Week 7: the rise of the Colorado Potato Beetle and the resilience of the garden.

It sure seems as if the growth of our potato and tomato plants has been matched by the arrival of the Colorado Potato Beetle. These pests, distinguished by their zebra-striped backs and hearty size (relative to the three-striped beetle that is) have made camp on our potato plants, unafraid to visit the nearby tomatoes.

07-02-16 CTGTT Potato beetles in hand
Two adult Colorado Potato Beetles with a fairly large larvae between. The larvae, hatching from a bright yellow-orange egg, begins its life as a dark red (nearly black) speck. It eats and eats and grows and grows, becoming plumper and lighter in color, eventually developing the markings shown here. Because the larvae must begin feeding as soon as it is born, simply wiping the eggs off of the leaves of the potato (or tomato) prevents the arrival of the next generation. It’s certainly more efficient to target the non-moving eggs!

Contrary to their name, the Colorado Potato Beetle is an invasive species that arrived here from Mexico. In Mexico however, the beetles are not pests because they are controlled by natural predators and distinct environmental conditions. In Vermont, we the gardeners are tasked with the predator role.

Our primary method of control has been careful, daily picking. I quite enjoy the act. It provides the opportunity to tune into each plant, touching its leaves and giving it a good once-over from above and below. I tend to carry a jar of soapy water and gently drop the adults, larvae, and eggs into the jar as they appear on the plants. Picking beetles is time consuming and, despite our best efforts, has not noticeably reduced the population. In fact, it appears to be growing – which makes sense as each cluster of eggs represents the beginnings of 10-30 beetles.

We’ve decided to introduce a foliar spray, hoping to get ahead of the problem and protect the potatoes growing below. We’ve begun an experiment of sorts – spraying a homemade garlic-chili repellent on one-half of the crops (recipe below), and using a store-bought Neem Oil on the other half. Results to follow…

07-02-16 CTGTT Cpb larvae on leaf.JPG
Neem Oil is an insecticide that can control the Colorado Potato Beetle in its egg and larvae stages, while also providing healthy enzymes to the plant. Said to be most effective on young plant growth, neem is used to manage over 200 species of chewing + sucking insects.

As I said, pests are matched by growth and growth allows for bountiful, colorful harvest:

06-30-16 CTGEA Gems of the earth - radish up close
The vital red of the radish
06-30-16 CTGEA Chrissy holds the bundle of greens
Spectrum of ‘greens’ from purple to red to blue
06-29-16 CTGTT Amy in a rainbow of cut flowers
Not to mention the oranges, yellows, bright whites, and pinks!

And the recipe for the garlic-chili spray:

·         5 garlic cloves

·         2 Tbsp hot pepper flakes

·         3 cups water

·         ½  small onion

·         1 tsp liquid soap

Put all the ingredients (except for the liquid soap) in a blender. Blend well until the solids are broken down. Transfer to a container and mix in 1 tsp of dish soap. Let it sit in the refrigerator overnight. Strain through a sieve and discard the solid bits. Use a spray bottle to evenly distribute the liquid over the foliage in order to deter the beetles from laying eggs.