By Mallory Kelley, Regional Extension Agent, Home Grounds, Gardens, Home Pests
 

Of course, I’m not talking about the earthworms, they are the beneficial crawlers down below the surface of the soil that create garden gold helping the plants grow and produce.  No, I’m talking about those worms that you don’t know are there until half of your plant disappears overnight and looks like it has been through an overnight war.
 
Yes, those worms, and boy are there a lot of them to battle this time of year.  From the cabbage looper, tomato hornworms, armyworms, and fruit worms there are lots of different larvae out there attacking the plants in the garden and for most of them we have to be ready early to wage a war we can win!
 
Let’s start with those in the lawn, most commonly the armyworm.  These will be coming soon, and this is the one we are least concerned about as they really will not kill the turf.  These worms are just eating the foliage of the leaf blades and cause the turf to look dead and brown, but no need to fear, just keep the ground moist and with time the grass will grow back.  Most people don’t know they have armyworms in their turf until they pull the lawn mower onto the driveway in park and later in the afternoon see the worms trying to find their way back to the protection of the lawn grass.

Next, let’s talk about those worms you may find munching on the leaves on your oak, hickory, or maple tree in the landscape.  Again, for these there is no major reason for concern, and I don’t recommend control.  This early in the summer the branch will leaf out again and if it’s late in the summer to early fall you can thank the worms as they are taking care of the leaves so you won’t have to rake them and the poop they leave under the tree is the added bonus!

Now, let’s talk about vegetable gardens!  These definitely need the battle plan to be in play early on to win the war against the worms in your vegetable garden.  From the cabbage loopers, tomato hornworm, and different fruit worms in plants like your corn and tomatoes you need to be scouting for these daily.  It is best to keep the plants sprayed or dusted regularly so that the product will kill the larvae when they are very small, and it only takes a small, ingested amount for control.  Once the larvae are large, easy to find, and they have taken down most of the plant before you notice, then hand picking is going to be your best option. Remember, the larger the insect the more product must ingested to kill it and most of their feeding has already been done and they are ready to pupate.
 
All worms in the vegetable garden come in as moths, (cabbage loopers, tomato fruit worms, armyworms, and hornworms).  There are many different chemicals that will control these, but you should go to sprays or dusts with the active ingredient Bacillus thuringiensis.  This is a bacterium that is a gut poison to worms and worms alone.  It has a zero post-harvest interval, which means you can apply the product and eat the fruit the very same day. The key to success against worms is to keep this product present on the plant. The most effective control is just after eggs hatch when caterpillars are still small.

Now, what about those worm larvae that are inside the stem like the squash vine borer in our cucurbits or the plum curculio in our plum or peach tree fruit?  Those are actually the larvae or wasps and beetles and those are very difficult to control as they are boring into the stems.  Scouting again is going to be key to success and control products like malathion on your peach and plum trees starting early in the season to pyrethroid on the squash will help with control, but early application and scouting is very important.
 

If you have other garden related questions, please call the Master Gardener Helpline at:
 1877-ALA-GROW (252-4769).