Higher temperatures increase risk of apple scab infection

Apple orchards in the coastal regions of the Western Cape, such as Elgin, are affected to a greater extent by rising winter temperatures than those in the colder inland regions such as the Koue Bokkeveld. The question we have been trying to answer through our research is whether this change in temperature has increased the risk of apples acquiring fungal diseases.

Apple scab, one such disease, is caused by, commonly known as Fusi. It is responsible for high economic losses to the apple export industry due to the blemishes and deformities it causes on the fruit. The fungus overwinters in fallen leaf debris, where it reproduces sexually to form round, spore-bearing structures, called pseudothecia, within the leaf tissue. When conditions are favourable for scab infection in spring (16°C to 20°C, during rainy periods), the spores are discharged, causing infection in young leaves and developing flowers and fruit.