Managing Guttation in Cannabis

The phenomenon of guttation is an interesting?one, so what exactly is it and why is it of special significance to cultivators and TAMC/TYMC counts…? Lets have a look.

Guttation is a natural process that occurs in plants, where droplets of sap or water are exuded from the edges or tips of leaves. It happens primarily during the early morning or night when transpiration is low, and the soil moisture is high.

Mechanism of action

The process is driven by root pressure, which is the result of active water uptake by plant roots. When there is sufficient soil moisture, water is taken up by the roots and transported through the xylem vessels up to the leaves. In certain plants, the excess water cannot be released through transpiration due to closed stomata or high humidity, so it is forced out through specialized structures called hydathodes (water safety valves) located along the leaf margins.?

This phenomenon?is more likely to occur under specific conditions:?

1.?Firstly, the plant must have well-hydrated roots, usually from an adequately watered growing medium or high soil moisture.

2.?Secondly, the transpiration rate must be low, which commonly happens during the night or early morning when the temperature and humidity are high, leading to closed stomata.

3.?Lastly, certain plant species or varieties are more prone to guttation due to variations in the size and structure of hydathodes.

Susceptible Growing Mediums

Regarding growing mediums, soil-based mediums with high water-holding capacity, such as peat moss or coco coir, are more susceptible to guttation. These mediums retain moisture well, leading to higher soil moisture levels, which can contribute to increased root pressure and guttation. Hydroponic systems, on the other hand, typically have better water management, and the growing medium used (e.g., inert substrates like rockwool) doesn't retain excess water, reducing the likelihood of guttation.

Pest & Pathogen Concerns

Most of the guttate consists of growth-promoting substances for various kinds of facultative parasites and saprophytes including bacteria, virus, fungus, and algae. The exudate's pH also seems to be moderate and favorable for the growth of microbes.

In the context of commercial cannabis cultivation, guttation can be a concern for several reasons.

1. Firstly, the exuded droplets can attract insects and pests, potentially leading to infestations and crop damage.
2. Secondly, the sugary sap within the guttation droplets can promote the growth of mold and fungi on the leaf surface, increasing the risk of diseases.
3. Furthermore, the presence of excess moisture on the leaves for extended periods can disrupt the optimal leaf-to-air ratio, potentially leading to issues like leaf maceration or increased susceptibility to foliar diseases.

Commercial cannabis growers aim to maintain strict environmental control to maximize yield and quality. Guttation, although not widely known, can be a sign of sub optimal?growing conditions or an imbalance in the water and nutrient management. Therefore, it is of concern to growers as it indicates potential issues that need to be addressed promptly to ensure the overall health and productivity of the cannabis plants.

References

https://link.springer.com/chapter/10.1007/978-3-642-38797-5_7

?https://www.cambridge.org/core/books/abs/guttation/plant-microbiology-and-phytopathology-of-guttation/CF20270754E0AB0C0AB094FC81C1DAB8#

?https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/guttation

https://bsppjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-3059.2012.02673.x

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