Induced Systemic Resistance (IRS) is a type of enhanced defensive capacity against drought, wind, pathogens and pests developed by a plant via prior infection or treatment

Although it sounds fairly complicated, it's very similar to what happens to human body, when it's exposed to viruses or harmful bacteria.

If a body was bolstered beforehand by the right diet, lifestyle, and what is even more important by direct contact with these microorganisms, it'll be able to activate an immune response, that will result in limiting the adverse effects they might cause otherwise.

IRS is thus considered one of the most important prevention mechanisms, that the plant has against biotic (caused by living organisms) and abiotic (caused by non-living elements) stress!

Let's break it down

Both stress factors affect the balance of chemical signals along the cellular wall, which botanists call apoplast, and which performs a couple of extremely important functions such as solubilisation of carbon dioxide, that plants absorb from the air.

These signals (which include reactive oxygen species and calcium) can change PH levels, and modify the chemical structure of dermal tissue, which is basically plant's skin, and the first line of defense against all pathogens.

What is important though is that a response of a plant to fungi such as Botrytis cinerea, that causes grey mould, or any other biotic stress, is usually affected by a prior contact with them, which teaches plants how to deal with their virulence.

However, there's an interesting crossover! Plants that experienced drought will develop mechanisms, that'll help them to deal with it next time, but that'll also become a component of resistance against pathogens, and vice versa!

Moreover, IRS can be also reinforced by growth-promoting rhizobacteria and mycorrhizal fungi (called altogether endophytes), which interact with plants on many different levels helping to develop drought immunity, pushing the vigour and supporting defense mechanisms against pests.

In fact , many recent studies have focused on fungi and bacteria mediated IRS. And among them we find a study funded by the Dutch Horticulture Product Board, that researched if fungus Lecanicillium muscarium was able to inhibit the growth of aphid population in sweet pepper and the bedding plant commonly known as Million Bells. The conclusion was positive as increase dropped down by 25-30% in both plants.

In another study thale cress was inoculated with a rhizobacterial strain Pseudomonas fluorescens, that proved to be effective inhibition agent of such parastic microorganisms as the bacterial leaf pathogen Pseudomonas syringae pv. tomato, Xanthomonas campestris pv. armoraciae, the fungal root pathogen Fusarium oxysporum, the fungal leaf pathogen Alternaria brassicicola and the oomycete leaf pathogen Peronospora parasitica.

It light of these findings it begs to call all cannabis growers to integrate beneficial microorganisms into their work as they can provide resistance, which plants badly need, without any need to contaminate buds with hazardous chemicals!


Photo credits: Indoor #highbrix Strawberry Recess (Second Generation) by Colorado Kid & indoor #highbrix Black Cherry Punch (IHG) by neikodog via 420 Magazine