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How to Manage Pests
UC Pest Management Guidelines
Walnut
False
Chinch Bug
Scientific Name: Nysius raphanus
(Reviewed 12/07,
updated 4/09)
In this Guideline:
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The false chinch bug is an occasional pest of young walnut orchards.
It hibernates as an adult and moves in late winter to preferred weeds, primarily mustard family weeds
such as London rocket, shepherd's purse, and common peppergrass, where it stays
to lay eggs in early spring. Nymphs are dull gray or brownish red and collect
in great numbers on the host plants.
When weed hosts dry up in late spring, chinch bugs move into orchard
trees where they may kill new foliage. This damage can occur within hours
because the nymphs apparently inject a toxin while feeding. The leaves dry up and are covered with fecal spots. Damage may be substantial on trees that are 1
to 3 years old. Several generations are produced each year, but damage in
orchards usually occurs only in spring.
Where damage has occurred, control weed hosts in and adjacent to the
orchard to prevent populations from developing in future years. Begin checking
weed hosts for false chinch bug in late February and early March, especially in
years when moisture is abundant. Mowing and discing cover crops before walnut
trees begin to leaf out prevents false chinch bug development and migration. If
potentially harmful populations are found on weeds or cover crops after walnut
trees have leafed out, consider spraying the weeds or cover crop; avoid mowing
or discing at this time to prevent migration to walnut foliage.
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UC IPM Pest Management Guidelines: Walnut
UC ANR Publication 3471
Insects and Mites
C. Pickel, UC IPM Program/UC
Cooperative Extension, Sutter/Yuba counties
J. A. Grant, UC Cooperative Extension, San Joaquin County
W. J. Bentley, UC IPM Program/Kearney Agricultural Center, Parlier
J. K. Hasey, UC Cooperative Extension, Sutter/Yuba counties
W. W. Coates, UC Cooperative Extension, San Benito County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
Acknowledgment for contributions to Insects and Mites:
W. H. Olson, UC Cooperative Extension, Butte County
L. C. Hendricks, UC Cooperative Extension, Merced County
G. S. Sibbett, UC Cooperative Extension, Tulare County
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