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Snails in the Garden

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We are in December, with below freezing temperatures at night, but there are still a few snails in the garden. Their continued presence among the greens (chicory, kale, lettuce, rocket) tells about the long season of rain leading up to winter here in north Georgia.

Snail on a chicory leaf, early December in Georgia.

I haven’t seen any serious damage to my plants, so I am not concerned about the snails. To be honest, I am amazed by their persistence in the cold.

If there were very many snails, and a lot of damage to crops, I would set out some organic-approved iron-phosphate bait. The one I have used most recently is called Sluggo, but there are many similar baits, with the same active ingredient, that work.

When I have used the iron-phosphate bait, it was actually for roly-polies, many years ago. For some reason their population had boomed, and roly-polies roiled every square inch of ground in the garden. These critters usually eat decaying organic matter, but there were so many of them that they started eating seedlings in the garden. That was a problem, but the Sluggo iron-phosphate bait for slugs and snails works on roly-polies, too.

It took a couple of years of persistent use of the bait to beat back the roly-polies, but my garden hasn’t been invaded like that again.

The Royal Horticulture Society (RHS), in the UK, where slugs and snails commonly invade gardens and farms and cause a lot of damage, has been studying methods of slug and snail control. Earlier this fall, the BBC reported on an RHS study of home-methods, using things like crushed egg shells, sharp sand, and copper strips to keep the pests away from garden crops.

The study found that none of those things really work, which is sad news for those of us who like to “DIY” as much of our gardening as possible. They had not yet tested beer-traps (beer in shallow saucers, set around the garden, to lure and then drown slugs and snails), so there may be one method left for us to use, other than placing boards in the garden for the pests to hide under, then turning the boards over to pick off the critters by hand to drown or otherwise dispatch.

In another RHS study, effectiveness of iron-phosphate baits and another organic control, nematodes that target slugs and snails, was compared to conventional (chemical) control options. The organic methods did almost as well as the chemicals. Based on my roly-poly experience, I would have guessed this outcome, but it is nice to have that guess confirmed.

Trap Crops for the Home Garden

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Since trap crops take up some space, it never occurred to me that using these was a suitable organic pest control strategy for small home gardens. However, I have unexpectedly gained experience with a trap crop, since that is what my zucchini have turned out to be.

What is a trap crop?

A trap crop is one that is planted as a lure to pest insects, to keep them away from the main crop. Most trap crops are not expected to yield a harvest; instead, they are offered up to pests as an alternative to the main crop of a farm. According to SARE, trap crops are often planted around the edge of the main crop, forming a protective barrier that pests are likely to stay within. Trap crops can also be planted as a block or patch near the main crop.

According to University of Georgia, trap crops to work best when they make flowers before the main crop that they are protecting. When the plants are making flowers and fruits, that is when they are most attractive to most pests.

My zucchini plants function as a trap crop

You may have read the two recent blog posts about pests on my zucchini plants — one about squash beetles and the other about cucumber pickleworms. The squash beetles are really less of a problem, since there are only four or five each day for me to smash and the damage is limited to holes in the leaves. The pickleworms, though, are another story.

They have caused serious damage to the zucchini plants, ruining flowers and boring into main-stems and leaf-stems. The plants are still standing, but all hope of harvesting zucchini from this late-summer crop is gone.

This is the good news: my cucumber patch, planted in early August like the zucchini, has supplied several cucumbers for our meals already. Checking the cucumber plants nearly every day, I have found only a few squash beetles, grand-total, on the plants. It has been easy to find and smash the one-every-few-days beetles as I check on the garden.

In an instance of amazing good luck, my zucchini variety was so fast to mature that the plants made flowers more than a week before the cucumbers did. When the pests first showed up in my garden, the squash beetles and cucumber pickleworm moths flew past the cucumber patch, which didn’t have flowers, and attacked the zucchini plants in the half-barrel planter, where flowers and little squashes were abundant.

Cucumber patch protected by trap crop of zucchini, example of organic pest control. Zucchini are in a half-barrel at left end of garden (not in this image).
My cucumber patch in late September. No leaf mildew diseases, no pickleworm damage. PHOTO/Amygwh

Even better, the cucumbers still do not show any pickleworm damage.

To combat any pickleworms that could be present, I have been treating both sets of plants with Bt for caterpillars (the one I am using is Thuricide), which is an organic pest control product. We have had a lot of rain, though, which washes the Bt away. I am not re-spraying my plants after every rain, so some days the cucumber crop is unprotected other than by the stronger allure of the zucchini plants.

At this point, the three remaining zucchini plants look hopelessly ragged, but they are still alive. I am leaving them in the garden for as long as they continue to work as pest-magnets.

The cucumbers remain pickleworm-free, but they are not perfect specimens. I had forgotten about the uneven pollination in hot weather that results in lumpy cucumbers. These are not headed for a pickle jar, which means the imperfect shapes are not really a problem.

Weird shapes from incomplete pollination, but no cucumber pickleworm damage. PHOTO/Amygwh

Because of pest-concerns, I am harvesting the cucumbers while they are fairly small. This is a bit like harvesting tomatoes before they are fully red. I know that if I leave tomatoes in the garden to fully ripen, some pest (stink bug, chipmunk, mockingbird, etc) will notice the beautiful, ripe fruit and take a bite before I get a chance to enjoy the harvest, myself.

Unlike for tomatoes, there is not a flavor-reason to wait for more mature cucumbers. They taste pretty much the same at smaller sizes, and leaving them out in the pest-filled world seems a little like tempting fate.

So, as I ponder my next year’s garden, it is good to know that zucchini plants can use some unseen come-hither chemistry to draw pests away from the cucumbers.

This is the kind of garden-discovery that any of us can make. I have been growing food in this yard for more than 25 years, and I learn more about gardening every year. And even though there are pests, the garden is producing good food. This is part of the joy of gardening!

Fire Ants in the Garden – Organic Control

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No gardener wants to encounter fire ants in the garden, but sometimes we find that they have moved in, unwanted. Getting rid of these pain-inflicting invaders can take some persistence, but options for organic control do exist. Knowing a little about the biology of these ants can help a gardener plan a successful counter-attack.

Flattened fire ant mound with deer hoof print in the middle.
Flattened fire ant “mound” shows deer hoof print. PHOTO/Amygwh

Fire ants do not tolerate freezing weather very well. If you treat a fire ant mound in fall, even if the whole mound isn’t dead within a few weeks, enough workers can be killed that the rest of the colony doesn’t survive the winter.

In spring and fall, too, most of the ants in a colony will be closer to the surface, so that a mound drench type of product has a good chance of reaching all of them.

In other words, both fall and spring are when organic controls are more likely to work well. Killing off smaller colonies in fall will also reduce the number of new colonies next spring, when mated queens that survived the winter will fly off to start new colonies.

The very first control to try, though, doesn’t use any products at all. On a cool day after a rain (when more ants are nearer the surface), pour a few gallons of boiling water on the mound, starting by circling the mound a foot or so away and then pouring the rest right on the mound. If this doesn’t kill the whole colony, move on to “Plan B”, a purchased mound-drench or a bait. (NOTE: Boiling hot water can burn people when accidentally spilled, and it will also kill plants near the mound it is being poured on. Please handle boiling water carefully, and do not use it near trees, shrubs, perennials, bulbs, or other desired plants.)

Another option is called “bucketing”. You gather up a few buckets, dust the inside with talcum powder or corn starch (to keep the ants in), and on a cool morning dig quickly into the mound, dumping shovels full of dirt into your buckets. Dig deep enough to find the bottom of the mound. Add a generous squirt of dish soap to each bucket, and add water to drown the ants. This works on small mounds, but not on old, deep colonies.

Organic-approved products for killing fire ants typically contain either d-Limonene (from orange oil) or a spinosad compound (from special bacteria) as their active ingredients.

One organic produce that contains d-Limonene, to be used as a drench, is Orange Guard Fire Ant Control. The d-Limonene products have worked pretty well in our area community gardens.

An organic product for fire ant control that uses spinosad as the active ingredient is Captain Jack’s Dead Bug Brew by Bonide. Instructions for using it as a mound drench are pretty far down the label, but they are there.

Whatever product you choose, be sure to follow package directions carefully.

Remember to NOT disturb a mound in any way before using a product on or around the mound. If the ants are disturbed, they go into “defense mode”; a whole lot of ants will boil up out of the mound where they can’t be reached by a drench.

Fire ants are not easy to eradicate, and new colonies will continue to move in from surrounding areas if they can, even when old colonies are killed off. It is their way.

However, gardeners can be persistent, too. Knowing the best times to work on the mounds for best effect helps keep our gardens fire-ant free.

For more information and the recipe for a DIY orange-oil-based soil drench, see Fire Ants in the Garden, Part 2.