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University of Nebraska–Lincoln

UNL Today

  : Confirming Soybean Rust

Identification of soybean rust will be critical for proper management actions to be taken. You are encouraged to contact your local University of Nebraska Cooperative Extension office if you are uncertain about a symptom in your field. For confirmation of an unkown sample in Nebraska please submit a leaf sample containing several leaves to the Plant & Pest Diagnostic Clinic. Any abuse of this system with sample submission for symptoms which are not likely to be confused with soybean rust will be billed.

Scouting

Scouting

 Sample check list for soybean rust:

* Use a sealed plastic bag for leaf samples.
* Do not add water to the bag. If leaves are wet, a paper towel can be used to wrap the leaves.
* Keep the leaf samples cool. Do not place in direct sun light as they can heat up very quickly.
* Accompany sample with a complete list of field and contact information.
* Use the P&PDC form if you have one.
* If you cannot deliver the sample to the clinic it is recommended that overnight mail be used for any suspect rust samples.
* Samples can also be logged into the PDIS system if you are an authorized user. PDIS Login

Tips to identification:

Using a hand lens is critical to identify soybean rust. The first time will be much more difficult until you gain experience.

 

tan_rust

 Lesions of soybean rust under a 16X handlens.
Note the sporulation (dusty appearance) within each lesion.

 

Suspected leaves can be placed in a sealed plastic bag with moist toweling for a make-shift humidity chamber. The optimum temperature is from 65 to 80 F, so room temperature will typically work well. Within 24 to 72 hours (depending on lesion maturity) sporulation should be evident on the lesion if the leaf has not been treated with a fungicide or the residual activity has lapsed.

 Rust ID in Brazil

  Rust I.D. in Brazil.

Federal and Non-Federal Responsibilities for identification:

The current responsibilities of parties identifying soybean rust can be found in the document ”Federal/Nonfederal Responsibilities for Identification of Phakopsora pachyrhizi”