Abstract: A composition and method for reducing plant transpiration and preventing drought-induced wilting and for reducing water use by crops is disclosed. The composition includes an aqueous solution of chitosan and a nonphytotoxic acid. In an embodiment, the chitosan is derived from ground fungal mycelia.

Abstract: The present invention provides novel methods of producing chitosan having a tap density of at least about 0.4 g/ml. In one aspect of the present invention, chitosan is selected having an average molecular mass of from about one thousand Daltons to about two million Daltons; a particle size that is smaller than 20 mesh; a viscosity of at least about 1 cps, and a percentage of deacetylation of from about 65% to about 98% A measured amount of the selected chitosan is then mixed with an amount of water that is from about two to about ten times the weight of the chitosan, and an amount of an acid that is at least about 0.1% of the weight of the chitosan. The acid is preferably an organic acid. The mixture of chitosan, water and acid is then mixed to a smooth paste, dried to a moisture content of from 0% moisture to about 20% moisture, and the particle size is preferably reduced to smaller than 20 mesh. In another aspect of the invention, chitosan is provided having a tap density of at least about 0.