Q

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Stock plants start and produce muchbetter at 70°F minimum than at lower temperatures. This, coupled with a good supply ofwater, gives optimum cutting production.

The real problem with plants, after propagating, begins to develop in late September.Shoestring bracts, curled down leaves, deadareas in the leaves, leaf fall, and unevengrowth or even death of plants are the symptoms '. The 1949 crop gave us much concernbut last year we were even more Impressed.The trouble has been attributed to such

things as potash or phosphorus deficiency,2,4-D injury, low temperature, low or highmoisture, and other causes.

Practically all such injuries have beenassociated with root rot. Dlmock has been

following this trouble for the past two yearsand it appears to be a complex situation.Trouble is apparently initiated in the latesummer in some cases but in the fall the

plants tend to grow out of it. Even so, theresulting plant has been seriously injuredand does not become the desirable subject itshould be. In other cases, plants look gooduntil early December, then begin to yellowand drop leaves, becoming completely defoliated by Christmas.

At present it looks like poinsettia growers should sterilize all soil, pots, benchesand other equipment used. Soils low in fertility should be used to avoid soluble saltinjury.

Prospects are for continued increase inpoinsettia demand with it the most popularChristmas plant. If greater satisfactioncould be given the customer, the demand wouldincrease further.

Hydrangeas - Good

Hydrangeas will be good for Easter andshould come sufficiently early if they havebeen properly stored. The fall temperaturewas optimum for bud set and development sothat they should force easily at 60°F fromthe start.

Perhaps some buds set too early in manyareas. Early pinching promoted this.

Azaleas - Normal

Azaleas forced fairly well for Christmasand will continue well during the year. Moregrowers are becoming equipped to store plantsat low temperature for early forcing and tohold plants in salable condition for longperiods. 40°F storage does both.

Begonias - Few

Begonias and cyclamen continue to be inlesser demand each year. Prospects are forno revival of these crops because of thereduced demand for them.

Tuberous rooted begonias may find a placefor cut flower production In winter in easternUnited States now that we can grow them wellat 60°F with long days. Lewis (Cornell) hasdemonstrated real possibilities for this asa corsage flower. Perhaps some of the multi-floras could be used as potted plants.

♦ This information was compiled with theassistance and Information supplied byGeorge Thompson, Agricultural Economics;A. W. Dimock, Plant Pathology; W. E. Blau-velt, Entomology; and Arthur Bing, Floriculture.

-- Kenneth Post

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Appearance of gladioli flowers sprayed witha Botrytis suspension following enclosureunder a bell jar with BAC (L). Control (R).

have promise as a protectant for plant material, not only in its role as a neutralizing agent for ethylene, but also because ofits fungicidal property. Should this methodof fungus control prove practical, It may bethat different absorbing media other thancharcoal or different chemicals other thanbromine will prove more adaptable for use.However, the use of brominated activatedcharcoal is of considerable Interest and hasapplication to commercial conditions.

Your Editor,