THE OPEN May beans:  7 lower May meal:  1.30 lower May soyoil:  64 lower May corn:  1/2 lower May wheat:  10 lower  The markets opened lower and were under pressure immediately as fund selling triggered sell-stops in all the markets.  The fact that funds were net sellers of corn last week may have been a foreshadowing of things to come this week.  Many thought we would break-out to the upside of commodity prices by the end of April, which does not appear to be the case.  All the commodity indexes last week were soft, and we continue that trend this week.  However, the larger part of this break could stem from China, where they are trying to control higher commodity prices.  China'...