Monday, April 19, 2010

Planting soybeans in April

Needless to say, planting conditions this spring have been fantastic. I talked to several producers toward the end of last week that were either finished with corn planting or planned on finishing over the weekend. One producer in Henderson County told me he finished planting on April 15, one day before he started planting in 2009. What a difference a year makes. Now we cross our fingers that the rain we saw in-season last year makes it's return this season.

In the past, convention has led to the delay of soybean planting until May 1, even if corn planting was completed earlier. A check last week in Daviess county revealed a soil temperature of 68 degrees, a number rarely seen this early in the year (more on Daviess county later). We could talk all day about the advantages of planting soybean early. You generally get more nodes, reduce evaporative water loss, get earlier canopy closure, and increase yield potential overall. Lots of good things, right? While all of the is great, we must also look at the potential negatives of planting early.

These elevated soil temperatures negate one of the major problems normally associated with early planting dates - reduced stand at low soil temperatures. This temperature is well beyond the low end, where cold damage can occur to seeds in the first 24 hours after planting.

As far as air temperatures go, we are beyond our average frost free date for this part of the state. While the extremely late frost dates are still in effect, it typically takes a temperature of 28 degrees or below to damage soybean tissue. I feel pretty confident that we are beyond that point. If it gets down that low again this year, we are all most likely in trouble. To view Kentucky frost free dates, click here.

With reduced stands and low air temperatures being less of an issue, we then turn our attention to some other issues with early planted soybean.

*Bean leaf beetles - This insect pest is more common in early planted soybean. Their feeding on unifoliates and early trifoliates must be monitored, as this not only causes plant injury but also may lead to Bean Pod Mottle Virus (BPMV). Insect levels must be monitored and insecticide applied if deemed necessary to combat these insects.

*Sudden Death Syndrome (SDS) - This disease is normally associated with early planting because early planting is normally associated with cool, wet soils. While this is not the case this year, we should still take some precaution, as earlier infection will lead to more severe symptoms later in the year. The best plant of attack for SDS is to plant resistant varieties. This hasn't been a trait that producers have considered extremely important in the past, but is one that should be, and is, getting more recognition.

*Photoperiod effects - While this is an extreme, it may be worth a mention since we are already on the subject. If the plants do emerge in April, there may be some effect of the shorter photoperiod associated with this time of year, compared to those beans emerging in early-mid May. These shorter periods could lead to soybean plants flowering extremely early, thereby shortening the reproductive period, an obvious detriment to yield potential.

I fully expect at least two of our SoyMVP fields to go in this week. Again, this is a huge contrast from 2009, when our first field went in on June 3. That's what this program is designed for though; actual field production and the issues that producers see every year. We saw one extreme last year, and are at the other end this year. I'm looking forward to it.


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