Prohexadione Calcium Rates Peanut Notes No. 177 2019

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The standard recommendation for Apogee and Kudos is 7.2 oz/acre at 50% row closure followed by 7.2 oz/acre 2 to 3 weeks later. Some growers are using lower rates while others are applying a higher rate at 50% row closure with hopes of not having to apply the second application. There seems to be a parallel between prohexadione calcium (peanut) rates and mepiquat chloride rates (cotton) in that growers are creative in their use patterns. I was recently asked by someone who applies 10 oz/acre at 50% row closure if a second application was warranted in terms of yield and return on investment. I did not have a clear answer. This farmer has a guidance system and it is difficult to know in any given year and field how economical a prohexadione calcium program will be. I suggested just to save expense to apply a rate at the second application that does not exceed 14.4 oz/acre for the season (this would be the same cost as 7.2 followed by 7.2). The reason I would prefer 7.2/7.2 rather than 10/4.4) is because the higher rate later might provide the greatest row visibility a month from now, especially under irrigation/adequate rain and good fertility. Of course, the lower rate early might play out before the higher rate and then force the later application to go on earlier (I’m not sure I can follow my own sentence here.)  But we have not ventured far in our research from looking at 7.2/7.2 in a very long time. We are currently part of a national project looking at lower rates but have not looked at a single high rate. As stated before, there are a lot of ways to approach prohexadione calcium just like there is with mepiquat chloride in cotton.