Cannabis Plant Diseases and Pests

Growing cannabis is a fulfilling experience, in more ways than one, but sometimes external elements come into play that can cause a lot of pain for the grower as well as the plants. Problems that can occur are environmental stresses, like extreme fluctuations in temperature, changes in humidity, severe weather, soil and water quality, and the dreaded arrival of pests and diseases.

Knowing how to identify the disease and critter that is attacking your plants will equip you with the right knowledge to go on the offensive and save your cherished crop.

Diseases

When the cannabis plant’s environment is out of balance, it can trigger harmful conditions.

Algae

The slight presence of algae must never be ignored as it can spiral out of control quickly and be fatal. Signs of growing algae include the yellowing or browning of leaves with dark spots and the roots start clumping together before turning brown and drying out.

Bud Rot

Bud rot/grey mold is a fungus that will destroy an entire crop when temperatures are cool and humid. The stems will become soft and brown as it starts rotting inside. Fungal spores will be noticeable.

Yellow Leaf Spot (aka Leaf Septoria)

These fungal pathogens thrive in warm, humid weather and can easily affect outdoor-grown cannabis plants. The lower leaves are afflicted first with the presence of white, grey, brown or yellow spots.

Powdery Mildew

Powdery mildew is easy to detect because of the visible white powder that spreads across the plant’s leaves eventually causing the leaves to pale resulting in the whole plan turning brown or yellow. If buds are growing, you will also notice a damp smell.

Fusarium Root Rot

A fungus in the soil attacks the stems causing them to turn red, swell, and break leading to the collapse of the plant.

Verticillium Wilt

Cannabis plants that are in rich soil or have stressed roots are susceptible to a fungus that starts at the base of the plant and discolors the lower leaves. The lower part of the stem will go brown.

Root Rot (Pythium)

This disease affects the plant’s roots and caused by unfavorable soil conditions or where the roots are already weak. The leaves will develop burnt spots before turning yellow and white then fall off.  The roots will become soft and emit a rotting smell.

Damping Off

This occurs when the nutrient distribution is unbalanced. The stems become weak, soft, and mushy with lesions developing between the nodes. If not rectified, the plant will collapse.

Pests and Bugs

For outdoor growers, it can be devastating to see an infestation of hungry creepy-crawlies munching on your plants or find unwanted garden visitors wreaking havoc. Regular spraying of neem oil or organic insecticides, as well as building protective barriers are just some of the ways you can prevent your crop from becoming a target.

Ants and Aphids

Ants can be a real pain and usually go for the plant’s root system. An invasion of ants is a good indicator that there is an underlying problem that needs close investigation. Aphids are easy to overlook as they hide underneath the cannabis leaves. They cause a lot of damage by depleting essential nutrients from the plant.

Birds

Both friend and foe, birds can help with eliminating other bugs but unfortunately, they also like to snack on seeds. Keep your newly-sown seeds covered for protection if growing outdoors.

Caterpillars, Crickets, and Grasshoppers

This bunch is infamous for their love of plants and insatiable appetites. Caterpillars can be missed while they secretly gobble up the leaves while others make their way inside the stem of the plant and eat up the interior. You need to keep a sharp eye on these pesky lodgers.

Cutworms

Cutworms are tricky buggers who get great delight in destroying seedlings at night, which makes them much harder to detect.

Mammals

Build a fence or barrier to prevent animals from using the area as a toilet (pet poop is not good for the soil where cannabis is grown). In rural areas, you want to stop farm animals or other wildlife from seeking out your plants to nosh.

Snails and Slugs

Snails and slugs are big garden enemies that can decimate crops. Getting rid of one is easier than getting rid of many.

Spider Mites and Thrips

These insects multiply rapidly and can harm your plants fairly quickly. If they get out of control, it can be difficult to resolve.