The present invention is directed to methods for inhibiting the growth ofdisease organisms, particularly fungi and bacteria, on plant tissues. Thepresent invention is also directed to methods for inhibiting the infestationof plants by insects and larva, particularly sucking and chewing insects.These methods are achieved by applying an auxin or a plant growth regulator(PGR) which will effect the level of auxin in the plant tissue to the seeds ortubers of the plant prior to planting or to the roots, foliage, flowers orfruit of the plant after planting. The auxin or PGR is applied in an amounteffective to inhibit growth of the disease organisms or insects, but in anamount insufficient to negatively effect growth of the plant tissues. Theauxin may be applied as a natural auxin, synthetic auxin, auxin metabolite,auxin precursor, auxin derivative or a mixture thereof. The presentlypreferred auxin is indole-3-acetic acid (IAA). The auxin or PGR may be appliedto the seeds, tubers or plant tissues. Seeds or tubers may be sprayed with orimmersed in an aqueous solution containing the auxin or PGR. Conventionalspraying and drip irrigation systems may be used to apply an aqueous solutioncontaining an auxin or PGR to plant tissues. The auxin or PGR may also beapplied to the plant tissues as a powder or may be encapsulated within abiologically compatible material to provide slow release to the roots of theplant. The plant tissues may be dusted with a powder, including the auxin orPGR. The encapsulated auxin may be placed in the root zone for uptake of theauxin or PGR by the roots.
