5 Ways to Get Rid of Spider Mites during Flowering
Whether you choose to grow cannabis outdoors or indoors, in soil or hydroponically, for your own personal use or commercially, any rewards to come at harvest time are well-balanced with a long list of risks along the way.
By the time your plants reach the flowering stage of their growth, when the buds begin to form and fill out, you are likely heavily invested in time and money to get them there and seeing them through safely to harvest day is among your highest priorities. During this phase, you want all of the plant’s energy going into feeding those bulging colas and swollen trichomes.
With an intimate daily relationship with your garden, farm, or grow, there are certain tell-tale signs that can express a plant’s health at a glance to help you determine if there is a potential problem that needs attention. Sometimes these signs point to a nutrient deficiency or airflow problem, often easily remedied. Other times they point to something more sinister, and that is the case with the resilient spider mite.
The spider mite is a microscopic 8-legged arachnid that enjoys life in gardens, whether they are growing cannabis or vegetables. As their name implies, they do spin webs that they use to protect their eggs and new offspring.
A female spider mite can lay over 1,400 eggs per year. Each egg hatches in three days and the resulting offspring is fully mature and ready to reproduce in just five days. This rapid and compounding population growth poses a serious risk to any gardener, farmer, or grower who hopes to eradicate the crop-threatening pest.
Spider mites puncture the surface of cannabis plant leaves to feed on the plant’s life-giving chlorophyll found in the cells within. Well into their infestation, the initial visible sign of their repeated feeding is a whitish or yellowish speckled or mottled effect called ‘stippling’ on the fan leaves of the plant.
Since the mites are so small, and their eggs even smaller, and both tend to reside on the underside of leaves, this discoloration of the foliage is often your first indicator that something is awry.
If left unchecked, the multiplication of numbers begins and you may see entire fan leaves curl up and drop from the plant once sucked dry by the mites. This is also when you’ll begin to notice the web-spinning as mature mites migrate from one leaf to the next, leaving behind fine white wisps of webbing as evidence of their infiltration.
Though they do try to avoid contact with the ultra-sticky trichomes that are hopefully beginning to blanket your buds by this point, spider mites can envelop an entire fan leaf or even a full bud in their webbing.
As you can imagine, you wouldn’t be too keen on smoking such a bud, and nobody will be interested in buying it either, so what can you do to get rid of spider mites during flowering?
You’re heard the expression “fight fire with fire”, well one good way to deal with spider mites is to fight bugs with bugs.
There are many predatory insects that can be introduced to your grow environment that will ignore your prized pot plants and instead immediately go to work feasting on your 8-legged unwelcome guests.
Ladybugs are voracious mite murderers and a cannabis grower’s best friend for an all-natural pest solution.
The most common spider mite affecting cannabis grows is the “Two Spotted Spider Mite”. Aside from ladybugs, there are other types of mites, thrips, and bugs that also love to munch on your enemy, but will leave your plants alone.
In outdoor cannabis grows, these predator bugs will feed until the food (spider mites) is gone, at which point they fly off.
This solution is best used when mite populations are still low.
By pruning, we don’t just mean clipping leaves – though we will get to that – but also physically removing the mites themselves from the plants by hand or with a very low powered vacuum tube.
If removed by hand, they need to be squished. Gross, yes, but no mercy for these intruders. If removed by vacuum, you need to get the contents of the vacuum into a sealable bag and into a trash can far, far away from your grow.
Again, these spider mites can be very hard to see with the naked eye and their eggs even more so. So this hand-pruning method is also best employed early in the infestation when numbers are low. Even then, expect to repeat the process for several consecutive days to effectively eliminate the problem.
Since mites thrive in warm, stagnant environments, try dropping the temperature if possible and increasing airflow to slow their reproduction as you squish away.
For the leaves themselves, if the leaf is showing obvious signs of distress and has 50% or more of its surface affected by mite feeding, it’s probably best to snip it off and allow the plant to focus its resources elsewhere.
If you’ve tried the methods above, or have just discovered a disturbing colony of spider mites, you can try hosing the plant(s) off with a gentle showerhead and regular water which can physically flush the mites and webs off of the plants.
Note that this will not kill them and they may scatter. This water shower also will not budge the eggs that are usually pretty firmly attached.
For a stronger solution, simple isopropyl alcohol can be mixed at a 1:9 ratio with regular water and applied with a garden sprayer. This will kill most mites on contact without harming the plant, but you definitely want to try to avoid spraying the buds with alcohol if you can avoid it.
Whichever method you try, remember to thoroughly wash the underside of the leaves, as that is where spider mites and their eggs tend to dwell.
4. ESSENTIAL OILS
Many cannabis farmers have reported success in the war on spider mites by using varying concoctions of different essential oils extracted from plants like peppermint, rosemary, cinnamon, eucalyptus, and more.
These oils are diluted with water and applied to your plant’s affected leaves with a garden sprayer or spray bottle. You’ll once again want to avoid coating your buds with this aromatic mixture, especially so close to harvest.
One of the most popular essential oils is Neem Oil. Though most won’t admit it, Neem Oil usually has a permanent place in a grower’s toolkit, and when used sparingly, can be a highly effective weapon when fighting mites. When this foul-smelling product is used incorrectly, you can ruin your plant or crop while trying to save it.
5. ORGANIC vs. TOXIC PESTICIDES
When all else has failed and your crop is on the line, there are dozens of commercial pesticides on the market that specifically target spider mites and do so very effectively.
Unfortunately, a significant number of these products are not intended for use on goods that are intended to be lit on fire and inhaled and so should be avoided completely.
The closer the crop gets to its harvest date, the harder it gets to properly flush these products from the plant or to avoid affecting the buds with these invasive measures.
Organic or otherwise, insecticidal soaps, solutions, and strips absolutely work, but they are rarely made from stuff that you want to breathe, smoke, or eat so treat them as a last resort.
Sometimes the infestation is so bad that an entire plant or harvest is lost to it. If it was an indoor grow, the entire growing environment needs to be methodically cleaned top to bottom with a bleach /water solution.
Any new plants or clones that come into the grow site need to be quarantined for at least a week before joining the rest of the garden to ensure that they are not carrying any near-invisible pests with them.
Mites and other invaders are often introduced to your grow by hitching a ride on you! So a shower and a change of clothes before entering your indoor garden is always a good idea. Keeping random friends and guests away is prudent as well. They can help you come trim later.
A sprinkle of diatomaceous earth around your pots, atop your soil bed, across your door thresholds, and at the ends of your dry-lines will shred and dehydrate mites that try to cross it and will not affect your plants.
The best way to fight mites is before the battle begins.
An ounce of prevention up front can lead to pounds of high-yielding cannabis at the end, and fewer headaches for you, the grower, along the way.
By: Jack Riordan