Encontramos pulgones y un hongo durante la plaga.

Encontramos can be either:

• preterite: we found
• present: we find

So by itself, encontramos is ambiguous. You know which meaning is intended from the context.

In this sentence, if the given meaning is we found aphids and a fungus during the infestation, then encontramos is the preterite.

This happens with some -ar verbs in Spanish:

• hablamos = we spoke or we speak
• trabajamos = we worked or we work

Context tells you which one it is.

Spanish often leaves out the article when talking about some things in general or when introducing unspecified plural nouns.

So:

• Encontramos pulgones = We found aphids
• Encontramos los pulgones = We found the aphids

The version with los would usually refer to specific aphids already known in the conversation.

Here, pulgones just means aphids in a general, indefinite sense.

Because the sentence is treating them differently:

• pulgones = aphids / some aphids → plural, indefinite, no article needed
• un hongo = a fungus / one fungus → singular, so un is used

So the structure is basically:

• aphids
  • a fungus

This is perfectly normal in Spanish.

The singular is pulgón.

So:

• pulgón = aphid
• pulgones = aphids

Notice the changes:

• the ending -ón becomes -ones in the plural
• the written accent disappears: pulgón → pulgones

This is a common pattern:

• camión → camiones
• lección → lecciones

Because when the word changes to plural, the natural stress changes.

• pulgón is stressed on the last syllable, so it needs a written accent
• pulgones is naturally stressed on go, so no written accent is needed

This follows normal Spanish stress rules.

Hongo usually means fungus, which is the broader biological term.

Depending on context, it can sometimes refer to a mushroom, but in a sentence like this, especially with aphids and plaga, it most likely means fungus.

So:

• hongo = fungus
• seta = often mushroom in everyday Spanish in Spain

In Spanish, nouns usually need an article in this kind of expression.

So:

• durante la plaga = during the infestation / during the plague

Saying durante plaga would sound incomplete or unnatural in normal Spanish.

The article la points to a specific event or situation:

• the infestation
• the plague
• the outbreak, depending on context

Plaga can mean several related things, depending on context:

• plague
• infestation
• pest outbreak

Because the sentence mentions aphids and fungus, this is probably an agricultural or gardening context. So plaga most naturally means infestation or pest outbreak, not necessarily something like the historical Black Plague.

Because the personal a is mainly used before specific human beings and sometimes pets or personified animals.

Examples:

• Vemos a María
• Encontré a mi hermano

But here the objects are things:

• pulgones
• un hongo

So no a is used:

• Encontramos pulgones y un hongo

That is exactly what you would expect.

The h in Spanish is silent.

So hongo is pronounced roughly like ONGO, with the first sound coming from the o, not the h.

Also:

• the g in hongo is a hard g sound, like in go
• the stress is on the first syllable: HON-go, though the h itself is silent

This is a very normal Spanish word order:

• Encontramos = verb
• pulgones y un hongo = what was found
• durante la plaga = when it happened

Spanish word order is often flexible, but this version is straightforward and natural.

You could move the time phrase for emphasis, for example:

• Durante la plaga, encontramos pulgones y un hongo.

That means the same thing, but it puts more focus on during the infestation.

No, not naturally in this sentence.

Encontrar can sometimes mean to come across, to find, or in some contexts to meet, but with objects like aphids and a fungus, the meaning is clearly found or came across.

So here:

• Encontramos pulgones y un hongo = We found aphids and a fungus

Not:

• We met aphids and a fungus

Spanish changes y to e only before words that begin with an i sound.

For example:

• padre e hijo
• España e Italia

But hongo begins with an o sound, because the h is silent:

• hongo → starts with o

So the correct conjunction is still y:

• pulgones y un hongo

Not e un hongo.