By: Bonnie L. Grant, Certified Urban Agriculturist
Like most plants in the mint family, catnip is vigorous, strong and aggressive. There are few pest issues or catnip diseases that will seriously affect the plant’s health. That means it can be hard to determine the causes if you have dying catnip plants. They take quite a lot of abuse in the form of overly interested neighborhood felines. However, if your plant looks sick, fungal issues are probably the most common diseases of catnip.
Catnip is probably one of the easier herbs to grow. In fact, they thrive in low nutrient soil, are drought tolerant when established and reliably come back in spring even after the harshest winter. So why would you have dying catnip plants? If they haven’t been loved to death by your local alley cats, the problem may be fungal or viral. Problems with catnip are usually related to site and conditions, and can be easily prevented.
Catnip is generally fast growing and has strong rigid stems that are tolerant of the vigorous rubbing by amorous cats. Hardly anything bothers this adaptable herb except too little light and boggy soil conditions. If your catnip is exhibiting foliage problems, malformed twigs and stems, and even entire stems that rot out of the soil, you may be facing a fungal disease.
Too much shade, excess water, crowded plants, overhead watering and clay soils are some of the conditions that promote disease spread of any type. Check your site conditions and make sure plants are in freely draining soil, sun and do not water when plants have no time to dry before sundown.
Cercospora is a very common fungus on all types of plants. It causes leaf drop and can be recognized by haloed, yellow spots that darken as they age.
Septoria leaf spots occur in closely planted plots during rainy periods. The disease develops as gray spots with dark margins. As the spores multiply, the leaf is suffocated and drops.
Many types of root rot can cause problems with catnip. They can be hard to spot until the stems rot out of the soil but, generally, the girdling of the roots will slowly kill the leaves and stems.
Correct cultural care and siting can help minimize each of these. An organic copper fungicide applied in early spring is also beneficial.
Bacterial leaf spot appears first on the leaves. Spots are translucent with yellow halos and darken with irregular red centers. This disease flourishes in cool, wet weather. Avoid working around plants when they are wet, as this can spread the bacteria. In severe cases, the plants need to be removed and destroyed.
Practice crop rotation with any mint family member. There are several types of virus but, overall, they cause mottled distorted leaves. Young plants are jaundiced and may become stunted. A virus normally spreads by handling, although some insects may also be carriers. Make sure to wash your hands if touching a catnip plant and keep beds clean and pest free.
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The first time I gave my cat Kit Kat catnip (say that five times fast), I have to admit that I was pretty worried. I'd heard wild tales of how even the tiniest pinch of the stuff could transform your cat's behavior almost beyond recognition, so I wasn't that sure how I felt about it. But I knew that cats usually love the stuff, so I decided to give it a try. Long story short, he was obsessed, and much more active than usual, for all of about five minutes, anyway. But is catnip bad for cats? If you've ever wrestled with the ethics of whether to introduce your kitty to the treat, there are a few things you should know ahead of time before you and your fur baby dive in.
First of all, you might be wondering what catnip even is. It's a plant from the mint family, according to The Humane Society, and its dried form can be found in a number of cat toys and treats. Partaking of the plant вЂ” either by smelling it or by actually eating it straight вЂ” can lead to a variety of behaviors, from aggression, to rolling around, and even growling.
If your cat doesn't seem very impressed by the catnip-filled toys you bought her, though, there's definitely no need to worry. Catnip sensitivity is hereditary, and an estimated 50 percent of cats have no reaction to the plant at all, according to The Human Society. Also, if your fur baby is under 6 months old, she probably hasn't matured enough to have a response.
As per The Humane Society, giving your cat catnip that they can smell, as opposed to the kind they can actually eat, can make them respond very differently. While being able to rub against something containing the plant targets feline "happy" receptors in the brain, chowing down on catnip can alternatively mellow your cat out, according to the organization.
When it comes to any animal-related ethical dilemmas, the first organization that comes to my mind is People for the Ethical Treatment of Animals (PETA), and it turns out that they've actually addressed this very question. вЂњPETA is all for treating cat companions to reasonable amounts of high-quality catnip," PETA media officer Sophia Charchuk told The Conversation, "and for keeping them indoors, where theyвЂ™ll be safe from cars, contagious diseases, predators, and cruel humans and able to enjoy toys (including those filled with catnip) for years to come.вЂќ
Even so, if you've been struggling with the issue of whether it's OK to give your kitty what is, essentially, a drug, here's some info that might settle your mind a bit: According to Scientific American, the plant isn't addictive, so there's no need to worry that you're encouraging a bad habit for your pet. In fact, any "high" that your cat feels will only last for about 10 minutes, so it's definitely a different ballgame than marijuana. (In case you're wondering, humans can't get high off of catnip the way their feline friends can, though apparently, you might be able to benefit from some of its health effects, as "catnip is commonly recommended by herbalists to lessen migraine headaches and to relieve cramps, gas, indigestion, insomnia," among other wellness issues, according to Scientific American.)
If you're still feeling unsettled about treating your sweet cat to catnip, it's totally fine to stick with fishy treats and a good ol' ball of yarn. But if you would like to experiment with it, just make sure to pay attentive to how your feline friend is acting during and after a catnip session. "Be mindful of overindulgence though вЂ” cats are unlikely to overdose on catnip, but they can get sick if they eat too much," suggests The Human Society. "Trust your kitty to know when they've had enough."
There are a few varieties of catnip. Some are more suited for the ornamental garden, while others are better if you’re looking for something to use medicinally.
This is the one you want if your main objective is to please your feline friends or if you’re growing catnip for its medicinal uses. It gets about 3 feet tall and has white blossoms with a faint purple spotting. True catnip is native to Europe, but it has naturalized across the U.S.
Catmint is in the catnip family, but the plants are different. It tends to have a bushier growth habit and to have showier flowers. The blossoms are purple, unlike catnip’s flowers, which are usually white. Catmint doesn’t have the chemical compound that drives kitties wild, so it’s more useful as a mint substitute or an ornamental.
As the name implies, this variety has a lovely lemony scent. It’s excellent as an insect repellent, and you can use the natural oils in the leaves to keep mosquitos away.
This variety is a little smaller than true catnip, only reaching about 18 inches tall. It has white or pale pink flowers.
This variety is so good looking in the garden that it can be planted as an ornamental. It has a ton of flowers and will bloom a second time in the summer if you trim it back after its first blossom. Six hills giant is extremely drought tolerant and gets 3 feet tall.
Camphor catnip has pretty white flowers with purple dots. In only grows about 18 inches tall.
Catnip (Nepeta cataria) may have a euphoric effect on cats, but the plant deters insects by triggering a chemical sensor for irritants, a new study shows.
Turnip Towers/Alamy Stock Photo
A whiff of catnip can make mosquitoes buzz off, and now researchers know why.
The active component of catnip (Nepeta cataria) repels insects by triggering a chemical receptor that spurs sensations such as pain or itch, researchers report March 4 in Current Biology. The sensor, dubbed TRPA1, is common in animals — from flatworms to people — and responds to environmental irritants such as cold, heat, wasabi and tear gas. When irritants come into contact with TRPA1, the reaction can make people cough or an insect flee.
Catnip’s repellent effect on insects — and its euphoric effect on felines — has been documented for millennia. Studies have shown that catnip may be as effective as the widely used synthetic repellent diethyl-m-toluamide, or DEET (SN: 9/5/01). But it was unknown how the plant repelled insects.
So researchers exposed mosquitoes and fruit flies to catnip and monitored the insects’ behavior. Fruit flies were less likely to lay eggs on the side of a petri dish that was treated with catnip or its active component, nepetalactone. Mosquitoes were also less likely to take blood from a human hand coated with catnip. Insects that had been genetically modified to lack TRPA1, however, had no aversion to the plant. That behavior — coupled with experiments in lab-grown cells that show catnip activates TRPA1 — suggests that insect TRPA1 senses catnip as an irritant.
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Puzzling out how the plant deters insects could help researchers design potent repellents that may be easier to obtain in developing countries hit hard by mosquito-borne diseases. “Oil extracted from the plant or the plant itself could be a great starting point,” says study coauthor Marco Gallio, a neuroscientist at Northwestern University in Evanston, Ill.
If a plant can make a chemical that activates TRPA1 in a variety of animals, none are going to eat it, says Paul Garrity, a neuroscientist at Brandeis University in Waltham, Mass., who was not involved in the work. Catnip probably didn’t evolve in response to predation from ancient mosquitoes or fruit flies, he says, since plants aren’t on the insects’ main menu. Instead, these insects might be collateral damage in catnip’s fight with some other plant-nibbling insect.
Catnip may deter insects like this yellow fever mosquito (Aedes aegypti) by triggering a chemical sensor that, in humans, detects pain or itch. Marcus Stensmyr
The finding “does make you wonder what the target is in cats,” says Craig Montell, a neuroscientist at the University of California, Santa Barbara also not involved with the study. The question is not only whether catnip targets TRPA1 in cats but also whether the plant might send signals through different cells — such as those for pleasure — in the feline nervous system, Montell says.
Luckily, the plant’s bug-off nature doesn’t affect people — a sign of a good repellent, Gallio says. Human TRPA1 did not respond to catnip in lab-grown cells. Plus, he says, “the great advantage is that you can grow [catnip] in your backyard.”
Though maybe don’t plant catnip in the garden, says study coauthor Marcus Stensmyr, a neuroscientist at Lund University in Sweden. A pot might be better, he says, since catnip can spread like a weed, taking over a garden.
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A version of this article appears in the March 27, 2021 issue of Science News.