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...
Small Aphid Colony on Calibrachoa

May 2, 2016

How To Stop Aphids In The Greenhouse

When untreated, aphids damage ornamental crops and act as vectors for disease. Integrated Pest Management combined with vigilant scouting can help you stay ahead of the problem.

Read More
Fine Americas Website Feature Image

April 26, 2016

Fine Americas Offers A Digital Resource For Plant Growth Regulator Questions

The blog section of Fine America’s website is updated regularly, with input from both technical managers and independent researchers

Read More
Cicada (Greg Hoover, Penn State)

April 26, 2016

Cicadas Set To Emerge In Several Eastern States This Spring

While there’s no immediate cause for alarm, experts say the cicada’s egg-laying process can damage woody ornamentals and make them vulnerable to diseases.

Read More
Latest Stories
Small Aphid Colony on Calibrachoa

May 2, 2016

How To Stop Aphids In The Greenhouse

When untreated, aphids damage ornamental crops and act as vectors for disease. Integrated Pest Management combined with vigilant scouting can help you stay ahead of the problem.

Read More
Cicada (Greg Hoover, Penn State)

April 26, 2016

Cicadas Set To Emerge In Several Eastern States This Sp…

While there’s no immediate cause for alarm, experts say the cicada’s egg-laying process can damage woody ornamentals and make them vulnerable to diseases.

Read More
Parisitic Wasp Aphidius colemani

April 25, 2016

Plant Growth Regulator Use Can Affect Biological Pest C…

The use of plant growth regulators may negatively influence the outcome of biological control programs, according to researchers at North Carolina State University.

Read More
Beneficial Insectary Orius insidiosus

April 22, 2016

Beneficial Insectary Increasing Production Of Three Bio…

The company is now producing Orius insidiosus, Dalotia coriaria, and Dicyphus hesperus at its California facility, reducing the transit time of perishable biocontrols between producer and grower.

Read More

April 21, 2016

Michigan State University Offers Tips On Greenhouse Soi…

Improper pH and higher than adequate nutrient levels are among the many reasons for regular soil testing.

Read More
Parasitized aphid mummies, ladybird beetle larvae

April 18, 2016

4 Things You Need To Know About Implementing Biological…

Biocontrols are useful alternatives to traditional pesticides that provide effective pest control in the greenhouse. Here are four ways to get started successfully.

Read More
John Wendorf Bayer Ornamentals

April 14, 2016

Bayer’s New Ornamentals Business Manager Aims To Help G…

John Wendorf, who previously managed BFG Supply’s grower division, says when Bayer launches into the ornamentals market this November, growers will have access to a wealth of resources, including a dedicated team focused on ornamentals growers.

Read More
Emerald Ash Borer

March 22, 2016

Canada Implements New Voluntary Biosecurity Standard Fo…

The voluntary standard is designed to protect the greenhouse, nursery, and floriculture industries from invasive plant pests.

Read More

March 22, 2016

EPA Approves Syngenta’s Mainspring GNL Insecticide For …

Featuring the active ingredient cyantraniliprole, Mainspring GNL provides broad-spectrum control of key pests, such as thrips, whiteflies, aphids, caterpillars, leafminers, and leaf-feeding beetles.

Read More
Black Root Rot on Vinca

March 15, 2016

How To Identify Different Root Rots In The Greenhouse

Root rots can cause similar symptoms on hosts. Here are some tips for scouting in your greenhouse.

Read More
One symptom of Botrytis blight is gray, fuzzy sporulation on foliage and flowers, similar to that shown on the flower of this hibiscus

March 11, 2016

Manage Botrytis With These Cultural And Fungicide Contr…

High relative humidity and low temperatures in the greenhouse open the way for Botrytis to develop on plants. A mix of cultural and fungicide control options will help you manage this common disease effectively.

Read More
Biocontrols and beneficials absolutely can be used in outdoor production, with the use of banker plant systems

March 8, 2016

France-Based InVivo Acquiring Bioline, Syngenta’s Bioco…

Bioline, a subsidiary of Syngenta, specializes in the production and marketing of biological control agents, and in particular macroorganisms active against insect pests in fruits, vegetables, and flowers.

Read More

March 5, 2016

Prevent The Spread Of Disease In Irrigation Water

Water-mold pathogens cause significant crop losses and reduce floriculture crop quality. Take measures in your greenhouse to prevent the spread of diseases like Phytophthora and Pythium.

Read More
Bayer Greenhouse Ribbon Cutting

March 1, 2016

Bayer Opens New Greenhouse Research Facility In West Sa…

The $12 million facility will feature two new high-tech greenhouses that will be used in the development of new solutions in vegetable seeds and biologicals.

Read More

February 20, 2016

Hydrogel Technology Means Growers And Their Customers C…

Water and nutrient management are critical elements for quality plant production in the greenhouse. Maintaining the right amounts of available moisture and fertilizer at all times can be pretty labor intensive, but there are tools available to help you keep these inputs at optimum levels as efficiently as possible. Recently, we visited Evonik Industries’ North Carolina production plant for to see how one of these products — Stockosorb — is made, how it works, and learn the benefits of incorporating these tools in your own operation. Learn more about Evonik Industries’ Stockosorb hydrogel product on the Stockosorb website.  

Read More

February 17, 2016

Why It’s Important To Stay One Step Ahead Of Thri…

Keep thrips populations in check and avoid pesticide resistance by using spray and drench products known for their effectiveness.

Read More
Rose-Rosette-Knockout-May-2013-A-Windham_featured

February 16, 2016

University Of Florida Researchers Join Multi-State Batt…

The collaborative effort to stem off the threat of rose rosette involves early detection and the development of new compounds to help plants defend themselves.

Read More

February 12, 2016

Managing Air Temperatures For Basil Growth And Develop…

Iowa State University researchers determine if increases in air temperatures can increase growth and shorten production times for basil.

Read More
[gravityform id="35" title="false" description="false"]