Catnip, also known as catswort or catmint, is a popular garden herb often used to make tea. And not only that; this herbaceous perennial is also well-loved by cats! Thanks to its active ingredient, nepetalactone, one whiff of the plant can give your furry friends a sense of euphoria. This is why you often see viral online videos of cats going crazy on catnip.
If you are growing catnip in your garden, it is probably because you and your feline friends enjoy the taste and scent of this lovely herb. But what if your catnip suddenly develops white spots?
White spots on catnip leaves are often indicators of a pest infestation. But do not worry – these sturdy herbs should recover quite easily with a bit of extra care and attention. Read on to learn what causes these unsightly white spots, and the best way to get rid of them!
What causes white spots on catnip leaves?
White spots on catnip leaves are a sign of damage to the leaf surface. Check out the common culprits below to determine the appropriate solutions to revive your plant:
1. Spider mites
Spider mites are insects that resemble miniature spiders. They are white or almost transparent, and often difficult to identify because of their tiny size. However, you can confirm their presence by the web-like structures they leave on the underside of your catnip’s leaves.
The early stages of a spider mite infestation cause just a few white spots on your catnip leaves. Since the pests can reproduce quickly, however, these white spots can become denser and engulf your catnip plants in a matter of weeks. Spider mites damage the plants by sucking the sap from the leaves, and without your prompt intervention, these sap-suckers will slowly weaken and even kill your plants.
Just like spider mites, thrips suck the life from your catnip’s leaves until they turn dry and white. At first glance, these tiny insects look like dark slivers, or sewing needles, and are so small that you can barely see them with the naked eye. But, with the help of a magnifying glass, you will see that these pests actually look like tiny lobsters! Depending on the variety, some thrips might be black or brown, while others are orange or golden in color.
Aside from leaving white spots on your catnip’s leaves, thrips are also carriers of viruses that can infect multiple plant species. These fringe-winged insects are also capable of flying to other nearby plants. Thus, if you suspect your catnip is infested with thrips, the plant must be isolated right away to prevent any spread of the infestation.
Catnip that develops white leaf spots despite being pest-free is likely struggling with sunscald. Check the area where your plants are growing and see whether they are constantly exposed to very harsh sunlight.
Sunscald, or sunburn, can damage the delicate leaves of most houseplants, especially those that are sensitive to intense heat and direct sunlight. Unfortunately, catnip is also susceptible to this problem, particularly on summer days when the weather is very hot.
Additionally, the damage and scars on the leaves can attract both fungal and bacterial pathogens. The presence of these microorganisms can make things worse for your struggling plants as they hasten the decomposition process.
Sunscald can also inhibit the transport of nutrients throughout the plant’s stems and foliage. This can leave your catnip nutrient-deprived, which can be yet another possible cause of white spots.
Signs your catnip has a pest infestation
By far, pest infestation is the most common reason for white spots on catnip leaves. But, since most of these bugs are so tiny and very mobile, how do you know if your catnip is being eaten by pests? Here are some of the tell-tale signs:
1. Presence of tiny insects
Insects love hiding on the undersides of the leaves. So, if you suspect an infestation based on other symptoms, carefully lift your catnip leaves to check the surface underneath. You might be able to see a cluster of tiny bodies living under your plant’s leaves.
2. Visible insect eggs
These tiny bugs are smart enough to lay their eggs underneath the leaves to keep them out of your sight. So check your catnip leaves – especially the more mature leaves – to confirm the infestation. If you see a mass of tiny balls, these are eggs. Depending on the type of infestation, the eggs might be brown, yellow, or white.
3. Honeydew-like substance
Do you see some spots that look like tiny water droplets on the surface of the leaves? If they are sticky, then what you are seeing is a byproduct produced by the pests. This is another visible sign that you can check to confirm an infestation on your catnip.
4. Small, delicate webs
If you notice web-like structures on the surface of the leaves, it is a sure sign that your catnip is infested with spider mites. Keep an eye on the leaves and nodes of the plant for signs of this webbing.
How to get rid of white spots on catnip
White spots on catnip leaves can be caused by several issues. Aside from pest infestation, leaf discolorations can also be associated with poor soil conditions and root rot. Hence, the first step to saving your precious plants is to identify the exact culprit based on the symptoms.
If a pest infestation is confirmed, you can try the following tips to get rid of the white spots and bring back the healthy green color of your catnip leaves:
- First, isolate the infected plant. This step is very important to prevent the infestation from spreading to other, neighboring plants.
- Cut off the damaged leaves and stems, including those with insect eggs. Gather the infected parts and burn them.
- Using a garden hose, spritz the affected leaves with water to dislodge the insects. Once you are done, allow the excess water to drain, to prevent waterlogged soil.
- Dilute one part isopropyl alcohol with three parts water and use this to clean the leaves of your plant. Pests hate alcohol, and the solution can also help get rid of the honeydew-like substances and webs left behind on the leaves.
- Use natural insecticides to eradicate any remaining pests you see. Some of the best options include diluted apple cider vinegar or neem oil. Catnip is an edible herb, so it is best to avoid harsh chemicals or synthetic insecticides that are toxic.
- Spray your catnip leaves with diluted insecticidal soap to kill both the adult insects and their eggs. Use a solution of about one to two percent, or two to five tablespoons of soap per gallon of distilled water.
- Finally, you may want to consider repotting your catnip after treating it, because some bugs can hide in the soil to resurface later on. Make sure to use fresh, well-draining soil for your catnip.
Tips to prevent white spots on catnip leaves
As the common saying goes, prevention is always better than cure. Once your catnip has fully recovered, it is time to implement some preventative measures to hold off re-infestation in the future. This can be done by creating favorable growing conditions for your plants to keep them healthy and disease-resistant.
The following tips are some of the efficient ways to protect your plants from pest infestation in the future:
- Although catnip can thrive in partial shade, it is best grown in full sunlight. Make sure that your catnip receives about six hours of sunlight each day. Aside from keeping its foliage green and healthy, the heat from the sun can also help dry the soil between waterings and kill potential pests.
- Plant your catnip in well-draining, nutrient-rich soil. Like most houseplants, this herbaceous perennial does better in lightly moist, airy soil. Use coco peat and perlite in your potting mix to keep the soil healthy and prevent standing water.
- Avoid overwatering your plants. Watery soil will not only damage the root system, but also promote fungal growth and attract pests. Water your catnip only when the top layer of soil has completely dried.
- Choose natural insecticides to control early signs of infestation. You can also apply neem oil once a month to discourage pests from devouring your plants.
White spots on catnip leaves are generally caused by pest infestations – particularly thrips and spider mites. Early intervention is critical as these bugs tend to reproduce quickly. To manage the early stages of infestation, it is best to choose the natural methods mentioned in this article as these options are not harmful to you or your plants.
Lastly, keep your catnip healthy and in top shape as this is your best defense against any form of disease or infestation!
Image: istockphoto.com / Stephanie J Connelly