Influence of Fertilizer Particle Size on Efficacy of Dithiopyr, Prodiamine, Oryzalin, and Oxadiazon for Southern Crabgrass (Digitaria ciliaris) Control

Abstract

A commercial fertilizer (40-0-0, N-P-K) was screened into seven particle size fractions (23, 58, 165, 465, 1,310, 3,728, or 10,606 particles/g) and coated with dithiopyr (0.345%, wt/wt), prodiamine (0.689%), oryzalin (3.28%), or oxadiazon (2.76%). Dithiopyr and oryzalin provided best southern crabgrass control with a fertilizer size of 465 particles/g or greater, whereas prodiamine controlled southern crabgrass greatest using a size fraction at least 165 particles/g. Southern crabgrass control with oxadiazon was not as dependent on particle size, with all fraction sizes of 58 or 165 particles/g or greater controlling southern crabgrass equally in 1995 or 1996, respectively.