This invention relates to multi-branched block copolymers suitable for use as wetting agents. The multi-branched block copolymers are comprised of an oxygen-containing polyfunctional base compound having at least 3 EO/PO block copolymer branches attached thereto. The improvement lies in: (a) the percent hydrophobic component, as defined as the weight % PO in the molecule, being present in an amount from 40% to 60% by weight and in (b) the molecular weight per branch (or arm), as defined as the total number average molecular weight of the polymer divided by the functionality of the base being greater than 1700 gmol−1arm−1. It was surprisingly discovered that this combination of intermediate hydrophobicity and high molecular weight give superior drought tolerance for plants treated therewith.