Which of the following diseases is typically associated with late-season issues in soybean?

Sudden death syndrome is typically associated with late-season issues in soybean primarily because it manifests significant symptoms during the reproductive stages of the plant's growth. As soybean plants progress toward maturity, particularly during late vegetative growth and into the flowering and pod-setting stages, they become particularly vulnerable to this disease. The pathogen responsible for sudden death syndrome, Fusarium virguliforme, affects the plant's vascular system, leading to distinct foliar symptoms like chlorosis and necrosis of leaf tissue, which are often not visible until late in the growing season. This late manifestation can reduce yields dramatically if not identified and managed properly.

In contrast, while powdery mildew can affect soybeans, it tends to occur earlier in the season and is more prevalent in conditions of high humidity and poor air circulation. Root rot diseases can also occur at any point but usually develop more prominently in wet conditions rather than strictly late-season. Leaf spot diseases may catch attention during various growth stages but typically do not present the systemic threats that sudden death syndrome does later in the season. Thus, sudden death syndrome is the most appropriate answer for late-season soybean issues among the options provided.