At the highest levels — say, in the English Premier League — soccer is played on immaculately groomed fields of vibrant green.

The reality is that you should not study the grass too closely unless you are a connoisseur of the dark art of spitting.

Throughout the history of the game, players have been spewing sputum with reckless abandon.

And “reckless abandon” doesn’t cut it in the era of Covid-19 — which is often transmitted through the mouth.

The top medical man at Fifa, the world soccer organizing body, wants to see spitting sanctioned with a yellow “caution” card shown for each salivary eruption.

An interesting and pressing topic, to be sure, but spitting and soccer go together like “corona” and “virus”.

Can we have one without the other?

The Premier League is trying to get back on the pitch, after the Covid-19 virus pushed them to the sidelines in early March.

Among the masses of topics to be discussed, spitting has become a target for sanctions.

Michel D’Hooghe, the medical committee chairman for Fifa, soccer’s organizing body, believes that spitting must be addressed before the game resumes.

“This is a common practice in football and it is not very hygienic,” D’Hooghe told the Daily Telegraph.

“So when we start football again I think we should have to avoid that, at maximum.

“The question is whether that will be possible. Perhaps they can give a yellow card.

“It is … a good way to spread the virus. This is one of the reasons why we have to be very careful before we start again.

“I am not pessimistic but I am rather skeptical.”

Scientists say that saliva could stay on the pitch for hours, and that coronavirus could be passed on by players, who may not show sign of the illness.

“If the person is infected … the virus is present in the throat and can ejected into the environment by spitting,” said Dr. Ian Brierley, a virologist quoted by the Telegraph.

D’Hooghe’s skepticism comes from watching the game. Players hack up phlegm and then spit it — the alternative being swallowing it.

If a yellow card is handed out for every sputum-launch, teams would run out of players before halftime.

And in this case, D’Hooghe has not addressed the even more appalling practice known informally as the “snot rocket” — which is getting rid of mucous via the nose.

I wrote about this six years ago. To quote myself:

“Whenever they have break in play — a ball goes over the line, or someone fakes an injury — and cameras zero in for closeups of someone who a moment ago was involved in something quasi-interesting, the odds are about 50-50 that guy is gonna launch some snot.

“Here is what they do.

“They place an index finger against one side of their nose, and then exhale violently through the other nostril — and snot is launched. Often, a gob of it. Flying through the air. Perhaps landing a few feet away.

“And if the camera hangs around long enough (and, really, directors should cut away from this the moment a player puts his finger on his nose), we often get to see the player place a finger on the other side of his nose, and then snot-blow the other nostril. The double snot-rocket launch.”

That needs to go, too, not just for the sake of being polite, but because it is more disgusting and just as virus-laden.

My suggestion to Fifa would be that both forms of blowing snot should be sanctioned, before games resume.

What better time than now, when nearly everyone on the planet knows the dangers of sharing a deadly virus?

It will involve breaking the habits of a lifetime, for most players. And maybe they could be given a slight aid by placing the modern-day equivalent of a spittoon on the touchlines.

It is time to act.