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September's 30-Day Weather and Mycotoxin Outlook

Published on: 9/9/2019
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Welcome to the 2019 series of monthly weather and mycotoxin reports provided by Adisseo’s mycotoxin specialists with the support of Novak Weather Consultants.

We are now entering a critical stage in the new corn crop development, where weather patterns can play a big role on grain quality at harvest time. The 2019 corn crop remains well behind average after a delayed planting pace.

On September 1st USDA reported 81% of the crop reaching dough stage, which was up from the prior week’s 71%, but significantly slower than five-year average pace of 93%. About 41% of the crop is now dented, compared to the five-year, 63% average. The quality conditions report shows that 57% of the corn crop is at good and excellent condition compared to 67% last year. One other problem being spotted in the field is the large variations between fields, what might lead to a problematic harvest time.

Data shows that corn reaches maturity about 20 to 25 days after dough and early dent stages (R4 and R5 respectively) , which will bring maturation to late September and early October. This could pose risks on an early frost, possibly stopping the filling stage but also delaying the drying process. This late corn maturity during lower temperatures days can result in a prolonged drying period in harvesting with higher than optimal moisture, leading to forced drying costs and risks of mold development during storage.

During dough stages, farmers are concerned about two major diseases, the Diplodia and Giberella, both generated by fungi. The Gibberella zeae , also known as Fusarium graminearum is favored by cool wet weather during and after pollination, with temperatures around 64F to 70F. This fungi can produce the mycotoxin Deoxynivalenol, also known as Vomitoxin.

Another fungus to be concerned in parts of the US is the Aspergillus, which can produce both Aflatoxins and Cyclopiazonic Acid. This fungus has its optimal growth conditions in hot dry areas, such as the ones seen on the Southern Plains and according to the Adisseo weather forecast, those conditions are going to persist in the next month.

As the crop develops, the Adisseo team will be scouting the fields to bring accurate and on time information, supporting our customers and partners to take decisions on their grain sources.

Adisseo will keep our industry partners informed on the progress of the new crop season in the following monthly reports, providing valuable information to future decisions on feed ingredients management and overall risk control.

United States:

The persistent summer weather pattern that features a strong northwest flow over much of the U.S. will likely continue through at least mid-September, then a change potentially occurs.     

Once again, the Jet Stream steering winds are expected to dive southeast out the western Canadian prairies into the Upper Midwest then continue southeast into the Tennessee River Valley and Mid-Atlantic states.  This jet stream pattern has been locked in place much of the summer and a significant change is not expected until the 2nd half of September, if at all this month.  This upper level wind orientation will likely continue to bring unseasonably warm conditions to much of the Southern Plains and portions of the western U.S. as a strong ridge remains anchored in place over the southwestern U.S. and southern Plains.  Meanwhile, periodic Canadian cold fronts will bring shots of much cooler than average conditions to a good chunk of the Great Lakes and New England regions.

As far as precipitation is concerned, the consistent battle zone that is wavering north to south across the northern and central Plains on east into portions of the Corn Belt will likely surge north some as a ridge of high pressure attempts to build over the southern Plains and southeast U.S., especially during the 2nd half of the month. This will continue to create a dry environment from Texas east into portions of the deep south and Tennessee River Valley. On the other hand, tropical moisture will likely dump heavy rains over portions of the Atlantic Coastal regions. Meanwhile, as the battle zone moves north into the southern Great Lakes region, periodic heavy rains can be expected from Minnesota on east into the northeastern U.S.

Upper Midwest:

As cooler and drier Canadian air collides with warmer air from the south, a battle zone is expected to surge north into this region. Temperatures will be rapidly changing along with periodic active weather episodes. Portions of this region that have experienced unusually dry conditions (Iowa, Wisconsin and northern Illinois) will likely see some moisture this month, especially as you travel north. There is concern that the heart of the Corn Belt will be just south of the battle zone keeping those areas drier than normal. Areas of the northern Plains, that have been hit hard by heavy rains, will have an opportunity to dry out as heat builds into these areas.


The potential for significant rains is real in this region as tropical moisture rides north along the Atlantic coast. There is great concern that southern portions of the Mid-Atlantic will be inundated with heavy rains from tropical systems. In general, plenty of moisture is anticipated in this region, especially during the first half of the month. Temperatures will be all over the board, but in general, average near normal as a tropical environment occasionally gives way to a dry northwest flow.

Deep South:

This region will experience a great variance in weather conditions as you travel from west to east. Dry and unseasonably warm conditions in the Tennessee River Valley and along much of the Gulf Coast will give way to flooding tropical rains once you reach the Atlantic Coastal areas. As usual in September, the wildcard is whether or not tropical systems affect this part of the U.S. and exactly where these tropical systems will track. Currently, the thinking is that the Atlantic coastal regions are most in jeopardy to be affected by ample tropical moisture. In turn, hot and dry air would dominate from Tennessee and Mississippi on west where a ridge is expected to build.

Southern Plains:

Little change is expected in this region as a strong high pressure ridge dominates overhead, especially over Texas on east into Arkansas and Louisiana. Texas has been unusually dry this summer and this trend is expected to continue. The concern is that this dry environment will extend further east as the month unfolds. Drought conditions have developed, especially over Texas, and this drought will likely persist and become more enhanced this month. Meanwhile, temperatures across the whole region are expected to average near or above normal. Portions of this region will likely experience a late summer/early fall heat wave..

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