Pests in The Growroom – Overview (Part 2)
It is important that pests be spotted early to minimise potential damage. This is critical because, in the case of most insect varieties, numbers can explode very quickly.
When dealing with pests it comes down to proactive growing practices. That is, tackling the problem before it becomes too much of a problem. For instance, there is very little point noticing the presence of spider mite at the point that their webs are covering your crop. If this were the case your plants would already be severely damaged/stressed.
Simple early warning systems such as placing yellow sticky traps in your room (particularly near entry points… eg. air inlets and hung above plant canopy level and placed horizontally on pots) will help you pick up the presence of unwanted pests before things get out of hand.
Yellow sticky traps are a non-toxic way to monitor aphids, cucumber beetles, fruit flies, fungus gnats (sciaridae), leafhoppers, froghoppers, moths, whiteflies, flea beetles, leaf miners etc. The special shade of yellow attracts a broad spectrum of flying insects. The traps are covered in a sticky substance so firstly, pests are attracted to the trap and then stick to it. Thus, you can be alerted as to the presence of pests in the growroom very early on.
Being able to recognize the most common insects found on sticky traps allows the grower to select an appropriate pest control strategy. For example, were traps to show a sudden increase in numbers of dark flies, the proper control measures could be a) do nothing (shore flies), b) drench the media with an insecticide (fungus gnats) or c) spray the foliage thoroughly (leafminers).
Similarly, checking your plants for insects should be a weekly ritual. Examine the tops and undersides of leaves as an early means of detection. Look for signs of leaf damage (rust like spots, silver residue on leaves and deformities etc) and for the insects themselves.
If you identify the presence of pests, combating them should be done with careful consideration. This applies to the type of pest, at which point of the grow or bloom cycle you are at, and how severe the pest infestation is.
Botanical compounds such as Neem oil should be used wherever possible. The compounds contained within Neem oil, which has insecticidal properties have been identified as a class of chemicals called limonoids. The most widely documented of these compounds is Azadirachtin, which is a potent growth regulator and feeding deterrent. Azadirachtin is structurally similar to the insect hormones that control the process of insects turning from larva to adults, thus breaking the lifecycle. Neem oil should be used in conjunction with a wetting agent for best effect.
Additionally, pyrethrins can be used to control some pest populations. Pyrethrins are natural insecticides produced by certain species of the chrysanthemum plant. The natural pyrethrins are contact poisons only which quickly penetrate the nerve system of the target insect.
Other low toxicity treatments – soft soap sprays and petroleum/paraffinic based products (eg. JMS Stylet-Oil® and Organic JMS Stylet-Oil®) – are extremely effective alternatives against whitefly and twospotted mite populations. Another advantage to using Stylet Oil is it combats botrytis and powdery mildew. As a word of warning here, don’t use sulfur on plants within 20-30 days of applying spray oils. Sulfur reacts with the oil to create phytotoxicity.
Botanical oils such as rosemary oil, soybean oil, cinnamon oil, eucalyptus oil etc are shown to work effectively against many pests. We’ll cover various botanical and other formulas at the end of this article.
Similarly, the use of natural predators should also be considered. For instance, fungus gnats – the bane of coco growers – are controlled extremely well by Steinernema feltiae (a predatory nematode that feeds on fungus gnat larvae).
In order for insects/pests to enter the growroom they must invariably come in from outdoors. As indoor growers we, unlike field growers, have the luxury of being able to create microenvironments that enable us to exclude insects of any kind.
For this reason, implementing best practice in growroom design and management is essential for the prevention of pests and the diseases.
Insects/Pests and Plant Viruses
Plant viruses are viruses that affect plants. Like all other viruses, plant viruses need a host. Hartowicz et al. (1971) screened 22 common plant viruses for their ability to infect wild hemp. Over half the viruses could infect Cannabis. 1 Viruses rarely kill Cannabis. They will, however, seriously reduce yields. 2
Insects/pests are most important factors in plant virus disease. Approximately 80% of the plant viruses depend on insect vectors (transmitters) for transmission (other vectors can be nematodes and fungi), and the plant virus vector interactions are very specific. Piercing, sucking insects are the main vectors of viruses.
Just one example is the whitefly, Bemisia tabaci (B. tabaci), is the exclusive insect vector for a large group of emerging plant viruses that infect several hundred plant species worldwide. Once considered an obscure whitefly, B. tabaci is now among the most invasive and economically damaging insects to agriculture, spanning food and fiber crops, and certain nursery grown ornamentals, with the ability to infest more than 500 plant species.
Another example is aphids. Aphids transmit more plant viruses than any other group. Aphid-borne viruses induce in plants a great variety of symptoms, the most important of which are the mosaic viruses. Many aphid vectors transmit virus after very brief feedings on diseased plants. Studies on this type of transmission have reached a point where the feeding intervals of individual aphids are closely observed and timed by a stopwatch. For example, the vector of beet mosaic virus requires an acquisition feeding of only 6 to 10-seconds.
For this reason, insecticides are inefficient in preventing noncirculative plant viruses spread by vectors becaue the time needed to kill the vector is longer than the time needed to inoculate the plant.3
For this reason, keeping insects/pests out of the growroom is imperative to realizing optimum yields.
- Hartowicz, L. E. et al. 1971. Possible biocontrol of wild hemp. North Central Weed Control Conference, Proceedings 26:69
- J. M. McPartland (1996) A review of Cannabis diseases
- B Raccah (2009) Plant Virus Transmission by Insects
Rule 1: PREVENTION IS ALWAYS BETTER THAN CURE!!!
The best way to defeat pests and the diseases they spread is to prevent them from ever getting into your growing environment. In order to do this, you need to create a pest resistant fortress. This means completely sealing off your growroom to outside air exchanges and closing off any gaps (under doors etc) where may gain entry to the growroom.
Air Filtration to Keep Pests Out
HEPA or Other Filters On Inlet Fans
Placing a filter over an intake port or inlet fan works well as long as the filter is fine enough to act as a barrier against pests. Some recommend A/C filters while others suggest an activated carbon filter; however, HEPA (High Efficiency Particulate Arrestance) filters are best suited to the task.
HEPA filters have many applications, including use in medical facilities, greenhouses, automobiles, aircraft, and homes. They stop mold spores as well as many bacteria and viruses and larger particles such as dust.
However, by design, HEPA filters will create resistance to airflow, and a high differential pressure drop will exist across the filter. HEPA filters, as defined by the DOE standard adopted by most American industries, remove at least 99.97% of airborne particles 0.3 micrometers (µm) in diameter. The filter’s minimimal resistance to airflow, or pressure drop is usually specified around 300 Pa (pascal) at its nominal flow rate. This needs to be compensated for by introducing fans suitable for maintaining adequate air intake.
Specialized HEPA filters have been developed for greenhouse and growroom purposes. Many of these can be washed to ensure maximum performance over a long period of time. Other than this, industrial HEPA fan and filter units are available that have high airflow values.
It is important to note that no matter what type of inlet filter you use, it will need to be regualrly washed of dust and other particles to ensure air channels do not become blocked and reduce airflow efficiency. Below are some images of HEPA filters. “Image 1” is a greenhouse unit and “Image 2” is an industrial unit which incorporates both fan and filter.
Activated Carbon Filters For Exhaust Fans
Pests can also enter the growroom through exhaust fans that aren’t filtered (ie. when fans are turned off pests can enter through the fan vents). For this reason exhaust fans need to be filtered.
Activated carbon filters are the ideal for exhaust filtration because not only do they act as a barricade against pests but they also elminate odour.
The basic principle of activated carbon filtration is that when volatile organic compounds (eg. odour) enter carbon filters they are intercepted and held/absorbed. This means that air is filtered of volatile organic compounds as it passes through activated carbon.
However, it is important to note that activated carbon filters, while preventing pests from entering the environment through inlet air, are not shown to filter pathogens such as bacteria and fungi. Below is a schematic of a fully contained pest resistant growroom. Of course, there is no reason for this level of sophistication. This growroom schematic includes CO2 and aircooled lighting. You could just as easily give these a miss and simply install HEPA and carbon filtration on any form of growroom.
Fan Type For Use With HEPA and Activated Carbon Filters
There are three types of fan commonly sold through hydroponic stores.
These are axial, radial/centrifugal, and mixed flow fans.
Axial fans are the cheapest of the three fan types and move adequate levels of air (based on wattage and blade design) but do not build air pressure/line pressure.
Because axial fans do not build air pressure they are not suitable for use with carbon filtration. We have conducted tests on axial fans with Can carbon filters and established airflow loss of approximately 85%. This would mean that a 200l/s axial fan could be moving as little as 30l/s through a carbon filter. In other manufacturers filters with less airflow (C centrifugal flow tests further on) this loss will be even greater.
Centrifugal fans are designed to build air pressure by sucking air in through the center of the fan and forcing it outwards in an enclosed area. This means that the centrifugal fan is good at what the axial is not; it is designed to push air through impedances such as ducting and carbon filters. Having said this, air loss will still occur as a result of static pressure, however, this loss is a significantly lower percentage than that of an axial fan (C centrifugal flow tests further on). Centrifugal Fans are the most flow efficient fans for carbon filtration.
Mixed Flow fans are a reasonably effective combination of axial and radial design. The blades on the mixed flow fan are arranged similarly to the axial fan but the whole assembly is enclosed.
About Fans (Airflow Dynamics)
Airflow needs to be considered in terms of airflow and air pressure. While airflow and air pressure are interrelated they are not the same thing.
Airflow rate is the volume of air moved per unit of time. Airflow rates are typically stated as cubic feet of air per minute (cfm), cubic metres of air per minute (m3/min), or litres of air per second (l/s).
Air pressure represents the level of force behind the airflow. If you like, air leaves the fan as airflow (volume) while air pressure forces it to keep traveling at a given rate. The more air pressure behind the airflow (volume), the further the air will travel at a given rate. More pressure equals more volume over a longer distance (put simply).
Air pressure is therefore responsible for forcing air along lines (ducting etc) and forcing air though impedances such as carbon filters.
The more air pressure and the more airflow, the more efficient a fan will be at moving air through impedance/s – however the laws of physics determine a balance between max air pressure and max airflow; the two are ultimately interrelated. Put simply, too much of one will compromise the other and vice versa.
Air Pressure = Noise (a sad fact of physics)
Noise (db) is relative to air pressure. A quiet fan is a fan that is lacking in air pressure. While it is possible to have efficient airflow with minimal noise, it is impossible to have the right combination of airflow and air pressure (relative to wattage and fan circumference/size) with low db. Fans that claim to be high performance and quiet are actually defying the laws of physics.
When it comes to equipment choices, first you must find the right product to suit the task at hand and then find ways of modifying the right equipment for your environment. For instance, a high output centrifugal fan may make more noise than you’d ideally like so you need to find a way of reducing the db without reducing airflow/air pressure.
This is relatively easy to do. Acoustic ducting, and inline silencers are available through hydroponic stores and these products will significantly reduce fan noise. Furthermore, you can place the fan body in a box and surround it with insulation (vermiculite is ideal for this) in order to further reduce noise. The possibilities are endless; it is simply about being creative and developing solutions for the problem.
Below is an illustration of an ideally configured carbon exhaust setup (no odours, limited noise), with illustration of a centifugal fan.
Other Prevention Methods For Pests and Diseases (Best Practice)
Once your growroom environment is filtered/sealed properly, these are handy rules to follow.
- Sterilize the grow room between crop cycles (and during the crop cycle) with a dilute bleach solution.
- Seal off any gaps between door and floors etc (even the smallest gaps/holes will provide an entry point to pests that are located outside the growroom)
- Keep things clean by removing dead plant material or other organic material from your grow space and dispose of it in sealed airtight bags.
- Do not store old soil or root masses in or around your grow room. Dead plant matter is extremely attractive to a variety of pests, especially fungus.
- Keep your indoor cultivation tools separate from your outdoor tools.
- Do not enter your indoor garden after having worked in your outdoor garden. Pests from outside can be inadvertently carried in.
- Wash hands and wear clean clothes whenever entering the growing area.
- Pests and their larvae can hide in the smallest crevices. Therefore, the floor should be laminate etc.
- Clean up spills, excess water or plant runoff. Leaving moisture on the floor raises humidity levels and increases your risk of mold or rot.
- Spray ornamental garden plants such as roses regularly with chemical pesticides. Pests such as aphids are very common on roses etc.
- Clear long grass and weeds in the garden and dispose of or burn.
- Compost heaps attract fungus gnats so consider composting at another location.
- If using compost, other organic media treat it for fungus gnats prior to introducing it into the growing environment
- Houseplants are susceptible to attack by many insects including whitefly and mites. For instance, the twospotted spider mite is one of the most common houseplant pests. Keep a close eye on indoor ornamental plants (those located in the same house as your growroom) as these can attract pests which may find their way into the growroom. If pests are identified take the plants outdoors and treat them with a chemical pesticides (relevant to pest species) at 5-day intervals.
- Most Importantly, be fastidious in always checking for pests by monitoring with yellow sticky traps and checking tops and undesides of leaves on a regular basis.
Other Important Practices In Pest Prevention
Always Dip Clones Sourced From Elsewhere
Probably the single most common way that pests come into the growroom is through the introduction of clones that have been sourced elsewhere.
Treat any cuttings sourced from outside parties before they go into your growing environment. We’ll talk more about this later.
Treat Mother Plants Regularly
For growers working with clones, infested mother plants are a common source of pest infestations.
For this reason, mother plants should be regularly treated with alternating pesticide treatments. We’ll cover more on this shortly.
Common Grow Room Pests
I’m going to cover only some of the more common grow room pests due to pest species and types being so many. If you really want to know your stuff about cannabis diseases and pests, I highly recommend the book ‘Hemp Diseases and Pests’ by J. M. Mc Partland, R. C. Clarke, and D. P. Watson.
Let’s start with the bane of all indoor gardeners first … The twospotted spider mite (TSSM).
Spider Mites (Twospotted Mite) – aka The “Borg”
The twospotted spider mite (TSSM), is a serious pest of many greenhouse plants, nursery grown ornamentals, and field crops. Twospotted spider mite damage may include webbing, fine stippling, leaf yellowing, and even plant death. Spider Mites usually congregate on the underside of leaves, but in heavy infestations may be found on both sides of the leaves. Spidermites initially tend to congregate in patchy distributions so early infestation may be missed.
Symptons are the worst during flowering when whole plants can dry up and are webbed together. It is thought that the shorter day length of the flowering cycle encourages them to migrate and cluster together at tips of leaves and flowering tops of the plants.
TSSM, Tetranychus urticae, was first described by Koch in 1836 (Pritchard and Baker, 1955). It is thought to originate from temperate climates (Fasulo and Denmark, 2000). It is a ubiquitous agricultural pest with a global distribution (Van de vrie et al., 1985; Nauen et al., 2001 and Stumpf and Nauen, 2002). TSSM is a member of the family Tetranychidae that contains many harmful species of plant-feeding mites (Borror et al., 1989).
TSSM is the most notorious pest responsible for significant yield losses in many economic crops, vegetables and fruit trees in Egypt (Ahmed, 1988 and Salman, 2007) and also horticultural, ornamental and agronomic crops worldwide (James and Price, 2002). This is because of its feeding habits on the underside of leaves results in removing vital chlorophyll and causing a reduction in photosynthetic activity (Steinkraus et al., 2003). The high reproductive potential and extreme short life cycle, combined with frequent acaricide applications, facilitates resistance build-up (Ahn et al., 1996; Stumpf and Nauen, 2002; Chiasson et al., 2004 and Van Leeuwen et al., 2005). See image below that demonstrates the Twospotted Mite’s lifecycle.
Adult female two-spotted spider mites can live for about one month. During this time they may lay from 100 to 200 eggs. Mite eggs are small, spherical in shape and are laid on the underside of leaves. Eggs hatch in about three days and develop into pale green to light-yellow 6-legged larvae. The larvae develop into eight-legged nymphal stages with a feeding and resting stage. Most TSSM activity peaks during the warmer months. They feed and multiply best when temperatures are high and humidity is low (below 60% RH). Optimum temperatures for mite development are between 85 to 95oF (29.4- 35 ºC); with a lower threshold for development of 54°F (12.2 ºC) and an upper threshold of 104° F (40 ºC).
The life cycle from egg to adult varies depending upon temperature, relative humidity levels, and age and quality of the host plant. The TSSM can hatch in as little as 3 days, and become sexually mature in as little as 5 days. One female can lay up to 20 eggs per day and can live for 2 to 4 weeks, laying hundreds of eggs. Female mites are three times more abundant than males. The fast development rate and high egg production can lead to extremely rapid increases in mite populations.
TSSM can be carried into growrooms on plants, people, and pets; they can even float on air currents. Glasshouses and growrooms should be surrounded by a weed-free zone at least 3 m wide. Chickweed (Stellaria species) is an important weed host (Howard et al. 1994). Other than this, castor bean is considered one of the main wild hosts for TSSM.
One of the most common ways that spider mites enter your grow room is through the introduction of cuttings sourced elsewhere. For this reason, it is important to treat cuttings for spider mite and other pests prior to introducing them into the growroom.
Spotting the Borg
Symptoms of injury to the plant include flecking, discoloration (bronzing) and scorching of leaves. Injury can lead to leaf loss and even plant death.
When you turn a leaf over, tiny, oval shaped mites, about pinhead in size, are scurrying around. Their eggs are best seen with a magnifier, will be scattered around at random. Spider Mite eggs are all perfectly round, the same size, ranging from clear to amber in color. With larger infestations a fine webbing, crawling with mites, covers the plant tops. Soon, the leaves are browning and dying. A sever infestation can lead to plant death.
Be 100 percent certain you are dealing with spider mites. Below are some photos of spider mites and their eggs. Use a 10x magnification hand lens to inspect leaves for them. Concentrate on the undersides of leaves.
Botanical Sprays and Other Non Toxic Treatments
J.M Mc Partland et al (1999) state that Cinnamaldehyde, extracted from cinnamon (Cinnamonum zeylanicum), kills all stages of spider mites, including eggs.1 The essential oil of cinnamon bark is about 90% cinnamaldehyde.
Research has shown that Cinnamaldehyde use in some crops results in high rates of phytotoxicity when compared to other control measures.2 Although tests conducted by CTAHR (College of Tropical Agriculture and Human Resources) indicate that the citrus red mite population on anthurium was significantly reduced seven days after one application of Cinnamite (Active: 30% Cinnamaldehyde); citrus red mite populations returned to higher levels at 14 days after one application…phytotoxicity tests at 2X the label use rate indicate that Cinnamite may be safe to use on dendrobium and cymbidium orchids. For resistance management, Cinnamite should not be used for more than two consecutive applications.3 After this, switch to a product such as Stylet-Oil.
A recommended starting rate is at 0.204% or 2040ppm which is 2.26ml 90% cinnamon oil added to distilled water to make a final volume of 1L (Ie. 997.74ml distilled water to 2.26ml 90% cinnamon oil). I would also add a surfactant such as tween 20 (polysorbate 20) at 2.5ml/L to ensure better coverage and aid leaf absorption. This concentration has been shown to be effective on spider mites, aphids, whitefly, thrips, and leaf hoppers. Additionally, Cinnamaldehyde controls Powdery Mildew.
Cinnamaldehyde spray works by contact action only, so proper coverage of all plant parts is essential for control. A follow up application after 5 days is also recommended. Preventing the spray from drying too fast will increase effectiveness. Application should, therefore, happen when the lights are off (during the night cycle) with the growroom extraction fans turned off for 6 hours. Keep in mind that spider mites congregate below the leaf area so particular attention should be paid to thorough wetting of both the undersides and topsides of leaves.
Nicotine – Tobacco Spray for Spider Mite and Other Pests
Homemade tobacco teas can be very effective in dealing with spider mite and other pests.
Nicotine, a key toxin in tobacco, has known insecticidal properties. One of the top three insecticides in the 1880s, nicotine in several forms is still widely used. Nicotine comes from the tobacco plant and is extremely toxic to insects. No insect has ever developed an immunity to this poison. One advantage of home made nicotine tea is that it is very short lived, retaining its toxicity for only a few hours after spraying. This means it can be applied relatively late in flower. We’ll cover more on this and some formulas later.
Horticultural oils (e.g., Sunspray, Stylet-Oil) are shown to be effective in controlling spidermites. The organic version of Stylet-Oil has a Federal EPA registration for use in organic production.
Stylet Oil leaves no taste so can be used late into flower.
Spray during the night cycle and switch off fans for 4-6 hours after spraying.
Read manufacturers labels and instructions re warnings etc before use.
You will need to spray every 3-4 days to control a mite population.
Rosemary and Neem Oil
The natural salts from fatty acids derived from rosemary extracts disrupt the insect cell structure and permeability of its membranes. Cell contents then leak from damaged cells and the spider mites quickly die.
Neem oil has wide usage as a bio-pesticide for organic farming, as it repels a wide variety of pests including the mealy bug, beet armyworm, aphids, cabbage worm, thrips, whiteflies, mites, fungus gnats, beetles, moth larvae, mushroom flies, leafminers, caterpillars, locust, nematodes and the Japanese beetle. Neem oil which has insecticidal properties have been identified as a class of chemicals called limonoids. The most widely documented of these compounds is Azadirachtin, which is a potent growth regulator and feeding deterrent. Azadirachtin is structurally similar to the insect hormones that control the process of insects turning from larva to adults, thus breaking the lifecycle.
- J.M. McPartland, R.C. Clarke, and D.P. Watson (2000) Hemp Diseases and Pests. Management and Biological Control
- Raymond A. Cloyd (2002) Phytotoxicity of Selected Insecticides on Greenhouse-grown Herbs
Predators – Biological Controls for Spider Mite
Predator mites and “spider mite destroyers” are another option to controlling spider mite. Biocontrol should be established before spider mite populations explode. If mite populations balloon, biocontrols never catch up.
Additionally, in my own experiences, predator mites of spider mite have limited efficiency unless conditions are ideal to sustain them (just one of these conditions is there are sufficient amounts of spider mites and eggs for the predator mites to feed on).
Their use, for this reason, comes with mixed feedback from indoor growers.
Various insects and predatory mites feed on spider mites and provide a high level of natural control. One group of small, dark-colored lady beetles known as the “spider mite destroyers” (Stethorus species) are specialized predators of spider mites. The problem is that it takes 4-6 weeks to really get these guys going.
A great many mites in the family Phytoseiidae are predators of spider mites. Some of these are produced in commercial insectaries for release as biological controls. Among those most commonly sold via mail order are Galendromus occidentalis, Phytoseiulus persimilis, Mesoseiulus longipes and Neoseiulus californicus.
Predatory mites often have fairly high requirements for humidity, which can be limiting when considering that spider mites feed and multiply best when temperatures are high and humidity is low (below 60% RH). What often seems to happen is that heat loving spider mites who thrive in low RH conditions congregate at the tops of the plants (where the temperature is warmest) while the predators congregate in the lower regions of the plants. This means that at least some species of predator mites can have low efficiency in biological pest control.
Raising lamps and reducing temperature may help; however, due to the fact that high humidity is undesirable in the flowering cycle (due to encouraging fungal infections such as botrytis) raising humidity is not a good idea (optimum humidity in the flowering cycle being 45-55%).
Phytoseiulus persimilis likes a temperature range of 55 – 105+ F and humidity range of 55 – 90%; Neoseiulus californicus likes a temperature range of 55 – 90 F and humidity range of 60 – 90%; and Mesoseiulus longipes likes a temperature range of 55 – 105+ F and humidity range of 45 – 90%.
You should not use neem oil, pyrethrum or other insecticides while your predator mites are active. Not only will these insecticides damage spider mites but also potentially damage the predatory mites. Additionally, many pyrethryn sprays are encapsulated. While pyrethryn is relatively safe (it breaks down quickly), because pyrethryn breaks down quickly under UV light pyrethryn products are often encapsulated Pyrethryn. encapsulation can make it last for weeks indoors.
Preventative Measures for Spider Mite
Dipping Clones Prior to Introducing Them Into The Growing Environment
OK, I’m going to say something controversial here and contradict myself somewhat.
That is, there is an appropriate time for the use of Avid or Floramite. This is prior to introducing clones purchased from outside sources into the growroom. Through this means you are able to ensure a 100% death rate of spider mites and eggs. I also recommend a follow up at 3-5 days after the initial treatment via foliar spray (if clones are in the system) or dipping (if clones have not been placed into the system).
Keep in mind, at this stage clones and young vegetative plants only have a few leaves and Avid and Floramite are non systemic (or, have very limited systemic activity). Other than this, it may be months before you harvest your produce and, therefore, any chances of residual Avid or Floramite in the consumable product is unlikely. Weigh up things and consider how long your crop cycle will be. Avid has a 28-day (4 week) withholding period in hops that are grown in the field. Double this, and if you have eight weeks, or more, before harvest then Avid is a safe option.
My advice here is pragmatic because I know that many/some growers will use Avid and Floramite at much later stages if needed and using it initially may circumvent this situation (prevention – not cure). That is, at this point, nuking the girls is far more preferable to having to deal with a spider mite infestation at a later date because mites and/or other pests came in with your cuttings.
Of course, if you’re a strictly organic grower this may not be appealing so preventative treatment may need to be handled with a product such as Stylet-Oil. Follow up treatments on a regular basis would be highly recommended.
Dipping in Floramite or Avid
To dip clones, simply mix a brew of Avid or Floramite in a suitably sized container and upend the clone completely into the brew being sure to dip the entire leaf and stem area, while ensuring the clone block is not dipped. (See illustration below). Saturate completely and leave lights off for four hours.
Safety Precautions When Working With Pesticides
Basic safety rules when working with chemical pesticides:
- Always wear protective equipment (glasses, respirator, long sleeved shirt, rubber gloves) when working with pesticides. In the case of dipping clones, at the very least wear rubber gloves and eyewear when mixing
- If foliar spraying, DO NOT re-enter the application area for 12 hours after spraying
- All labels should be carefully read for directions, and all safety precautions taken
Treating Mother Plants Regularly
For growers working with clones infested mother plants are a common source of new mite infestations.
For this reason, mother plants should be treated with alternating pesticide products in order to avoid pest resistance/immunity. Again products such as Avid and Floramite are fine for this purpose.
If you are a diehard organic grower than this may not suit you so regularly apply a product such as Stylet-Oil to your mother plant/s.
Treat the Growroom after an Infestation
Note: Once you have twospotted mite they can be extremely hard to get rid of and will potentially infest following crops.
Therefore, thoroughly cleaning the growroom is extremely important if you have encountered spider mites during a crop cycle.
Firstly, ditch any media you have into airtight bags and seal and dispose of it elsewhere.
Clean the environment thoroughly of any plant debris (trimmings etc) and seal in airtight bags. Either burn the debris or dispose of it elsewhere. If possible, dry the harvest at another location.
Spray all walls, floors, ceilings, and equipment (pots, tools, etc.) with a pesticide (Avid or Floramite) treatment. Spray with fans on. Be fastidious and pay particular attention to ensuring that pesticide is applied everywhere it can be. Don’t apply to ballasts and other electrical equipment (ie. water + electrical = danger).
Turn off fans after spraying. Be sure to wear the appropriate safety wear (respirator, gloves, eyewear, long sleeved shit and trousers) while spraying and stay out of the growroom for 12 hours after application. After this period turn the fans on to vent the environment.
When done, wash down the walls, floor, pots, shades etc with bleach and water. Wipe ballasts and other electrical equipment with alcohol solution (70%).
(Following page covers more pests)