Damping-off and root rot
These are caused by the soil-borne fungi Phytophthora parasitica, P. palmivora and Pythium aphanidermatum. Phytophthora and Pythium also occur in the orchard, causing root rot.
Stem and fruit rots are produced on papaya. Infected young fruits develop water-soaked lesions that exude milky latex. These fruits may eventually shrivel and fall off the trunk. Infected trees show yellowing of leaves, which later collapse and hang limply around the trunk before falling. Small roots are generally absent and large ones show a soft, wet decay extending towards the trunk. At that stage, the lateral roots and taproots are entirely destroyed and a foul odour often emanates from diseased trees. Stem cankers, which develop most frequently in the top of the stem where the fruit is borne, induce fruit and leaf fall. These fungi may also cause trunk rot of mature trees. Infected trees eventually die.
Plants are susceptible at all ages but roots of young seedlings are most susceptible.
- Ensuring good soil aeration.
- Good drainage and hygiene are important to control these fungi in the orchard as well as in the nursery.
- If possible do not replant pawpaw on the same land.
- Copper based fungicide treatments at the very beginning of first symptoms can reduce fruit rots. However papaya fruits are very senstive to copper. For more information on Copper click here.