Humate-based Biostimulants Affect Early Post-transplant Root Growth and Sapflow of Balled and Burlapped Red Maple

Abstract

Application of biostimulants, humate-based products marketed as aids to plant establishment, may increase early post-transplant root growth and water uptake of landscape trees. We tested three distinct types of biostimulants on root growth and sapflow of balled and burlapped red maple (Acer rubrum L. `Franksred') trees. Treatments included: humate, 1) as a wettable powder formulation, applied as a soil drench; 2) as a liquid formulation to which various purported root growth—promoting additives had been added, also applied as a soil drench; 3) as a dry granular formulation, applied as a topdress; and 4) a nontreated control. Root growth was monitored through single-tree rhizotrons, and sap flow was measured with a heat balance sapflow system. Roots were first observed in the rhizotron windows 38 days after planting. No biostimulant-treated trees had more root length than nontreated controls, and the two soil drench treatments had the lowest root length throughout the 20 weeks of post-transplant observation. All biostimulants increased sapflow.