Because the %ENV hash is not propagated to the shell..
This works fine for me:
#!/usr/bin/perl

$ENV{foobar} = "baz";
my $res = `echo \$foobar`;
print $res; #prints 'baz'

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In reply to Re^2: Problem using Backtick having quotes by runrig
in thread Problem using Backtick having quotes by perlmoon

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