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Soybean group selection still important

Currently, I am estimating that we have about 20 percent of the soybean acres planted with the remaining 80 percent either having too much or not enough moisture to plant. However, some of this acreage is drying rapidly and is now being planted. In general, up to now what has been planted are Group 4 beans. My concern is that with the weather conditions that we have been experiencing, producers are being forced to plant between rains and need to think about staggering maturity groups as the planting season progresses.

Some of my colleagues may disagree with me regarding my position on maturity groups but I feel that history speaks for itself. Historically in Louisiana, Maturity Group 4 beans have not done as well as Group 5, 6, and 7s even when planted at optimal planting dates. There have been some years, when rainfall and temperatures were just right and the Group 4s have out performed the later maturity groups, but overall that is not the case.

Calls have been coming in regarding whether it is still OK to plant a Group 4 in an optimal planting date for Group 5 and 6s. My answer, according to research and past performance, is yes as long as it is tall, later maturing and has an indeterminate growth habit.

Essentially, with May coming to a close, I am urging clientele to plant later maturing Group 4 beans if they are going to plant a Group 4. The reason is that planting these early maturing varieties now may lead to stunting, premature flowering, increased herbicide costs due to lack of canopy closure and eventually a yield loss.

I strongly support planting portions of acreage in Maturity Group 4 beans because it staggers equipment usage in addition to spreads risk over the long term. But planting Maturity Group 4 beans later than May 15th has risks associated with it. The planting window for Group 5, 6 and 7 soybeans has just opened in Louisiana and will remain open until around June 15. After June 15, we term soybeans planted “late planted” and some cultural practices need to be followed to maximize yield.

I did a little non-scientific averaging from last year’s soybean yield data. Over several locations across the state, the recommended Group 4, 5, and 6 and 7s combined, yielded 34.4 bushels per acre for the Group 4s, 43.6 for Group 5s and 44.3 for the 6s and 7s combined.

With these numbers you can see that there is tremendous yield potential with the soybean varieties that we have available. Planting Group 5 and 6 beans now have been very successful in the past and will continue to be as long as we can harvest the crop. I fully realize that weather conditions, late season insects and diseases are the main reasons that acreage is shifting to earlier varieties. However, the question remains “can you afford it?”

In Louisiana, we are experimenting with Maturity Group 3 beans this year, so we are definitely trying to see what works and where. I see and hear of more success stories from producers who are pushing the planting window earlier with Maturity Group 5 and 6 beans rather than pushing the window back with Maturity Group 4 beans. This concept is something that we are going to be exploring further.

David Lanclos is the Extension soybean specialist with the LSU AgCenter. e-mail: [email protected]

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