Secondary roots and right angle branching are reduced when the tap-root is attacked during the early growth stages. Sting injury is often followed by Fusarium wilt fungus infection. The Fusarium wilt fungus usually penetrates through root injury caused by nematodes. Infected areas are irregular in shape and size. Water-conducting stem tissues turn brown and become inactive, resulting in wilted foliage.
Leaves turn yellow between veins and eventually shed as plants die to leave bare stems.
Diagnosis is confirmed by splitting the stem to reveal dark brown, vascular discoloration and streaking characteristic of wilt.