Common problems with cannabis plants.
SYMPTOMS
Leaves turn yellow and the plant wilts. Leaf tips may turn upward. Leaves and stems dry to yellowish tan color and hang on the plant. Only one side of the plant may be affected. Cutting into dead stems may reveal dark brown streaks.
DIAGNOSIS
wilts: fusarium wilt (Fusarium oxysporum), verticillium wilt (Verticillium dahliae, V. albo-atrum).
SYMPTOMS
The plant wilts topple and dies. Wet-looking spots appear on stems and twigs. Spots collapse to form hollow, light brown, brown-black, dark green, or gray cankers. Tiny, hard, black fungal fruiting bodies may form on the canker surface.
DIAGNOSIS
stem cankers: brown stem canker (Neodidymelliopsis cannabis, Phoma exigua, Phoma glomerata, Ascochyta arcuata), twig blight (Dendrophoma Marconi, Botryosphaeria Marconi), Cladosporium stem canker (Cladosporium herbarium), Ophiobolus stem canker (Ophiobolus cannabinus, O. argillites)
SYMPTOMS
The whole plant turns yellow, wilts, and dies quickly. Tiny black dots develop inside the stem.
DIAGNOSIS
charcoal rot (Macrophomina phaseolina).
SYMPTOMS
The plant wilts turns yellow, and dies. Wet-looking brown spots appear on the stem at the soil line and twigs. Collapsed areas form sunken, light brown cankers. Fuzzy white mold may grow on cankers in high humidity. Stems rot at the soil line. Hard, black, seedlike growths appear inside stems and on white mold.
DIAGNOSIS
canker and blight: hemp canker (Sclerotinia sclerotiorum), southern blight (Sclerotium rolfsii).
SYMPTOMS
Plant wilts and turns yellow. Brown rot spreads from roots; the base of the stem rots at the soil line. The plant may die. Look for a rotted root system or sunken spots on roots. Dead roots may be red. Thick mats of red fungus may encase stem bases.
DIAGNOSIS
root rots: damping off (Pythium aphanidermatum, P. ultimum), collar rot (Rhizoctonia solani), fusarium foot and root rot (Fusarium solani)
SYMPTOMS
Plant fails to thrive, wilts easily at midday, turns yellow, and becomes stunted. Wilted plants recover at night. Look for lumpy, distorted, knotted, and deformed roots. Swollen, infected roots may be covered by bushy little rootlets. Entire root system may be stubby and discolored.
DIAGNOSIS
root nematodes: root-knot nematodes (Meloidogyne incognita, M. hapla, M. javanica), sugar beet cyst nematode (Heterodera schachtii), hop cyst nematode (Heterodera humuli), lesion nematode (Pratylenchus penetrans)
SYMPTOMS
Plant wilts and collapses. Leaves and stems turn brown and die. Cut stem in half to look for highly viscous fluid oozing from stem. Early symptoms are small, dull green leaf spots. Pathogen is transmitted by cucumber beetles and also affects cucumbers, squash, and pumpkins.
DIAGNOSIS
bacterial wilt (Erwinia tracheiphila).
SYMPTOMS
Plant wilts, turns brown, and dies. Dead leaves hang on plant. Look for signs and symptoms of pests or diseases in root zone. If pests or diseases can be ruled out, consider salt damage resulting from too much fertilizer or damage from brackish water.
DIAGNOSIS
salt damage
SYMPTOMS
Plant in pot wilts, recovers when watered, but quickly wilts again. Pull the plant from the pot; root system fills entire pot.
DIAGNOSIS:
root bound
SYMPTOMS
Plant wilts and soil is bone dry. Plant recovers when watered. Leaves turn brown on edges and tips if wilting is prolonged. Brown necrotic tissue will never be green again.
DIAGNOSIS
insufficient water
SYMPTOMS
Plant wilts and soil is soaking wet. Plant does not recover when watered. Leaves turn yellow and drop.
DIAGNOSIS