and its polymers are particularly useful for this purpose they may be used in conjunction with a surfactant such as an alkyl phenol ethylene oxide condensate suitable coating formulations may contain from 10 to 98 of the said coating materials such as di 1 p menthene and polymers with from 1 to 30 of a surfactant or wetting agent or mixture of these water may be added as a diluent in forming a satisfactory emulsion the rates of application will vary with the estimated weight of the hay crop the application rate of the coating material in the formulation should be between 0 03 liter per tonne of crop to 0 5 liter per tonne of crop a crop of alfalfa estimated to yield 25 tonnes per hectare would thus receive 0 75 12 5 liters of the said coating material per hectare the material may be sprayed from the ground or the air suitable application rates would be from 25 to 75 liters per hectare by air or from 40 to 600 liters per hectare by ground where appropriate the formulation containing the coating may be used in tank mixture with a desiccant the application of the coating may precede or application of a desiccant within a period in which the desiccant has not significantly affected the crop suitable desiccants include diquat and endothal alfalfa.