It’s Poinsettia Time, Again!

August 10, 2004 - 11:34

The dog days of August are upon us, so it must mean growers are about knee-deep in poinsettias. There are some smart growers out there who bring in pre-finished points later in September, thereby avoiding all the problems associated with getting started in the heat. Then there are some real smart growers who don’t grow any poinsettias at all. They are the ones laughing right now!

But for those of you who have to grow poinsettias to bring in the cash to meet your bills, the following words of advice are for you. In dealing with a number of growers around the country, I see the same issues year after year that need attention for the production of a quality poinsettia crop. The biggest poinsettia problems occur in the first six weeks of the crop, from when you take or receive a cutting; through propagation, rooting out and pinching; and up to initiation. If you can get through those critical six weeks in great shape, you have 80 percent of the work done! After that, it is just a matter of growth control, expanding and protecting bracts, and protecting the roots. So, here are my Top Five “Points” to Remember!

1. Start with a quality cutting. For those of you who grow your own stock plants, make sure your cutting crew takes a uniform cutting every week. If you buy in cuttings, make sure they are cool when you receive them, no rot or disease is evident and that they are fairly uniform in size. I suggest you cool them overnight at 55º F after opening the boxes. Make sure your sticking crew practices good sanitation and sticks the cuttings straight without bruising them. Do not plant a poor-quality cutting, as you will get a poor-quality finished plant out of it. Maintain the proper mist schedule to keep enough moisture on the leaves without promoting rot or Botrytis, but avoiding a lot of leaf curl.

2. Get the cuttings to root out properly, protecting against fungus gnats and root rots. If you root out cuttings, you should get to callous by seven days, at which you need to back off the mist and start watering by hand. Feed the cuttings with 150 ppm 13-2-13 or some other low-phosphorus fertilizer 1-2 times per week. Light levels should be 1,500-2,500 foot-candles. Control fungus gnats early and often with Gnatrol, Nemasys, Distance, Azatin and Ornazin, making sure to treat under benches. There are other chemicals that can be used, but make sure to consult the label to see if they can be used safely on poinsettias. Other growers have incorporated Zero Tol or hydrogen peroxide in their mist system, which helps control diseases as well as fungus gnats. Spray for Botrytis weekly. You can drench the liners or pots for root rots after the roots have come out. If direct-sticking, make sure pots don’t stay wet too long. If using Oasis wedges, make sure the wedges are thoroughly wet before potting and cover up the top of the wedge to avoid moisture wicking. Bottom line — Get the roots out to the side of the liner or pot and protect them from rot, fungus gnats and damage from planting!

3. Pinch the crop on time and properly. You should not pinch any poinsettia until roots are to the side of the pot. Otherwise, the breaks will come out unevenly, resulting in poor growth and quality. Make sure your pinching crew counts nodes instead of pinching to height. Low-vigor varieties should have a soft pinch with leaf removal. Otherwise, use a medium to hard pinch without leaf removal on all other varieties. Remember, too hard of a pinch means your cuttings were too old or tall, and you may not have good breaks because of it. Use a chemical growth regulator before pinching if needed to keep the nodes stacked. After pinching, shade the crop a little more and syringe with mist for the first couple of days to reduce stress on the plants. This will allow the breaks to come out more uniformly. Some growers are using Florel before and after pinching as a growth regulator and to bring breaks out more uniformly.

4. Control growth for variety and pot size. I am seeing problems with growers using too much chemical on varieties that are not as vigorous as they think. If using B-Nine + Cycocel tank mixes, use lower rates more often if needed, or just use Cycocel. The general trend with varieties is less vigor. With Freedom being a medium-vigor variety, you know that there are a lot of lower vigor varieties being introduced. Some growers are dropping Monet Twilight in favor of DaVinci. There is a big difference in vigor between those two! Quit using the tank mix when you get to initiation, or you will delay flowering. To help with your growth control, I strongly suggest you use graphical tracking for each variety and pot size. You can download the program for free from Ecke Ranch’s Web site (www.ecke.com). Start your measurements after pinching. Graphical tracking will help you stay on top of all varieties.

5. Control whiteflies. Marathon has made it easy to control whiteflies later in the crop, but every year I hear problems from growers about whiteflies early. For most locations, apply your Marathon drench around the last two weeks of September. This will give you the 10 weeks you need to finish and sell the crop. However, you need a spray program before then. Start with whitefly-clean cuttings, and set up a weekly or biweekly spray program regardless of whether you see a whitefly or not. Best chemicals to use include Endeavor, Distance, Talus, Tri-Star, Flagship and Marathon II. Just remember not to overdo using Tri-Star, Flagship and Marathon II if using Marathon as a drench. These chemicals are in the same family, so resistance to one will quickly create resistance to all. Also, it takes about one week for the roots to absorb the Marathon drench, so continue your spray program until October. If you apply the drench to pots too early, you run the risk of not enough roots to take up the chemical, or the control running out when bracts are coloring up.

About The Author

Roger Styer is president of Styer’s Horticultural Consulting, Inc., Batavia, Ill. He can be reached by phone at (630) 208-0542 or E-mail at carleton@voyager.net.

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