What can burn the roots of roses and potentially kill the plant?

Fertilizer can burn the roots of roses and potentially lead to the death of the plant if not applied properly. When fertilizers contain high concentrations of nutrients, particularly nitrogen, and are not diluted or are applied in excessive amounts, they can create a salt buildup in the soil. This high salinity can draw moisture away from the roots, essentially causing root burn and jeopardizing plant health.

It's important to follow recommended application rates and timings for fertilizing roses to ensure they receive the nutrients they require without harming them. On the other hand, water, pesticide, and mulch are generally beneficial when used correctly. Watering is essential for plant growth, pesticides are applied to protect against pests (albeit they need to be used with caution), and mulch helps retain soil moisture and regulate temperature. Hence, the proper understanding of fertilizer management is critical in horticulture to promote healthy rose growth while avoiding detrimental effects.