Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu
Identification of the first find of the Kudzu bug in Delaware was recently confirmed as the result of a collaborative effort between the University of Delaware Cooperative Extension and consultants (who found the first bugs), the Delaware Department of Agriculture’s Plant Industries Section who submitted the bug found by the University of Delaware to the USDA identifier and the USDA folks who responded quickly to the request to provide a positive confirmation. The first find came from a pole lima bean field in Sussex County. Entomologists at the Un of DE and DDA who looked at the specimen were fairly confident of the ID but we needed to hear back from the USDA identifier to officially confirm the identification and establish this find as a new state record. We also received another specimen from a soybean field in Sussex County last Friday.
So, be sure to carefully sample all beans crops (soybeans and all succulent beans) for this new insect pest. If you have suspect specimens you can contact Joanne Whalen at jwhalen@udel.edu or call 302-831-1303.
Entomologists in the south have done a great job of developing sound management strategies for Kudzu bug in soybeans that should apply to management of this bug in soybeans in Delaware. In addition, they have evaluated a number of insecticides labeled in soybeans for control of this insect and there are a number of effective labeled options.
Information on the identification and management of Kudzu bug can be found at the following link — http://www.kudzubug.org/. You should also follow Virginia’s Plant Pest Advisory since my colleague Ames Herbert does a great job of updating what is occurring in Virginia – including documenting the range of spread in Virginia and management options — http://www.sripmc.org/Virginia/View.cfm?lngNewsID=992.
Here is a brief summary of information on management from the south on soybeans:
(a) A threshold of one immature nymph (big enough to see) per sweep should be used in fields that are flowering or developing pods. Information on the kudzu bug.org website also indicates that if adult populations are extremely high and beans are stressed for some other reason, a control should be considered. However, this is a judgment call since they do not have a threshold for adults at this stage of crop development.
(b) Since many fields will be planted late this year and you may see bugs on small plants, there is new research from Georgia regarding management on seedling and vegetative plants. They recommended treating at V2-V3 stage soybeans if you find an average of 5 bugs (adults and/or nymphs) per plant. The threshold increases to 10 bugs per plant for plants from 1-2 feet tall. The established threshold of one nymph per sweep should be used for plants above 2 feet tall. It should also be noted that you do not want to treat too early for adults and you will want to sample the entire field – not just field edges. In other areas, treating too early has resulted in the need to make multiple applications for this insect pest.
Most of the management work on Kudzu bugs has been done with soybeans regarding treatment timing and yield impacts. However there is current work being done in Georgia looking at host plant preference, including succulent beans. Initial findings are that they do not prefer non-soybean beans, but will occur on them. They will be continuing this work this summer and have more information by the fall. In the meantime, you will want to watch succulent beans to see if this trend is true in our area. We may have to use the information developed for soybeans this season to help us make management decisions in succulent beans if the need arises. We will keep you posted of any new finds as well as new management information as it is developed.