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 some years, rainfall patterns and resulting wet soil may prevent some of the intended April and early May plantings. Thus, those acres are being pushed into a later planting window.

This article will deal with the ramifications of later planting of soybeans. The items addressed are based on the fact that later-than-normal plantings in the midsouthern US will require a management strategy that is different from that for earlier plantings.

It is a foregone conclusion that late-planted soybeans in the midsouthern US will yield less than early-planted counterparts. That yield penalty cannot and will not be overcome by increased management of the later plantings. Thus, the below general management hints should be used as a guide to ensure that the maximum though reduced yield potential is realized from later plantings.

• Results from recent reseach indicate that MG IV varieties can be planted with maximum though reduced yield expectation through mid-July. They should be planted in narrow rows during this later period.


• Preventing and/or alleviating short-term stresses during early vegetative development is more critical with later plantings. Therefore, seed treatments should still 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 a relatively inexpensive insurance to prevent stand losses and the early-season stresses caused by seedling diseases and insects.


• Planting late will result in later calendar-date maturity, and this will necessarily mean a higher probability of detrimental infestations of both foliage and pod-feeding insects during reproductive development (See MSPB Project No. 58-2014Annual Report). 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 the Mississippi 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 potentially means more irrigation before and/or during reproductive development with subsequent higher input costs. 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 the early reproductive stages of varieties planted in late May/early June.

Since these plantings will not reach R6 until about mid-September, 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. This will require more frequent scouting.


• Later plantings will be ready for harvest 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.

Other important points to consider are:

• Do not till prior to planting. This will result in the earliest possible planting after soil dries, possibly planting before weed emergence, and conservation of soil moisture.


• Plant in narrow rows, preferably less than 20 inches. Forming a crop canopy as quickly as possible in these later plantings is critical for success.


• Use a broad-spectrum seed treatment and inoculate seed with nitrogen-fixing bacteria. See the article by Dr. Tom Allen for a list of seed treatment and inoculant products.


• Do not apply starter nitrogen fertilizer. Inoculants are cheaper.


• Ensure a weed-free seedbed at planting. This may mean an additional burndown and/or residual herbicide application since those applied in anticipation of early planting will have lost their effectiveness. Any early-season competition from weeds will be more critical in later plantings. A reasonable option is to apply a tankmix of a burndown/residual herbicide combination (see following point).


• Using pre-emergence herbicides that require rainfall for activation will be a higher-risk practice because of the lower probability of summer rain following planting on these later dates. If pre-emergence herbicides are used, be sure to match the herbicide rate with the soil texture to prevent any early-season stunting.


• Prevent any early-season weed competition with the soybean crop after emergence. This means more intense scouting for weed emergence and more timely post-emergence herbicide applications following soybean emergence if residual herbicides are not used or are not activated by rainfall or irrigation.


• Finally, remember that nonirrigated yields will be low from these plantings and may not be profitable if expensive inputs for weed and pest control are necessary.

I re-emphasize two important points.

• If you haven’t already, bookmark the pest advisory links provided above. Their information will be invaluable to you in planning pest management activities in later 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.


• If you are looking for an average daily yield loss estimate for soybeans that are planted after a certain date, you won’t find it here. I place neither value nor credibility on these calculations because they do not represent what will occur in any given year. As you know, the yield from these later plantings will be depend on their subsequent management and the growing conditions that follow the planting no matter what the date is.

Composed by Larry G. Heatherly, May 2015, larryheatherly@bellsouth.net