Cucumber Beetles

Thanks to those of you who came out to help on Saturday’s work day.  The gardens look beautiful and food is really starting to grow now that is finally warm.

UnknownUnfortunately that also means that pests are beginning to find us too.  The cucumber beetle has appeared in abundance.  Here is some information about these pests.  Be aware that cucumber beetles don’t just eat cucumbers. They eat 270 different plants and flowers.  Below, please find some information about controlling them.
As you go about caring for your plants, be sure to check the undersides of leaves for eggs and larvae and let me know about any pests you find so I can alert other gardeners. You can even send me pictures that you take with your cell phone if you can’t identify the creatures.  In a community garden with so many of us growing the same things, pests can become “epidemic” very quickly.   Working together is our best chance of keeping these pests under control.
Happy Gardening!  Ellen

Predators: Tachnid flies, soldier beetles, parasitic nematodes and braconid wasps. Lacewings and ladybugs eat the eggs.

Repellent plants: Broccoli, calendula, catnip, goldenrod, nasturtiums, radish, rue and tansy. If you want to try marigolds to repel them use the more pungent varieties like African, French or Mexican marigolds. The more common marigolds may actually attract them, therefore could be used as a trap crop.

Control Methods:

  • Use a portable vacuum to get the adults in the early evening. Put them right into a plastic bag, seal it and dispose of them.
  • Try placing cuttings of the tansy plant as a mulch in-between rows in the garden.
  • Spread any type of onion skins on the soil around the planted areas.
  • Consider building a bat habitat: Bats are predators of a wide range of pest insects, including cucumber beetles.
  • Make a trench 3″ deep by 3″  wide filling it with wood ashes. Moisten it so it won’t blow away and don’t let it get on the plants. Ashes can be toxic to plant foliage!
  • A deep mulch of straw helps by keeping the adults from walking plant to plant. Heavy mulching can deter cucumber beetles from laying eggs in the ground near plant stems and may hinder feeding by larvae migrating to fruits. This cultural control method, however, does not protect the leaves against attack from adult insects. Injury to fruit by tunneling of larvae is dependent on very moist soil as fruits ripen. Limiting irrigation at this time can minimize damage
  • Plant white varieties of radishes or rattail radishes with your cucumber plants to repel the beetles. Rattail radish roots are not edible but the seed pods are!
  • Mix a spray of 1 ounce wood ashes, 1 ounce hydrated lime and 1 gallon water. Spray upper and lower leaf surfaces. Hydrated lime is a powdered substance. Or use a spray of hot peppers, water and garlic.
  • Trellising plants can make leaves less accessible to insect larvae and may decrease egg-laying. Like mulching, trellising does not protect plants against attack by adult insects
  • Plant radish seeds right in the hills with the cucumber plants.
  • Floating row covers are an effective control method during the early season of plant growth. They prevent insect attack by forming a barrier between insects and plants. Row covers need to be removed during the late vegetative stage, at the onset of flowering, to allow for bee pollination. Once floating row covers are removed, other control measures such as treatments with botanical pesticides should be employed.
  • To fool cuke beetles: flatten a square of aluminum foil around the base of plants to bounce light on the undersides of leaves. This also helps the plants in giving them more light.
  • Plant any type of beans with cucumber.
  • Cultivate in the fall to expose the eggs.
  • If the infestation is beyond control use either of the botanical poisons: pyrethrum or rotenone. You want to hit the adults with these when you observe them feeding on pollen in flowers.
  • Sticky Traps: For the home gardener and small scale growers these can be an effective monitoring tool and a control! Cut some plywood board into rectangles 8 inches by 10 inches. Cardboard could also be used. Paint with yellow paint and coat with Tanglefoot or some other adhesive. Now what you want to do is to bait these traps specifically to trap cuke beetles. You can use pieces of cotton wicks stuck to the boards that have been soaked in a Eugenol based oil which is what attracts the female beetles. 2 types of oils that contain 60 to 90 percent eugenol are allspice oil and clove oil. Squash blossoms contain indole which are very attractive to the adults. If you can spare some you might mash them up and stick them to your trap. Stake your traps vertically at ground level or no more than 12 inches above. As the traps fill up you can scrape and recoat them until they become unusable.
  • Nematodes: Hexamermis spp. parasitizes the adults. Studies have indicated up to 90%  of a population of cuke beetles being infected by the nematodes. Apply beneficial nematodes to kill the adults in mulch, seed furrows and around plant roots.
  • Neem Oil: Neem oil, which can act as an ovicide, can be used as a soil drench to treat eggs and larvae. It does seem to help with control of the adults as a repellant and antifeedant. Further tests must be done using Neem but it does look promising.