Japanese beetles and corn silks.

Tue Jul 17, 2007 11:10 pm

The Japanese beetles are eating the heck out of my sweetcorn silks. It looks like the pollen has all dropped, so it may be OK. Anyone else see this? Is there anything to do?


Wed Jul 18, 2007 6:22 am

Trent, get the problem here too. Don't like using spray's and powder's as eventually the stuff goes into my mouth? What I've done is to mix up a strong solution of soapy water, and spray the leaves and stalks of my plants. Of course, if you get a hard rain just afterwards, it'll just wash away. You'd be surprised how the little pests don't seem to like the flavor of soap.

Wed Jul 18, 2007 6:31 am

Trent, wish I had that problem here. It's been so dry that my corn is only about a foot high now. In the past I have fixed a powdered coffee creamer plastic container and drilled small holes in the top and sprinkled 5% Sevin dust on the silks. If you have an acre or two of corn, that's not feasible though. I don't really like using Sevin, but neither do I like eating the corn where a bunch of Japanese beetles have been doing their two things, EATING AND MAKING LOVE :roll: :oops: . Pete

Wed Jul 18, 2007 10:53 am

time consuming, but the old timers around here would take an eye dropper ant put a couple of drops of mineral oil down in the silks.

Wed Jul 18, 2007 11:15 am

John, maybe we should use a mixture of EXLAX and something. Then they wouldn't have time to eat all day :oops: . Pete

Wed Jul 18, 2007 12:45 pm


From the University of Illinois Cooperative Extension Service;

"Japanese Beetles

Huge numbers of Japanese beetles have been reported in Illinois this year. It was reported that a total of 71,984 Japanese beetles were caught in a single trap in a 24-hour period in Massac county southern Illinois on June 20-21. The beetles have mainly been a problem near urban areas. The beetles will feed on soybeans and corn (as well as hundreds of other species of plants), but the damage to soybeans usually isn’t sufficient to pay for an insecticide treatment. A general threshold for soybeans is to consider an insecticide if there is 20% leaf defoliation during the reproductive stages. Most people tend to greatly over estimate percent defoliation. The pictures in the following ICM article can help in estimating leaf defoliation: http://www.ipm.iastate.edu/ipm/icm/2002 ... ation.html.

The beetles can cause a substantial yield loss in corn, since they often feed on the silks, so corn fields need to be watched closely in the next few weeks in the areas where Japanese beetles have been observed, such as eastern Clinton, Jackson, Muscatine, and Scott Counties. An insecticide should be considered if the beetles are keeping the silks clipped to within 0.5” of the ear. In past years, much of the silk clipping was done by the beetles after pollination was complete. It seems like the beetles are emerging earlier than in the past, which means any silk clipping is more likely to affect pollination. The beetles will continue to emerge for several weeks and can live for 30-45 days, so they can continue to cause problems into August. For more information including pictures of the beetles, see the August 19, 2002 ICM Newsletter at http://www.ipm.iastate.edu/ipm/icm/2002 ... etles.html.

Hope this may help.


Wed Jul 18, 2007 9:30 pm

Didn't have a problem with the beetles on my sweet corn but they seem to like to eat on my okra leaves. Fed them a little Sevin and that seemed to help my problem.

Wed Jul 18, 2007 9:56 pm

They were on my okra and I put the sevin to 'em. They went right to the sweet corn. :(


Thu Jul 19, 2007 6:16 am

Need to go look at my corn,finally got rain last night!!!!Hope the beetles arn't getting mine!!!!We have 3 traps out and the bags fill up quick!!!!!Kevin

Thu Jul 19, 2007 9:13 am

KETCHAM wrote:... We have 3 traps out and the bags fill up quick!!!!!Kevin


Take your traps to the neighbors! Proven fact: the traps attract more beetles than they catch. End result - - you have more beetles than you would have without the traps. Traps are an example of excellent marketing. Save your money.


Thu Jul 19, 2007 9:51 am

just emptied the bags this morning,after my post!!!Clear full!!!Silks are OK on the corn.Kevin

Wed Aug 01, 2007 12:05 pm

I have some nice ears, the corn was pollenated when those little buggers started eating away at the silks, I guess. Its that time of year, eatin' real good!!


Wed Aug 01, 2007 2:18 pm

Good tip Bill !
But , that is what I would expect from a Extension agent, Retired or not, you are still the man.

Wed Aug 01, 2007 6:32 pm

I've got those beetles as well. Sprayed once with liquid Sevin - now there are dead beetles all over the ground, but still they come. Doesn't matter too much - I think the pollen thing was done before they arrived. I've picked some ears that they had chewed the silks all the way off, and they seem ok. Just hasn't been a good year for corn here - too dry for too long. And we are still about 7" below normal rainfall. As much as I hate to say it, we almost need one of those good ol tropical storms from the Gulf to catch up. Planted it twice - 1st time, it didn't even come up. Once it did sprout, seems like the weeds in the row grew faster than the corn, so now I have weeds as tall as the corn. We will still get enough to eat, but don't look like we will get enough to freeze this year.

Maters are doing good - almost too good! Canned 30+ quarts of juice, and we will be canning maters this weekend. Picked four 5 gal buckets full of maters Monday, and there are more ready today. 3 dozen plants. Checked the green beans - they are almost ready. Got 4 watermelon Monday, and my first two cantaloupes today. Life is busy, but good.

Know what you mean about those ag agents. Our main agent here has quite the following. We hated to see him retire a few months ago. Would like to have just an ounce of his knowledge!


Wed Aug 01, 2007 7:09 pm

Craig, I know what you mean by the grass growing quicker than everything else after we finally started getting a little rain. I have just given up on the garden this year. As they say, just wait till next year :roll: . Pete