Rains which bode well for the condition of the US soybean crop are proving a threat to US spring wheat, slowing the harvest provoking increasing talk of quality concerns, including of vomitoxin.
The proportion of US corn rated "good" or "excellent" showed a surprise increase in the week to Sunday, rising by 1 point to 71%, a US Department of Agriculture report showed.
That returned the crop to being the highest rated on records going back to 1994, with expectations for a record US yield also underpinned by results of the first day of the much-watched ProFarmer crop tour of the Midwest
One arm of the tour showed the pod count in South Dakota at 1,057.80 per square yard (ie 3 feet by 3 feet), up from 1,016.68 last year, with the second arm putting the Ohio pod count at 1,342.42 per square yard, up from 1,283.61 last year.
The rise in the USDA rating reflected the coming of rains to many states where dryness was beginning to tell in, with scouts in Missouri, where the proportion of soybeans rated good or excellent rose 2 points to 78%, reporting that "much-needed rain fell across the state".
In Ohio, which also saw a 2 point rise, to 72%, in the proportion of soybeans in the top two condition bands, "rain combined with significantly cooler-than-normal temperatures helped alleviate some moisture stress issues", scouts said.
The improvements offset losses to condition in the likes of Iowa, the top soybean growing state, where the proportion of the crop rated good or excellent dropped 2 points to 73%, as "below-average precipitation caused a drop in soil moisture".
In Kansas, the soybean condition rating dropped 3 points, "dryland row crops that have been missed by the recent rain were showing signs of stress," scouts said.
Kansas looks poised for further dryness this week, with weather models foreseeing "little if any rainfall this week" in the state, besides in Missouri, and the lower Mississippi Valley as a "stable high pressure takes control", Gail Martell at Martell Crop Projections said.
However, more northerly states, including Iowa, appear poised for heavy rains which could boost soybean yields in increasing pod size.
"At least 1 inch of rainfall is predicted this week, but 1.50-2 inches locally" across a "wide swathe of the Upper Midwest", comprising Minnesota, North Dakota, South Dakota, northern Iowa, northern Illinois, Wisconsin, Michigan and Ohio, Ms Martell said.
Weather service MDA said that "additional rains in the north western and eastern Midwest this week will continue to replenish moisture, which will favour the late growth of the soybeans".
However, the rainfall is ill-timed for grain crops, such as barley and spring wheat, that are well developed or being harvested ï¿½ posing a threat to both crop condition and the progress of combines.
"The active rains in the northern Plains and southern Prairies will stall spring wheat drydown and early harvesting, and will lower quality a bit," MDA said.
Farmers are already behind in the spring wheat harvest, with 17% completed compared with 33% typically by now, according to the USDA, particularly in North Dakota and South Dakota, albeit a factor in part down to a crop lagging on development, as well as rain delays to harvest.
And, on quality, there is growing talk of crop that has been cut showing high levels of vomitoxin, a toxic fungal residue than can render grain unfit even for feed.
"Currently on everyone's radar are vomitoxin levels. Several reports are coming in well over maximum levels," broker CHS Hedging said.
"With harvest upon us, moisture will become troublesome as quality will be watched closely."
At Minneapolis-based Benson Quinn Commodities, Brian Henry said that "talk of vomitoxin continues in the early samples".
In barley, USDA scouts in Idaho noted that last week "rain increased the level of disease and mould in many barley fields".
Furthermore, barley "sprouted in the heads which was decreasing the quality of the crop".
Indeed, the proportion of Idaho barley rated good or excellent tumbled 15 points week on week to 61%.
That lowered the national rating to 62%, taking it below the year-ago figure, an unusual occurrence in USDA crop data for 2014.