hayake to gaityuu wo kakuninsuru.

It is read:

• 葉焼け = はやけ (hayake)
• と = to
• 害虫 = がいちゅう (gaichuu / gaichū)
• を = o (written wo in romanization, but pronounced o)
• 確認する = かくにんする (kakunin suru)

So the full reading is:

はやけ と がいちゅう を かくにんする。

These are both noun phrases:

• 葉焼け

  • 葉 = leaf
  • 焼け = burning, scorching, discoloration from being burned
    Together, 葉焼け means something like leaf scorch, leaf burn, or sunburn/scorching damage on leaves.

• 害虫

  • 害 = harm, damage
  • 虫 = insect/bug
    Together, 害虫 means harmful insects, pests, or plant pests.

So the sentence is grouping two things you are checking for: leaf damage and pests.

と is being used to connect two nouns, like and in English.

So:

• 葉焼けと害虫 = leaf scorch and pests

This is a very common use of と:

• A と B = A and B

Here it simply lists the two things that will be checked.

Because 葉焼けと害虫 works as one combined object of the verb.

Structure:

• [葉焼け と 害虫] を 確認する
• check [leaf scorch and pests]

In Japanese, when two nouns are joined by と, you usually do not need to put を after each one. The whole list gets marked once.

So this is natural:

• 葉焼けと害虫を確認する。

Not this:

• 葉焼けを害虫を確認する。 ✗

You can think of it as:

• A and B
  • object marker + verb

確認する means to check, to confirm, or to inspect.

It often has a more deliberate, practical feeling than 見る.

• 見る = to look at / to see
• 確認する = to check and make sure

So in this sentence, the idea is not just look at leaf scorch and pests, but more like:

• check for leaf scorch and pests
• inspect the plant for leaf damage and pests
• confirm whether there is leaf scorch or pest damage

This kind of verb is very common in instructions, manuals, care guides, and checklists.

The dictionary form is often used in Japanese for:

• instructions
• labels
• headings
• checklist items
• general statements
• plain, neutral descriptions of an action

So 葉焼けと害虫を確認する。 can sound like:

• an instruction: Check for leaf scorch and pests.
• a procedure step
• a note in a plant-care guide
• a to-do item

Japanese often uses the plain dictionary form in places where English might use:

• the imperative: Check ...
• an infinitive-like label: To check ...
• a manual style instruction

Yes, most likely.

Japanese often omits the subject when it is obvious from context. This sentence does not explicitly say who is doing the checking.

Depending on context, it could mean:

• You should check for leaf scorch and pests.
• We check for leaf scorch and pests.
• One should check for leaf scorch and pests.

In a care manual or instruction list, the implied subject is often you.

Yes, that is a very natural way to understand it.

In Japanese, the direct object of 確認する is often the thing being checked, but in English we often phrase it as:

• check for leaf scorch and pests
• check whether there is leaf scorch or pest damage

So even though Japanese says 葉焼けと害虫を確認する, the natural English interpretation is often inspect for signs of leaf scorch and pests, not literally confirm the leaf scorch and the pests as already-known objects.

It is natural, but it has a slightly instructional or checklist-like feel.

Because of the plain dictionary form and the concrete nouns, it sounds like something you might see in:

• a gardening guide
• a plant-care manual
• a troubleshooting chart
• a work procedure
• a checklist

For example:

• 葉焼けと害虫を確認する。
  Check for leaf scorch and pests.

In everyday conversation, a speaker might use a fuller sentence depending on the situation, such as:

• 葉焼けや害虫がないか確認してください。
  Please check whether there is any leaf scorch or pest damage.

But the original sentence is still perfectly natural in the right context.

Usually, no.

Standard Japanese is normally written without spaces:

• 葉焼けと害虫を確認する。

Spaces are often added only for learners, teaching materials, or special formatting. So the version with spaces is helpful for study, but the normal written form would be the one without spaces.

Good question. Both can connect nouns, but they feel a little different.

• と = A and B
  a more complete, direct listing
• や = A and B and so on
  a non-exhaustive or example-based listing

So:

• 葉焼けと害虫を確認する。
  = Check for leaf scorch and pests.

This sounds like those are the two specific things to check.

If you said:

• 葉焼けや害虫を確認する。

it would sound more like:

• check for things such as leaf scorch and pests

That is possible in some contexts, but と is better if these are the clearly intended items on the checklist.