These were assessed using the parameters outlined below: Disease severity was scored on a scale of 1-5 by the method of Ikotun and Hahn (1991) where: 1 = No symptom (resistant); 2 = Development of shallow cankers lower on the stem; 3 = Development of successive cankers higher up the plant with older cankers becoming larger and deeper; 4 = Development of
dark brown lesions on green shoots, petioles and leaves. Young shoots collapse and are distorted; and 5 = Wilting and drying up of shoots and young leaves and death of part of or whole plant.