Planting Time Decisions

Soybean producers are faced with making decisions about planting date and planting time inputs every year.

This blog contains most of the information you will need to prepare for and conduct planting. I have listed what I consider the main issues that should be considered at planting time, and have linked to resources that contain pertinent information about these subjects. Please bookmark these links for use during the next couple of months so that you will have access to any of the subjects and their information sources with one or two clicks.

Soybean Maturity Group (MG). SOYMAP is a new tool that can be used to determine the soybean MG that best fits a particular planting date at a specified Midsouth location. Both the tool and a video that explains its use are now available through the above link.

Varietal sensitivity to Metribuzin. With the continual evolving of herbicide-resistant (HR) weeds, preemergent (PRE) residual herbicides are increasingly being used as a component of weed control programs to control and/or delay the development of HR weeds and to introduce multiple modes-of-action. Many of these herbicides are mixes that contain metribuzin.

Varietal sensitivity to metribuzin exists, especially when varieties are planted on coarser-textured soils with low organic matter following PRE application of metribuzin. Thus, producers need to ensure that their selected varieties are tolerant of metribuzin in situations where metribuzin-containing residual herbicides will be used. See results from the 2011-2015 varietal screening for metribuzin sensitivity.

Nematode-resistant varieties. Click here for information about the nematode pests that may affect soybeans grown in Mississippi. Information about resistance in current varieties is available from Arkansas and Tennessee variety trial results, extension service personnel, crop consultants, seed dealers, and originating seed companies.

Planting date. Early planting is now the norm in the Midsouth as indicated by results from a survey of Mississippi soybean producers. The decision of just how early to plant soybeans should be based on the safest early planting date at a particular location to avoid cold injury to emerging seedlings.

Click here for a table that gives the estimated dates of the last spring frost (36°) and freeze (32°) based on 90%, 50%, and 10% levels of probability at indicated Mississippi locations. These data should be used as a guide for choosing a safe early planting date.

Remember, early-planted soybeans will usually take up to 4 extra days to emerge compared to soybean planted a month later, so this extra time should be factored into a projected planting date to avoid a spring cold event that may damage emerging seedlings. As a producer, you must decide the level of risk you are willing to take when considering the earliest safe planting date in relation to air temperature.

Additional information that should be considered when selecting a planting date is provided in a white paper on this website.

Seeding rate. There is no perfect seeding rate for all planting conditions. However, estimates for optimal soybean plant populations provide a reasonable starting point for most conditions in the Midsouth. The University of Illinois developed a seeding rate calculator (see also Calculate your soybean seeding-rate needs that is available for the PC, Android, and iPhone/iPad platforms). Using these tools takes the guesswork out of this important calculation.

Seed treatments. The most important point to remember about seed treatments is that a product that is effective against both seed- and soil-borne fungal pathogens should be used in all situations since these pests are the ones most likely to reduce emergence and the likelihood of attaining an acceptable stand. Click here for information about fungicide seed treatments that should be used to protect against the prominent pathogens that will affect emergence of soyeans.

Handling bulk planting seed. Today’s high cost of planting seed makes this step in the planting process a money-saving issue. Click here for valuable tips on how to avoid damage to seed during the handling process.

Disposal of treated seed. As environmental stewardship becomes more important and necessary, the guidelines outlined here and in the linked articles should be followed.

Iron deficiency chlorosis (IDC). Iron Deficiency Chlorosis occurs to some extent in soybeans that are grown on the high-pH soils in the Black Belt region of east Mississippi. This deficiency can cause moderate to severe yield reductions. The best strategy for managing IDC is to select a soybean variety with tolerance. Ratings of tolerance to IDC made by the originating company are likely the best source for selecting tolerant varieties. Ratings of several varieties grown in East Mississippi can be found in the above-linked article.

Composed by Larry G. Heatherly, Mar. 2016, larryheatherly@bellsouth.net