INFO-BUG
Crop Selected: Wheat
Crop Development: Late spring maturation
Pest Selected: Wheat Jointworm Tetramesa tritici (Fitch)
Biology
The wheat jointworm is a chalcid wasp which lay eggs in the wheat stems in the spring that hatch into larvae that cause gall-like
swellings and subsequent breakage of the stalks. The larvae remain in the stems and pupate by late fall. The pupae overwinter
in the stems and the adults emerge the following spring.
Within the gall caused by larval development, multiple larvae may be found.
Extensive infestations may lead to a reduction in grain yield.
Assessment
Wheat jointworm infestations may or may not be detected since the gall swellings are sometimes not readily visible. In some cases
the galls can only be detected by feeling for hard areas above the infested joints.
If infestations are severe, infested stems often bend over and sometimes break off due to the stems becoming brittle.
Severe infestations should also exhibit noticable galls.
Control
The wheat jointworm is an old pest of wheat and normally controlled by a complex of parasitic wasps.
Cultural practices - especially conventional tillage - has generally contributed to control of the jointworm by destroying
the overwintering pupae in the infested stems.
Adoption of reduced tillage may lead to an increas of jointworm, although the problem has not been significant for many years.
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