2020 Soybean Stem Canker Inoculated Variety Trial Evaluations

Stem canker continues to be a devastating disease in MS when stem canker-susceptible varieties are planted.

All of the entries contained in the 2020 Mississippi State University Official Variety Trials (OVT) were evaluated for their reaction to the stem canker fungus.  In addition, a few varieties (n=7; not including the checks used) were added to supplement the trials and obtain information on those particular varieties that were not entered by the seed respective 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 (four 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.

Please note: The statistical analysis used on these data, a rank transformation prior to the means analysis, may make some values appear skewed.  The letter groupings listed after values are for the rank transformed values, but the non-transformed data are presented to present the true mean of the scores assessed in the field.

Xtend varieties:

Maturity Group IV Early (2020 MG IV early Xtend)

Maturity Group IV Late (2020 MG IV late Xtend)

Maturity Group V Early (2020 MG V early Xtend)

Enlist varieties:

Maturity Group IV Enlist (2020 MG IV Enlist)

Maturity Group V Enlist (2020 MG V Enlist)

Conventional/LibertyLink/RoundUp Ready varieties:

Maturity Group IV Conventional/LibertyLink/RoundUp Ready (2020 MG IV Conventional LibertyLink RR)

Maturity Group V Conventional/LibertyLink/RoundUp Ready (2020 MG V Conventional LibertyLink RR)