Major diseases affecting granadilla yields in South Africa include:
Damping off of seedlings caused by fungi as a result of poor seedbed management. In ‘damping off’, various pathogens (germs) kill or weaken seeds or seedlings before or after they germinate. It is most prevalent in wet and cool conditions.
- Control: Plant on a well-drained site in virgin soil, or sterilised soil/growth medium.
Foot rot (dikvoet), where the base of the stem thickens, causing cracks in the soil surface through which numerous secondary organisms can enter. This results in complete rotting of the stem. Waterlogging and over-irrigation increase the incidence of the disease.
- Control: Plant in well-drained soils.
Various viruses causing symptoms such as spots, mosaics and distortion. It is usually very difficult to identify the specific virus involved.
- Control: Break affected shoots off the plant. Frequent handwashing reduces transmission. Wipe instruments with a mixture of water and 10% household bleach, such as Jik, after pruning each plant. Pests that frequently occur on granadillas include stinkbugs and tip wilters. Carry out field inspections frequently. Collecting insects by hand can help to control them.
Source: Infopak compiled by department of agriculture, in co-operation with the ARC-Institute for Tropical and Subtropical Crops.