Imagine that you are part of a team of phytopathologists working with your state’s Department of Conservation in an effort to protect the native plant species in your state. In your role, you are to determine the mechanism by which diseased plant species are being damaged. Plant Species: Big-leaf Maple (Acer macrophyllum) Field Notes/Physical Symptoms:
Wilting then yellowing-browning of leaves in early summer
Premature shedding of leaves before autumn
Progressive death of entire branches, ultimately death of roots and entire plant typically over several years
Soil pH: standard for the region
Soil nutrients: standard for the region
Laboratory/Metabolic Analysis:
Dark streaks in sapwood (the area between the vascular cambium and the remains of primary tissue) are observable when branches are sectioned
Reduced photosynthetic rate
Water levels in the canopy of the tree are deficient
The tissue or structure that is directly impacted is most likely what, and why?