Foliage usually dark green ( or sometimes faded ) with dark brown or black necrotic spotting along major leaflet veins often appearing first on under surfaces and also along petiole ; profuse black spotting an sometimes black streaks along stems ) ( “ stem streak necrosis ” ) 马铃薯锰中毒：叶片通常深绿（有时褪色） ，深褐色或黑色坏死斑点首先出现在表面内沿着主叶脉一直到叶柄，大量黑色斑点有时沿着茎连成一条黑色条纹（ “茎条纹病” ） 。
