What risk is associated with the over-application of micronutrients?

Over-application of micronutrients can lead to toxic effects in plants, which is why this is the correct choice. While micronutrients are essential for plant health and development, they are required in much smaller quantities compared to macronutrients. Excessive amounts can create imbalances in the plant's nutrient uptake, leading to symptoms of toxicity. This can manifest in various ways, including stunted growth, chlorosis (yellowing of leaves), necrosis (death of tissue), or even plant death in severe cases.

In contrast, improved plant yield, lower financial costs, and better nutrient availability do not directly result from excessive application of micronutrients. In fact, these outcomes are typically associated with balanced nutrient management. Over-application can lead not only to negative agronomic impacts but also environmental issues as excess micronutrients can leach into the water supply, further compounding the risks. Thus, the focus on managing micronutrient application is crucial to prevent potential toxicity and ensure optimal plant health.