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Arkansas Corn and Grain Sorghum Weekly Update – July 10, 2015
Author: Arkansas Row Crops

Disease Update – Dr. Travis Faske (Extension Plant Pathologist)


Earlier this week southern rust was reported in five Arkansas counties:  Desha, Jackson, Jefferson, Lincoln, and Lonoke (Fig. 1). In 2014, southern rust was also detected in early July, but unlike last year warmer summer temperatures will promote crop maturity and disease development.  Therefore it is very likely southern rust will be detected in other counties by the end of the week.  For more information on southern rust identification and management considerations see earlier post on this blog, “Southern rust returns to Arkansas”

Southern rust figure 1

Figure 1.  Current distribution of southern rust in Arkansas and part of Mississippi.

Since southern rust is specific to corn it will not infect grain sorghum, but there has been a few reports of foliar diseases of grain sorghum.  One of the more common early season diseases is sooty stripe, which is caused the fungus Ramulispora sorghi.   Symptoms consist of a 1 to 3 inch lesion surrounded by a yellow halo, which are often located in the lower 1/3 of the canopy (Fig. 2).  On mature lesions, the yellow halo disappears and takes on a sooty appearance, which is numerous sclerotia, produced by the fungus, hence the name sooty stripe. One of the most common fungal leaf spots on sorghum in Arkansas is target leaf spot; however, these spots don’t look like a “target” as the name implies.  Symptoms appear as reddish spots confined by the leaf veins, resulting in a rectangular shape (Fig. 2).  These spots often have a yellow to tan margin.  This disease is caused by the fungus Bioplaris sorghicola, which can infect other grasses like Johnson grass and forage sorghum.  Finally, one disease imposter that is often mistaken as a foliar disease is herbicide injury.  Specifically, Gramoxone injury has a red margin on sorghum (Fig. 3), which differs from that on corn, which has no red margin.  So, to prevent unnecessary applications of a fungicide for spots on leaves, make sure they are leaf spots caused by a fungal pathogen.  Anthracnose is very common disease of sorghum that often occurs at later growth stages.  Currently, there are no reports of this disease, but it will likely be confirmed some time this season.  Questionable samples for disease identification can be sent to the disease diagnostic lab in Fayetteville.  Though fungicides are effective (see MP 154 for available fungicides) to manage foliar grain sorghum diseases, there is no economic threshold for a fungicide application.   Factors to consider when treating a disease with a fungicide include; yield potential, stage of growth, severity of disease, and prolonged conditions that favor disease development.  The main point is to know what disease sorghum disease you are trying to control before treating with a fungicide.

Sooty Stripe pic

Figure 2.  Sooty stripe (left) and target leaf spot of sorghum (right).

Herbicide Injury Pic

Figure 3.  Gramoxone injury on grain sorghum.

Corn and Grain Sorghum Research Verification – Kevin Lawson (Corn & GS Verification Coordinator) 

After some big rains, producers are trying to figure out when to start back with water.  The fields that didn’t get rain this week are starting back now, and the fields that did receive more rain will start back at the beginning of the week.  Southern rust was found in the state this week, and after scouting the verification fields the disease was found in St Francis and Lee counties at low levels.  All the corn fields will be scouted again next week again to determine progress of the disease.  The late planted fields are the ones of greatest concern right now.

The grain sorghum fields are flowering and midge scouting is the main focus.  The fields are being scouting twice weekly, but as of right now no midge have been found.  The fields were also absent of aphids this week.

Corn Borer Moth Trap Counts:   Lonoke Co – 2 moths      Conway Co – 2 moths    Pope Co – 0 moths

July 10 corn update

July 10 gs update

Southeast Arkansas Update – Wes Kirkpatrick (Desha County)

Rainfall over the past weekend has allowed irrigation pumps to take a break for a few days.  Corn growth stages range from blister to 20-30% starch.  Grain sorghum is mostly headed.  The corn and grain sorghum looks good for the most part.

Central Arkansas Update – Anthony Whittington (Jefferson County)

The majority of the corn in the area is at tassel with some already at R3.  The 3.5 inch rain we received will give a break to irrigation for a bit. Some southern rust has been found in the county as well as in Lonoke County so be on the lookout as you scout corn. Midge and sugarcane aphid scouting is underway in grain sorghum.

Northeast Arkansas Update – Stewart Runsick (Clay County)

Rainfall over the past week has saved a watering on most corn. We have had several days of rain since July 1st with totals from 1-3 inches depending on where you are. The earliest planted grain sorghum is heading with no reports of midge or aphids yet. Fall army worms are easy to find feeding in the grain sorghum with most of the grain sorghum a week or two away from heading.

River Valley Update – Kevin VanPelt (Conway County)

Much of the corn in the River Valley has reached dent and looks good. There’s been no need for irrigation with most areas receiving over 5 inches of rainfall in the last week.

Market Update – Scott Stiles (Economics Specialist)                          

Corn futures settled Thursday about 4 cents higher, with December corn trading up to $4.43 at one point–the highest level since July 7, 2014.  September corn traded as high as $4.33 today.

Ahead of tomorrow’s July USDA supply/demand report, expectations are that the USDA will lower 2015 production and ending stocks.   The latest Bloomberg survey has the average trade guess for US new crop corn ending stocks at 1.549 billion bushels compared to 1.771 billion in June.  Normally, the USDA does not adjust yields in its’ July report.  However, many in the trade believe a downward revision is possible. The Bloomberg survey indicated that the US average yield would be adjusted down to 165.2 bushels (from 166.8 in June).  The average guess for July production is 13.414 billion bushels compared to 13.630 billion last month.

Old crop ending stocks are expected to have some revisions as well due to the June 30 Grain Stocks report. For 2014/15, the trade is looking for comfortable ending stocks of 1.814 billion bushels compared to last month’s 1.876 billion.

The June 30 Acreage report indicated that US corn planted acreage was 88.9 million acres; below expectations of 89.1 million acres. The acreage estimates used in the July supply/demand report will be updated to reflect the recent June 30 Acreage report.

Looking ahead, many in the trade believe that the current US yield estimate of 166.8 bushels per acre is too high, especially given the excessive June rainfall that extended from Kansas across to the eastern Corn Belt.  But, there is very weak correlation historically between June weather and final yield.  At present, most private weather forecasters are calling for favorable pollination weather in the last half of July.

Crop conditions across the Corn Belt are incredibly variable.  Some states such as Iowa, Minnesota and Wisconsin are on track for great crops with condition ratings between 82 and 84% good/excellent.  In contrast, ratings in Indiana and Ohio are 45 to 48% good/excellent. Thus, there is much debate about whether or not the US average corn yield should be adjusted lower at this early stage with so much variability in crop conditions.

Recap of USDA Reports:

Monday:  Crop Progress

The USDA rated 69% of the US corn crop good/excellent as of Sunday, up 1 point from a week earlier, but 6 points below last year. Ahead of the report, the trade expected a 1 point drop in ratings.  Crop conditions stabilized in the eastern Corn Belt and improved in the western Corn Belt states.

Grain sorghum ratings slipped 1 percentage point lower in Monday’s Crop Progress to 67% good/excellent.  This compares with 61% good/excellent last year.  Planting still lags behind in some states and brings into question final harvested acreage.  Missouri was shown to be 72% planted as of Sunday.  Normally, planting would be 98-100% complete at this point for all states.

Thursday:  Export Sales

Old crop (2014) corn export sales continued at a good clip last week, as total commitment (sales + shipments) rose just over 21 million bushels to 1.819 billion bushels. Sales were made in fifteen (15) markets with Japan and South Korea being the most active. The June USDA 2014/15 export estimate was 1.825 billion bushels.  With eight (8) weeks now remaining in the 2014 marketing year, weekly sales only need to average 725,322 bushels per week to reach USDA’s June export target.  However, it’s becoming doubtful that the remaining 361 million bushels (the difference between shipments to date and USDA’s 1.825 billion bushels export target) can be shipped over the next 8 weeks.  Shipments would have to average slightly above 45 million bushels per week for the rest of the marketing year.  There have only been four (4) weeks in the entire marketing year that weekly shipments have been above 45 million bushels—none of which have occurred since April 23.

There were no old crop or new crop export sales of grain sorghum last week.  Total Commitment (sales + shipments) for old crop (2014/15) grain sorghum stands at 331 million bushels compared to the June USDA export target of 350 million bushels.  Export sales need to run about 2.4 million bushels per week for the remainder of the marketing year to reach USDA’s June target.  Shipments will need to make a strong recovery as well. Old crop shipments last week amounted to about two trailer truck loads, with Canada taking delivery of 1,653 bushels.

New crop corn basis on the Mississippi river has held steady this week.  New crop sorghum basis is collapsing rapidly, losing 25 cents over the past week.  With the strong rally in corn futures, no export sales last week and slow shipments, this is placing tremendous pressure on sorghum basis.

Table 1.  CME Corn Futures Closing Prices.

July 10 Table 1

Table 2.  Mississippi River New Crop Corn and Sorghum Basis.

July 10 Table 2

Heat Units

Heat units were down this week and close to the 30 year average.

July 10 gdd update

Twitter – Jason Kelley @AR_Feedgrains, Kevin Lawson @ar_cornverify

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