It looks like the White House vegetable garden — first lady Michelle Obama’s effort to model healthful eating for the nation — is infested with a pest previously unknown to horticulture. It’s the boll weevil of the blogosphere: the conspiracy theorist.

President Obama’s detractors are suggesting that the garden on the South Lawn (planted by Michelle Obama and schoolchildren in March) is fake. The conspiracy theorists claim that, despite a lot of compost and a very rainy spring, the vegetables harvested by the first lady and those same schoolchildren last week could not have grown so big in just 90 days.

These critics surmise that the White House substituted mature plants for immature ones — in the dead of night, I guess — in order to fool the public. An actual-dirt dirty trick that would live up to the name Watercressgate.

I wear two hats here at the Baltimore Sun. I write this column and a gardening blog called Garden Variety. It was in that capacity that I was invited to the White House last week to cover the harvest of the spring crop — snap peas and lettuces — and the picnic Obama and the children prepared with the results.

It was in the comments posted to Garden Variety that this new conspiracy theory emerged.

“That garden was bought at a produce section and faked,” wrote Clint Brown. “That is staged and you all know it.”

“That’s what they do on every issue,” wrote Mike A. “1) bait 2) switch 3) media say ‘who cares.’ ”

An Internet search revealed the same skepticism elsewhere, on news feeds like the Drudge Report and on conservative “Obama-watch” blogs.

My own nephew (he is a Republican) sent me a text message saying, “There’s no way those are the same plants. If they are, then I’m moving to D.C. and starting a farm and raking it in.”

The garden appeared legit to me.

The Swiss chard and the collard greens and the kale and the lettuces looked just like the produce being sold at my neighborhood farmers’ market.

The tomato plants look further along than mine, but then, Washington is 40 miles farther south.

Other readers of the Garden Variety blog jumped in to defend the Obamas and said “Vanderleun” and Clint Brown wouldn’t believe the garden was real if the White House produced time-lapse photographic proof.

I’d be laughing if this wasn’t so scary.

There are people who believe President Obama’s Hawaiian birth certificate is forged. And those who are convinced he is a Muslim mole.

But a fake vegetable garden?

And the point of faking a vegetable garden would be … what? To trick the American people into believing that the first family is eating nutritious food when they are really sneaking out for burgers?

Wait. The president already did that.

I didn’t just fall off the turnip truck, to keep the vegetable analogies going here, and I know the White House vegetable garden is more than a good example of being a good example.

While the fifth-graders from Bancroft Elementary School waited patiently to chow down last week, the first lady addressed the attending media on the role a healthful diet plays in good health and — ba-da bing! — the importance of the health-care reforms her husband is undertaking.

But to secretly truck in full-formed vegetable plants and plant them when no one was looking seems like a long way to go to make a point. She could have just visited a D.C. farmers’ market and saved herself some dirty knees.

Well, if all politics is local, I guess all local vegetables are political.

Susan Reimer is a Baltimore Sun columnist. This commentary appeared in Wednesday’s Sun.