Asian Soybean Rust

Phakopsora pachyrhizi and P. meibomiae
Soybean rust is an important foliar disease of great concern in many parts of the world, resulting in up to 90% yield losses.  However, it has never been found in NY.  The pathogen causes different lesions types, from tan, brown, to red-brown depending on the cultivar and race of the pathogen.  Tan lesion types, a result of sporulation, are a product of susceptible reactions.  Whereas the red-brown lesion types are the result of incompatible reactions or partial resistance.  Prior to rust sporulation visible on the underside of leaflets, early rust lesions and symptoms can be confused with those of common foliar diseases such as bacterial blight, bacterial pustule or brown spot.  The soybean plant is susceptible to rust infection at all growth stages, and typically develops in the lower canopy on older leaves first during periods of high humidity.  Severe infection can result in premature defoliation.  Race specific resistance is available in some commercially available soybean varieties for maturity groups where the disease is common.  Foliar fungicides are also effective at reducing epidemics, and it is recommended that growers use an integrated approach of combining resistance with timely fungicide applications to manage the disease.
From 2006-2008, a network of sentinel plots were established, in collaboration with a nationwide effort, throughout NY to intensively monitor for the presence of soybean rust.  Over the course of the three year survey, the disease was never identified in any of sentinel plots in any of the 23 counties monitored.  Though the pathogen spores can travel long distances on wind currents, it is unlikely it will become a disease of concern to NY growers because the climate in NY is not conducive for the pathogen to overwinter and reach epidemic levels.

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