True or False: Most soil organisms cause disease or decay in tree roots.

The statement that most soil organisms cause disease or decay in tree roots is false because the majority of soil organisms play a beneficial role in the ecosystem, particularly in promoting plant health. Many microorganisms, including bacteria and fungi, are essential for nutrient cycling, improving soil structure, and enhancing the uptake of water and nutrients by plants. These beneficial organisms can form symbiotic relationships with tree roots, such as mycorrhizal associations, which significantly improve the tree's ability to absorb nutrients and water.

Although some soil organisms can indeed be pathogenic and lead to diseases in trees, they are a minority compared to the overall pool of microbes present in healthy soil ecosystems. The beneficial microorganisms help combat disease organisms, effectively preventing or mitigating decay under normal conditions. Thus, the focus should be on the positive impacts of the majority of soil organisms rather than a blanket statement regarding disease and decay.