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Cannabis leaf symptoms

Plenty of things can happen when growing marijuana and most problems manifest on the leaves. Therefore, it’s important to check the plants often in order to detect any possible cannabis leaf symptoms that could be reflecting nutrient excesses, deficiencies or plagues.

Types of cannabis leaf symptoms

Unfortunately, there is no precise manual to avoid all cannabis problems during cultivation as each grower, place and genetic is different. Experience is a key factor to avoid the problems that occur when growing marijuana for the first time.

The climate, the growing area or the quality of the fertilizers make a difference, being also very important to know how to choose the marijuana seeds. Depending on the conditions in which it is going to be planted, it will be more interesting to buy feminized or autoflowering seeds, which will help to avoid stains on the leaves.

One thing is for certain, when plants are suffering some sort of illness or deficiency, cannabis leaves change color and it is very important to know the reasons in order to react on time and prevent the crop from getting ruined.

Yellow stains in marijuana leaves

Yellow stains are the most common type. There are plenty of reasons why leaves turn yellow. Leaf stains can appear due to the following situations:

This problem is most often due to irrigation deficiencies. There are plenty of factors that need to be known and controlled as it will determine the quality of the yield.

Insufficient nutrients

Badly fed plants will display cannabis leaf symptoms. Always use good quality and well-balanced fertilizers.

Excesses and deficiencies

Excesses and deficiencies of nutrients cause symptoms that we can identify and remedy.

If you overdo it with the amount of nutrients provided to the plants, the foliage will have a dark green color and a plastic-like appearance. In addition, the leaflets of the leaves will curve inward in a claw shape. In these cases it is recommended to wash the roots and continue with a soft and progressive fertilization.

n the other hand, if they do not have enough food, they will show paleness and the leaves will turn yellow. The most common lack of nutrients has to do with nitrogen and iron, although it can also be due to other less important minerals such as potassium, calcium or magnesium.

It is always easier to fix nutrient deficiencies rather than excesses, but in both cases, the main thing is to detect it on time and put a solution to it.

Other causes of yellow leaves are:

PH levels outside optimum parameters

pH acidity or alkalinity of the irrigation solution must be within certain limits (5.8-6.5) for plants to absorb nutrients correctly. If the cultivation medium or the water doesn’t meet this criteria, plants will display mineral deficiency symptoms. The solution is to flush the roots, reach correct pH and EC levels and continue with the cultivation process.

Irrigation mistakes

The amount of water plants receive, as well as the time that goes by between each irrigation is very important. This is the dry-humid cycle. The roots need for the substrate to lose most of its moisture before hydrating it again because this way, the roots extend looking for water, and they become longer, thicker and stronger.

If you water the seedlings too much or if the plant is in a pot too big for its size, the roots will probably rot, weakening the root system. In this case, the leaves will turn lime green and get curvy with a soft texture that can cause fungi problems.

Light

Another factor that can turn the foliage yellow is light. Indoors, if the lamps are too near, the plants can get burnt. On the contrary, if they don’t receive enough light, the photosynthesis process won’t be correct. The solution to this is to place the lights further from the plants or in a spot where they receive better light, depending on the case. If you spray the plants when the lights are on, the magnifying effect can cause burns.

Some insect and fungi plagues can also turn leaves yellow. The following pathogens are often culprit:

  • Leaf miners: They show a trace on the leaves. Easy to detect and treat.
  • Red spider: They form micro yellow and white spots on the leaves.
  • Septoria: They create yellow stains with a brown center.

Take into account that if the leaves turn yellow at the end of the flowering period, there is nothing to worry about. The plant is using up all of its energy in forming the flowers, not paying attention to other parts, which means they wear out.

Orange or brown stains in marijuana leaves

Orange or brown stains in marijuana leaves (it’s very hard to tell them apart) can cause the following pathologies:

  • Lack of phosphorus, calcium or magnesium: This happens, usually, at the end of the flowering period, which is when the plant needs more nutrients to produce buds.
  • Excessive temperature: Very high temperatures can burn the leaves.
  • Ozone exposure: Ozone generators are very useful to neutralize marijuana scents, but make sure that it doesn’t get in contact with the plants as it burns them and can ruin the yield.
  • Acid pH: If pH levels are higher than 8, leaves will probably turn brown.
  • Mildew: This fungus starts off as white stains that turn brown if not detected on time, which can compromise the survival of the yield as it is very hard to eliminate once it has spread all over the grow.
brown stains cannabis leaf

White stains in marijuana leaves

White stains are initially hard to spot. Most of these stains are caused by insect or fungi plagues. Quite often, oidium is the one to blame for them. Combat this fungus as soon as possible to stop it from ruining the yield.

If you observe tiny white spots, then your plants are probably infested with red spiders. This small insect can colonize a plant in only five days, therefore, you must act fast and detect it as soon as possible. A microscope can come in handy. If the stains are still white, you caught it on time.

If you see the white stains moving, it’s not because the weed you consumed is very potent, what you are seeing is mealybugs. These insects are easy to detect at plain sight.

Be very careful with the molasses that these insects segregate as it can attract other plagues, increasing the problems of your crop.

Black stains in cannabis leaves

Molasses cause fungi infestations, such as sooty mold. Insects such as cochineals, aphids or white flies feed off the sap of the plant, segregating molasses afterwards. This sweet substance adheres to the spores of the fungi, feeding them and promoting their proliferation.

Although this fungi doesn’t attack the plant directly, it does stop photosynthesis by colonizing the leaves and causing their death.

The best products to prevent cannabis leaf symptoms

Tripack Protección Boom

Tripack Protección Boom, by Boom Nutrients, is the perfect pack to forget about plagues in your cannabis crop. Soil Care Boom protects the soil, Spider Boom removes red spiders and other predators and Fungi Boom prevents fungi. This amazing fusion will care for your grow so that you don’t have to worry about anything.

These three products prevent and heal. The recommendation is to use them from the very start; as it is always easier to prevent problems than to fix them.

Bio-Eco Quelatos

Bio-Eco Quelatos is a nutrient corrector that needs to be combined with the usual fertilizer. It includes assimilable micro nutrients, such as zinc, manganese and iron.

Neem boom

Neem Boom is an organic solution that acts as an insecticide and improves plants’ defenses; perfect for those that don’t want to use chemical products. These neem seeds are crushed to make flour with fantastic properties.

Composition of Neem Boom:

  • 36% amino-acids
  • 23.7% humic acids
  • 10.4% fulvic acids
  • 7% nitrogen
  • 1.01% phosphorus
  • 1.34% potassium
  • 100% Neem tree Seed press
  • 80% organic matter

Cola de caballo ECO

Agrobeta, a leading fertilizer company, brings us a horsetail based product. This plant features insecticide and fungicide properties and it is perfect to prevent and to heal plants that suffer insect or fungi infestations. Do not use it during the sunny and hot hours of the day.

Ultimately, growing cannabis is a difficult process that can get complicated due to lack of nutrients or external pathologies; which can display cannabis leaf symptoms. Therefore, it’s essential to know how to detect these symptoms and know why they are coming up.

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Erik Collado Vidal

Con más de 10 años de experiencia en la industria del cannabis, sus experiencias y aprendizaje son la base del éxito de GB The Green Brand.

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