What defines a foliar spray in nursery practices?

A foliar spray is specifically defined as a liquid nutrient application that is directly applied to the leaves of plants. This method allows for the rapid absorption of nutrients through the foliage, which can enhance plant health and growth more effectively than soil applications in certain situations. Nutrients can be taken up through the stomata on the leaves or through the leaf membranes, making this method particularly useful for addressing nutrient deficiencies quickly.

Other approaches, such as solid nutrient applications to soil, provide nourishment but do not target the plant's foliar surfaces in the same way, which can result in slower uptake. Insecticide treatments, while related to pest management, focus on controlling pests rather than providing nutritional benefits through leaf absorption. Similarly, mulch serves a very different purpose, mainly for moisture retention and soil temperature regulation, and does not involve direct nutrient application to the plant leaves. Thus, the definition of foliar spray is clearly encapsulated in its purpose and application method.