What type of plants are at the highest risk for black knot infection?

Black knot is a fungal disease caused by the pathogen Apiosporina morbosa, primarily affecting certain types of trees. Stone fruit trees, such as cherries and plums, are particularly susceptible to this infection due to their structure and the way the fungus interacts with their tissues. The spores of the black knot fungus thrive in humid conditions, which are often present in orchards or areas where stone fruit trees are cultivated.

These trees are prone to infection because they can sustain the fungal spores that produce the characteristic black, elongated galls on branches and twigs. Over time, these galls can hinder the tree's growth and lead to significant damage or even death if not managed properly. The specific composition of stone fruits allows the fungus to take hold more readily compared to other plant categories, like evergreens or drought-resistant plants, which may have better defenses or less favorable conditions for the fungus to thrive.

In summary, the vulnerability of stone fruit trees to black knot infection stems from their biological traits and environmental preferences of the black knot pathogen, making them the highest risk for this disease among the other plant types listed.