It’s time to get your poinsettia crops past the finish line and out the door. There is a myriad of disease issues on poinsettias this growing season, including bacterial soft rot, Pythium and Phytophthora root rots, Rhizoctonia stem rot, Alternaria leaf spot, powdery mildew, and Botrytis to name a few. As bracts are coloring and temperatures are cooling, it is important to watch for anything that may damage the bracts. Calcium deficiency and Botrytis are two major issues that can cause bract burn and unmarketable plants.
Botrytis blight can be explosive within greenhouses on damaged or senescing tissues where humidity levels are high (greater than 85%). The pathogen produces an abundant amount of spores on infected tissues that can be dispersed by water splash and air movement to nearby leaves and adjacent plants. If you are not already using a fungicide to reduce Botrytis, you should consider it depending on the stage of growth, sale date, and weather conditions in your area. Overcast, humid, and wet conditions will favor Botrytis infection.
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