Medpot Minstrel: Hydroponics Medical Marijuana

Friday, February 16, 2007

Insects and Microorganisms that Attack Cannabis

If you have good control over the environment of your grow room and feed your cannabis plants with a reputable base nutrient (such as those from Advanced Nutrients Medical), as well as beneficial root colonizers and helpful supplements, you can be fairly certain that you’ll be free of cannabis diseases and pests. However, even the most impeccable grow room can be attacked once in a while, so awareness of these dangers is not unwarranted.

About a year and a half ago I started noticing a pale green chlorosis on the leaves of my medpot plants. At first, I thought it was some kind of nutritional deficiency, but I checked and rechecked the make-up of my nutrient solution and couldn’t find anything essential missing. Conversely, no macro or micro nutrients were present in excessive amounts. Overfeeding can sometimes be just as much of a problem, as underfeeding.

Then I picked up a book by J.M. McPartland, an excellent authority on the subject of cannabis diseases. Under the heading “Hemp Streak Virus” I found “pale green chlorosis” as the number one sign of this impossible to get rid of malady. The discoloration soon developed into yellow streaks on the leaves, then brown, necrotic flecks appeared.

It was a nightmare coming true. This cannabis plant was acting as if it had read McPartland’s book and was following the instructions to the letter. But the book said that this virus most often appeared on fibre cultivars in Europe. Reading further, however, I found a statement that dozens of viruses could infect cannabis, regardless of location.

Viruses do not kill your pot plants but they do reduce your yields. Once your plants catch a virus (usually vectored by an insect) they are permanent. Subsequent generations will be infected through pollen and seed infections. The only cure—pull the plant and burn it!

I did just that and I watched my remaining plants like a hawk for any signs of infection. Contrary to what endangers humans, viruses and bacteria relatively seldom attack cannabis, especially in comparison to fungal infections. Over 88 fungi are known to attack marijuana, with the most prevalent being pythium, powdery mildew, and gray mold.

Pythium causes root-rot as well as the rot of the lowest part of the stem. It is especially fond of attacking young plants and cuttings. It flourishes in wet and humid environments. Pythium spreads its spores only through water.

Avoid fluctuations in the temperature of your grow medium to avoid this infestation. Another obvious action to take is to colonize your root zone with beneficial fungi. Advanced Nutrients Piranha both fights and prevents Pythium, as it does most fungal infections.

Piranha contains live fungi that feed on harmful fungi. Bacterial diseases can be prevented by colonizing your roots with the beneficial bacteria of Tarantula. Viral infections can be prevented by avoiding the infestation of the insects that vector these diseases.
Piranha and Tarantula can also be used as foliar sprays, in case you see signs of fungal or bacterial infestation on your leaves or stems. This is especially helpful to counteract gray mold or powdery mildew.

Another foliar spray made by Advanced Nutrients is Scorpion Juice, which, if used judiciously, imparts induced systemic resistance in medpot plants, which gives them the strength to ward of numerous pathogens and pests on their own.

Advanced Nutrients Barricade is another good way to strengthen the cells of your cannabis plants. Stronger cell walls ward off many pathogens and pests that try to attack your plants. Sap sucking insects go elsewhere when there is resistance to their activities.

Common sense sanitation practices, good ventilation, and lower levels of humidity go a long way in preventing these infestations. Educating yourself as to the symptoms and prevention techniques is also a good idea. The Advanced Nutrients Medical website features detailed description of all the diseases and pests that plague cannabis.

By far the most troublesome cannabis pest are spider mites. They’re not actually insects, rather tiny arachnids that can take over your entire grow room, if left unchecked. I had a minor infestation not so long ago and took care of it by spraying with Scorpion Juice.

The mites suck the sap from the underside of the leaves, causing white specks to appear on the top of the leaves. They also weave a very fine webbing. If you use a magnifying glass you can see the tiny spiders as they busy themselves ruining your cannabis plants.

Some people use the baking soda, horticultural oil combination as a spray. Perhaps a spoonful of each in a Liter of water. However, I found that the mites reappeared after this treatment, so I went back to using Scorpion Juice. That got rid of them real quick.

Whiteflies can also be a problem, particularly if you have vents without fine mesh screens, or if you leave the door to the grow room open for any length of time. Getting rid of weeds near the entrance to your grow room also helps to prevent such insects from invading your grow space.

Yellow sticky traps hung over the canopy of your medpot plants will give you an idea of how serious the infestation of whiteflies might be. You can tell by shaking the branches of your plants. The flies will swarm and fly around.

They’re harder to get rid of than spider mites, but there is an assissinator wasp that is smaller than the white fly and it can be utilized to get rid of these pests. This wasp is called the ichneumon fly (Latin name Encarsia formosa) but it is very small so it takes quite a while to get rid of all the white flies, which are more numerous.

Every two weeks you have to put new assassinator wasps into your grow room, so it’s a head ache. It’s much better to take preventative action. Remember, white flies and other pests can also enter your grow room on your clothing or in your hair, so it’s a good idea to take off your outer clothing and always clean yourself thoroughly before working in your grow space.

Aphids, thrips, and scale insects can also invade your grow room, especially if you let down your guard with regard to personal hygiene and sanitation.

Damping off, hemp canker, yellow leaf spot, pink rot, and white leaf spot are all fungal diseases that cannabis is vulnerable to. So are Fusarium Wilt and Verticillum Wilt. Wilt diseases are more prevalent in field-grown cannabis, than in indoor cultivation.

McPartland’s book is called “Hemp Diseases and Pests.” It is a valuable addition to the libraries of those medpot growers who keep worrying about insects and microorganisms that might attack their cherished medicine.

posted by Wes @ 3:05 PM


At 10:03 PM, Anonymous Marijuana Grower said...

I agree with you because i already faced the same issue while i was new in marijuana growing. If you are a hydroponic medical marijuana grower and not supplementing your nutrients with microorganisms, you are depriving your plants of optimal growing conditions. Read more for shelf hydroponic microorganisms for medical marijuana.


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