Phylloxera are tiny yellow soft-bodied insects that feed in groups on roots especially in summer and
fall. They are oval and less than 0.10 inch long; a hand lens is required to see them.
Phylloxera cause a premature yellowing of leaves and stunted growth. Root tips are swollen with yellow
brown galls. Roots may be dead or dying.
There are no satisfactory controls available once vines are infested. Good irrigation and fertilizer practices
help offset damage to roots. Use resistant rootstocks.