Growing successful spring crops with Topflor

This spring crop season is going strong! With so many species being grown and so much to do, your head will spin trying to keep everything in order. It is only a matter of time before something must be done to control the growth of all the different spring crop species, particularly those aggressive cultivars and those grown too tight together, too hot or too shaded.

We have learned to manipulate temperature, fertility and moisture to control plant growth, but plant growth regulators (PGRs) remain the best way to achieve precise control of height, size and appearance in spring crops.

There are many PGRs available for use on spring crops. Each one of these PGRs can help achieve different specifications in plant characteristics. Topflor (flurprimidol) from SEPRO Land is the one PGR that can stop your head from spinning, because Topflor can simplify your growing process. SEPRO Land’s A-Rest (ancymidol) is the favorite for those who produce plugs and young plants or want a lighter touch on finishing spring crops.

How can Topflor simplify and bring value to your operation? Let me tell and show you how.

Topflor can be used on all major spring bedding plant species. This feature is particularly helpful when you grow more than two dozen plant species or cultivars in a single house.

Through decades of collaborative research with university and contract researchers, as well as trials by growers throughout the country, we have determined the starting trial rates for 75 ornamental plant genera.

You can find the recommended trial rates of the spring crop you are growing by asking your SEPRO Land representative for a custom Topflor and A-Rest Rate Chart.

Topflor can be sprayed, drenched, sprenched, dipped, soaked or chemigated. For example, spraying at 20 ppm can provide the same growth regulation and quality of calibrachoa as drenching at 4 ppm (Figure 1). The flexibility in application method allows you to pick what’s most convenient for you. You can find application method-specific starting trial rates by asking your SEPRO Land representative for a custom Topflor and A-Rest Rate Chart.

As shown in Figure 2, the dose response of Topflor is highly consistent and predictable, which means you can get consistent results from specific application rates and methods that give you the best results. These results are replicable from one crop season to the next.

Topflor can be used at any time during the crop cycle. Low rates during the growing period can help you achieve the perfect shapes and sizes. Higher rates near the end of the crop will help you maintain the desirable shape and size and tone the plants while not hurting blooms.

Spring crops are about flowers. While Topflor effectively regulates plant size, it does not reduce bloom number and size like some other PGRs (Figure 3). Topflor also creates greener foliage. The end results of using Topflor are show-stoppers that are uniformly sized, with dark green foliage and prolific blooms. Topflor makes sturdier stems, which means less breakage during handling and shipping.

Topflor has lower risk of over- or under-regulation than other PGRs because, in general, flurprimidol and ancymidol have moderate activity, whereas paclobutrazol and uniconazole have high activity (that is, easy to over-regulate) and diaminozide and chlormequat chloride have low activity (require a high application rate to achieve regulation).

(The activity of a PGR is determined by how sensitive a plant is to the particular PGR and the residual duration of effective growth regulation of the PGR.)

Topflor also has shorter half-life than some other PGRs, such as paclobutrazol, so the residues do not linger on plastic, ground cover or water. You can use Topflor confidently without worrying about surprising and unwanted phytotoxicity and stunting or a lack of results or fewer flowers (Figure 4).

Topflor is economical without sacrificing results. The use rate of Topflor, especially when drenched or micro-drenched, can be quite low, but the results are equally stunning as other application methods or PGRs.

For example, research conducted by Dr. Jim Barrett at the University of Florida demonstrated that a Topflor drench at 0.5 ppm every week provides better regulation (and more flowers) of Wave petunia than a program that depends on foliar sprays of B-Nine (at 2,500 ppm) and a final stop-growth drench of Topflor at 4 ppm (Figure 5). Topflor drenched at 2 ppm every other week can provide even tighter regulation without diminishing blooms. You can choose the precise Topflor application rate and frequency to achieve the desirable results.

Refer to this earlier Plant Health Secrets article for a detailed discussion of Topflor’s benefits. If Topflor is new to your program, we recommend testing several starting rates to dial down to the precise rate that achieves your expected quality.

We’ve developed dilution tables and rate guidance for over 75 ornamental genera, and our technical team is available to help you fine-tune application timing and methods based on crop, environment and production goals.

Juang Horng (JC) Chong, Ph.D., is the technical development manager for ornamentals at SEPRO Land.