Brown stem rot can negate the benefits of management practices intended to maximize soybean yield. Soybean productivity has increased in recent years by the implementation of practices such as earlier planting, narrow row widths, increased seeding rates, and the addition of N fertilizer. The benefits of these management practices are enhanced by crop rotation, superior soybean varieties, good weed control and optimal growing conditions.

The difference in yield between BSR-resistant and BSR-susceptible soybean varieties will be greatest in high yield potential environments. In one 2-year study, there was no yield response to either earlier planting date or narrow rows by a soybean variety susceptible to brown stem rot (Figure 1).

Differences in yield between BSR-susceptible and BSR-resistant varieties were greatest at early planting dates. The significant increase in yield of a BSR-resistant variety in response to high yield management practices emphasizes the importance of BSR pressure (Figure 2).

The yield advantage of a BSR-resistant variety is greatly reduced when planted later in the season: yields of a BSR-resistant variety (BSR 101) were 25-31% lower when planted in late May than when planted in early May. The BSR-resistant variety planted in narrow rows yielded 19% more than in wide rows when averaged over all planting dates (Figure 3).

Figure 1. Yield loss due to brown stem rot can negate the benefits of an early planting date or narrow rows

Figure 2. Differences in yield between BSR-susceptible and BSR-resistant varieties were greatest at early planting dates, emphasizing the importance of BSR pressure under high yield environments.

Figure 3. The yield advantage of a BSR-resistant variety is much greater when planted early, and yielded 19% more when planted in narrow rows compared to wide rows when averaged over all planting dates.