On Sept. 17  the soybean rust (SBR) fungus was found and confirmed on soybean leaves collected from one of the sentinel plots at the Tidewater AREC in Suffolk.

At that time, 10 out of 34 leaflets (30 percent) had a few pustules with leaf coverage of approximately 2 percent.

We are continuing to monitor these plots. In the most recent samples from the TAREC plots, 30 percent of the leaflets had SBR pustules but with greater leaf coverage (up to 100 pustules per leaflet and approximately 5 percent coverage).

Furthermore, pustules were actively sporulating, and airborne spores are what leads to the spread of the fungus.

We are currently assessing soybean samples from additional counties/cities in Virginia, and this week we confirmed SBR in Isle of Wight County.

SBR was detected at a low incidence (4/40 leaflets with less than 1 percent coverage), but this does indicate the fungus is spreading.

Samples from two other locations in Isle of Wight County were negative for SBR.

To reiterate previous recommendations, growers with soybeans that have not yet reached the R6 stage should consider spraying fungicides for control of SBR.

Triazole or pre-mix fungicides are best, and some examples of the various products available were described in the Sept. 19 SBR update. (See Virginia Extension providing updated soybdean rust status, treatment guidelines).

The general “rule of thumb” is that soybeans within 100 miles of confirmed SBR that have not yet reached R6 be sprayed. Currently, this includes areas within 100 miles of Suffolk and Isle of Wight County.

Growers outside this area, or those who want to wait and see how SBR progresses, should still be prepared to spray in the near future.

As always, feel free to contact me if you have any specific questions or concerns: 757-657-6450, Ext. 423 or hlmehl@vt.edu.

 

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