Nifty Neem Oil Treatments For Ornamentals & Edibles
As late winter turns to early spring, I always feel relaxed about garden chores. There’s plenty of time, right? Every year without fail I am brought up short by our sudden springs. Last Tuesday, not a blossom was in sight. By Friday, all the pink cherries were in bloom, folllowed in a day or two by the white ones. Daffodils were out in force, rapidly joined by hyacinths and other minor bulbs.
Suddenly, it’s getting late. As I work feverishly, trying to replant and replace everything that needs moving, a thousand baby weeds leap joyfully from cold storage. They’re back, they’re happy, and I am running behind. While rearranging, I can’t help but notice that despite the cold snaps, certain pests seem to be in mighty good supply. Aphids were thriving on roses by mid-March and slugs seem to be waking up even more hungry than usual.
Beating The Beasties
Slugs can be dealt with safely and simply, thanks to a range of reliable and non-toxic slug baits. While metaldehyde baits can harm or kill pets and people, concentrated baits based on iron phosphate such as Worry Free and Sluggo do no harm. This naturally occurring mineral is already present in soil and water, so it poses no environmental threat.
Harmless to mammals, birds, and beneficial insects, iron phosphate has a deadly effect on molluscs. When slugs and snails nibble the bait, they develop instant anorexia as their digestive systems become paralyzed. Instead of dissolving into puddles of slime, they dry up into tidy little mummies.
Put Your Bait Where The Baddies Are
These baits are quite rain-resistant and a little goes a long way. Instead of broadcasting it all over the yard, just tuck a small amount (about 1/4 teaspoon) next to the plant you want to protect. In my garden, I bait every month or so in spring and finding that this gives plenty of protection.
It’s also wise to put a bit under large containers and under flats of new plants that are waiting placement. Hide a little more near stone walls and at the edges of ivy hells (if you haven’t cleaned them all up yet), where slugs and snails proliferate happily.
Aphid Eaters In the Fridge
If you had a house invasion of Korean ladybugs in February and captured them to store in the fridge, now is a good time to release them. If you don’t, other good options abound. When aphids arive too early for ladybugs to be of much use, savvy gardeners turn to neem oil concentrates.
Many companies are now producing insecticides and even fungicides based on this powerful yet safe substance. Extracted from the nuts of the neem tree (Azadirachta indica), neem oil concentrates contain azadirachtin and related compounds (liminoids) that have an astonishing number of practical applications. Most recently, HIV researchers found that neem treatments attack a protein the the HIV virus needs in order to multiply, and further research may well turn up even more far-reaching uses.
Neem Toothpaste Fights Decay
In India, every part of the neem tree is put to use. Neem leaves are used in analgesic teas and skin-soothing tinctures. Neem leaf powder, long used in folk remedies for cuts and abrasions, is today considered to be an effective antibacterial agent. Neem bark is incorporated into men’s and women’s body care products and cosmetics.
Indian families use neem twigs like dental floss and neem extracts are often included in Indian toothpastes, where they help fight cavity-causing bacteria. Neem seed oil is also antibacterial and has been used to combat a wide range of plant pests for centuries. Residues of all parts of the neem tree are routinely added to garden composts and the crushed seed is considered a valuable soil amendment.
Bashing Black Spot With Neem
In organic farming and gardening circles, neem oil is used to repel or prevent many plant pests and diseases. Azadirachtin and its related liminoids act something like steroids. When insects eat neem-coated foliage, the liminoids disrupt normal hormonal production and processing, causing loss of appetite in some insects and interfering with reproduction, maturation, and molting patterns in others.
Quickly biodegradable and nearly non-toxic (except in large doses) to mammals, neem sprays smother aphids, whiteflies, and certain other pests on contact and prevents their eggs from hatching. Neem sprays also help to control disfiguring foliage diseases such as mildews and black spot by smothering the causative pathogens. Commercial growers use concentrated sprays of azadirachtin to control greenhouse pests. Home gardeners can use milder solutions (generally containing 0.5% azadirachtin) on both ornamentals and edible crops.
Safer Caterpillar Killers
In gardens and in greenhouses, neem oil sprays are used to kill mature whiteflies and to smother whitefly eggs. Neem oils are as effective as Bt (Bacillus thuringiensis) against many caterpillars. Japanese beetles will not feed on neem-treated plants. Sprayed on lawns, neem oil can kill the larvae of a number of lawn pests (usually lumped as “white grubs”) and is repellent to mature June beetles and scarab beetles, among others.
Neem product manufacturers list dozens of target insets, including adelgids, aphids, cabbage loopers, imported cabbage worms, earwigs, flea beetles, grasshoppers, green stinkbugs, gypsy moth caterpillars, harlequin bugs, Japanese beetles, lacebugs, leafhoppers, mealybugs, psyllids, rose slugsø, sawflies, spider mites, squash bugs, tent caterpillars, thrips, tomato hornworms, web worms, weevils, whiteflies, and white grubs.
Neem Safety For Edibles
When used on garden herbs and vegetables, neem oils may be sprayed up to the day of harvest. After harvesting, soak vegetables, fruit, and leafy greens in warm water and wash well with food-safe soap before serving. To protect pollinating insects, avoid spraying open flowers when treating affected foliage. Drought-stressed plants may be burned by neem oil sprays, so if affected plants are dried out, water well before using neem.
However safe this or any least toxic pesticide may be, it is still important to use it respectfully. Read all label cautions and warnings before using neem products. For instance, since it is an effective antibiotic, neem oil can harm soil biota if overused. As with any herbicide or pesticide, do not spray when beneficial insects are present and do not spray open blossoms, where beneficials might be accidentally exposed.
Neem has a lot going for it, as do some of the other oil-based pest products which may be formulated of fish oil, sesame, soy or lecithin etc, but there are some real downsides too. For one, they really clog sprayers badly–you should mix the product in very hot water and then pour that into quite warm water in your sprayer, and then empty and rinse the sprayer with soapy water when you’re finished for the day. Also, they must contact the pests in order to smother them, which means very thorough spraying including the undersides of foliage, which is actually quite hard to achieve. By the time you have been this thorough, you have really coated the plants, and these oils leave a funny taste on the leaves. If it were a leaf I planned to eat soon, I wouldn’t want it to be sprayed with neem oil or fish oil like Organocide. As Ann hinted, these oils can and do damage young foliage esp. if high temperatures come into play. I do like them a lot for roses, though, because of the double whammy they give for blackspot too.
I used to use an awesome dairy teat washing sprayer that sprayed upside down. Wonder where that went…? It made coating the undersides of leaves really easy.