The present invention is directed to methods of treating a plant having a plant part. One method involves providing a plant having a plant part; applying an aqueous treatment formulation to the plant, where the aqueous treatment formulation comprises a thickener, a water soluble divalent salt, a foam control agent, a complexing agent, a film forming agent, and water; and harvesting the plant part, where the aqueous treatment formulation, when applied to a surface of a plant, creates a water fast film on the surface that permits permeation of an aqueous material to the plant while minimizing loss of moisture or loss of a plant treatment chemical from the plant as compared to when the composition is not applied to the surface of the plant. The present invention also relates to a methods of treating a harvested plant part and to the treated harvested plant parts.