Boron deficiency can be a serious problem with pansies. Symptoms are initially expressed on the new leaves and stems, with the young growth being thick texture strap-like. With advanced conditions, death of the growing point can occur, thus resulting in axillary shoot growth. It is important to prevent B deficiency before symptoms appear because growing point death or distorted leaves can not be reversed. If deficiency symptoms are severe, it is rarely economical to try to reverse the damage. It is more economical to dispose of the crop and start over. Excessive levels of Ca can have an antagonistic effect on B availability and growing the crop at substrate pHs above 6.2 can tie up B. Make sure your fertilizer or irrigation water contains ample levels of B. Limit excessive Ca applications by avoiding calcium nitrate based fertilizers. Maintain the pH within the acceptable range of 5.4 to 5.8 to assure B is readily available to the plant. Some growers are supplying a weekly B drench application to the plants for the first three to four weeks of the crop as a preventative measure. For a 0.25 ppm B rate, mix 0.85 g borax (11% B) or 0.48 g solubor (20% B) per 100 gallons of water.
Photos of boron deficiency in pansies from NC State University.Information from "Managing Fall Pansy Fertilization" by Brian E. Whipker, Todd J. Cavins, and James L. Gibson, Department of Horticultural Science, North Carolina State University.
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