Control Stem Length With Liner Dips

Control Stem Length With Liner Dips

As you are getting ready to place your early plug and liner orders before winter, you may be reflecting on the incredible variety of spring annuals you are growing in your greenhouse. One of the biggest challenges in bedding plant production is controlling unwanted stretch or stem elongation. But how can you effectively control stem elongation of so many different species in a single greenhouse or in a combination container?

There are several techniques growers may use to control stem elongation. For instance, a warmer night air temperature than day air temperature creates a negative DIF (DIF is day temperature minus night temperature), which has been shown to minimize stem elongation. However, the effectiveness of a negative DIF varies with species. With today’s high energy costs, it can be cost prohibitive.

Therefore, a more practical and economical tool is to treat each species with plant growth regulators (PGRs). Chemical PGRs are usually applied as foliar sprays to plants in packs or containers. However, some PGRs such as ancymidol (A-Rest, Abide), flurprimidol (Topflor), paclobutrazol (Bonzi, Piccolo, Paczol, Downsize, Florazol) and uniconazole (Concise, Sumagic) are taken up by roots and have growth-regulating activity when applied to the growing substrate. Growers may apply substrate drenches containing these PGRs, which often result in increased control and uniformity in curbing stretch.

Dipping trays of rooted liners and plugs into a PGR solution, or liner dip, is a newer method of efficiently applying root-absorbed PGRs that controls stem elongation after transplanting. The use of liner dips allows growers to efficiently apply the required PGRs to a large number of plants. It can also give growers the ability to treat individual plants with the PGR they need before combining them with other species or cultivars in a mixed container or basket.

While there is information about using liner dips on flowering annuals in both trade and scientific literature, little to no information is available for using liner dips with foliage annuals. We wanted to see if we could control stem length of several common foliage annuals that are used in combination planters and hanging baskets using PGR liner dips.

The Experiment

Trays of ‘Royal Tapestry’ alternanthera (Alternanthera dentata), ‘Silver Falls’ dichondra (Dichondra argentea), ‘Silver Mist’ helichrysum (Helichrysum petiolare), ‘Black Falls’ and ‘Marguerite’ sweet potato (Ipomoea batatas), ‘Goldilocks’ lysimachia (Lysimachia nummularia), ‘Emerald Lace’ plectranthus (Plectranthus oertendahlii) and ‘Variegata’ vinca (Vinca major) were received from C. Raker and Sons (Litchfield, Mich.) and Four Star Greenhouses (Carleton, Mich.). Liners were dipped into trays filled with solutions containing 8, 16 or 32 ppm ancymidol (Abide; Fine Americas); 4, 8 or 16 ppm flurprimidol (Topflor; SePRO); 4, 8 or 16 ppm paclobutrazol (Piccolo; Fine); 2, 4 or 8 ppm uniconazole (Concise; Fine); or deionized water (untreated control) for two minutes.

The day following chemical treatments, liners were planted in 4-inch round containers filled with a commercial soilless substrate composed of (by volume) 80 percent peat and 20 percent perlite. Plants were grown in a polyethylene-covered greenhouse under natural daylight with day and night temperature set points of 70°F and 67°F, respectively. Plants were fertilized with 200 ppm nitrogen from a balanced feed with each watering. Six weeks after treatments the length of the longest stem of each plant was recorded.

The Results

So what did we see? No PGR was effective in suppressing stem length of ‘Marguerite’ sweet potato (Figure 1) or ‘Silver Falls’ dichondra. Alternatively, every PGR at each concentration resulted in ‘Black Falls’ sweet potato plants with shorter stems compared to control plants (Figure 1, see slideshow below).

Only ‘Variegata’ vinca dipped in 32 ppm ancymidol had shorter stems than control plants (Figure 2, see slideshow below). ‘Emerald Lace’ plectranthus did not require any PGRs (Figure 3, see slideshow below). Stem length of ‘Silver Mist’ helichrysum was only shorter than control plants when treated with 16 or 8 ppm flurprimidol or uniconazole, respectively (Figures 3 and 4). All PGRs, at different concentrations, were effective for controlling stem length of alternanthera and lysimachia (Figures 3 and 4, see slideshow below).

In our experiment, we documented a variety of responses to different PGRs with the species we used. For example, we observed three general responses to PGR liner dips across species and cultivars used: 1) did not require chemical growth regulation (plectranthus); 2) were unaffected by most or all PGRs (dichondra, ‘Marguerite’ sweet potato, and vinca); or 3) were affected by each PGR at nearly every concentration (alternanthera, helichrysum, lysimachia and ‘Black Falls’ sweet potato).

Species and cultivar clearly interact with PGR active ingredients and concentration to affect stem length. Additionally, the variation between cultivars of the same species (i.e. sweet potato) underscore the importance of conducting in-house PGR trials to develop effective protocols for applying PGR liner dips to control stem length of herbaceous foliage annuals.

Using Liner Dips In Your Greenhouse

So what does this mean for you and your crop production? Liner dips can clearly be an effective PGR application strategy for aggressive foliage and flowering bedding plants. However, before dipping your liners or plugs into PGR solutions, get a clear idea of what you want out of your liner dips.

For instance, are you treating liners that will be planted individually in containers that will eventually be planted in a landscape, or are you treating liners that will be part of a mixed container planting? If you are treating plants that will eventually be planted in the landscape, you may be interested in a lower PGR concentration that will “hold” stem elongation until plants are placed in the landscape. Alternatively, for those plants that are going to be planted in a mixed container or basket, a higher PGR concentration that will slow or stop excessive elongation when the container is brought home by the consumer (Figure 5, see slideshow below).

Once you have identified what you want your dips to do for you, there are a few steps you can take to ensure success. First, identify the PGR you want to use and the desired concentration for that PGR. For a “hold” application, you’ll want to use concentrations that would be lower than those necessary for a “slow” or “stop” application.

Second, water your plugs and liners a day or so before you plan on applying the liner dips. This will ensure more uniform substrate moisture leading to more uniform uptake and subsequent control. If a plug tray or liner is too dry, too much PGR solution will be absorbed, resulting in too much suppression of growth. Alternatively, if a plug tray or liner is completely saturated, not enough PGR solution will be absorbed and you will not get enough control. Lastly, be sure to time your dip. Dipping plugs or liners in PGR solutions for 30 seconds to up to two minutes has been shown to be an appropriate range for application time. Treatments less than 30 seconds will not provide you with much control, while dips over two minutes may provide excessive control.

Takeaways

Next time you grow annuals from plugs or liners, consider using liner dips. They are an effective method for treating a wide variety of species and cultivars during a season in which variety in the greenhouse can be overwhelming. This research was conducted in the Northern U.S. during late spring. Rates will vary based on location and time of year.

Be sure to do some in-house trialing with the plant material and PGRs you use to identify which PGRs and concentrations work for the plants you grow.

 

Leave a Reply

More From Crop Inputs...
Triathlon BA container shot

May 24, 2016

OHP’s Triathlon Biofungicide Now Listed By The Organic Materials Review Institute

Triathlon BA is a broad-spectrum preventative biofungicide that provides control of many foliar and soilborne diseases in ornamentals and herbs.

Read More
Pythium On Chrysanthemum

May 20, 2016

How To Prevent Pythium In Fall Garden Mums

Avoid profit loss in fall garden mums due to pythium root rot with good drainage and integrated pest management practices that reduce risk factors.

Read More
Agro-K

May 19, 2016

Agro-K Expands Distribution In New England Through Partnership With Northeast Agricultural Sales

Agro-K, which manufactures conventional and organic foliar plant nutrients, will distribute its full line of foliar fertilizers and soil biological products through NEAG.

Read More
Latest Stories
Triathlon BA container shot

May 24, 2016

OHP’s Triathlon Biofungicide Now Listed By The Organic …

Triathlon BA is a broad-spectrum preventative biofungicide that provides control of many foliar and soilborne diseases in ornamentals and herbs.

Read More
Two-spotted spider mites, adults and eggs

May 11, 2016

SePRO Launches Summer Insecticide Management Program Fo…

The program is designed to help growers use SePRO’s insect management tools to prevent plant damage from a variety of pests.

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