Molybdenum deficiency is rare. But if it hits your cannabis plants, it could be the beginning of the end. You really don’t have time to waste if your marijuana is suffering. Stricken cannabis plants need to be worked on urgently. Ignore this mineral at your peril.
Molybdenum deficiency will test the most eagle-eyed of cannabis growers. This one really is tough to diagnose correctly. Troubleshooting molybdenum deficiency will not only cost precious time, but most likely worsen the condition. Chlorosis striking the middle portion of cannabis plants foliage is commonly mistaken for nitrogen deficiency or calcium and magnesium deficiency.
As is the case with the majority of micronutrient deficiencies, the best way to avoid the headaches later is to invest in high-quality substrates and nutrients in the beginning. Using cannabis-specific growing mediums and fertilisers is recommended.
Step two is making sure the pH is perfect, per growing medium, for the follow-up feed of nutrient solution. Direct supplementation is not really an option as only trace amounts of molybdenum are required.
In fairness, there is sound logic behind such assumptions. But don’t assume anything when it comes to unhealthy cannabis plants. Take a closer look. N deficiency tends to creep up a plant from the bottom up. Ca/Mg deficiency is rare in soil grows and more of a mid-late bloom problem in coco and hydro cultivation. Also, take note of the leaf discoloration, which will have brown crispy fringes and orange to pink shades in the centre. Eventually in a week or so, you will notice it is highly mobile as new growth begins to wither and curl.
Step three is pruning away the necrotic growth. If plants are still in vegetative growth, it’s not the end of the world. Top plants and remove the dead and dying leaves. 2-3 weeks recovery will be required, depending on how far chlorosis spread. On the other hand, if you must prune during bloom, make sure to remove leaf stems when pruning flowers to avoid bud mould. Yield will be reduced. But a smaller stash is better than no stash.
Coco and soil growers are not exactly in the clear, although these cultivation styles are less prone to molybdenum deficiency. Peat and coco coir-based soil and soilless mix substrates act as a buffer for the root zone. 6.0-6.5pH is preferred. However, should the pH of nutrient solution be administered too low, too often a molybdenum deficiency can and likely will develop due to nutrient lockout.
For whatever reason, if you are delayed treating molybdenum deficiency, expect some permanent damage to your cannabis plants. In addition to the above 1-2 solution, a third, less pleasant step is required.
Catch molybdenum deficiency early and it’s a simple 1-2 solution. Step one to remedy molybdenum deficiency and most cannabis ailments is a cleansing flush of the medium with pure 6.0pH water. The micronutrients the roots need are locked-out and the excess fertilisers need to be leached.
Easier to correct than it is to pronounce, molybdenum deficiency is a lesser known marijuana problem. This is the cannabis E.R. blog with the solutions.