Illinois soybean producers should be on alert for suspicious-looking stink bugs. A stink bug resembling the red-shouldered stink bug was observed south of Champaign, but the report could not be confirmed because the actual specimen was not available for physical examination.
However, Mike Gray, University of Illinois (U of I) Extension entomologist, warns producers to be vigilant in scouting fields and to report any stink bug species that resemble the red-shouldered, red-banded or brown-marmorated stink bugs.
For years, Illinois producers have seen green (Acrosternum hilare) and brown (Euschistus servus) stink bug species in fields. These bugs are attracted to soybean plants in the bloom to early pod-fill stages and use their piercing and sucking mouthparts to remove plant fluids.
“Because of their ability to damage tender plant tissues, especially developing seeds, they are capable of causing economic losses to soybean producers,” Gray says. “The economic threshold of one bug per row foot during the pod-fill stage has been suggested.”
Throughout the past several years, other stink bug species have become more numerous in soybean production areas in the southeastern U.S. The red-banded stink bug has been observed in several states including Arkansas, Louisiana, Mississippi, Missouri and Tennessee.
“The red-banded stink bug has caused significant management challenges, particularly in Louisiana where densities of the pest have reached economic levels,” Gray says. “The suggested economic threshold for the red-banded stink bug is 24 insects/100 sweeps as compared to 36 insects/100 sweeps for the brown stink bug.”
The brown-marmorated stink bug has been reported in Illinois and is considered a potential pest of some species of shade and fruit trees, vegetables, and legumes (including soybeans).
If you spot suspicious stink bugs, contact Kelly Estes, State Survey Coordinator with the Illinois Cooperative Agricultural Pest Survey Program, at 217-333-1005 or [email protected]. For more information, read The Bulletin online.
Goss’ wilt was detected in a corn leaf sample last week at the University of Illinois Plant Clinic. Although Goss’ wilt has been observed in Illinois in past years, it is not typical, says U of I Extension plant pathologist Carl Bradley.
Goss’ wilt, caused by the bacterium Clavibacter michiganense subspecies nebraskensis, is commonly found after hail storms, high winds and heavy rainfall. Symptoms of this disease appear as large tan to gray lesions on the leaves with dark spots, often referred to as “freckles,” within the lesions.
“Some plants may wilt, as the pathogen can infect the xylem,” Bradley says. “In some cases, darkening of the vascular tissue can be observed in affected plants if a cross-section is cut through the stalk.”
Bradley says symptoms of Goss’ wilt may be confused with other foliar diseases such as Stewart’s wilt, northern corn leaf blight, or Diplodia leaf streak. In order to properly diagnose this disease, send suspicious samples to the U of I Plant Clinic.
No in-season control options are available to protect against Goss’ wilt infection or to reduce disease spread within a field, he says. Foliar fungicides are not effective, either.
The best method of controlling Goss’ wilt is to plant corn hybrids with high levels of resistance. Bradley recommends checking with your seed dealer to obtain Goss’ wilt ratings
He says, “Fields affected this season should be tilled after harvest to bury affected residue and rotated to a non-host crop, such as soybean, the next season.”
For more information, read The Bulletin online.