What problem arises from fall armyworm infestations in late grain sorghum plantings?

The correct choice is focused on the impact of fall armyworm infestations, particularly on late grain sorghum plantings. When these pests infest sorghum, they primarily feed on the leaves, leading to defoliation. This not only reduces the overall leaf surface area but also creates a tattered appearance as the leaves are chewed and damaged. The loss of leaves is particularly detrimental because it can significantly affect the plant's ability to photosynthesize effectively, ultimately impacting grain yield.

In contrast, the other options address issues that are either not directly associated with fall armyworm feeding or are less specific to the known effects of their infestations. For instance, severe leaf curling is more commonly associated with other pests or diseases rather than the feeding habits of fall armyworms. Likewise, while wilting can occur due to various stress factors, it is not the primary concern with armyworm infestation alone. Increased soil erosion is generally an environmental concern that relates to other agricultural practices and conditions rather than a specific consequence of armyworm pests. Thus, option C encapsulates the most pertinent and observable problem related to fall armyworm damage in late grain sorghum plantings.