CDFA Pest Prevention Plant Regulation Practice Exam

Which tree species is primarily attacked by phloem necrosis?

1. elm trees

2. hickory trees

3. walnut trees

4. pine trees

The correct answer is: elm trees

Phloem necrosis is a disease primarily associated with certain tree species, most notably elm trees. This condition is caused by specific pathogens, including bacteria and fungi, which target the phloem tissue, leading to the wilting, yellowing, and eventual death of the affected branches. Elm trees are particularly susceptible because of their vulnerability to disease, especially in urban environments where stress factors like pollution and compacted soil can exacerbate health issues. While hickory, walnut, and pine trees may experience other types of pests or diseases, they are not primarily affected by phloem necrosis in the same way that elm trees are. Understanding the relationship between specific tree species and their susceptibility to certain diseases is crucial in pest prevention and management practices. Therefore, elm trees' significant association with phloem necrosis makes them the correct answer.