“Preemptive measures are vital to keeping flowers and sales healthy.”

Working in the floral industry, you need a full complement of flowers in the best condition possible; flowers with diseases can ruin your business quickly. Here are some of the top flower maladies to watch for and ways to keep them from impacting your floral supply.


Botrytis is considered one of the biggest blights in the floral industry, especially postharvest, where it survives easily – even in the cold, moist conditions of a flower cooler. Often referred to as gray mold, this fungus (Botrytis cinerea) produces brown spots that are often followed by abundant fuzzy gray structures that produce spores on the surfaces of infected plant tissues. These spots grow in size and result in soft, mushy flowers that are often unsellable, and the fungus can cause significant losses to those in the business. Flowers often show no symptoms when they are packed at the farm, but the disease develops during the shipping process, leaving the recipients of the flowers unhappy.

Botrytis spores are everywhere, including flower fields and greenhouses, remaining dormant until conditions are favorable for germination. The disease is most prevalent under moist/humid conditions, which promote spore germination and infection of flower tissue; petals that have physical damage from rough handling may be particularly susceptible. In addition, certain types of flowers may be more susceptible than others.

Botrytis can be kept at bay by proper cold-chain management and controlling the humidity – keeping it between 75 percent and 85 percent. Below 75 percent causes water loss, and above 85 percent promotes condensation; spores will germinate in four to eight hours if free water is present. In addition, temperature fluctuations in the cold chain, from warm to cold and vice versa, promote condensation and stress the flowers, resulting in infection. Stems are always best when stored at 34 F to 37 F.
Unfortunately, Botrytis is contagious. Infected flowers should be removed from inventory immediately and discarded.
Good sanitation practices are critical to control Botrytis; spore loads can accumulate in plant debris, processing areas and flower coolers. Plant debris from processing should be disposed of routinely, and coolers, drains, floors, walls and diffusing fans should be cleaned on a quarterly basis with proper floral cleaner to reduce spore load.

Black Edges on Roses

One of the most important times of the year for florists is Valentine’s Day, and roses are obviously the best-sellers on that special day. That’s why knowing how to keep black edges on red roses from appearing is vital to success on that day.
Black edging on red roses happens due to light and temperature fluctuations, as well as high UV light during production. The pigments in red roses are sensitive to sunburn, so spending too much time under the hot sun can cause black edges. Additionally, big changes in temperature can play havoc with pigments.
The best way to control this is to control temperature fluctuations before harvest, so that means working with your suppliers to ensure that the flowers you receive aren’t overexposed to the sun.

Ethylene-related Issues

Ethylene is a gaseous plant hormone that is problematic to flowers. In fact, industry data shows that ethylene is responsible for approximately 30 percent of postharvest flower waste. It causes leaf yellowing, petal drop, irregular opening and premature death, among many other maladies.
One problem with ethylene is that it’s practically everywhere in a retail setting. Ripening produce – fruits and vegetables – and older flowers generate ethylene, which can affect surrounding flowers; therefore, flowers should never be stored near fruits and vegetables. There’s also a presence of atmospheric ethylene in coolers and shipping containers. Finally, exhaust from gas/diesel-powered vehicles, including forklifts, can produce ethylene, causing a potential risk around loading docks/areas.
The most effective solution is to treat flowers with ethylene action inhibitors, and it’s important to make sure your suppliers use one, too, because this is an integral factor in protecting the flowers you sell.
Temperature also plays a crucial role; lower temperatures can minimize flowers’ sensitivity to ethylene. That’s why maintaining the cold chain is critical at all levels of flower post-harvest production and distribution.

Physical Damage

Although not a disease itself, physical damage can lead to stress and encourage the development of diseases, such as Botrytis. However, physical damage may not show on the flowers when the damage is done; it could take a couple of days, which means that the damage might not appear until flowers reach the consumer’s home.
Some ways physical damage is caused include the mishandling of boxes – throwing, carrying upside down or incorrectly, etc., all of which tend to create petal and leaf creases, giving bacterial/fungal growth a foothold. Other causes of physical damage can be handling and cutting flowers incorrectly; placing them in warm water; touching or rubbing the blooms; packing the flowers incorrectly or in warm boxes; dirty cutting tools, tabletops and coolers; and over-packing boxes, which causes physical damage along with a reduction in air exchange.
Like ethylene damage, physical damage stresses flowers, and both can lead to the development of Botrytis. So take the time to work with your suppliers and condition your flowers correctly, and your profits will bloom in no time at all.

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Floralife, a division of Smithers-Oasis Company, is a worldwide leader in postharvest flower care and handling. Inventors of the first cut flower food in 1938, Floralife has developed products to feed, hydrate, nourish and protect cut flowers at every level in the distribution chain. To learn more about cut flower care and handling, visit www.floralife.com.