As expected, the stocks numbers were bearish.

But the lower than expected estimate of planted area, especially for corn, caught the market by surprise and reversed the recent downward price trend.

Recall last year when the USDA pegged corn plantings at 37.11 million hectares, which was only a 445,000 hectare decline from the March Prospective Plantings Report and well above trade expectations.

That was despite the slowest planting pace on record due to prolonged wet weather, and it sent corn futures limit down that day.

Meanwhile, the latest June 2019 acreage report had soybean seeding at an estimated 1.86 million hectares lower than the March intentions number, which was the biggest ever March-to-June decline in the soybean planted area.

Fast forward to June 2020, and the opposite has happened.

The market had been expecting a decrease in the corn area to be largely offset by an increase in the soybean area.

What resulted was a lower than expected soybean area and a dramatically lower corn area.

The USDA estimated the total area planted to corn at 37.23 million hectares, which was more than 400,000 hectares below the lowest trade estimate and a whopping 2.02 million hectare drop from the March projection. This came despite excellent planting conditions across most regions this year.

The area planted to soybeans came in at 33.91 million hectares, which was up a mere 121,000 hectares from the March intentions - but 370,000 hectares below the average trade estimate.

That puts the total US area planted to corn and soybeans at 71.1 million hectares, a massive 1.9 million hectares lower than the March projection of 73 million hectares.

The biggest question following the release of the report was where has the lost crop area gone?

But maybe the expectations were too high from the start - particularly in light of the corn price on offer at seeding time.

Perhaps the US farmer is reluctant to grow corn at these prices and is happier taking the prevent plant payment.

In March, the USDA estimated that the corn and soybean planted areas would be 39.25 million hectares and 33.79 million hectares, respectively.

This represented an increase in the corn area of 2.95 million hectares, or 8 per cent, and an increase in the soybean area of 3 million hectares, or almost 10 per cent, compared to 2019.

So, in reality, US farmers have not lost acres, they just haven't grown as much corn and soybean area as the USDA expected back in March.

Based on the June figures from the USDA, the combined area for these crops has still grown by 4.05 million hectares, or 6 per cent year-on-year.

Nevertheless, fund managers certainly didn't expect such a low corn planted area - going into the report short at about 280,000 contracts.

When the news broke, they ran for the exit and pushed corn futures sharply higher.

Despite some profit-taking ahead of the July 4 US holiday, they still closed the week at three-month highs.

The short-covering rally probably would have been more significant but for a few bearish elements.

The lower corn area will trim about 23 million tonnes from US production this season. But this was partially offset by a higher than expected stocks figure.

Corn stocks in all positions came in at 132.7 million tonnes, compared to the average trade estimate of 126 million tonnes and 132 million tonnes at the same time last year.

Weekly ethanol production in the US was up less than 1 per cent, and the pace remains at about 10 per cent below the level needed to make the USDA's corn for ethanol demand number.

In addition, the current crop rating of 73 per cent good-to-excellent (compared to 56 per cent last year) suggests this season's grain yield could be above the USDA's current projection of 11.2 tonnes per hectare.

Corn may have stolen the limelight last week, but wheat also produced its own surprise.

The all wheat area planted estimate set another 100-year low, rolling in at 17.91 million hectares - compared to the average trade estimate of 18.1 million hectares and 18.3 million hectares last year.

Breaking that down a little further, the winter wheat area was down 2 per cent from last year at 12.36 million hectares; the spring wheat area was lower than expected at 4.94 million hectares; and the area sown to durum wheat rose 12 per cent year-on-year to 600,000 hectares.

Of greater concern from a wheat viewpoint is the deteriorating condition of the spring wheat crop, which has dropped from a rating of 81 per cent good to excellent in mid-June to 70 per cent this week.

The condition of the winter wheat crop has stabilised at about 51 per cent good-to-excellent and the harvest has now passed the half-way mark.

Last week's USDA report certainly produced a few surprises.

The market was expecting a bigger swing to soybeans; the lower than expected corn area took some comfort out of the balance sheet; and the US farmer continues to favour row crops over winter cereals.

Consequently, weather across the US will definitely be a significant driver of global markets in the coming months.

But, the uncertainty surrounding COVID-19 and its impact on global demand remain the biggest questions.

Expect some carnage when the June quarter growth and consumption numbers hit the screens in coming weeks.