“Where have all the flowers gone?” You may be asking yourself the 1960’s song title if you have recently been on or around the Sassafras Creeks and noticed that, in some locations, little or no American Lotus (Nelumbo Lutes) blossoms are evident. The bright yellow flowers, held high above the 12”-18” lotus pads, are known as the largest flower blossom in the continental United States. In many of the creeks along the Sassafras River, the blossoms are spectacular and abundant.
In several of our creeks this year, however, there has been a drastic reduction in the numbers of American Lotus. When the lotus began breaking the surface of the water in early May, I noticed that the pads looked weak, small, and brownish. Missing were the strong, dark green pads that usually welcome a boater into Sassafras Creeks in summer. Chris Cerino of the Sultana Education Foundation also reported a stark reduction of Lotus in Turner and McGill Creeks where they lead many kayak and canoe paddles.
To help answer the questions that were beginning to come into our office about the “Lotus problem”, I contacted the University of Maryland Plant Diagnostic Laboratory to request an evaluation of our Lotus. Paul Schlenker, one of our volunteer Sassafras Samplers, helped secure three complete plants from bloom to roots and we shipped them off to Dr. Karen Rane for evaluation.
The Lab’s diagnosis was that the plants have been damaged by a Phytopythium species, one of the group of fungus-like microorganisms called water molds, “which is usually a secondary invader of roots damaged from other causes.” So the disease attacks susceptible roots that were already weakened by another factor…but what was the other factor? What caused the weakened condition of the roots? Without a clue from the Plant Diagnostic Lab, the mystery deepened.
Fortunately the Sassafras River Association records a variety of water quality indicators on a weekly basis, and our data shows a possible answer to the weakened plants. When I compared the data over the last few years, I noticed that in the summer and fall of 2016 the salinity levels were unusually high in the Sassafras – sometimes 8-10 times higher than in a normal year. I recalled confirming our readings at the time by comparing them against the Maryland Department of Natural Resources Sampling Station at Budd’s Landing which had recorded similar readings.
While there is always some salt in the Sassafras, it is considered to be tidal fresh water containing less than 0.5 mg per liter. The mixing zone where the river meets the Bay is regularly flushed by storm flows from the Susquehanna River, but the salinity was definitely higher than usual last year and corresponded to the August and September drought conditions in Southeastern Pennsylvania as reported by the PA Department of Environmental Protection:
Could the higher salt levels last year have caused this year’s lotus problem? My research found that American Lotus is a fresh water plant generally found in ponds and along slow, fresh rivers, leading me to conclude that the elevated salinity over the summer and fall of 2016 may have been the catalyst that weakened the Lotus roots and allowed Phytopythium to kill many of our beautiful American Lotus plants in 2017.
Now for some good news. This year's water quality sampling shows that salinity levels during the spring and summer have returned to a low-to-normal state, and there still appears to be many healthy Lotus plants in most of the creeks along the river. We can be hopeful that the huge blue-green pads and spectacular yellow blossoms of the American Lotus will continue to thrive – and that our precious Sassafras will continue to be one of the most beautiful rivers on the Chesapeake Bay.
I’ll see you on the river!
Captain Emmett Duke