FAO - there is confusion in commodity markets

The impact of uncertainty in commodity markets is strong. If there is greater price volatility, it will be harder to plan for next year's production. The cost of production will also fluctuate with the price of energy. The cost of buying seeds will also be less certain. Even if prices have fallen from their highs, there is uncertainty with what should be the right crop mix by farmers which creates an impact on food security as reported in the latest FAO study. The impact on certain regions such as Africa are significant. The impact of food price variability is much stronger on the poor because they spend a significant greater portion of their income on food.

Confusion and uncertainty is never good for both consumer and producers of food. 

Sugar and corn connection

"Corn and sugar are becoming increasingly linked in the global markets, something that has implications for the prices of both commodities." from Agrimoney

Sugar is used as a sweetener and bioethanol simialr to corn. Hence, there is a substitution between these two crops that did not exist in years past. 

It may not show-up in short-term correlation but the relationship between corn, sugar, and oil is going higher. The cost of production in corn is more driven by oil. The output is oil driven. The same is true of sugar. 

The role of corn as a sweetener is also increasing. Corn syrup has been a cheap substitute for sugar. This relative cost will create a further link.