Due to their very short life cycles, populations of aphids such as Cinara pinivora can multiply rapidly on a host, leading to the formation of dense colonies. It preferentially attacks younger plants in the nursery and below the age of 4 years in the field. However, they can also attack older trees, preferentially attacking the new shoots and growth tips.
Feeding by the aphids lead to discolouration and pre-mature needle drop. This can then further result in branch discolouration and die-back, affecting the photosynthetic capabilities of the trees resulting in stunting and reduced growth.
In addition to the direct feeding damage caused by the aphids, they also excrete honeydew during the process of feeding. This sticky and sugary substance is an ideal substrate for fungal growth, and the presence of high numbers of aphids feeding typically goes together with the occurrence of sooty mold.
