Q. My question today is, how to deal with white grubs in
established landscape plants. I have seen them in a few yards in
Mesquite, NV this year. Is it just a seasonal thing? I just found 7 more
yesterday in Mesquite on one property. How do I get rid of any
there now and how to prevent in future? Are some plants more
susceptible than others? Some of the plants I found them in the
dirt: Eucalyptus just planted, texas mountain laurel, african sumac, and
I think they got a bunch of myoporum, agave parryii, Santa Barbara Daisy.
A. I will tell you as much as I know about these grubs. They like to feed
off of decaying organic material. I think sometimes they get confused between
dead and dying organic matter and small roots of plants like Lantana and so you
find them everywhere.
I guess I just figure that wherever the soil is been
enriched and there’s healthy plants you’re going to find these critters. They
mature into June bugs, metallic green June beetles, rose chafer’s and just
about anything else in that particular family of bugs.
They are fairly easy to
kill with a soil drench of Sevin insecticide but the problem is which plants do
you drench? All of them? The adults pupate around May or June so if you are
going to treat plants with an insecticide then you’re going to do it fairly
early in the season or fall. It doesn’t make much sense to put down an
application close to may because the are adults are going to emerge and fly
around and meet and be back in the soil by July or so.
You can try spreading the bacteria that are supposed to kill them long term or the nematodes. These biological control insecticides may take a bit longer to get established in the soil or they may require you to treat every year. Read the label!
So if I were to get a
jump on them you would probably be in fall. The question still remains which
plants do you treat because they are going to all look healthy even if they
have these guys feeding on the roots or not.
They ate the roots of my large agave which looked fine until it fell over, it's root base smelling really bad.
I used Merit soil drench and the neighboring plant stayed healthy. That was 10 years ago and reading this post will remind me to drench it again. I wonder what solutions to this problem the Tequila producers use?