Row spacing and plant population, can be covered together. By widening your row spacing, the research from Brazil has not shown any differences in incidences of Asian soybean rust, but the severity can be different.
If you have a low plant population, wider row spacing, you have a chance to get more dispersal in the fields, whereas, if not you will get hot spots. So they both equal each other out, so in general, row spacing with plant population, we shouldn't change our management distribution this year because we are still not 100% sure about it, but based on research from Brazil and Asia and Australia, row spacing does not have specific impact on pathogen.
Related to maturity group, some farmers have talked about if we should plant a shorter maturity group so we can hit flowering earlier on, because we know the reproductive stages are where the pathogens will be more epidemic, but it does not really determine flowering date. Maturity two, three, four, if you plant them on the same day, will flower at the same day, plus, minus one, two days. Determined by the temperature, photo sensitive, so that's really not going to determine anything there, but the maturity really will tell you how fast you go from flowering to maturity.
So if you want to harvest early on, then you plant a shorter maturity group soybeans, but we also know there can be a very strong correlation to yield, so in that case, I would not change my recommendation there either.
And then the last one you asked, planting date, what that really does to you is to get more time into vegetative period, so if you plant maturity group three, on May 1 versus June 1, a lot of times they will flower plus or minus, probably three to four days, but the only difference between planting early versus late, you get a longer vegetative period, and have more potential to get more parts of the plant. So to answer all your question, no, we haven't seen any impacts on that. It's mostly related to when the pathogens show up, and if you apply fungicides in a timely manner. – Palle Pedersen
