Creating a new column using existing categorical data

I have two columns with categorical data. One of which is called "Variety" and the other is called "Pollen_donor". I want to create a new column that designates each row as either "self-cross" or "out-cross" based on if the variety and the pollen donor are the same or different. I've been advised to try combining the mutate function with ifelse() but have been having issues.

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