When do the highest yield losses from NCLB typically occur?

The highest yield losses from Northern Corn Leaf Blight (NCLB) typically occur right after pollination. This is a critical period for corn plants, as the kernels are developing and are particularly susceptible to disease pressures. During this time, the plant’s energy resources are focused on kernel formation and development, making it vulnerable to stress from pathogens like NCLB. If NCLB is present in the crop at this stage, it can disrupt photosynthesis and weaken the plant's overall health, leading to significant yield reductions.

In contrast, before flowering may see some impact from diseases, but the full yield potential is not yet established, and any damage done at this early stage may not directly correlate to significant yield loss as observed right after pollination. Similarly, while conditions before harvest can also lead to yield loss, it's more about the accumulation of previous stresses rather than the immediate impact of the disease. Also, dry conditions can stress crops but wouldn't be the primary timing for disease-related yield losses associated with NCLB, as the critical damage typically happens right after the plants have pollinated.