2023 Soybean Stem Canker Inoculated Variety Trial Evaluations

DR. TOM ALLEN

STONEVILLE, MISSISSIPPI

All of the entries contained in the 2023 Mississippi State University Official Variety Trials (OVT) were evaluated for their reaction to the fungus that causes stem canker.  In addition, a few varieties (not including the checks used) were added to supplement the trials and obtain information on those particular varieties that were not entered by the respective seed companies in the MSU-OVT.  Trials consisted of single rows of each cultivar planted in 10 foot plots and replicated 4 times.  Within each row, a total of 10 plants were inoculated with a single toothpick that contained the fungus that causes stem canker (multiple isolates of the fungus were used for a fungal cocktail on toothpicks).  Plants were inoculated approximately 8 weeks post-planting.  Evaluations of stem canker severity were conducted between R6 and R6.5 by observing the stem of each inoculated plant for the presence of a canker.  Observations of each variety were conducted using a modified 0-9 scale.  Information contained within each table contain the analyzed stem canker rating as an average of all inoculated plants within the four replicate plots.  In addition, each cultivar includes a stem canker designation: R=resistant, MR=moderately resistant, MS=moderately susceptible, S=susceptible.  In field situations where stem canker has previously been observed, select soybean cultivars that have been observed to contain resistance to stem canker.  However, with that said, stem canker can occur anywhere soybean has been planted with or without rotation.  In fact, MSU Extension suggestions state that stem canker-resistant cultivars should be planted to reduce the likelihood of losses associated with stem canker.  In addition, keep in mind that observations of stem canker tend to be more obvious when the environment is conducive for disease development.  Therefore, over time, and in years when the environment may not be conducive for the development of stem canker, it is possible that stem canker designations change between years.  Moreover, as additional fungal isolates are added to the collection it is possible that the rating as well as cultivar designation can change accordingly.

Xtend varieties:

Maturity Group IV Early 2023 MG IV early Xtend stem canker

Maturity Group IV Late 2023 MG IV late Xtend stem canker

Maturity Group V Early 2023 MG V Xtend stem canker

Maturity Group V Late 2023 MG V late Xtend stem canker

Enlist varieties:

Maturity Group IV and V Enlist 2023 MG IV and V Enlist stem canker ∆

 DR. TOM ALLEN: Mississippi State University