Learn Spanish (Latin America): Viendo un tallo podrido, córtalo inmediatamente. - If you see a rotten stem, cut it immediately.

In Spanish, the gerund (the -ndo form) can act as a conditional clause, replacing si (if). Using Viendo un tallo podrido is a concise way to say Si ves un tallo podrido. This structure is especially common in instructions, manuals, or proverbs.

Can I use this conditional -ndo structure for any "if" statement?

It works best when the person doing the gerund action is the same person doing the main action. Here, "you" are the one seeing the stem and "you" are the one cutting it. If the subjects are different, it is usually better to stick with a standard si clause to avoid sounding awkward.

Why does córtalo have an accent mark?

The base command is corta (cut), which has its natural spoken stress on the second-to-last syllable: cor. When we attach the direct object pronoun lo (it) to the end, the word gains an extra syllable. To keep the spoken stress on cor, we have to add a written accent mark.

What verb does podrido come from?

It is the past participle of the verb pudrir (to rot), functioning here as an adjective to describe the stem (tallo). Notice that because it acts as an adjective, it ends in -o to match the masculine singular noun it modifies.