Marlene asks: I was told I could make a low-tox, organic pesticide from tobacco. Is this true and if so, how do I make it?
Tropical Gardener answer: As you certainly know, the nicotine in tobacco is toxic. In many formulas it is effective against insect pests, but caution is advised when using it.
The effectiveness of nicotine as a pesticide is well known. It is actually one of the oldest botanical insecticides. In fact, some commercial insecticides contain imidacloprid, which is a chemical formula that mimics nicotine. These insecticides are applied to the leaves and the soil and most work systemically by poisoning the insects that eat the plant containing the pesticide. None of these products are approved for use in organic operations, however.
Several commercial insecticides that contain nicotine sulfate are certified for organic use. These products do carry a “Danger” warning on their label though. This means that they can be toxic to humans and pets when they contact bare skin, are inhaled or eaten. They should be used cautiously.
Nicotine’s wide range of toxicity means it can kill beneficial insects as well as sucking insect pests like aphids, thrips and white flies. It is lethal to the pests that eat it and is also deadly upon contact to soft bodied creatures like slugs and worms. Some plants, including roses and many plants in the Solanaceae family (including tomatoes, potatoes, eggplants and peppers) are also sensitive to nicotine and you should not use products containing nicotine on them. A homemade formula is likely to be less toxic than the commercial ones and will probably be effective against many garden pests.
It is pretty easy to make and use your own nicotine insecticide but do so with personal protection in place.
Add a cup of dry tobacco leaf to a gallon of water. You can use pipe, rolling, chewing and cigarette tobacco. The less additives, the better. Let the tobacco sit in the liquid for at least a half an hour up to 24 hours. The longer it soaks, the stronger the resulting product. Though stronger products may work faster, they are also more threatening to beneficial garden insects like lady bugs and bees. To the “tobacco tea,” add a teaspoon of liquid soap to improve the ability of the solution to sick to the plants.
Strain the tobacco pieces from the liquid and either use it immediately or store it in a cool place for up to two weeks. Spray it only on the leaves where you see the target insects and try to contact them directly with the liquid. You can apply every few weeks until the pests are gone.
The internet abounds with other recipes for homemade organic pesticides that may be less toxic. Many are based on a combination of soap and oil and some add strong herbs or vegetables to the mix. Do try a DIY recipe for pest control and let us know how it works.
Diana Duff is a plant adviser, educator and consultant living on an organic farm in Captain Cook. Some questions that appear here were originally directed to Kona’s Certified Master Gardeners. You may contact them with questions at konamg@ctahr.hawaii.edu.
Gardening Events
Monday – Sunday: “Early Registration for Hawaii Tropical Fruit Growers Conference” $50 discount offered to those registering by Monday, Aug. 1 for HTFG’s weeklong conference starting on September 30. Go to www.HTFG.org for conference information or to register.
Saturday: “Work Day at Amy Greenwell Garden” from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers will be able to help with garden maintenance and are invited to bring a brown bag lunch. Call Peter at 323-3318 for more information.
Farmer Direct Markets
Wednesday: “Hooulu Farmers Market” 9 a.m. to 2 p.m. at Sheraton Kona Resort &Spa at Keauhou Bay
Wednesday: “Sunset Farmers Market” 2 p.m. to sunset at the north makai corner of the Kmart parking lot.
Saturday: “Keauhou Farmers Market” 8 a.m. to noon at Keauhou Shopping Center
“Kamuela Farmer’s Market” from 7 a.m. to noon at Pukalani Stables
Sunday: “South Kona Green Market” 9 a.m. – 2 p.m. at Amy Greenwell Garden in Captain Cook
Tuesday – Saturday: “U-Pick greens and produce” 10 a.m. to 4 p.m. Tropical Edibles Nursery, Captain Cook.
Plant Advice Lines
Anytime: konamg@ctahr.hawaii.edu
Tuesdays, Thursdays: 9 a.m. to noon at UH-CES in Kainaliu – 322-4892
Monday, Tuesday and Friday: 9 a.m. to noon at UH CES at Komohana in Hilo 981-5199 or himga@hawaii.edu