73.041 Acquiring or perfecting title after appropriation.—In any instance, where the petitioner has not acquired the title to or a necessary interest in any lands which it is using, or if at any time after an attempt to acquire such title or interest, it is found to be defective, the petitioner may proceed under this chapter to acquire or perfect such title or interest; provided, however, that the compensation to be allowed the defendants shall be determined as of the date of appropriation.