Keeping Streptocarpus Vegetative Using Ethephon

Potted streptocarpus are great flowering plants for consumers. Relatively easy to maintain, streptocarpus flourish on a windowsill inside a house or outside in the summer in a shady location. Ladyslippers streptocarpus is a newer series that flowers profusely in a range of colors and patterns. While streptocarpus have traditionally been propagated sexually from F1 hybrid seed, the Ladyslippers series is vegetatively propagated using tissue culture (Figure 1). One challenge with these tissue-cultured plants is that flowering can begin when plants are small and not ready for sale.

 

 

Streptocarpus are not photoperiodic — that is, flowering is not controlled by daylength. While this may be good for growers who don’t have night-interruption lighting or black cloth, it can be more of a challenge to control flowering for crop scheduling. When streptocarpus start to flower prematurely, flowers are usually removed by hand. This is done to: 1) increase the vegetative growth and bulk-up plants to a size suitable for sale; and 2) minimize dead flowers and flower stalks on the plant, which can both harbor disease and appear unsightly.

Ethephon is an ethylene-generating plant growth regulator with several uses in commercial greenhouse crop production. It is commonly used to produce compact plants and to increase branching. However, another popular use of ethephon is to abort flowers and keep plants in a vegetative state. We wanted to evaluate the effectiveness of keeping Ladyslipper streptocarpus plants vegetative using ethephon sprays.

Calculating Time To Flower, Number Of Inflorescences And Growth Index

We planted rooted liners (96-cell) of ‘Ladyslipper Blue Halo,’ ‘Ladyslipper Deep Blue’ and ‘Ladyslipper Red Rose’ streptocarpus into 6-inch round containers filled with a commercial soilless substrate. Plants were grown in a glass-glazed greenhouse with fog cooling, radiant hot-water heating and retractable shade curtains controlled by an environmental computer.

The day and night greenhouse air temperature set points were 73°F and 66°F, respectively, with supplemental lighting provided between 6 a.m. and 10 p.m., when ambient light was low. Plants were irrigated as necessary with water supplemented with water-soluble fertilizer providing 150 ppm nitrogen (N).

Two weeks after planting, we began our ethephon treatments. Foliar spray applications of solutions containing water (control) or 125, 250, 500 or 1000 ppm ethephon (Collate; Fine Americas, Inc.) were applied at a rate of 2 quarts per 100 ft2. Sprays were applied either two weeks after planting (a single application) or two and four weeks after planting (two applications).

The time to flower from planting was calculated when the first flower in a plant opened, and the total number of inflorescences each plant produced was recorded throughout the study. Thirteen weeks after transplanting, the height of the plant from the surface of the substrate to the tallest growing point, and the widths of the plant at the widest point and 90 degrees from the widest point, were recorded. These measurements were used to calculate the Growth Index, an integrated measurement of plant size.

Ethephon Delayed Flowering Without Suppressing Growth

Ethephon delayed flower for all three streptocarpus cultivars (Figure 2), but the effectiveness varied among cultivars with concentration and number of applications. A single application of 500 or 1000 ppm ethephon delayed flowering of ‘Ladyslipper Blue Halo’ by 19 or 26 days, respectively, compared to untreated plants, while 250 to 1000 ppm ethephon applied twice delayed flowering by 20 to 40 days (Figure 3).

Alternatively, a single ethephon application of 125 to 1000 ppm had no effect on the time to flower of ‘Ladyslipper Red Rose.’ Flowering was only delayed when 1000 ppm was applied twice.

Ethephon affected the number of inflorescences differently for all three cultivars of streptocarpus in this experiment. Compared to the untreated control plants, applying 125 to 1000 ppm ethephon once or twice reduced the number of inflorescences of ‘Ladyslipper Blue Halo’ by 24 to 87 percent, whereas two applications of 1000 ppm ethephon reduced the number of inflorescences of ‘Ladyslipper Deep Blue’ by 39 percent. Ethephon did not affect the number of inflorescences compared to untreated ‘Ladyslipper Red Rose’ plants. Although the total number of inflorescences produced for ‘Ladyslipper Blue Halo’ and ‘Ladyslipper Deep Red’ during the study was reduced with ethephon application, this did not reduce the marketability of the plants.

The study was concluded when the size of the plant was large enough to be considered marketable and, at that point, all the plants (regardless of ethephon treatments) had an appropriate amount of flowers to be considered marketable.

The Growth Index of streptocarpus cultivars was minimally affected by ethephon applications. For example, one or two applications of 500 or 1000 ppm ethephon to ‘Ladyslipper Blue Halo’ resulted in plants that had a slightly smaller Growth Index compared to untreated plants. However, although the Growth Index was reduced in response to some ethephon applications, these plants were still considered commercially acceptable and marketable, even with the smaller size. Ethephon did not affect the Growth Index of the other streptocarpus cultivars.

In our study, we did not observe any phytotoxicity with the ethephon concentrations and number of applications with the cultivars in this study. Epinasty (the downward curling of a leaf) or cupping of leaves may result from an over-application of ethephon, but neither were evident on the foliage of strepotocarpus in our work.

Conclusions And Future Research

Ethephon sprays are useful tools in delaying the flowering of Ladyslippers streptocarpus without negatively impacting plant size or marketability at maturity. While we did not use streptocarpus cultivars from other series in this work, it may be worth trialing. For instance, the seed-propagated Cape Cool streptocarpus is a great series for 4-inch containers. However, this series also starts flowering before the vegetative growth has filled in the pots, so ethephon sprays may be useful for this crop, as well.

There was some variation in response to ethephon among the different cultivars used in this work, and there could be different responses with other streptocarpus series. Producers should always perform in-house trials to determine what concentrations will work best for the cultivars they are growing.

Topics: ,

Leave a Reply

More From Crop Inputs...

May 22, 2015

Nexus Greenhouses Is Optimistic For Expansion Into New Markets

Cheryl Longtin and Mike Porter, who own Nexus Corporation, say they were excited to attend the grand opening of Gotham Greens’ new structure atop the new Whole Foods grocery store in the Gowanus neighborhood in Brooklyn, N.Y., when it opened in December 2013. The project is just one example of some of the new and expanding markets that Nexus Corporation has expanded into over the past few years. Jeff Warschauer, vice president of sales for Nexus, says the company has enjoyed getting to know and working with the founders of Gotham Greens, Viraj Puri and Eric Haley, and Jennifer Nelkin Frymark, the chief agriculture officer, on their innovative approach to business. “They are very excited and work hard internally – just great people,” he says. “From our perspective, it’s great to see that excitement and vision. The employees there are happy and there’s no turnover; they’re only adding new people […]

Read More
Farwest2015

May 20, 2015

2015 Farwest Show Announces Second Annual Equipment Innovation Day

The second annual Equipment Innovation Day will be Tuesday, Aug. 25, prior to the 2015 Farwest show, which will be August 27-29 in Portland, Ore. Equipment Innovation Day, which was enthusiastically received in 2014, offers a real-time opportunity to see new heavy and automated nursery equipment in action. The demonstrations take place in manufacturing and nursery settings, adding value to the showcase. Attendees will be able to talk with participating manufacturers and learn first-hand from innovative growers who use the equipment in daily operations. The day-long event will be held at the main manufacturing plant of GK Machines, Inc., Donald, Ore. Further demonstrations of field equipment will take place at the nearby nursery of A&R Spada Farms, LLC. Bus travel to and from the event is planned, starting at and returning to the Oregon Convention Center. Attendees are welcome to provide their own travel to and from the site. Preregistration is required. The cost […]

Read More
Bee On Flower

May 20, 2015

White House Task Force Releases Pollinator Health Strategy

An interagency Pollinator Health Task Force commissioned by President Obama released its “Strategy to Promote the Health of Honey Bees and Other Pollinators” on May 19. The strategy, released in accordance with the Presidential Memorandum issued last June, is accompanied by a Pollinator Research Action Plan, which outlines needs and priority actions to better understand pollinator losses and improve pollinator health. The recommended actions will be supported by a coordination of existing federal research efforts and accompanied by a request to Congress for additional resources to respond to losses in pollinator populations. Pages 47 through 52 specifically address pesticides and pollinators. The report calls out plant production, native plants, mosquito control and all urban uses in its Pollinator Action Plan. RISE (Responsible Industry for a Sound Environment) says it supports the goals of improving pollinator health and habitat contained in the White House Pollinator Task Force’s release of its National […]

Read More
Latest Stories
Bee On Flower

May 20, 2015

White House Task Force Releases Pollinator Health Strat…

An interagency Pollinator Health Task Force commissioned by President Obama released its “Strategy to Promote the Health of Honey Bees and Other Pollinators” on May 19. The strategy, released in accordance with the Presidential Memorandum issued last June, is accompanied by a Pollinator Research Action Plan, which outlines needs and priority actions to better understand pollinator losses and improve pollinator health. The recommended actions will be supported by a coordination of existing federal research efforts and accompanied by a request to Congress for additional resources to respond to losses in pollinator populations. Pages 47 through 52 specifically address pesticides and pollinators. The report calls out plant production, native plants, mosquito control and all urban uses in its Pollinator Action Plan. RISE (Responsible Industry for a Sound Environment) says it supports the goals of improving pollinator health and habitat contained in the White House Pollinator Task Force’s release of its National […]

Read More
r3bv2 disease

May 20, 2015

SAF And AmericanHort Ask Government To Take Ralstonia O…

The Society of American Florists (SAF) and AmericanHort want Ralstonia solanacearum, Race 3, Biovar 2 (R3Bv2) taken off a list of animal and plant diseases that the federal government has determined could be misused as terrorist weapons. SAF and AmericanHort submitted formal comments together on the horticulture industry’s science-backed position on the matter. According to Lin Schmale, SAF’s senior director of government relations, extensive research has proven R3Bv2 does not belong on the government’s list of animal and plant diseases that can be misused as terrorist weapons. Every two years, USDA’s Animal and Plant Health Inspection Service (APHIS) requests a public review of the Select Agent list, asking for comments on whether plant or animal diseases should be taken off the current list or added to it. In the floral industry, R3Bv2 can have a devastating impact on geranium (pelargonium) crops, Schmale says, and both the potato and tomato industries also could be adversely affected by introduction […]

Read More
Two-spotted spider mites, adults and eggs

May 18, 2015

Beware Of Spider Mites In Bougainvillea And Mandevilla …

Greenhouse growers need to scout for spider mites on bougainvillea and mandevilla and use appropriate treatments that minimize pesticide resistance.

Read More
CrownBees_Blue-Orchard-Bee-Female_Artz

May 14, 2015

Pollinator Health 2015: What’s Next For Horticult…

The news on pollinators and neonicotinoids continues to fluctuate between good and bad. Research and outreach efforts backed by the Bee and Pollinator Stewardship Initiative help move the industry in a positive direction.

Read More
empress-intrinsic-brand-fungicide

May 13, 2015

BASF’s Empress Intrinsic Fungicide Is Approved Fo…

BASF’s Empress Intrinsic brand fungicide received supplemental labeling, providing California growers with an effective drench fungicide for disease control and plant health. The supplemental labeling is for use on herbaceous and woody plants in greenhouse, nursery container and field production in California. Empress Intrinsic fungicide provides protection against the four major root and crown disease pathogens: fusarium, phytophthora, pythium and rhizoctonia. Research shows Intrinsic fungicides control the broadest range of ornamental diseases while improving plant resilience to quality and reducing stresses that commonly occur during commercial production, handling and transportation. “More and more growers across the country are discovering the benefits of Empress Intrinisic brand fungicide treatments at propagation for rooted plugs, cuttings and seedlings, and in drench applications on transplants during the production cycle to protect against the major root diseases,“ says Joe Lara, senior product manager for BASF ornamentals. “A BASF fungicide program utilizing Pageant Intrinsic and Empress Intrinsic […]

Read More
Green Mum Basket

April 21, 2015

Growers Face Dilemma In Managing Plant Growth

Whether you’re applying plant growth regulators, manually pinching plants or using automated trimming, the most important thing is to find the right balance.

Read More

April 20, 2015

Three Michigan State University On-Demand Webinars Offe…

The first rule of effective insect and disease control for vegetables is to take action to prevent problems before they occur. But in order to do that, you need to have an effective pest and disease management strategy in place that incorporates best practices to ensure a successful outcome. Michigan State University offers three pest and disease management on-demand webinars that will get you started and keep you on the right track.

Read More

April 15, 2015

BASF’s Pageant Intrinsic Fungicide Registration A…

The state of California has approved the supplemental label registration of Pageant Intrinsic brand fungicide for disease control in the commercial production of greenhouse-grown tomatoes and tomato transplants for the home consumer market.

Read More
Egg card used for insect control in Parkway Garden’s retail area.

April 13, 2015

Biocontrols Use Requires Commitment

For some companies, a switch to biocontrols is an easy decision to make. Parkway Gardens of Ontario, Canada, began using biocontrols nine years ago after Erik Jacobsen, the company’s owner, wanted to expose Parkway, its customers and the environment to fewer pesticide products. “Many pesticides were increasingly ineffective, and in Canada, new product registration moves with glacial slowness,” Jacobsen says. “The labor cost of applying pesticides is much greater than using biocontrols.” In addition, it was also an opportunity to market the company’s eco-friendliness to a younger demographic, he says. In a Q & A with Greenhouse Grower, Jacobsen explains what biocontrols and methods have proved effective for Parkway Gardens Greenhouse Grower: In what types of greenhouse structures are you using biocontrols? Erik Jacobsen: Our greenhouses are all poly covered. About half the range is a Westbrook 14-foot at peak gutter-connected block, and the remaining half a mix of quonset-style […]

Read More

April 11, 2015

Lowe’s Announces Commitment To Phase Out Neonicotinoids…

Home improvement retailer Lowe’s companies announced April 9 that it has committed to eliminate neonicotinoid pesticides from its stores in a gradual phase-out over the next 48 months. In response, horticulture industry associations issued a statement that Lowe’s position is surprising, considering the most recent and positive reports on the state of honeybee health and recent peer reviewed research, and that this is an issue for which sound science must take priority.

Read More

April 9, 2015

Survey Snapshot Shows Biocontrols Mainstreaming

Have you incorporated biocontrols into your greenhouse operation? If so, you’ve got plenty of company. An anonymous online survey by Greenhouse Grower magazine in December 2014 of more than 156 ornamental plant and flower growers across the U.S. found 81 percent used biocontrols in 2014.

Read More

March 31, 2015

Manufacturers Are Taking Biologicals To The Next Level

Through acquisitions and new products, many crop protection companies are making firm commitments to the future of the biocontrols industry.

Read More
OxiPhos_BioSafe2

March 23, 2015

BioSafe Makes Label Changes To OxiPhos And ZeroTol 2.0

There have been some recent label changes made to the BioSafe Systems product OxiPhos, a systemic bactericide/fungicide that reduces downy mildew spores when tank mixed with ZeroTol 2.0.

Read More
Nufarm_logo

March 23, 2015

Nufarm Fungicides Now Registered For Use On Edible Crop…

Nufarm Americas announced label expansions for two of its fungicides that will provide more pest management options for the ornamental industry. The Cleary 3336 F and EG fungicides are now registered for use across a wider range of edible crops, including select greenhouse vegetables and transplants, herbs and backyard fruit.

Read More
ColeusDMLeafSporulation_Daughtrey

March 11, 2015

Research Gives Clues For Preventing Coleus Downy Mildew

Maintaining awareness of coleus downy mildew is more important than ever to safeguard these attractive plants for reliable garden performance.

Read More
Rose Rosette on Knockout rose, May 2013. Photo credit: Alan Windham, University of Tennessee

March 2, 2015

Rose Rosette Disease Fight Gets A Boost From Government…

In 2014, $4.6 million was awarded through the Farm Bill to tackle rose rosette disease, a devastating pathogen that affects one of the industry’s most important crops.

Read More
Fig 1 Leafy Gall On Leucanthemum Becky

March 2, 2015

How To Prevent Leafy Gall Before You Lose Plants

Leafy gall is a nasty disease that can go undetected until plant damage is done. Take these steps to protect your crops from infection.

Read More

February 17, 2015

A New Look At Biological Control: Can Plants Affect The…

The success of a biological control program depends on a number of factors including quality of natural enemies, timing of release, release rates and environmental conditions. However, what is typically not taken into consideration is how plants can affect the performance of natural enemies, including attack rate and searching ability. Biological control agents work hard to protect plants, but plants have ways to help themselves, too.

Read More