Archer, T.L., Bynum Jr, E.D., 1990.
Economic injury level for the Banks grass mite (Acari: Tetranychidae) on corn. Journal of Economic Entomology, 83: 1069-1073.
Abstract
Banks grass mite, Oligonychus pratensis (Banks), feeding on corn, Zea mays L., between the late-vegetative and dent growth stages caused significant yield loss but did not affect test weights. Regression analysis was used to compare several independent variables (mite abundance, damage ratings, and percentage of the leaves infested) with yield loss and plant lodging. Data were analyzed the week of maximum yield loss from mite feeding at predetermined damage levels and the week before this event. The best relationship was between yield reduction and percentage of the leaves infested the week before maximum yield loss from mite feeding occurred. There was a 0.2% yield loss per 1% infested leaves per plant. A flexible economic threshold for Banks grass mite on corn can now be calculated based on crop value and cost of control. Mite feeding on corn in the dent growth stage did not affect yield. Banks grass mite feeding did not have a definitive effect on incidence of plant lodging, although there were indications that increased lodging may have been associated with mite feeding in some situations. Grain moisture declined as densities and feeding damage by Banks grass mite increased.
