black walnuts fall into my pond which is surrounded by ferbs, hostas, lilacs. If I drain of the water to clean it and it goes on
these plants will they die
Black walnuts do produce a yellow to dark brown-colored substance that is toxic to other plants. Whether it will kill them probably depends on how many black walnut fruits or leaves have fallen in the pond compared to how much water there is. Put some of the pond water in a glass and let it settle out. If the water appears yellow or brown after settling, it would probably have enough of the toxin in it to harm or kill your other plants.