IPM for Mexican Bean Beetles


>>If you are a gardener in the
State of Georgia growing beans, you will at some time or another
run into the Mexican Bean Beetle. Good afternoon. I’m Becky Griffin, Community and School Garden
Coordinator for UGA Extension. Today we’re going to talk
a little bit about an integrated pest management
strategy for dealing with the Mexican Bean Beetle. When you have bean beetles
in your bean patches, damage can vary from lacey
leaves to complete defoliation of your bean plant. In order to understand how to
combat the bean beetle, we have to learn a little bit
about its biology. Mexican Bean Beetles
came up from Mexico and if you live east of the Rocky
Mountains, they can be found in just about any bean
garden or bean patch. The adult beetles over
winter in debris. It can be garden debris from
your community garden plot or home garden or nearby woods;
anywhere where those beetles feel protected. When the sun warms the earth
early in the spring, the bean beetles will emerge
and they’re strong fliers, so they’ll find your beans. Generally, we have a big flush
of emerged bean beetles in June when it’s pretty warm. There will be a secondary
emergence two to four weeks later depending on the weather. Once the bean beetles find the
bean patch, the females will lay eggs on the
underside of the leaves. Generally, she’ll lay between 40 and 70 per batch of eggs and she’ll lay eggs multiple times. Within about a week, the eggs
will hatch and the larval stage will go through four instars. For two to five weeks,
again weather-dependent, these larvae will eat
on your bean leaves. Finally, we’ll get to the pupal
stage which occurs around the bean plants or nearby and,
depending on weather again, between one and two weeks
the adult beetle will emerge. One of the problems we have with
this particular pest is that not only do the larval stages
eat on your bean plants but the adult stages
do as well. If you look at this beautiful
beneficial lady beetle it’s easy for gardeners to
confuse this beneficial bug with the bean beetle. Make sure your
pest ID is correct. So, how do we come up with an
integrated pest management plan? The first step is sanitation. You want to make sure at
the end of your garden season you have cleaned out your bed. If you have a history of bean
beetles in that particular bed research has shown you can take
that debris, put it in plastic bags, seal those bags up, and
leave them for one to two weeks and that should kill any
remaining beetles in that area. Next, think about altering
your planting dates. We talked about how the main
group of bean beetles will emerge when the sun first warms
the earth in the spring; what if you wait until that
first flush was done then your chances of bean beetle
infestation would be lower. Also, think about
your plant selection. If you’re growing bush beans
then you know your crop will be finished early
and you can move on. If you’re growing pole beans you
know that plant needs to stay in the ground the whole
summer and just invites bean beetles to visit. Also make sure you’re starting
with healthy plants. I know this is Horticulture 101
but it can’t be overemphasized. Make sure your plants have
all the nutrition and water they need and they may
be able to tolerate some bean beetle damage. Next, think about attracting
beneficial insects to your garden. We know that there are many
insects that actually will help you control bean beetles but you
need to get them to your garden. By planting flowers that attract
beneficial insects, like wasps, they’ll come to the garden
and maybe do some of the bean beetle
control for you. So think about adding
beneficial flowers to your vegetable garden. What about floating row covers? Community garden plots are
designed well and they can easily adapt to having these
PVC pipes added and then a floating row cover put on top. Beans don’t have to have
pollinators to make a crop for you and by putting a
floating row cover over, you have prevented bean beetles
from entering your plot. Finally, scouting and removal
of eggs and larvae is really easy to do when you have
a small bean patch, a community garden plot
of 4 by 8. It’s not too much to ask you
to look on the underside of the leaves and when you find
those bright yellow eggs and those bright yellow larvae
to remove them. One easy way to do that
is to use packing tape. You can fold it over your hand
so that the sticky side is out, gently press the sticky side of
the tape to the underside of the leaves capturing
any larvae or eggs. The eggs should pull off gently
saving the leaf from damage and you can fold that tape over
itself that way you are smashing and removing any
larvae or eggs that you find. Education is key. Make sure you know the
pest you’re dealing with, know its history, and use
these IPM methods to have a successful bean crop. © 2016 University of Georgia College of Agricultural and
Environmental Sciences Center for Urban Agriculture

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