As we celebrate the birth of our nation by getting together with family and friends for parties, parades and fireworks, an old farming adage comes to mind; one that has been used for generations to help benchmark the progress of corn crops — knee-high by the 4th of July.

Although I can’t say with absolute surety when, where or how the expression originated, it appears that the saying has roots in the Farmer’s Almanac, which used to predict that if corn was knee high in early July, the crop was off to a good start, that it would likely continue to thrive and that it would be a bountiful harvest year — perhaps even a bumper crop.

But this spring (on into early summer) has been one of persistent showers, heavy rains and thunderstorms. And while wet weather early on may promote germination, sooner or later plants need a dry spell, if they’re going to establish deep, healthy roots. Surplus moisture and saturated soil conditions can stress young plants, promote disease and make fieldwork difficult – even impossible. Dry conditions are essential when applying pesticides and fertilizer.

Still, many corn fields are knee high, or nearly knee-high, even in the face of such soggy conditions, which is good, right? Well, some farmers say yes. Some say no. Many believe that the idea of “knee-high” corn on the fourth is outdated because, even though growing techniques have remained essentially the same for generations, plant breeders have made remarkable strides in improving the genetics of corn plants.

Many high-yielding, modern-day cultivars can be planted earlier. And they’re able to grow well in conditions that would almost-surely stunt the growth of older varieties. These newer varieties are able to tolerate wet, dry, hot, cold, and otherwise harsh and varying conditions that would have certainly resulted in reduced-crop-quality and/or quantity in years past. And, while some farmers will tell you the old adage is still a good general rule of thumb, others will tell you that, as a result of these advances, knee-high corn in early July might just be cause for concern.

Now, I’m not saying that fields don’t look good. Perhaps the best way to describe the overall corn-crop-outlook for this year is variable.

Cornell Cooperative Extension’s Regional Ag Team notes that, as of early June, corn planting on northern New York farms ranged from barely started to nearly finished, depending on soil type and weather patterns. They believe that switching full-season corn hybrids for shorter day varieties, if possible, represents the best-yielding option even into July (although substituting a seed with shorter maturity generally results in some decrease in production),but warn that planting into too-wet soils can result in compaction and poor seed-to-soil contact, which leads to inconsistent germination and restricted root growththroughout the season. They also note that, rather than taking on the expense and risks of planting a crop that is new or less familiar, farmers should consider fertilizing corn (and grass) fields well, in order to reach optimal yields, maximizing returns on what is already planted.

Corn is a principal field crop in New York State with, according to Cornell University’s College of Agriculture and Life Sciences (CALS), more than 1 million acres planted annually, 55% of which is typically grain corn (including dry-shelled and high-moisture). Corn silage represents the remaining 45% of the planted acreage.

CALS recommends growing corn on moderately-well-drained to well-drained soils because corn grown on poorly drained soils can drown out during wet May conditions or show yellowing and reduced growth and delayed development during wet June conditions. What’s more, if Nitrogen (N) fertilizer is applied on poorly drained soils before or at planting, much of it can denitrify and escape into the atmosphere during a wet spring. On excessively drained soils, much of the N applied before or at planting will leach out and escape into the water table.

Corn is the largest, and perhaps the single most important crop produced in the United States today. Worldwide, it is second in production only to rice. American farmers planted more than 94-million acres into corn in 2016, with most of the crop providing the main energy ingredient in livestock feed (United States Dept. of Agriculture [USDA] Economic Research Service). They harvested about 15.1 billion bushels, up 11 percent from 2015. Corn yield in the U.S. is estimated at 174.6 bushels per acre this year; 6.2 bushels above last year’s average yield (USDA National Agriculture Statistics Service).

Most people don’t realize that corn is actually a type of grass or, more precisely, a member of the grass family of plants. It does not exist in the wild. It was created and has been perpetuated and improved for centuries. In fact, corn could very well be mankind’s single most domesticated field crop.