Latin Adjectives for Masculine 1st Declension Nouns

This is a side note to First and Second Declension Adjectives:

• In Latin, nouns and adjectives must agree in gender, number, and case.
• Most, but not all nouns of the first declension are feminine.

Masculine first declension nouns require masculine adjectives. While today an agricola (farmer) may be feminine, in antiquity, a farmer, sailor, or pirate was assumed to be masculine, and so the first declension nouns that correspond with these English words are also masculine:

• agricola
• nauta
• pirata

In order to modify the masculine agricola, nauta, or pirata, there must be masculine endings on the adjectives.
The good farmer would be:

agricola bonus

The great sailor would be:

nauta magnus

In the familiar phrase: "Carthago delenda est," Carthage is a feminine noun and is modified by a feminine form of the passive periphrastic -- which includes an adjective ("delenda") and a form of the verb to be ("est").
Were we to translate "the pirate must be destroyed" into Latin, we could do it using the passive periphrastic in this way:

pirata delendus est.

We would probably want to say "pirates must be destroyed," in which case, we would need, not only a change of gender (delenda to delendus), but a change in number (singular to plural):

piratae delendi sunt