* The benchmark CBOT December wheat contract ended slightly higher in consolidation trade after the market posted its biggest rally in two weeks on Thursday. * Prices fluctuated between positive and negative territory throughout the day. * Traders said most investors were unwilling to stake out new positions in the volatile market ahead of the weekend. * For the week, CBOT wheat ended up 2.3 percent, its third straight week of gains. During the past three weeks, wheat prices have risen 6.4 percent. * CBOT wheat volume of more than 83,000 contracts was greater than the 30-day average but less than the 250-day average. * Rainfall and snow this week benefited the emerging hard red winter wheat crop in the US Plains but more is needed.