August 15, 2020
When growing medicinal plants at home/indoor grow tent, it’s hard to imagine everything running smoothly and problem-free for the entire cycle. There are all sorts of issues you could experience… pests and pathogens can invade the tent, equipment( indoor grow light，etc) can break, waterings can be forgotten… learning how to deal with issues first-hand is the best way to become a better gardener.
Fungus gnats are one of those potential problems. They’re annoying little bugs about the same size as a mosquito. If you allow fungus gnats control of the grow, they could damage and even destroy your entire crop.
Fungus gnats are tiny (adults are sized at 2 millimeters) pests that consume fungus near the soil. When they run out of fungus, they start to eat the hairs and other parts of your medicinal plant’s roots.
This can have serious effects on your plant’s growth, and could lead to changing colors, and higher vulnerability to fungal diseases. They are brown, black or gray, and both males and females both have long legs.
Females lay up to two hundred eggs every week. These eggs are found on the lower half of your medicinal plants. Larvae, or maggots, have clear bodies and black heads, but are impossible to see because they are too small. Maggots and adult fungus gnats are equally harmful to your medicinal plants.
In addition to eating plant roots, the fecal matter they leave behind is also harmful. The gnat poop causes the soil to hold too much moisture. This, of course, can lead to increased problems with other pests and mold.Fungus gnats are attracted to plants when the soil is overwatered and covered with decaying organic matter.
You won’t see the fungal growth because it is too small for human eye detection. But the fungus gnats can see it, and when they do, they will want to feast, and lay eggs on your medicinal plants.
A fungus gnat infestation is relatively easy to diagnose. Fungus gnats are small, but you can see them if you get close to your plants. Here’s how to spot them:
• Tiny “flies” crawling and jumping on the soil around your plants.
• White maggots wiggling in the soil. Not as easy to spot as they are very tiny and may be hidden in the soil.
• Otherwise unexplainable plant issues including, but not limited to, pale leaves, spots, brown edges on leaves, and drooping plants. Signs can vary and may appear as other plant issues and diseases.
Larvae attack tender new plant roots and root hairs, which cause these problems:
How to get rid of Fungus Gnats
You need to get rid of an infestation as soon as it starts, even if negative signs haven’t yet shown. While trapping the adults by using the yellow sticky cards is a fairly easy way to remove them, the larvae are not so easy to deal with. The first thing you should do is:
Water less frequently
The first, and most important, thing you should do is rethink your watering routine. Allow the soil to dry out fully between waterings—it will be fine. Most of the time, if you do that, the fungus gnat problem will go away on its own.
Yellow sticky cards: A fungus gnat trap
Fungus gnats love yellow and some careful placing of yellow sticky cards can draw them away from your plant, trapping them in the process.
You can monitor the effectiveness of your treatments with a regular body count. As the number of trapped gnats decreases, you’ll know your actions are having an effect.
Get a fan blowing air over the top of the growing medium.
This helps dry out the top layer of your soil, and also helps prevent the fungus gnats from being able to fly around and lay more eggs.
Neem Oil Fungus Gnats
Neem oil is safe to use and it kills gnats almost immediately. The problem is that it really stinks, and will do so for a few days at least. If your plant is in full flower and close to harvest, don’t spray it on the buds. It will alter the flavor of the cured medicinal plants and will be a disappointing end to your grow.
Neem oil is a great product to have on hand. Apart from fungus gnats, it’s also a great way to treat aphids, caterpillars and other garden pests.
Diatomaceous earth
Diatomaceous earth is another way to get rid of bugs naturally. Sprinkle the fine powder on the soil around your plants. This should take care of the nasties in no time.
BT bacteria
“BT” or “BTi,” which stands for Bacillus Thuringiensis, is a bacteria contained in pest treatments that effectively kills the fungus gnat larvae. It prevents the larvae from eating and, therefore, kills them off effectively. This also will have no harmful side effects to you or your plants. Simply pulverize the store-bought pellets, and sprinkle it on the soil. Be sure to buy the dry (not liquid) version. After treatment, water your plants generously.
How to prevent Fungus Gnats
Prevention is always better than treatment—here’s what you can do to keep those nasties away.
Water less frequently
More than anything else, pay attention to the amount of water you give to your plants! Wet, warm conditions are practically begging for fungus gnats. Allow the soil to dry out. If you are not sure when to water, you can do the “lifting test”. Simply lift up your plant with its pot and compare the weight when fully watered versus dry. Water only if the pot feels noticeably lighter.
Cover the soil
Since fungus gnats live and breed in soil, you can cover it with sand, gravel, or perlite to prevent them from getting cosy. Keep in mind, however, that while covering the soil may prevent the gnats from appearing, your plants may still be water-logged.
Sterilise your soil
Sometimes, you simply can’t prevent bugs from appearing, for instance if they were already present in the soil. To be on the safe side, sterilise your soil first. Do this by putting some soil in a flat, oven-safe container like a baking pan and cover with foil. Place a meat thermometer into the centre and “bake” for at least 30 mins at 82–93°C. While you’re at it, ensure your pots and growing area are clean as well. This way, you can minimise the risk for all manner of diseases, fungi, and pest infestations.
Consider alternative growing media
If you find your medicinal plants are frequently "bugged", consider growing in an alternative medium. When you grow medicinal plants in coco, perlite, or hydroponically, pest infestations are less likely.