Management Decisions For Late-Planted Soybeans

In my previous writings, I have touted the yield and economic advantages of early planting of early-maturing soybean varieties in the midsouthern US. However, in the last 5 years an annual average of about 300,000 acres of the Mississippi soybean crop was doublecropped with wheat(NASS), and these soybeans will by necessity be planted after early June, which I classify as late.


Late plantings in the midsouthern US will require a management strategy that is different from that for earlier plantings.

  • Long-term research indicates that MG VI soybean varieties (or late MG 5's) are the best fit for late plantings because of their greater yields compared to MG IV and MG V varieties. It is presumed the greater yields result from their longer vegetative period (CM 2005).


A MG VI variety planted from about June 10 to June 15 will typically take about 110 days to reach full seed stage or R6 on about Oct. 1, and about 125 to 130 days to reach maturity or R8 on about Oct. 20 (CM 2005). The estimated R6 date will safely avoid the earliest estimated frost date for northern Mississippi (MSSOY).

  • Preventing and/or alleviating short-term stresses during early vegetative development is more critical with late plantings. Therefore, seed treatments should be used, even though the threat of seedling diseases associated with cool, wet soils is not considered as serious with later planting. Using a combination product that contains both fungicides and an insecticide is relatively inexpensive insurance (<$14/acre) to prevent stand losses and the early-season stresses caused by seedling diseases and insects.

  • Planting late results in later calendar-date maturity and a higher probability of detrimental infestations of both foliage and pod-feeding insects during reproductive development. This will result in either increased cost associated with more spraying or unacceptable yield loss if control measures are not applied. Up-to-date information and advisories about pest outbreaks during the growing season are available from AgFax Media and theMississippi Crop Situation blog.

  • Planting late results in a higher risk of detrimental effects from drought during both vegetative and reproductive development. In irrigated plantings, this means more irrigation before and/or during reproductive development with subsequent higher input costs (>$10 to $12 per acre). Escalating fuel prices will increase this extra cost.Information in the Irrigation White Paper posted on this website will help with irrigation decisions for late plantings.

  • The threat of soybean rust to the midsouthern US soybean crop is always a major concern. Rust usually is detected in soybean sentinel plots in the extreme southern part of the region no earlier than late July/early August, which coincides with beginning bloom or R1 of MG VI varieties planted in mid-June.Since these plantings do not reach R6 until about Oct. 1, they are susceptible to rust incursions during their entire reproductive period. Thus, they are more likely to require treatment to prevent or control late-season rust infestations that may occur. Up-to-date information and advisories on the occurrence and expected movement of soybean rust in the US are available from the soybean rust pest information platform.

  • Late plantings will have less time to recover from stresses, especially during reproductive development. Therefore, it is critical that manageable stresses caused by pests, weeds, and drought are either prevented or are quickly identified so that remedial measures can be applied as soon as possible.

  • Later-maturing varieties used in late plantings will be harvested in October and November when there is a greater probability of wet soil. Harvesting at this time usually results in some level of rutting that may require remedial tillage. This may interfere with a continuous no-till system in some years, but as stated in the Tillage White Paper on this website, this occasional tillage does not necessarily compromise the long-term goals of a no-till system.

  • It is a foregone conclusion that late-planted soybeans in the midsouthern US will yield less than early-planted counterparts. Thus, the above general management hints should be used as a guide to ensure maximum yield is realized from late plantings.


I re-emphasize one important point from the above. If you haven’t already, bookmark the pest advisory links I have provided. Their information will be invaluable to you in planning pest management activities in late plantings. Also, by following the advisories they give, you will save time and money by avoiding applications of unnecessary control measures for the major soybean pests.

larryheatherly@bellsouth.net