Keep Your Points Disease-Free

Kurt Becker

Poinsettia Bract Edge Burn is a common occurrence in this Christmas crop. Brown necrotic lesions occur on the bract margin. The primary cause for this is low levels of calcium in the bract. Some poinsettia varieties have difficulty translocating calcium to the bract margin as the bract expands. Once necrosis begins, Botrytis can follow, often leading to more plant damage.

Pictured: Keep your poinsettia crop from experiencing calcium deficiencies by fogging.

Calcium sprays are a common method for preventing bract edge burn. Foliar application of calcium chloride, cal-mag or calcium chelates can help boost calcium levels in deficient bracts. When started at the first sign of color on the bracts, these applications can significantly reduce bract edge burn.

Even with the inclusion of surfactants, calcium applications can leave residue on the bracts that need to be dealt with. But, given the impact on the health of the crop, these applications are well worth it.

Fogging calcium is another method that can have a benefit to the plant. Fogging calcium can reduce the labor needed to apply as a foliar spray. As fogging is often automated, no applicator is needed during the spray. Additionally, fogging calcium can eliminate visible residue. Because the droplets are much smaller, no large droplets sit on the plant and evaporate to leave residue.

However, the biggest benefit to fogging versus spraying is that the levels of calcium in the bract increase at a greater rate with fogging when compared to spraying. In various trials using the Dramm Autofog, applications of CaCl2 at 200 to 400 ppm provided between two to three times more calcium in bracts when compared to wet spray applications at the same rates, reducing the frequency of the applications required. GT

Kurt Becker is the Executive Vice President—Sales & Marketing at the Dramm Corporation in Manitowoc, Wisconsin.