Abstract: A liquid fertilizer composition having a substantial ability to retard leaching of constituent plant nutrients is prepared by dispersing glyoxylated hydroxypropyl guar in an aqueous mixture containing a fertilizer chemical in a preferred concentration of 0.4-1.5% by weight. Similarly, a liquid herbicide, fungicide, insecticide, fire retardant or other liquid plant treatment composition having the ability to adhere to applied surfaces to resist washing is prepared by dispersing glyoxylated hydroxypropyl guar in an aqueous mixture of such a plant treatment chemical in a corresponding concentration. A method is disclosed for producing glyoxylated hydroxypropyl guar by reacting guar gum with propylene oxide and the reaction product thereof with glyoxal in the absence of alcohol or any solvent.