Soil and water

Turning the soil in winter will thwart tomato hornworms

Q. Last summer my tomatoes developed hornworms and I hand picked them to help the plants thrive. Unfortunately, I have to use the same beds this year for tomatoes. Is there a better way to treat the soil before planting to prevent new hornworms from invading again this year? – ME, Los Ranchos

A. My first hope is that you have been turning the garden soil periodically over the last few months of dormancy.

Flipping a dormant bed can help eliminate a whole host of insects and eggs, especially if it’s very cold.

It was the tomato hornworm that started all your troubles. Here is the life cycle of the horned worm. In June and July, the butterflies emerge from the pupae of the soil, that is to say an enclosed young which turns into an adult. The “skin” of the pupae splits, the adult butterfly comes out of it, goes to the surface of the soil, dries up and spreads its wings.

Once the outer “skeleton” has dried and taken on its adult color, it peels off, finds a mate, and then lays that year’s egg crop on the undersides of tomato plant leaves. These eggs, usually laid in precision rows, are a bright orange-yellow color and hatch quickly within a week.

The larva (hawkmoth caterpillar) feeds on your plants for about a month, then drops or crawls to the ground to pupate (I call this morph) during the dormant months, waiting and developing into pupae for become next year’s adult tomato hornworm.

The tomato worm is also a remarkably beautiful creature. About the size of a hummingbird, they have gray-black-brown patterned wings with a body that sports purple-orange flecks.

If you notice a hummingbird-sized creature hovering around your plant from dusk till night, be on your toes and start carefully inspecting the undersides of the leaves for eggs.

If you find eggs, pick the leaf and throw them away. DO NOT COMPOST these leaves or put them in the trash. If you are brave, step on them and crush them.

You asked for the best way to treat soil now to be successful this year. I know of no pesticide that would affect the nymphs of the horned worm except faithfully till the soil during the winter to expose the nymphs enough to cause its death.

If you have a hornworm outbreak, treat the plants with Bacillus thuringiensis var. kurstaki, or BTK for short.

BTK is a bacterium that affects insects in the larval stage. You can find BTK at any well-stocked nursery pharmacy.

Also, rereading on hornworm, I learned that if you want to start your tomatoes from seeds, you should soak the seeds in a 10% bleach solution for 10 minutes, then rinse them. with clear water before planting them. (That’s 1 teaspoon of bleach to 9 teaspoons of water.) Obviously, soaking and rinsing reduces the risk of seed-borne diseases. Who knew?

I also read that you should add a cup of bone meal to each hole if you are planting already growing plants.

So get out there and give the space where you’re going to plant your tomatoes a good look, keeping an eye out for any scaly rusty brown cocoon things, and if you find any, throw them out before planting this year’s crop. of tomatoes.

Happy digging!

Tracey Fitzgibbon is a Certified Nurseryman. Send garden-related questions to Digging In, Albuquerque Journal, 7777 Jefferson NE, Albuquerque, NM 87109, or [email protected]