Spider Mite Control
Spider Mite Control:
There is much information about Spider Mite control on the web that is inaccurate I thought I would use your question to touch on some of the basic spider mite facts then you can choose which product best suits your needs.
First of all, you do not need to have spider mites. Most growers do not have them in their rooms. To those with continuing problems I would recommend you strive to eradicate them completely so that in the future you do not need to use pesticides. Since people ingest the products you produce I recommend the least toxic insecticides, used in the most effective way.
About Spider Mites:
"The two spotted spider mite was originally described from European specimens. It is considered to be a temperate zone species, but it is also found in the subtropical regions. It is found throughout the USA in greenhouses where it survives the winters beyond its natural limits. Tuttle and Baker (1968) report this species to be found on deciduous fruit trees in northern regions of the U.S. and Europe". Spider mites and their eggs are found on the underside of leaves and are very hard to spot without magnification. Many spider mites produce webbing, particularly when they occur in high populations. This webbing gives the mites and their eggs some protection from natural enemies and environmental fluctuations. If you see webbing you have definitely waited too long.
"For detection of spider mites, a 10X to 15X magnifying glass is a necessity. Examine the undersides of the leaves closely for mites, cast skins and webbing. A more efficient technique is to place a sheet of white typing paper beneath the leaves and strike the foliage sharply. The mites will fall onto the paper and can be more easily observed and identified than on the green foliage."
"Spider mite development differs somewhat between species, but a typical life cycle is as follows. The eggs are attached to fine silk webbing and hatch in approximately three days. The life cycle is composed of the egg, the larva, two nymphal stages (protonymph and deutonymph) and the adult. The length of time from egg to adult varies greatly depending on temperature. Under optimum conditions (approximately 80ºF), spider mites complete their development in five to twenty days. There are many overlapping generations per year. The adult female lives two to four weeks and is capable of laying several hundred eggs during her life."
"Most spider mite activity peaks during the warmer months. They can develop rapidly during this time, becoming full-grown in as little as a week after eggs hatch. After mating, mature females may produce a dozen eggs daily for a couple of weeks. The fast development rate and high egg production can lead to extremely rapid increases in mite populations.
Dry conditions greatly favor all spider mites, an important reason why they are so important in the more arid areas of the country. They feed more under dry conditions, as the lower humidity allows them to evaporate excess water they excrete. At the same time, most of their natural enemies require more humid conditions and are stressed by arid conditions. Furthermore, plants stressed by drought can produce changes in their chemistry that make them more nutritious to spider mites.
Chemical control of spider mites generally involves pesticides that are specifically developed for spider mite control (miticides or acaricides). Few insecticides are effective against spider mites and many even aggravate the problem.
Furthermore, strains of spider mites resistant to pesticides frequently develop, making control difficult. Because most miticides do not affect eggs, a repeat application at an approximately 10- to 14-day interval is usually needed for control."
Some pesticides may make your problem worse (Malathion, for example). Mites may be resistant to your control methods.
Where did my mites come from?:
Originally they come from plants that you introduced or, less likely, from you working in your garden and transferring them into your room. If you have a continuing problem they are probably on your young plants and the adults and eggs may be hiding in cracks and crevices which then return when conditions are perfect for their multiplication.
What is an insecticide and how do they kill insects?
When I was in one of my first physiology classes the instructor hooked a fly up to an encephalogram machine (measures brainwaves) and then sprayed it with raid. The tracings on the EEG machine went crazy and the insect died from sensory overload and respiratory failure. This is the classic organophosphate poisoning where the pesticide blocked the action of cholinesterase at the nerve junctions and so the nerves fired continuously, killing the insect. This is an old and toxic class of insecticides that we hope nobody uses. This is the basic action of nerve gas, highly toxic and deadly to people.
With modern technology there are effective and more sneaky ways of defeating our insect enemies without all of the toxic fallout. Some of the fancy methods include Neuronal Inhibition, Chloride Channel Activators, Electron Pump Inhibitors, Inhibition of Lipid Biosynthesis, Ecodysone Agonist/Disruptor, Feeding Inhibitors and simply Smothering.
Pesticides are rated for toxicity in several areas:
1-PAN Bad Actor Chemical- These are chemicals rated by the Pesticide Action Network as "most toxic" and have at least one of the following:
a) Carcinogenic
b) Reproductive toxicants
c) Neurotoxic cholinesterase inhibitors
d) Groundwater contaminants
e) Highly toxic
2-Lethality- Rats are exposed to either the specific pesticide or to the active ingredient(s) and an oral dose that is lethal to 50% of them is called the LD50. The higher the LD50
the more likely the pesticide is less acutely toxic. For example the LD50 for Nicotine is 50mg/kg. For aspirin it is 1750mg/kg. For caffeine it is 53mg/kg. Table salt is 3300mg/kg.
3-Amount of time they last in the environment.
Here is a short list of chemicals that kill mites, the mode of action, the LD50, the amount of time to use the chemical prior to harvest, maximum number of doses allowed etc. Most of these products are not listed for use on food products but your State and the Federal Government regulate that. Follow the product label directions if you use any of these products. Use at your own risk. This chart is for informational purposes only and is not meant to diagnose or treat any kind of infestation. Keep all chemicals away from children in a locked location. Hydro4less, Inc. and its affiliates are not responsible for any use or misuse of these products. USE AT YOUR OWN RISK!
PRODUCT |
Active Ingredient |
Action |
LD50 |
Time to Harvest |
PAN* |
Toxicity |
Carcinogen |
Max. Doses |
Acramite |
Bifenazate |
Neuron Inhibitor |
5000mg/kg |
3 Days |
NO |
Slight |
NO |
1x |
Avid |
Abamectin |
Cl Channel Activator |
300mg/kg |
? |
YES |
Moderate |
NO |
? |
Don’t Bug Me |
Pyrethrin |
Na Channel |
200-1500mg/kg |
12 Hours |
NO |
Slight |
POSSIBLE |
N/A |
Judo |
Spiromesefin |
Inhibit Lipid |
>2000mg/kg |
7 Days |
NO |
Slight |
NO |
Unknown |
Azatrol |
Neem |
Repel etc. |
5g/kg |
0 |
NO |
Slight |
Unknown |
? |
Talstar |
Befenthrin |
Na Channel |
70mg/kg |
? |
YES |
Moderate |
POSSIBLE |
? |
Safer |
Oils and Soaps |
Smother |
? |
0 |
NO |
NO |
NO |
? |
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*PAN Bad Actor Category: any highly toxic, cholinesterase inhibitor, carcinogen, reproductive effects, groundwater contaminant.
Do and Don'ts of Mite Control:
Do keep a clean room.
Do treat all incoming plants with a mitacide (preferrably a dip to wet all plant parts).
Do watch for early mite infestations on the underside of your leaves.
Do use all products with care.
Do understand how the pesticide works (do I need to spray the underside of the leaves or is the product "translaminar" and so penetrates the leaf).
Do repeat sprays as required to control hatching eggs.
Do keep a cool room less hospitable to mites.
Don't get plants from untrusted sources.
Don't use pesticides indiscriminately, without specific cause.
Don't stress your plants.
Some helpful hints:
If you have a continuing, serious mite control problem remove all of your plants. Clean and vacuum your room. Spray the walls and floor with Bayer Advanced Home Pest Control Indoor/Outdoor following label directions. This will kill pests for 9 months. If possible lay down plastic sheeting so that it covers the floor and 2-3 feet of your walls. When you harvest your plants you can simply roll up the plastic and put down a fresh piece. Dip all of your new plants in a dilute miticide.
Final Thoughts:
How dangerous are these products? Consider Judo which has an LD50 greater than Aspirin (less toxic) and it is used at 2 drops per quart (about 9 drops per gallon). That is approximately 67mg of spiromesefin (the active chemical ingredient) per quart and you can spray about 100 plants per quart so each plant can potentially get .67mg spread over the plant leaves. 1 Milligram is ½ a drop (approximately) so .67mg is a little more than ¼ of a drop per plant. If you can use these products when the plants are small then there is probably no residue left at harvest. The ½ life of spiromesefin (time it takes for ½ of the chemical to disappear) is approximately 7 days with 90% gone in 33 days.
