Why Are There Brown Spots on My Autoflowering Cannabis Plant Leaves?

Is your autoflowering cannabis plant covered with yellow or brown spots on leaves during flowering? Unfortunately, your plant could be suffering from cannabis leaf septoria.

What is cannabis leaf septoria?

Cannabis leaf septoria (also known as ‘yellow leaf spot’) is a fungal infection that autoflowering cannabis plants are particularly vulnerable to, especially if they are being grown outdoors.

This plant disease is caused by the fungal pathogens Septoria neocannabina, and S. cannabis. The disease spores can spread through bacteria, nematodes, animals, and other plant disease agents to infect your plant with cannabis leaf septoria. A warm and wet environment is particularly helpful in allowing spores to germinate.

Cannabis leaf septoria typically affects plants as soon as they enter the flowering stages. It begins spreading on the lower leaves first and then slowly climbs upwards to attack multiple layers of leaves. The fungus may also attack the stem.

Why is cannabis leaf septoria dangerous?

If not controlled during its earlier stages, pot leaf septoria can wreak havoc in your autoflowering cannabis garden.

This plant disease interferes with leaf processes such as photosynthesis and weakens your cannabis plant’s health by inhibiting plant growth, destroying foliage, and affecting the size and quality of yield. Damaged leaves can dry out, die, and even fall off entirely.

Despite not being a deadly plant disease, cannabis leaf septoria still has the potential to suck the strength out of your autoflowering cannabis plant, which can lead to a poor harvest.

How to tell my plant is suffering from cannabis leaf septoria?

The most telling sign of a cannabis plant suffering from cannabis leaf septoria is the formation of yellow and brown spots on the upper and lower sides of your plant’s leaves. On average, these spots measure anywhere between 1.5 to 6.5 mm across in length.

This fungal infection begins with spots being small, round, and light in color, but they progressively get larger, darker, and more irregular in shape. You may notice that some spots have a reddish-brown perimeter. This observation is the result of infected plant tissue, which has fallen off. Meanwhile, other spots may have a stiff growth in the middle, similar to a pimple.

Note that each spot represents the containment of a fungal spore that was able to germinate successfully upon landing on your plant.

How to treat cannabis leaf septoria?

To begin your plant’s leaf septoria treatment, you will have to get rid of every leaf which has been affected by the disease.

Pruning away dead foliage will help minimize your plant’s exposure to leaf septoria vectors, and allow improved plant nutrient circulation to new leaves. Depending on how far the disease has progressed, merely getting rid of infected leaves may be enough to prevent it from spreading further completely.

Here are some helpful leaf septoria treatment tips that you can implement:

• Enable better air circulation by introducing a fan, opening all windows, and creating space between your plants. Better ventilation can help humidity come down by as much as 50%.
• Avoid watering your plants in the evening and night. Water management helps prevent moisture from building up and can help avoid fungal growth.
• Try to make sure that day and night temperature variations within your cannabis garden have a maximum difference of 5 degrees Celsius. A narrow margin of temperature change helps plants recover quickly.
• Organic treatments such as 20% horsetail tea solution and neem oil can help your plant combat against marijuana leaf septoria. Spray this on your plant every fifteen days.

How to avoid cannabis leaf septoria?

Despite being a common cannabis plant disease, leaf septoria is entirely avoidable in a cannabis garden.

Cleanliness and plant hygiene are critical to avoiding cannabis leaf septoria from latching itself onto your autoflowering cannabis plants. Dust accumulation, dead leaves in your growing area, and dirty gardening tools are common culprits in helping leaf septoria incubate in your cannabis garden.

Clear out any weeds in your growing area, as they can host fungal spores. Rake your soil, remove fallen dead vegetation, and apply a layer of mulch to restrict the spread of fungal spores from reaching your cannabis plants.

Keep track of temperature and humidity to lower the risk of your autoflowering cannabis plants contracting cannabis leaf septoria.