CakePHP 2, CakePHP conditions, Dynamic condition on search, MySQL expression - php

Question

I am trying to build a search query for report in my CakePHP application. In my query condition building go through a if, else statements. On initial load of report I want to load the pre-defined criteria and when user submit the search conditions will be changed on selection.
This is my initial conditions
$conditions['Report.expense_status'] = array('COMPLETED');
$conditions['DATE(Report.created) >='] = "date_sub(now(), interval 2 month)";
When user do a search conditions should update as below.
if ($this->request->is('post')) {
$search = $this->request->data('Report');
if( strlen($search['From']) > 0 ){
$conditions['DATE(Report.created) >='] = date( 'Y-m-d',strtotime($search['From']) );
}
}
But my initial condition code output the SQL expression as below and it is not getting populate the result.
DATE(`Report`.`created`) >= 'date_sub(now(), interval 2 month)'
it is adding quotes to the expression.
How should prevent adding quotes around condition?
Form:
<?php echo $this->Form->create('Report', array('action' => 'index')); ?>
<div>
<?php
echo $this->Form->input('Keyword');
echo $this->Form->input('Status',
array(
'options' => $status,
'multiple'=> 'false'
)
);
echo $this->Form->input('Child',
array(
'options' => $children,
'multiple'=> 'false'
)
);
echo $this->Form->input('From',
array(
'id' => 'report_from'
)
);
echo $this->Form->input('To',
array(
'id' => 'report_to'
)
);
?>
<div class="footer">
<div>
<input type="submit" value="Search" name="action">
<input type="button" value="Cancel" name="action">
</div>
</div>
</div>
<?php echo $this->Form->end(); ?>