Jul 15, 2016 9:00 AM

How to Deal With 3 Most Frequent Cannabis Plant Diseases

There is nothing like walking along an emerald garden with healthy, strong cannabis plants. Unfortunately, everyone who has experience in growing marijuana knows how difficult it sometimes is to defend tender plants from the menace of horrible diseases.

Most Frequent Cannabis Plant Diseases

There are plenty of different diseases that can if not destroy then at least significantly damage your garden. In most cases, healing the plants and getting rid of pests or other contamination may cost you a fortune. That is why it is better to protect cannabis from the very beginning.

Every region has its own diseases that contaminate plants more often than others. You can find this information at the local flower store; people there usually know the problems local growers meet most often, and they also can offer you the best fungicides or pesticides. If you do not want to specify what plants you want to protect or cure, just ask for some products for edible plants like tomato and cucumbers.

If you are a new grower, and you do not have any experience with managing plant diseases yet, we would recommend you to learn how to prevent three most frequent problems that may ruin your cannabis garden.

Marijuana Grow Guide: Fighting Spider Mites, Fungus Gnats and Root Aphids
Marijuana Grow Guide: Fighting Spider Mites, Fungus Gnats and Root Aphids
Cannabis growing requires a lot of work and requires constant attention to many significant details. One of these details is fighting pests. Even the most experienced growers may face a pest outbreak; you should always be ready to stop the pests before they get to your plants.

Powdery Mildew

This is one of the most frequent diseases in cannabis gardens that appears on the leaves and buds in the form of light white powder. Usually, it first infects the lower leaves and branches that have limited access to light and air flow. Powdery mildew likes a high level of humidity, so the more humid it is in your garden, the faster the disease spreads from one plant to another.

The good thing is that the white powder is nicely visible, and if you check your plants carefully and regularly, the chances are high that you will notice the problem on the early stage. When the disease is still located on a small area of the plant, it is possible to remove it (together with the leaves and the branches) so that the damage to the plant is minimal.

It is rare for a plant to die from being infected by powdery mildew, but if it damages the buds, the final product will be ruined. So if the risk of powdery mildew exists, it is better to take some preventative measures and not give the disease even the smallest chance.

  • Prune your plants, pay special attention to the lower leaves and branches.
  • Install an additional fan so that the airflow goes not only to the buds but also to the lower parts of the plants.
  • If the plant’s crown is dense, spray it with organic fungicides.
  • Spray or compost your garden with tea or other solutions that have a different pH level; it helps prevent the spread of the disease.

If the infection has already contaminated a significant part of your garden, you still have a chance to remove it by showering each single plant with H2O2/H2O solution. Mix water with a small amount of 3% hydrogen peroxide, cover the pot so that the water does not go to the soil, and abundantly spray the plant with the solution. This procedure is very time/labor-consuming, but it can save your crop from the disease. However, we would recommend you to apply this method only to the plants in their growing stage.

If powdery mildew is your nagging problem, maybe the strain genetics are susceptible to this disease, so you had better focus on other similar strains that are genetically more resistant to it. Lollipopping your plants or applying Screen of Green technique is also an option, though it requires more attention and time from your side.

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How to Save Your Marijuana Plants From Mold
To grow weed successfully, any grower worth their salt should manage three key problems: chemical contamination, pests, and mold.You can keep pests from appearing in your garden by checking everything you bring into the growing room and filtering the air.

Root rot

While the state of the leaves is something you can see directly, the roots’ state is in most cases hidden from the sight. However, the root system is responsible for delivering nutrients to the leaves and buds of the plants, and once the system is damaged, it can have dramatic consequences.

When the soil is moderately watered, roots take in oxygen, which is also very important for the plants' wellbeing. That is why the soil should not be too heavy and too moist. Too much water that stays in the pot prevents air access to the roots and kills the roots. So the next time you water the plant, it will create ideal conditions for root rot to damage the root system further.

If you grow cannabis with aeroponics or hydroponics, you may notice the problem on time. Look for the brown roots that are slimy and sleazy, and remove them immediately. If you grow marijuana in flower pots, checking whether the roots are damaged is usually not possible. That is why it is better to prevent root rot than to manage the ongoing problem.

  • Water your plants every day at the same time and with the correct amount of water. This means you need to observe how the plant responds to the usual amount of water: if it suddenly cannot handle it, there might be a problem with the roots.
  • Try not to overwater your garden.
  • Do not use poor soil for your plants. It is essential to have beneficial microbe and bacteria populations inside it. They help prevent fungus from develop keeping the right balance of water and oxygen in the soil.
  • Always make drainage in your flower pots.
  • Add some perlite to the soil so it is able to “breathe” easier.

If you have noticed that some of your plants drink less water than usual, have a sick look, or grow slower than other plants, it may mean that root rot took over the root system. Let the soil dry completely and water it with a special rot treatment you may find at a flower store. If it does not help, you can carefully take your cannabis out of the pot and look whether you can find the rotten roots. This procedure is very dangerous for the cannabis health, so we would recommend you to do it only if there are no other ways to save the plant.

What You Should Know About Spider Mite Infestation in Your Marijuana Garden
What You Should Know About Spider Mite Infestation in Your Marijuana Garden
If you have a marijuana garden and never faced problems with spider mites, then you may consider yourself a lucky person. These pests may contaminate both outdoor and indoor gardens and turn the growing process into a real headache.

Leaf septoria

If root rot is mostly dangerous for an indoor garden, leaf septoria can damage both indoor and outdoor cannabis. If you have one of those hot summers with frequent rains, beware of leaf septoria. It can also attack your plant in growing rooms if the temperature and humidity are too high, or if the leaves become wet after every watering.

Leaf septoria reveals itself as ugly brown spots on the leaves. The area around the spots becomes yellow and lifeless, so after some time, the leaf dies. This disease cannot kill your plant, but it can significantly reduce the yield. The less leaves your plant has, the less energy it gets to form nice buds.

That is why it is important to react immediately once you have noticed the first signs of leaf septoria. Remove all the damaged leaves, even if the brown spots are small. These leaves will die anyway, but while they are still on the plant, they can contaminate other branches. We would recommend you to burn the damaged leaves or at least to avoid putting them in your compost pile. Do not give the disease even the slightest chance to spread over your garden.

If you know that the chances of getting the leaf septoria are high, or if one of your plants is already damaged by it, it is necessary to take some measures:

  • Keep your growing room clean, remove all the fallen leaves.
  • Prune the lower branches, especially if they lie on the ground.
  • Water your plants using drip lines so the leaves do not get wet.
  • Leave enough space between your plants.
  • Do not use soil from outside for your indoor garden. It is better to buy some at a flower store or at least to sterilize it in the oven for a couple of hours.
  • Spray your plants with Bacillus subtilis fungicides that can slow the spread of the disease.

Most of the diseases can be avoided by simply keeping your garden clean and observing every change in your plants. Sometimes, it is difficult to notice the first signs of the diseases, especially if the garden is big, but then the growers' achievements come in handy: plants with new genetics that are more resistant to the common diseases regularly appear on the market. Care for your plants nicely, and they will give you the best reward ever!

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