How to disable selectOneMenu in primefaces?

I am using primefaces and trying four hours to disable p:selectOneMenu tag when date is picked from p:calendar. But this doesnt not work, and it refreshes page.

<p:calendar id="deadLineDate" value="#{projectsController.selected.deadLineDate}" title="#{bundle.CreateProjectsTitle_deadLineDate}" pattern="dd/MM/yyyy">
                        <p:ajax event="dateSelect" onsuccess="$('.ui-selectonemenu-label:last').attr('disabled','disabled'); return false;" />
                    </p:calendar>

I have tried to do this on many ways, but I cant get this to work. By this I mean to disable p:selectOneMenu when p:calednar have input