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Got gas? Ethylene — the silent killer

Ethylene is Mother Nature’s ripening hormone for fruits, veggies, flowers and potted plants. It is used in distribution centers across the country to ripen bananas as part of their journey into supermarkets.

Maybe you’ve created a mini-ethylene chamber at home by placing an avocado into a paper bag with two apples. The ethylene produced by the apples speeds up the rate at which the avocado ripens so the guacamole is ready in time for the party.

This naturally occurring gas is colorless and odorless. Ethylene is non-toxic to animals and humans, but deadly — in minute amounts — to many cut flowers, blooming and green plants. The following symptoms of exposure are the only clues to what is causing the problems:

Shattering petals — delphinium, sweet peas, wax flower, leptospermum, rice flower.

Shriveled florets — freesia, Asiatic lilies, orchid buds, bouvardia.

Distorted bloom opening — carns, cut roses, potted roses.

Flopped or hanging flowers — hydrangea, spathiphyllum, orchids (cut or potted).

Bud abscission — Asiatic lilies, aggies, wax, phals and kalanchoes.

Weird discoloration —white dendrobium blooms turn chartreuse-y green, red carnations turn bluish.

Transparent florets —alstroemeria, freesia, sweet peas.

Leaf abscission — leaf drop in roses, tree fern, azaleas, Ficus benjimina, Graveillea.

Leaf yellowing — potted mini roses, perlargonium, campanula, begonia, dicentra.

The degree of damage is dependent on many variables — length of exposure time, amount of ethylene gas, the age of exposed flowers and temperature. Because damage is irreversible, it is important to treat sensitive flowers immediately after harvest or during transit from Miami to DC.

Stay tuned for more details. In the November issue of The Produce News, we continue this ethylene discussion with ways to circumvent the problem, provide photos to identify ethylene damage on different species, include a “sensitive” list of susceptible flowers and plants, and share insights used to troubleshoot and report ethylene problems.

Gay Smith is technical consulting manager at Chrysal Americas. She can be contacted at