Issue 2, April 30, 2010
Bridal wreath spirea, or Vanhoutte spirea (Spiraea x vanhouttei), is blooming in most of Illinois. This is a major phenology plant in Don Orton's book Coincide. Following are the most common pests that are in susceptible treatment stages during Vanhoutte spirea bloom.
Full bloom: Birch leafminer young larvae; elm leaf beetle young larvae; European pine sawfly feeding larvae; Gypsy moth feeding larvae; pine needle scale crawlers (first generation), black turfgrass ataenius (first generation).
Full to late bloom: Lilac (ash) borer newly hatched larvae; euonymous caterpillar early webbing, oystershell scale (brown) crawlers.
Finishing bloom: Bronze birch borer newly hatched larvae.
Most blossoms brown, still a few white: Flat-headed appletree borer larval hatch; peach tree borer newly hatched larvae; viburnum borer newly hatched larvae.
Bloom finished: Oystershell scale (gray) crawlers.--Phil Nixon