How can excess fertilizer use lead to pest problems?

Excess fertilizer use can lead to pest problems primarily by promoting lush growth that attracts pests. When plants receive too much fertilizer, especially nitrogen, they tend to grow more rapidly and produce softer, lush foliage. This abundant and succulent growth can be particularly appealing to certain pests, including aphids, caterpillars, and other insects that thrive on tender plant tissues.

In a balanced ecosystem, plants with moderate growth are better able to withstand pest pressures, as they often have tougher tissues and are less appealing to herbivorous insects. However, when fertilizer is over-applied, it not only encourages excessive growth but might also lead to an imbalance in the plant's natural defenses. This scenario can inadvertently create an environment where pests can thrive and reproduce more quickly, leading to infestations that can harm the overall health and productivity of the crops.

In contrast, other options like nutrient deficiencies, inhibited microbial activity, or increased water retention don’t directly result from excess fertilizer in the same way and may not lead to an immediate surge in pest populations.