Tech Update: Controlling Cyathia Drop on Poinsettia


Poinsettia flowers (cyathia) or the yellow fruiting structure in the center of bracts can overripen and fall out of the center. Many consumers view cyathia drop in a negative light. Some varieties are more prone to this than others.


Factors such as high temperatures, low light, long bench time and plant variety are key factors to cyathia drop. It can be a real problem for crops in the South if shipping time in a truck is long and temperatures are high.


To prevent or delay cyathia development a grower can increase light levels or cool the crop.


Cyathia starting to ripenCyathia starting to ripen
Normal cyathia
developmentNormal cyathia development

They can also apply a PGR such as one of the anti-Ga's (Giberellic Acid). Products such as Paczol® or Cycocel® will block Ga synthesis which is in part a blocker to the ripening of the cyathia.


This research and rates noted below were developed some 25 years ago with paclobutrazol and Cycocel.


The key to this is that a grower should only apply the material from one-to-two weeks before shipping/sale.


Rates for Paczol are 10 to 20 PPM (spray) and 500 PPM (spray) for Cycocel. Again, timing is critical — one-to-two weeks before shipping/sale.


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