Which of the following factors can lead to root rot in ornamentals?

Root rot in ornamentals is primarily caused by waterlogged soils that create an environment conducive to fungal growth. When plants receive too much water, the roots are unable to access the oxygen they require, leading to stress and potential decay. This condition is exacerbated if the soil does not drain well, either due to its inherent properties or because of poor drainage in the pot or garden bed. The pathogens responsible for root rot thrive in these overly moist conditions, attacking the roots and leading to a decline in plant health.

While low humidity, insufficient sunlight, and excessive pruning can stress plants or lead to other issues, they do not directly cause root rot. Low humidity often affects foliage and can lead to issues like leaf drop or increased pest populations. Insufficient sunlight can prevent proper photosynthesis and weaken a plant over time, but it does not contribute to the standing water that fosters root rot. Excessive pruning can stress a plant and leave it vulnerable to disease or pests, but it does not create the moisture imbalance necessary for root rot to occur. Thus, understanding the significance of proper watering practices is crucial in the prevention of root rot in ornamental plants.