Genetic Sleuthing Reveals New Weakness in Corn's Herbicide Armor : USDA ARS Small bonsai tree growing in a traditional japanese rock garden 59892866 Stock Photo at Vecteezy Lebanon TRIMEC 1.81% Broadleaf Herbicide Fanelli's Landscape Supply Birds Nest Fern Brown spots and brown edges on the leaves. This can also be caused by too much heat (sun burnt) and will only show on the area of the plant that was exposed to too much light or sun.