These are probably strange growths that you usually see on the whole weed plant. Although they cause damage to the body and are very harmful, there are still some benefits that can be obtained from them. This article explains what those benefits are.
It can be very hard to determine whether or not a leaf is affected by mildew. They look almost identical!
SYMPTOMS
Yellow-orange, thin, spaghetti-like plant stems spread over cannabis plants. This parasite draws nutrients from host plants, which become stunted and may be killed. It also spreads viral diseases from plant to plant.

DIAGNOSIS
dodder (Cuscuta campestris, C. europaea, C. pentagona, C. epilinum, C. suaveolens)
SYMPTOMS
Yellow and brown (not green) flower stalks, 4 to 8 inches (10 to 20 cm) tall, grow in the soil near stunted, sickly cannabis plants. Stalks bear clusters of small blue and purple flowers. This parasitic plant lives in soil and feeds off cannabis roots, transmitting viruses from plant to plant and damaging root systems, providing a point of entry for root rot fungi.

DIAGNOSIS
broomrape: branched or hemp broomrape (Orobanche ramosa), Egyptian broomrape (Orobanche aegyptiaca), tobacco or nodding broomrape (Orobanche cernua)