I have found that my canna bulbs have grown well but some of them have yellow streaks from the mid rib ,but the leaves are not mottled .I also found out that in the early morning hours the leaf margins of all the bulbs i bought are showing watery exudates from atleast more than 3 spots per leaf with a distance of 1-3 inches between the exudation spots.other cannas i brought as potted plants are perfect with no exudation."exudation".....is it canna blight? or DOES IT OCCUR as a natural process in cannas.What should i do with these plants.I brought them at WIL-KIN-SON STORE in london.The MAIN QUESTION is _do cannas exudate water naturally or is it a disease?