Later planted soys – do I need shorter maturity?

By Robert Moloney, Syngenta Seeds

Since someone seems to have forgotten to turn the tap off across most of Ontario, the planting season has been pushed back farther than we would like.  At this point (May 19), most growers are moving to shorter season corn hybrids.  But what should we be doing with our soybean maturities?

First realize that soybeans and corn react very differently to late planting in Ontario.  Corn generally requires X number of days and X amount of heat and sunlight to reach maturity.  The soybean varieties we grow in Ontario are considered indeterminant varieties, which means that flowering and seed production is controlled more or less by daylength rather than requiring a set amount of heat/time.  In the southern part of the United States they do grow determinant soybeans that behave more like corn.  And most of the edible beans varieties grown in Ontario are also determinant in their behavior (require a relatively fixed number of days to reach maturity).  What growing indeterminant soybean varieties means for us is that a 1 week delay in planting at this point will likely only cause a 2 day delay in maturity in the fall.  As we get into June a 1 week delay will likely cause less delay than this in the fall.  So as a general rule there is no need to move to shorter maturity bean until we get to June 15^th.

 Some growers are concerned about moving to a shorter maturity soybean in order to get wheat planting done in a timely manner this fall.  While this seems logical, the odds are that harvest/wheat planting weather this fall is going to have a bigger influence on getting the wheat in than a small change in the maturity of the soybean variety you grow.  Obviously the sooner you can get the soybeans in the ground this spring will have an even bigger influence than either of these factors.  Choosing a soybean variety that is properly adapted to your farm (i.e. disease resistance, drought tolerance) will be of more benefit than trying to get a shorter maturity bean.

What to do if you’re planting late?

Do make sure you are planting into a fit seedbed.  Soybeans have a weaker root system than corn or wheat so they are much more sensitive to being “mucked in”.  As the planting season gets late for your area consider moving to narrower rows (7.5” ideally) as they will have a bigger advantage to wider rows.  As long as lodging or white mould are not a concern consider bumping your seeding rate up slightly.  Late planted soys will have less vegetative growth so narrow rows and higher seeding rates will help maximize filling in the rows.  A higher seeding rate will also tend to make the beans taller which should increase the height of the bottom pods and reduce harvest loss this fall.  Given the current conditions scout your fields regularly for Bean Leaf Beetle feeding (especially if you are not using Cruiser treated seed).  With the late planting and current cooler conditions slowing plant growth there will be lots of hungry Bean Leaf Beetles that may clip the seedlings before they get established.