Strawberry Root Weevils

by Lisa Linderman on April 20, 2011

in berries,pest control,spring planting

I grow a lot of strawberries.  There’s nothing better than a fresh strawberry from the backyard, and I love to make jam and strawberry pie and strawberry shortcake.  At the end of the season, of course the berries send out runners and make new plants, so I have more and more and more plants.  The walkways around my raised beds are wood chips, and the strawberries think it’s the best rooting medium ever, so I have lots of healthy starts with healthy roots, as soon as I dig them all up.  Usually in the spring I dig them up, and replant them or give them away or sell them.

This year I decided to more than double the space I’m giving to strawberries.  The reality is, no one in my family eats that many vegetables, and the ones we do eat are rather boring, so I didn’t need quite as much space as I have.  Awesome, more strawberries means maybe next year I won’t run out of strawberry jam in March and have to wait for berry season to make more!   So I began digging up the berry bed and sorting starts, renovating the old plants, and getting ready to replant.  Then I discovered — them.

Strawberry Root Weevils

Strawberry Root Weevils. Ew.

Little white semi-circular grubs with orangish heads, curled up tight in the soil.   Sometimes one, sometimes a little patch with five or six.  AUGH.  Strawberry Root Weevils.  I’ve had them before, at my old house, but this is the first go-around with them here.  Rotten little critters, they’re beetle-like weevils in their adulthood.  Despite their names, the adults nibble the margins of leaves including strawberries, euonymous, peonies, and lilac,  and the grubs will feed on the roots of strawberry, raspberry, clover, spruce, Douglas-fir and other woody shrubs.  Articles will tell you they don’t do much damage, but my strawberries sure don’t like them.  They reduce yield and make the strawberry susceptible to stress and other diseases.

Root weevil damage

The small round spot in the middle of the picture was caused by root weevils.


When I dug up my berries, I found most of the older berries (2nd and 3rd year) had little in the way of “fine” rootlets, and some had outright damage to the roots and lower crowns.  While the plants were still growing, the root structure didn’t look healthy at all.  I ended up digging them out, and since I have so many young and very healthy starts, I will probably discard them.  If I didn’t have so many starts to repopulate the area, I would replant these; they’re not terminally ill, they’re just depressed.

Healthy strawberry roots.

Healthy strawberry roots, no weevil damage.

So what do you do about strawberry root weevils?  Me, I let my chickens follow me through the garden and toss them all the squirmy little nasty larvae, and the chickens love me for it.  But if you don’t have chickens, you can do what I also do…turn the soil and pick the grubs out by hand.  It’s a bit tedious, and you won’t get them all, but you should be able to make a good dent in even a large population in fairly short order.  The best organic control is application of parasitic nematodes in the family Heterorhabditis.  Remove the leaf debris first, and then apply the nematodes in late spring or early summer, when adults are out and eggs begin to hatch.  Nematodes can be purchased at many nurseries.  Ask for them at the counter, as they are usually kept refrigerated.  Application is usually with a sprayer, as the nematodes are mixed with water to apply.  (They’re not visible to the naked eye.)   There’s a good paper on the subject from the WSU Extension if you care to read the gory details!

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