These weather rally spikes seldom last long unless higher prices become necessary to ration the crop. I don't think we are in that situation, but if we sell too much this week, we can always take re-ownership later should we need to. This is why a brokerage account is necessary for most farmers.
The chart below for JJG (corn, soybean, wheat etf) clearly shows that these events tend to last only a few weeks. They are usually triggered by some sort of event such as weather, but not necessarily. I think the overall reason these events happen is due to a large number of short contracts held by large speculators, which in the rush of getting out of positions creates buying frenzies. Eventually the market runs out of buyers (green circles) and the sellers seize control again and the market driving prices back to where they were before (red lines).