Pests in the vegetable garden can be more than a nuisance. They can make produce inedible.
Flea beetles, root maggots, cabbage butterfly larva, Colorado potato beetles and spit bugs are some of the most common problems.
In the case of flea beetles, they feed primarily on plants from the Mustard Family (Brassicaceae or Cruciferae); radishes, cabbage, kale, broccoli etc. An infestation of flea beetles in the early spring can strip the first leaves off of a row of newly germinated radishes in a day. As the leaves get older, flea beetles feed on top of the leaves, leaving behind round holes. Flea Beetles will fly but they tend to hop on their highly developed back legs. Removing all weeds, and vegetation from the garden in the fall and rotating crops is the best defence against these pests.
There are two types of root maggots that are commonly found in local gardens. Delia antigua feed on onions while Delia radicum feed on the roots of the mustard family; radishes, cabbages, turnips etc.
The maggots are the larva of small flies that lay their eggs at the base of host plants. In the case of the onion maggot, they are drawn to sick or old host plants. Removing all old onions reduces chances of infestations.
There are simple things that can be done to lessen the chance of a root maggot infestation in crucifers. Do not mass plant different varieties close together. In other words, do not plant, radishes, cauliflower, broccoli, kale or kohlrabi side by side. A smaller patch is less attractive to insects than a large one.
Using a barrier to cover plants such as plastic or polyspun cloth in the spring can stop flies from reach plant roots and laying eggs.
Placing ashes or Diatomaceous Earth in the planting beds has proven to be successful deterrent against root maggots.
Cabbage butterflies are common visitors to the garden. They deposit their eggs on the underside of cabbage, broccoli, kale and kohlrabi leaves. The eggs hatch into larva that feed on all parts of the plants. If there are only a few larva, they can be handpicked and destroyed but a large number will make the produce inedible.
Placing a barrier of a fine net or polyspun cloth over the plants will keep the insects from laying eggs, stopping the larva from developing.
Bacillus thuringiensis kurstaki known as BTK is a natural virus that can be applied to infected plants. Once ingested, BTK kills the larva. BTK needs to be applied on a regularly to eliminate all larva.
Colorado Potato Beetles has an orange head with a yellow and black striped body. It lays barrel shaped orange eggs on the underside of tomatoes, potatoes and eggplants. Infected plants have ragged edged leaves where the insects have eaten. A large outbreak of the beetles will strip too many leaves resulting in fewer or smaller tubers.
The best control is to watch for the insect in the spring and remove all eggs from the underside of leaves as they appear. If the insects are found continue looking for larva and adults throughout the season. Destroy larva, and adults by squishing them.
Slugs are the bane of most gardeners. Expect to find slugs hiding in a cool location during the hot part of the day; under leaves, rubbish, rotting wood or in a lawn. When it is cool out they come out and feed on plants.
Slugs can be removed by hand, or lured into traps. Set the traps in areas that slugs are usually found and clean them out each day to keep the slug population in check. A strip of soil between the garden and grass also works as a deterrent. Spreading Diatomaceous Earth around the plants to be protected will kill all slugs that try to cross the barrier by slicing them open.
Watching the garden for insects and removing them when they first appear tends to keep most insect in check.
Linda Tomlinson is a horticulturalist that lives near Rocky Mountain House. She can be reached at your_garden@hotmail.com