Septoria Leaf Spot in Hemp Plants

Identify and Treat Septoria Leaf Spot in Hemp Plants

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Weather conditions in the southeast make the hemp plant a perfect target for Septoria. It's important that growers understand how to identify this terrible leaf eating disease.

More importantly, growers need to be equipped with the right knowledge to get it under control before it destroys their crop. Let's take a brief dive into one of the most commonly reported leaf spot diseases known in the industrial hemp market. 

What is Septoria Leaf Spot

Septoria cannabis is a species of plant-pathogen from the genus Septoria, which is an ascomycete and pycnidia producing fungus, otherwise known as Septoria leaf spot.

This fungus spore survives in old plant debris, and it usually infects plants by wind and the splash of water from falling rain.

Septoria requires moist and high humidity to germinate that begins in older bottom leaves. One of the first symptoms you will notice is yellow spots followed by browning and chlorosis.

In severe cases, it will attack the foliage of the whole hemp plant, leading to a reduction of vegetative growth.

Treating Leaf Septoria

There are four products that I've had great success with when it comes to a septoria leaf spot organic treatment.

The first one is OMRI Regalia CG (Reynoutria sachalinensis). It's a plant extract that boosts the defense system of the hemp plant.

In my opinion, the OMRI and NOP Approved Cease (Bacillus subtilis) is the best contact biological fungicide for septoria that works in multiple ways.

First, the beneficial bacterial spores occupy space on the hemp plant surface and compete with the pathogens.

Second, the active compounds called lipopeptides produced by each bacterium disrupt the germination and growth of invading pathogens.

These products together are great for septoria leaf spot fungicide and act as a great plant immune system booster.

Another great option to incorporate into your Integrated Pest Management solution is OMRI listed Dr Zymes. This is an excellent secondary option to treat septoria leaf spot  and covers a wide range of other fungal, bacterial diseases, and pests during the more sensitive flowering stages. 

Last but not least, I highly recommend a contact fungicide and bactericide Zerotol which controls both foliar, and root diseases. It is also safe to use on foliage and most open blooms.

Prevention is The Best Way to Avoid Plant Diseases

In the case of septoria, when growing hemp plants be sure to remove all debris and old dead leaves (do not put them in your compost pile). Remember, Septoria spores survive through winter in the debris of old leaves.

To avoid spreading the pathogen through water droplets, prevent overhead watering and use mulch as a layer to prevent spores on the ground from splashing up onto the lower leaves.


Let me emphasize how important planning and preventative maintenance is to a successful grow. There are many tools available to Hemp Farmers and no reason you can't be one step ahead of all these pesky diseases.

Please do not forget that our Hemp Resource Agents are here to support you and answer questions, We want every farmer to feel supported as if they have their own consultant, on-call, that leads them through their growing season and post-harvest solutions. Contact one of our agents here

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