Cotton Yield Loss from Mid-to-Late Season Twospotted Spider Mite Damage

Damaged and undamaged cotton were marked before defoliation in two production fields.  At harvest, 6-row ft samples were boxmapped from damaged and undamaged areas in each field.  In a second experiment, mites were manually infested in cotton starting at first bloom and again at 200 heat unit intervals until cutout.  In the production field test, spider mite damage resulted in yield losses of ~50% in the dryland field and ~10% in the irrigated field.  Boxmapping revealed that yield loss was associated with both boll weight reduction and fruit loss on nodes 10 to the top of the plant.  The second experiment is currently being harvested.