I know that the Early Winter Rose series does not typically require a lot of PGRs. We are having a warm fall and we've already sprayed Cycocel at 1250ppm. The plants are on the border of being too tall. Would a Piccolo drench be safe on this series? We do use the drenches on other varieties and are pleased with the results.

erine, I have used the early and late paclobutrazol (Bonzi, Paczol and Piccolo) drenches on the Winter Rose variety for three seasons now and it works quite well......Michael Pawelek

This message has been edited. Last edited by: Michael Pawelek,

erine -

The low dose paclo drenches can also be used effectively on Winter Rose but it is really important to remember that even the lose doses have the potential to reduce bract size. On a variety like Winter Rose any reduction in bract size will be very noticeable because it already has a naturally small bract. To avoid any potential reduction in bract size you just want to keep the rate as low as possible.

would .5ppm be too high a rate?

erine, Until there is already some substantual color in the bracts I would only use a low dose paclo drench of 0.1-0.2 ppm which would be 1 ml. of the Paclo to 10 galloons of water to 2 ml. of Paclo to 10 gallons of water. Wait until Dr. Barrett writes in for a definite answer. A .5 ppm at this stage might be too high so let's be sure before you apply. Below is a summary of Dr. Barret's current recommendations for the "early" and "late" Paclo drenches
...Michael Pawelek

GUIDELINES FOR EARLY BONZI (Paclo) DRENCH: Used between final pinch and start of color.
Effects of drench will usually last 10-30 days depending on strenght used.
The objective of early drenches is to achieve good size control with less effect on bract development compared to PGR sprays. The early drench is sometimes referred to as a low-dose drench because the rate used is much lower than late drench rates. An early drench is applied as needed using the same decision process as currently used for making spray applications. The low rate that is used does not stop elongation and only slows plant growth similar to the effect of a spray. The early drench can either replace some or all of the sprays. An
important point is that there is not a cutoff date for early drenches and they can be applied as late as the end of October. While, early drench applications are generally safer than sprays at the same time, problems can occur if too much is applied just like all PGR usage. Any of the media active growth regulators can be used for drench applications, but rates will vary depending on activity of the chemical. We will use Bonzi in these examples.

Bonzi rates for early drenches are 1/10 to 1/5 ppm (0.1 - 0.2 ppm) for medium to very vigorous varieties.
0.1 ppm rate is only 1ml. Bonzi per 10 gallons of water / 0.2ppm rate is only 2ml. Bonzi per 10 gallons of water.
You must also be careful how much solution you add to each container.
Examples: 4 ounces of solution to 6” container.
At this time, it is not suggested using this technique on low vigor varieties like Chianti and Pepride without extensive testing to determine the optimum rates.


GUIDELINES FOR LATE DRENCH: This will usually stop or greatly reduce further Poinsettia height until the end of the crop.
The objective of this procedure is to stop elongation and hold the crop at the desired size. The later the drench is applied the less it affects bract size. The rates used for the late drench are too high for earlier applications. Rate is usually 1ppm. 1 ppm rate is 1ml. Bonzi per 1 gallon of water.

In warm climates the guidelines for when to apply the late drench is…
We will use Bonzi for the late drench and 1 ppm is the standard rate in warm climates for medium vigor varieties like Freedom Red.
(1) We want the plants within 1 inch of final size.
(2) We want one bract in full color.

In cool climates the guidelines for when to apply the late drench is…
(1)The plants should be within ½ inch of final desired size and…
(2)There should be at least two bracts in full color. Remember the later it is applied,
the safer it is. In cool climates, the standard Bonzi rate for medium vigor varieties like
Freedom Red is 0.5 ppm.

This message has been edited. Last edited by: Michael Pawelek,

erine, first a couple background notes for all readers. Piccolo is a Paclo product with same active ingredient as Bonzi. The newer variety Winter Rose Early (WRE) branches better and flowers earlier then the older Winter Rose Dark Red (WRDR). Also, WRE is less vigorous and more responsive to pgr than WRDR. I have done early micro drenches and late drenches on WRDR with considerable success – good size control and minimal reduction in bract size. One example I show in talks is WRDR treated twice with early drenches at 1/7 ppm each. WRE is a different animal. We have grown it here 4-5 years and the tendency is to get them too short if we do any pgr sprays. This year, our WRE are growing more than they ever have. I have not used an early drench on WRE. I have tried early drenches on very low vigor varieties like Pepride and Chianti – where 1/20 ppm (0.05 ppm) does not affect them and 1/10 ppm (0.1 ppm) is a little too much. I have not done enough work and I have not heard of enough grower experiences with the very low vigor varieties to give a sound recommendation. 1/2 ppm (0.5 ppm) is likely too much this early in the crop.

My suggested approach is first if you can get a good marketable tall plant, then do not treat WRE with anything. Based on our experience with WRDR, if you feel you must reduce height then a drench at the proper rate is better than doing it with Cycocel sprays. If you want to try drenching, I suggest using a rate of about 1/12 ppm (0.08 ppm) on a portion of the WRE crop to see how they respond. If you get some control but not enough this could be repeated in 10 days or so. If you go 2-3 weeks then you could do a late drench at a lower than normal rate in the range of 1/4 ppm (0.25 ppm).

Good luck with the crop and please let us know how it turns out. Also, if anyone else is doing drenches on very low vigor varieties, let us know how it works. Jim

I hit a small group of WRE with a Bonzi drench at 0.2ppm while I was drenching the other varieties on Oct. 8. These are 3 plants in an 8" pot and are near final height. I'll keep an eye on them and letcha know how they turn out.

I am also having to watch my WR closer this year to keep them in bounds. I use a 1 plant per 6" container pinched for 3-4 blooms and as of today mine are 7-8" above the rim of the containers though I have used 3 early drenches so far. For my tropic like conditions and the fact I use quite a bit of pine bark in my mix next year I will use the 0.2 Paclo strenght from the start. The lower 0.1-0.15 are keeping things under control but I'm having to make too many applications per crop so hopefully by upping the strenght I can cut back one or two applications. Picture of WR as of this morning with the 3 early Paclo applications. They look fine now but I can expect another 4-5 inches of stretch if no more PGR's are applied and the final plants will be too tall. Someone please send some cooler weather, 92F here today!!!...Michael Pawelek

Michael, is this WRE or WRDR? They look very much the way our WRE look this year – larger leaves and taller than usual. It looks like you have a “cold” front passing through today. It is predicted to weaken by the time it gets here, but we are supposed to cool off to only slightly above normal. Jim

Dr. Barrett, The picture is of the standard WRDR as I do not grow any of the earlier varieties. Maybe I'm having to apply more applications of the early paclo drenches this year because I bought a new bottle of Bonzi. Prevoiusly I used the same container of Bonzi for three consecutive poinsettia crops and maybe it fermented in the barn during storage and became stronger over the years! The new container of Bonzi may not be as good. As you have heard the phrase "they just don't make it like they used too"!!! Michael Pawelek

Michael, you do need some cool weather

I just finished measuring and logging my WREs and I'm not seeing any effect from the Bonzi drench (0.2ppm) that I applied 9 days ago. Hmmmm.... I think I was a little light in quantity applied (8oz. instead of 10oz./ 8" pot), but still! It's this Indian "Simmer" we've been having! When will I be able to get my long pants out???!!!