Cannabis, like any other plant, requires a series of nutrients – categorized as macro and micronutrients – to develop properly throughout all the different stages of its growth cycle. In this article, we will be covering the micronutrient Manganese deficiency marijuana. While this nutrient is only used by plants in very small amounts along with the other micronutrients, any insufficiencies will still result in adverse effects on the plant’s various biological systems.
What is Manganese?
Manganese (Mn) is an important plant micronutrient that plays a vital role in photosynthesis. As we all know, photosynthesis is the process used by plants to harness energy from the sun and turn it into energy to grow, adapt, and live. A byproduct of this process is the oxygen that we breathe. Aside from photosynthesis, manganese is also a major contributor to the plant’s respiration system, pollen germination, root cell elongation, and resistance, as well as nitrogen assimilation. This makes the micronutrient of capital importance to any healthy plant.
How to identify Manganese deficiency marijuana?
Manganese defects are quite infrequent and are usually always linked with iron and zinc deficiencies due to their symbiotic relationship. To spot manganese deficiency in plants, you have to closely observe the color of the leaves. Yellowing which starts between the veins at the bottom of the leaf and moves towards the leaf tips is the calling card of manganese insufficiency. The veins on the leaf usually stay green. If the problem is not treated, the chlorotic areas will turn brown or tan and the leaf dies.
Manganese vs Iron Deficiencies. As mentioned, manganese deficiencies are often linked to a lack of another micronutrient, iron (Fe). Manganese deficiencies are often misdiagnosed as iron deficiencies. Both deficiencies are expressed as interveinal chlorosis symptoms and usually affect newer leaves. The key difference between both insufficiencies, however, is that while manganese deficient leaves turn from yellow to brown, iron-deficient leaves turn to an almost white appearance.
Manganese vs Magnesium Deficiencies. Another nutrient deficiency in plants that is often confused with a lack of manganese is magnesium deficiency. Much like the latter, magnesium deficiencies can be identified by observing the color of the leaves – leaves will turn yellow while veins remain green. The key difference between these two nutrient insufficiencies, however, is the age of the leaves affected. A lack of magnesium can be spotted on older, established leaves first while manganese deficiency will most likely affect only the newer leaves.
How to treat Manganese deficiency marijuana?
Identify the source
To treat nutrient deficiency in plants, you have to identify and understand the source of the problem. Oftentimes, manganese deficiency occurs when the pH of the growing medium exceeds 6.5 or there is a nutrient competition with iron.
Manage your pH levels
Conduct a pH test of your media run-off and check on your pH level. Remember that the best pH level to allow efficient absorption of manganese is anywhere between 6.0 to 6.5 (when in soil) and between 5.5 to 6.5 (when doing a hydro grow). Anything above these levels will render manganese unavailable for absorption by the root system.
Flush out using clean, pH-controlled water
If your media is out of range, you need to flush your plant’s system with clean water. This should effectively reset your pH to a healthy level, supply the plants with any missing nutrients, and stop any deficiencies from spreading to other leaves. Take note, however, that damaged, crispy leaves will most likely not be able to improve nor bounce back.
Use foliar feeding methods
If flushing is done correctly, any manganese deficiency should stop spreading to other newer, unaffected leaves within a week. Otherwise, some foliar feeding may be in order as a quick fix to replenish manganese levels. Recharge your plant’s system with a carefully adjusted 6.0 pH nutrient solution mix that contains a lot of manganese. This can be a special Fe-Zn-Mn fertilizer, a manganese chelate, or a hydro micro added to a water/nutrient mix. Close and routing monitoring is then needed to prevent a recurrence.
Defoliate if necessary
It is important to consider defoliation if the nutrient deficiency has hit your plants during their bloom stage. Otherwise, you run the risk of inviting diseases and pathogens to your entire crop. If defoliation is considered, make sure to do it in stages as this can stress your plants.
Consider Manganese greensand and compost
Greensand and compost provide great sources for the nutrient although the absorption rate is slower. These sources are, however, great for a long-term solution. A small amount of these products to your media should be able to do the work efficiently.
Nutrient competition with iron
All plants need iron and manganese. Unfortunately, these two can compete for absorption. If there is an excess in one nutrient, it is highly likely that the levels of the other nutrient will drop rather quickly. This means that manganese deficiency most likely means your plant there is too much iron for your plants. The good news is by simply flushing out the system with pure high-quality pH water is enough to help remove any excess nutrients and reset the system back at a neutral pH. Maintain a 1:2 manganese to iron ratio to avoid nutrient deficiencies in the future. Continually check the media to verify that all nutrient levels are within their normal ranges.
If after following the above steps, any new areas of growth are coming in bright green with no brown specks, then it means that your plants are finally receiving a sufficient amount of manganese.
Although it is called a micronutrient, manganese is very important to healthy cannabis plant growth. Among others, it plays a significant part in the process of photosynthesis and nitrogen assimilation. More often than not, this nutrient is plentiful and should be readily available in your media for uptake by your plants. If, however, you observe manganese deficiency marijuana, it is important to treat the problem immediately to avoid any further damage to your harvest.