I'm going to assume that these two lines are just typos.

my $start "some start time";
my $start "some end time";
[download]

It always helps us if you cut and paste your code into your question rather than trying to retype it.

Other than that, your problem is the line:

push @{$task},{%hash};

You are trying to use $task as a symbolic reference. Symbolic references can be rather dangerous so they are one of the things that use strict marks as illegal.

I'm not entirely sure what data structure you're trying to build, so I can't really suggest an alternative without more information.

--
<http://www.dave.org.uk>

"The first rule of Perl club is you do not talk about Perl club."
-- Chip Salzenberg