Ajuga is very susceptible to root knot nematode . Infected plantings will begin to thin-out in spots and plants may die. Roots of infected plants will contain small knots caused by nematode feeding. Southern blight , also called Crown Rot, is a soil-borne disease of ajuga that will be more serious in poorly drained soils.
Plants suddenly turn yellow and die in patches during warm, humid weather.
Bases of stems rot and turn brown or black. These sclerotia survive the winter and other unfavorable conditions. Brown lesions on the leaves, in which tiny fungus fruiting bodies may be seen with a hand lens. Apply dithiocarbamate or copper fungicides. Both the stems and roots may have good size galls.