Continuing on with our discussion of those nasty thieves that want to take all your veggies – and what to do about them. If you haven’t read PESTS AND DISEASES INTRO, and PARTS 1 & 2 yet, please go back and read those first – and remember, prevention of problems is by far the best cure. So, here we go!
MITES – Mites are nearly microscopic pests that suck plant juices, almost always from the underside of the leaves. You may see evidence of them on all sorts of broad-leafed vegetables including tomatoes, peppers, eggplant and beans. There are many varieties of mites in Hawaii normally appearing in the hotter months – they typically like it hot and dry and even dusty. In fact mites can be carried to your plants on blowing dust. The first evidence of a mite attack is a multitude of very tiny yellow spots on the leaf tissues almost making the leaves look bronzed. Webbing may or may not be present depending on the variety of mite (i.e. Spider Mites). You may also see brown scarring on the top of eggplant fruits (or coconuts) from the mites feeding under the cap.
Because they like it dry, hosing the underside of the leaves with a strong spray of water will do a lot to cut back their numbers – and soapy water (made with Ivory Dishwashing liquid or pure Castile soap) is even better – and the first thing to try every morning for a few days in a row. If that doesn’t do it, a mixture of Thyme and Clove Oil (Trifecta Crop Control, or Eco-1 Fruit and Vegetable Spray) with a good squirt of Ivory and sprayed on the UNDERSIDE of the leaves every day for a few days should take care of the problem. Again, as in all infestations, observe and catch them early. For non-food plants, like palms (and they do attack the growing crown of certain palms) a commercial miticide like Avid is necessary to knock them back.
CHINESE ROSE BEETLES – If your plants appear to be shot through by a shotgun and you see no pests present, it could very likely be the Chinese Rose Beetle. The beetle that is about a ¼” long and a dusky brown color, and attacks many different plants here in Hawaii, but most notably eggplant, beans, cacao and hibiscus. It will chew all the way through the leaves, leaving a network of holes, sometimes to the point that the leaves are skeletonized.
I devoted an entire BLOG post to these pests so I would like to direct you back to the post entitled “Chinese Rose Beetles” accessible in the archive at the bottom of this post.
CATERPILLARS, CUTWORMS & GRUBS – Caterpillars are the larval stage of butterflies and moths and may be found chewing on the tender actively growing tips of your veggie leaves. They can do very little damage, but they can also strip a plant of leaves virtually overnight. I like to just pick the large caterpillars, like Tomato Hornworm, off the plants and crush them. Smaller ones like those found on cabbages and Kale can be hard to see and more numerous. Fortunately, there is an extremely effective treatment for caterpillars that uses a bacterium that is harmless to humans and pets but devastating to caterpillars. This is called Bacillus Thuringiensis, or BT. BT is found in several organic insecticides like Thuricide or Bio-worm. Mix according to the directions and spray all leaves early in the morning or late afternoon. Caterpillars will stop feeding in an hour or so and be dead in a day.
Cutworms/Grubs are the larval stage of some beetles and mature underground. They look like caterpillars but with a “bettley-looking” head and emerge at night to chew off your freshly planted seedlings. If you see a patch of seedlings gone, either cutworms or snails are at usually work. Fortunately, cutworms can be controlled with the same bacterial weapon. At the first sign, sprinkle a biologic bait like Spinosad around the affected garden areas. Sluggo makes a great product called Sluggo Plus that is a combination of a safe iron phosphate slug and snail bait with Spinosad for the cutworms. I like to use this because it’s often very hard to tell which one you have: snails or cutworms, and this product takes care of them both.
Rotenone powder, made from a flower petal, is also quite effective against caterpillars, cutworms and beetles – so if I am not sure what is doing the chewing on my eggplants, for example, I’ll use Rotenone. Rotenone is quite benign and can be easily dusted right out of the can onto affected plants or on the ground on your fresh seedlings without worry of burning your plants. One word of warning, is that Rotenone will kill fish, so don’t use around ponds.
FRUIT FLIES – Fruit flies can attack lots of soft-skinned fruits and veggies here in Hawaii and are extremely difficult to eradicate. The best preventative solution is to keep rotting fruit (and veggies) cleaned up and choose resistant veggie varieties. I love the large hamburger and “beefsteak” type of tomatoes, and plant lots of them every year, however, I only plant varieties that have a thicker skin and are, thus, resistant to fruit flies and sucking insects. I get big perfect tomatoes every year and seldom if ever use any insecticides. Best tomato varieties that I know of are Carbone, Pantano, Bella Rosa, Big Beef and Amana Orange – I’ll be publishing a complete list of tested varieties of veggies in a later article, so keep checking back.
Prevention is the best approach for fruit flies, however, if you start getting desperate, the most effective treatment is dusting the affected fruit with Bonide Garden Dust or spraying with a Pyrethrin-based insecticide like ExciteR – always with a squirt of Ivory liquid added.
Remember P&O, prevention and observation! Prevent problems by building healthy living soil and choosing well-adapted fruit and veggie varieties, and catch problems early by close daily observation. We will finish up this series in Pests and Diseases Part 4 when we cover, Thrips, Ants, Molds and Fungus, Rats and Mice, and Birds.
Happy Organic Gardening!
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