Cosmic strings and the string dilaton

The existence of a dilaton (or moduli) with gravitational-strength coupling to matter imposes stringent constraints on the allowed energy scale of cosmic strings, eta. In particular, superheavy gauge strings with eta similar to 10(16) GeV are ruled out unless the dilaton mass m(phi) greater than or similar to 100 TeV, while the currently popular value m(phi) similar to 1 TeV imposes the bound eta less than or similar to 3 x 10(11) GeV. Some nonstandard cosmological scenarios which can avoid these constraints are pointed out.