Plant health issues and deficiency

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BIOTIC OR ABIOTIC

Experienced growers who perform regular scouting can easily recognize patterns in their canopy. With multiple cultivars, as most cannabis growers tend to run, this can get tricky. However, if you pay attention to each cultivar as its own project it is greatly simplified. Growers should be looking for areas of chlorosis, yellowing of the plants, and necrosis, brown dead tissue that cannot regenerate. Wilting and leaf angles are more important as environmental signalers rather than as indicators for nutrient issues and we will discuss that separately. The first step we need to take in diagnosing a plant issue is to determine the cause of the visual cues we are evaluating. That first step is to determine if the cause of your plant's stress is biotic (think pests and pathogens) or abiotic (think nutrients and environment).

A biotic symptom is almost always displayed randomly throughout the crop, unless you wait far too long and then it will affect the entire crop. Pests and pathogens tend to jump around from area to area and plant to plant, skipping some plants entirely and going after others. Be sure to include a sufficiently strong scope in your scouting tool kit. Examine the underside of leaves with a strong handheld scope. The crucial importance of proper scouting can not be over emphasized! A real life example would be a grower showing signs of K deficiency that after scoping realized he had been fighting russet mites for months with K inputs! You can't act appropriately without a proper identification, regardless of whether you are dealing with a biotic or an abiotic issue. If you are looking at an individual plant for symptoms ask yourself if there is a discernible pattern on the leaves? If you were to fold a leaf over would it line up with damage on the other side fairly consistently? If your response is yes and you are seeing patterns; entire benches or quadrants within your canopy, then you are most likely dealing with an abiotic stress. Abiotic stresses are caused by nutrient issues and environmental issues. If you are dealing with a pest issue contact a professional about an organic IPM regimen with beneficial insects and predators

 

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. A dichotomous key offers clearly defined options for the investigator. To begin our key we first need to determine where on the plant we first started seeing issues. Again, this is another reason that regular scouting should be performed by the same individuals. If scouting is delayed or skipped altogether it will be next to impossible to determine where the issue first started showing on your plant. This is incredibly important as the location of the initial deficiency clue will tell us whether the nutrient is mobile or immobile within the plant.

Obviously all nutrients are "mobile" as they have to move into the plant. What we are discussing is whether they are able to be translocated from one location in the plant to another. If they are able to translocate then they are mobile. The apical or growing tips of the plant are the most important to the plant for reproduction so they will get the benefit of moving mobile elements from the lower leaves to the top leaves if sufficiency is not maintained throughout the growing cycle. That is why you will see mobile element symptoms at the bottom of the plant. Those nutrients are being sacrificed in lower tissues and reallocated to the important growing, apical tips.

If an element is immobile it cannot be translocated. Therefore, if there are insufficient mineral nutrients for an immobile element it will show in the growing tips first. If a nutrient is partially mobile then you will see it throughout the entirety of the plant.