Tomatoes are an exciting choice when planning a garden. They’ll gladly drink your beer and even enjoy Epsom salts on occasion. Most people love to add them to their gardens because they’re relatively fast and easy to grow.
But, several pests will attack tomato plants if the opportunity arises. One of these is the infamous spider mite.
Tomato Plants And Spider Mites
Chances are, if you see webs on your tomatoes, it’s not a spider but a fellow arachnid known as the spider mite.
These tiny pests can do a lot of damage to your tomato crop, but they’re not impossible to eliminate.
The Nasty Truth About Spider Mites
The two-spotted spider mite (Phytoseiulus persimilis) is the species most people talk about, but it’s not the only one that will target tomato plants.
There are approximately 12,000 species of spider mites, all in the family of Tetranychidae.
They measure less than 1/16” inch. These tiny pests spin messy webs to protect themselves from predators and serve as bridges between plant leaves.
They prefer the undersides of leaves and will pierce the leaf with their long proboscis to drink the sap.
Of course, you probably won’t notice one or two spider mites setting up home on your plant, but it doesn’t take long for them to make their presence known.
A single adult female will lay as many as 20 eggs per day and live between 2 and 4 weeks.
Under the right conditions, the eggs will hatch in as little as three days, and the nymphs will reach sexual maturity as quickly as five days later.
This means a massive population explosion within a month or two.
All of those little vampires will drain leaves dry, removing chlorophyll and causing brown spots on the tops of the leaves that are surrounded by yellow rings.
This latter sign is proof the infested leaf is dying.
With sickly leaves, the plant won’t get enough energy to bear fruit, resulting in smaller yields or no fruit.
Should I Use A Pesticide?
This is a tricky question for many, especially regarding a vegetable garden. Not every pesticide will work against spider mites, but there’s a particular type known as acaricides, specially formulated to kill mites and ticks.
As with older miticides, acaricides have both systemic and non-systemic options.
Unfortunately, they also share their predecessors’ flaws, such as a high risk of developing tolerance and toxicity towards some aquatic life.
There’s also a question of how toxic pesticides are to people and how long you may have to wait before you can harvest the tomatoes.
If you choose to use an acaricide, ensure each dose is a different brand or formula and follow all instructions carefully.
Changing it up can significantly reduce the risk of creating superbugs.
However, if you don’t mind a slightly slower method, we strongly urge you to use neem oil instead of an acaricide.
Companion Planting (Prevention Only)
Sometimes the best solution is the simplest one, and it doesn’t get much more simplistic than companion planting.
This is the practice of planting two or more plants with similar care needs but different root depths and creating some benefit for each other.
A perfect example is alliums, which can chase off a slew of pests, including deer and rabbits.
Garlic, perhaps the most famous edible alliums, will also repel spider mites, although many of the ornamental species are less effective against this pest (but can still help).
Brassicas such as broccoli, radishes, and turnips can also repel spider mites, so consider adding them near your tomatoes.
Strong-smelling plants such as basil or celery also work, or you can use a more decorative repellent like chrysanthemums.
Hiring Tiny Help (Prevention and Control)
Mother Nature is skilled at ensuring no one creature can completely upset the balance, although we humans sometimes put in a reasonable effort.
The Phytoseiidae family is an excellent example of this balance.
The family consists of several tiny predatory mites that happily feed on spider mites and other pests.
The most famous of these is perhaps Phytoseiulus persimilis, a deadly enemy of spider mites.
A member of this species can eat five adult spider mites or 20 eggs in a single day, so you can imagine how deadly they are when you have a few dozen or even hundreds tending to your garden.
But those aren’t the only natural predators you can rely on.
Ladybugs are a welcome addition to any garden and love feasting upon all sorts of more minor plant pests.
Likewise, parasitic wasps can damage a spider mite population, which they use as living incubators for their young.
Just keep in mind that natural predators will want companion plants that keep their interest, or they might begin migrating elsewhere once your pest problem is under control.
Neem Oil: The Ultimate Cure (Prevention and Control)
We’ve saved the best for last. Neem oil is a natural extract from the tree Azadirachta indica. It can kill hundreds of species of common plant pests yet is non-toxic to humans, pets, and livestock.
Even better, it has multiple active chemical components and won’t result in resistance or immunity no matter how often you use it.
And best of all – you can harvest your fruit a day after using any neem product with no risk of contamination!
This excellent product comes in three primary forms:
- 100% percent cold-pressed pure neem oil
- Neem cakes (the solids left after extracting neem oil and a tremendous insecticidal fertilizer)
- Clarified hydrophobic neem oil (the oil after the main component Azadirachtin has been removed.
Azadirachtin mimics the natural hormones in insects, cousin them to lose their appetite and disrupt their reproduction ability.
To use neem oil, you will need to make an emulsion by adding a teaspoon of Dawn dish liquid or pure castile soap to either a quart or gallon of lukewarm water.
The soap breaks water surface tension to mix water and oil, so you don’t need much.
For a neem foliar spray, use clarified neem oil (we suggest .5% percent for most infestations and 1% percent for the most challenging cases.
Mix 1 teaspoon of the clarified neem oil per 1 quart of water (or one tablespoon per gallon).
Spray every part of the tomato plant, especially the undersides of leaves and crevasses.
Be sure to only use the spray at dawn or dusk, so you don’t harm any beneficial insects, as this form kills on contact and dissipates safely in about an hour.
Reapply every other day for two weeks or until the infestation is gone, and you can use it every two weeks as a preventative.
For neem soil soaks, mix one teaspoon per quart or two tablespoons per gallon and pour 2 to 3 cups of the mixture around the base (don’t get any on the plant itself!
The roots will soak up the neem and turn it into a systemic pesticide.
It can take a few weeks for the results to be noticeable, and the oil remains effective for up to 22 days.
Reapply every three weeks as needed or as a preventative.
Recommended Reading For Growing Tomatoes
- How To Care For Tomato Plants – Over the years we all learn little tips and tricks that help us grow our vegetables… Here are 13 do’s and don’ts on growing tomatoes.
- 8 Mistakes Tomato Growers Make – Growing mistakes to avoid when planting, increasing size, flavor, and overall output.