Disclosed are solid forms of 4-(2-bromo-4-fluorophenyl)-N-(2-chloro-6-fluorophenyl)-1,3-dimethyl-1H-pyrazol-5-amine (Compound 1). Methods for the preparation of solid forms of Compound 1 and for the conversion of one solid form of Compound 1 into another are disclosed. Disclosed are compositions for protecting a plant or plant seed from diseases caused by fungal pathogens comprising a biologically effective amount of a solid form of Compound 1 and at least one additional component selected from the group consisting of surfactants, solid diluents and liquid carriers. Compositions comprising a mixture of a solid form of Compound 1 and at least one other nematocide, insecticide and/or fungicide are also disclosed. Also disclosed are methods for protecting a plant or plant seed from diseases caused by fungal pathogens comprising applying to a plant or seed, or to the environment of the plant or seed, a biologically effective amount of a solid form of Compound 1.
