Black knot disease is a fungal infection that can impact your trees

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By Laurie Weir, InsideOttawaValley, November 26, 2019 Plum trees are absolutely spectacular in full flower. They bloom early in the spring with blooms that line the branches before the leaves appear. Many people grow them simply for their spring beauty but there are cultivars that are hardy in eastern Ontario, although some of the cultivars may not be widely available. Cherry trees are also a beautiful addition to the spring landscape and some varieties such as Nanking or Manchu produce a delicious cherry crop if you can harvest them before the birds get to them.

As beautiful and productive as these small fruit trees can be, one problem that can gravely impact your trees is a fungal infection known as black knot. Black knot appears as unsightly swellings (galls) on twigs and branches. At first, these galls appear relatively harmless. They are rather subtle and velvety green in appearance. Gradually, they increase in size, harden and become black. The tips of the infected branches often die back. Severe infections can kill whole limbs, and the tree may become stunted.