Saturday, November 07, 2009

IPM – Part 1

Integrated Pest Management (IPM)

Man at the market: "My wife asked me to buy ORGANIC vegetables. Have these been sprayed with any poisonous chemicals?" - "No," replied the gardener, "you'll have to do that yourself." Anon.

I sat in on an IPM class at Lehigh County Extension this week. I came away determined to better understand IPM use in a home garden. It turned into a major project. I’ll try to follow my steps on this and subsequent posts. I hope I don’t cause you to doze off or run screaming from your monitor.

Integrated Pest Management definition: A scientific approach to effectively manage pests while minimizing negative effects on the environment.

“IPM for the Home Garden” by Karen Delahaut, Integrated Pest Management Specialist, University of Wisconsin-Madison explains it better than I ever could.
Possible slug damage on Rudbeckia.

(The basic management methods for IPM including plant selection, maintenance, etc. are listed in my IPM post of December 7, 2007 and are a very important part of Integrated Pest Management.)
IPM is a decision making process. The steps: 1) Properly identify the pest and it’s life cycle. 2) Monitor the pests’ presence, locations and abundance. 3) Establish a limit to the amount of pests you can tolerate. 4) Decide on a plan of action (or non-action).

I’ll try to follow the Japanese beetle through the IPM process.


Most gardeners recognize the hard-shelled, iridescent beetle and it’s destruction on trees, vines, roses, canna and other ornamental plants. That’s the simple part and the reason I chose Japanese beetle. Some pests are not so easy to recognize. And Japanese beetles give most gardeners fits in my area. So . . . check off identification.

Japanese beetle on bean leaf.

In 2007, Japanese beetles overran my garden. The last two years populations have been much less. How many beetles are too many? For some gardeners the answer is one. Others will put up with a few. Some will gardeners tolerate a chewing mob of beetles and just ignore them.


I’ll begin a year-long life span of the Japanese beetle when they are seen happily chewing away on a plant. The female leaves the plant from time to time and burrows into the soil to lay eggs. The eggs hatch in midsummer and the grubs begin to feed on roots. They remain in the soil becoming inactive going deeper in cold weather. They move toward the surface again in early spring. In warmer weather they turn into pupae and adults emerge to start the cycle over.


Japanese beetles are difficult to kill in the adult stage. Pheromone traps that have been developed confuse breeding beetles but tend to eliminate only about 50% or 60% of the population. Traps actually attract more beetles to the garden. There are sprays that may kill the beetles. I have not heard many good reports of the effectiveness of sprays.

Hand picking into a bucket of soapy water every morning when they are slow to move is an excellent non-chemical solution but it may not be an option for every gardener. This may be the best practice if there is a low count or if the gardener has a high tolerance for large populations.

There are options that are effective in the larval stage. Here timing is important. Grubs need to be near the surface which usually happens in June or July here in zone 6. We can tell when there are grubs near the surface in our yard. When the skunks forage for grubs at night, they leave round shallow holes in the grass. This is a sure sign that grubs are near the surface. Lifting a small clump of sod will also unearth some grubs.

I am trying to keep an open mind. I’ll look at the options in the next blog. Are we having fun yet?

In the meantime, here are two publications recommended by Lyn Garling, Program Manager PA IPM, Penn State University “Welcome to IPM” and the ”Extension Toxicology Network”.
(Comments, arguments, corrections welcome.)


Tatyana@MySecretGarden said...

Marie, your post is precious! Teach us, educate and enlighten us please! I'll check the publications which you recommended, but I hope you'll post more on this subject. I love the beginning of the post, too! Have a great weekend!

maría cecilia said...

Hello Marie, this is a very useful information, but I don´t think I´ve seen this insect Japanesse beatle in my garden, but some others like those little ones that overcrowed the roses in springtime, very little ones, perhaps the solution would be the same one as for the japanesse beatles... I´ll try.
Thank you so much for sharing these tips, and enjoy your classes!!
María cecilia

Marie said...

Thank you Tatyana,
I'll posting Part 2 and maybe even Part 3 until I get through it all. It is a lenghthy process but worth the effort, I think.

Marie said...

Maria Cecelia,

Do you think the little tiny bugs on your roses are aphids? Once you have identified the pest you can decide on the best solution.

Gerry Okimi said...

Japanese beetle attack gardens on 2 fronts. Adults feed on the leaves of many plants. They like birches, grapes, maples, other shrubs and flowers. The larvae = white grubs which feed on grass roots- lawns. Control grubs to protect the lawn. Less grubs can mean less adults in your yard, but the adults can also fly in from the neighbours.

Marie said...

Exactly, now the next few blogs will examine how to use the IPM Process to select something that solves the problem with the least effect on the environment. This process can be used for any pest in the garden/lawn. These blogs are meant to be an example of the Process and find out how easy or difficult it is for a home gardener. Thanks for your comment. I do appreciate it.

Kathy said...

your thoughts about milky spore to combat bugs?

Marie said...

Milky spore is definitely one of the options. I am trying to look at all the possible choices and illustrate their effect on environment. But I will certainly get to milky spore!

Sorry it's such a long process. I'm trying to be objective. It will take another two posts to get to milky spore. Please let me know if you notice any errors. Thanks for the comment.