When looking at MASC data on a weekly basis (Table 1 – Relative Grain Corn Yield in Manitoba by Week-Month (2008-2012)), yield potential is impacted by planting date. However, there remains good yield potential going into the third week of May where the 5-year average shows grain corn yielded about 90% of the provincial average yield (97 bu/ac). If planting is pushed back to the last week of May, yields were still 79% of the provincial average yield (85 bu/ac).
Data is also presented by MASC Risk Areas (where there was an average of >500 acres grown over the past 5 years). However, data for risk areas such as the combined Risk Area 1,2 & 3 should be viewed with caution as there have been limited acres grown in those areas in the past. But the data does provide some guidance, particular for those newer growers who may have limited experience with grain corn on their own farm.
So although we will be entering that second week of May timeframe soon, there is still lots of time to get corn seed into the ground and still have good yield potential. One final note is during the planting operation, make sure you aim for uniform emergence, as well as ensure adequate fertility and reduce early season weed competition. This will help ensure your crop gets off to the best start possible.