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Avoid this herbicide, if you love your trees

Tuesday - 7/26/2011, 9:12am  ET

How much should you water your lawn in the heat?

WTOP's Mike McGrath talks about what you need to do.


Warning: New lawn herbicide imprelis is killing trees

The EPA had high hopes for Imprelis, a new herbicide it approved for lawn care professionals last fall, as it seemed to be less toxic to humans and other mammals than previous weed killers. But now reports are coming in from all over the nation of massive die-offs of trees located in or near the treated lawns, especially Norway spruces and white pines. Thousands of dead and dying trees have already been reported.

Although not available directly to homeowners, the herbicide has been embraced by lawn care professionals and used on home lawns, athletic fields and golf courses. Dupont, the manufacturer of Imprelis, has issued a warning to landscapers not to use it near susceptible trees. Make sure your lawn care service complies.

And if you have a conifer that's suddenly turning brown and is located on or near a lawn that's -ahem-"professionally" cared for, contact your local EPA office.

Note: You wouldn't have to worry about this if you lived in New York or California. Neither of those states granted it approval-so their trees are safe.

Where are the stink bugs?

Greg in Vienna is one of many listeners who have written in to ask, "Where are the stink bugs? I haven't seen any this summer!" Well Greg, the consensus so far is that the recent winter that was so hard on us must have been darned hard on the stinkers too. I've only seen a few in my garden; and so far -- knock on particle board -- no one seems to be infested with them. Yet.

And if they do show up, trap them

Even if the current situation changes and we end up under assault again, we have a brand new weapon to fight them. A stink bug pheromone trap just has been released under the Rescue brand name. It's been popping up at stores throughout our area the past week or so. The trap attracts males, females and the immature nymphal stage. Because it doesn't seem to lure more bugs onto your property, it looks to be a great control option.

Click here for retailers that are carrying the traps and lures.

Virginia gets feds to allow use of bee-killing pesticide

Earlier this week, a short AP news item that appeared on the WTOP website () announced that the state of Virginia had gained an emergency exemption from the EPA to allow fruit growers to use the pesticide Dinotefuran this summer and fall to control the imported mamorated stink bug that caused so much crop damage last season.

You've probably guessed by now that I don't like any chemical pesticides, but this emergency exemption seems especially misguided, as the chemical in question is extremely toxic to honeybees and is one of the agents suspected in the massive honeybee colony collapses that have devastated beekeepers recently. Fruit growers, please use common sense and restraint here-and beekeepers be warned!

Slime mold? Wood mulch

Elsie in Haymarket is our wood mulch victim of the week. She writes, "A spotted yellow and pink mold has appeared in my vegetable garden. I remove it, but it keeps coming back. It's also starting to crop up in my perennial beds. Did my garden center give me bad mulch?"

Elsie, as I've been warning our listeners for over a decade, all wood mulch is bad mulch. No, you didn't tell me you were using a wood or shredded bark mulch in your beds. The slime mold told that tale.

Now, this particular 'nuisance fungus' is harmless, but other types are not like the dreaded artillery fungus, which stains homes and cars irrevocably with little tar-like balls. And all wood mulches steal food from plants.

Rake it all up, replace it with a nice black compost mulch and all will be well.

Sorry, but gypsum won't cut the clay

Tim in Ashburn writes, "Two years ago we moved into a house with typical hard packed clay soil (I'd be lucky to get a shovel more than 2 inches deep into it). Last fall I aerated and top dressed with about an inch of compost and re-seeded. The lawn came in like gangbusters, but burned up during our first heatwave in June. I put most of the blame on our brick-like clay soil. I've read that putting gypsum on the lawn might help break up the clay. Would that work for us?"

I really doubt it, Tim. Despite many rumors and assurances to the contrary, gypsum has very little effect on clay soil.

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