Poinsettias: the problem children

From MSU Extension:

For some of us, poinsettias are a signal that the holidays are upon us and it is time for another cup of hot cocoa. But for greenhouse growers around the country, poinsettias can be a very challenging crop to grow. According to Michigan State University Extension, poinsettias are extremely susceptible to diseases such as Pythium root rot and scab (Sphaceloma poinsettiae), heat stress, plant growth regulator (PGR) overdose and phytotoxicity, and numerous nutrient deficiencies. Cultural practices such as keeping a clean greenhouse, not allowing dramatic swings in temperature, and providing a fertigation program with micronutrients can help prevent some of these production issues.

Poinsettias with Pythium root rot are often stunted, wilted despite media wetness, and slightly chlorotic. The roots are often brown, squishy and exhibit “rat tails,” where the outer cortex of the root slips away from the vascular tissue.

Click here to read more.