Beetle Borers

Marijuana Horticulture

by Jorge Cervantes

Identify

Larvae from several boring beetles tunnel or bore into stems or roots. Look for their entry hole and dead growth on either side of the entry hole along the main stem, often discolored and accompanied by sawdust. Borers are more common outdoors than indoors.

Damage

Tunnels inside the stem and roots; curtails fluid flow, and causes plant parts to wilt. If borer damages the main stem severely, fluid flow to the entire plant could stop, causing death.

Controls

Seldom a problem indoors. Borers often cause so much damage on a particular stem that it has to be removed and destroyed.

Cultural and physical control

Handpick all beetle grubs.

Biological

Several mixes of beneficial nematodes control these borers in soil.

Sprays

Bacillus popilliae is specific to beetles or rotenone individually injected into stems.