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What Disease is on my Soybean Leaves? (08/17/17)

In the last few weeks, we have had many questions about leaf diseases impacting soybeans.

What Disease is on my Soybean Leaves?

In the last few weeks, we have had many questions about leaf diseases impacting soybeans. To help everyone identify (or rule out) diseases, we are highlighting several diseases/ailments we have had questions about, whether or not they occur in North Dakota. These are arranged by how common we usually see these diseases in North Dakota.

Bacterial Blight.

Importance: Common in North Dakota but rarely economically important

Symptoms: Begins as small angular lesions often with a yellow halo (Figure 1). Lesions enlarge slightly, turn black and centers will fall out (Figure 2). Occurs most frequently on upper leaves.

Favorable conditions: Short/no crop rotation, storms or winds that wound leaves, rainfall, cool-moderate temperatures.

Management: Typically, not associated with yield loss. Fungicides are not effective.

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Downy Mildew.

Importance: Increasingly common in North Dakota. Traditionally not thought to be economically important nor widespread. However, as the disease has been occurring in greater frequency and severity in North Dakota it is possible that yield loss could occur under high severity.

Symptoms: Lesions begin on upper leaf surfaces as small discrete light-yellow to pale-green spots (Figure 3) that may turn brown as they age. Fluffy gray tufts of mold appear on the underside of the leaves immediately opposite the light-yellow to pale-green lesions (Figure 4).

Favorable conditions: Short/no crop rotation, high humidity, moderate temperatures.

Management: It is unclear if management options are warranted. Limited fungicide efficacy data on downy mildew exists.

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Bacterial Pustule.

Importance: Very rare and not economically important in North Dakota.

Symptoms: Small pale-green to brown specks (Figure 5) often with yellow halos. Pustules may form on undersides of leaves within brown lesions (Figure 6). Of note, this disease is commonly confused with soybean rust, which has never occurred in North Dakota.

Favorable Conditions: Hot and wet weather.

Management: Not necessary in North Dakota.

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Unknown leaf stress.

Importance: Commonly we see leaf purpling and bronzing that we have trouble identifying the cause(s). We think sunscald, ozone, or other abiotic stresses may be contributing to these symptoms. It appears that there are differences between varieties in their response to stress conditions.

Symptoms: purpling and or bronzing of leaves (Figure 7-8)

Favorable conditions: Unknown, seems to occur more frequently under high temperatures and moisture stress.

Management: Unknown.

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Cercospora leaf blight.

Importance: Not thought to be common in North Dakota. However, symptoms closely resemble abiotic stress commonly seen in the region.

Symptoms: Brick red lesions on the petiole. Purpling of leaves leading to defoliation (Figure 9). Pink-purple discolored seed.

Favorable Conditions: Hot and wet conditions. Much more common disease in southern states.

Management: Not thought to be necessary in North Dakota.

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Soybean Rust.

Importance: Does not occur in North Dakota. Very significant economic problem occasionally in Southern States.

Symptoms: Small discrete lesions that form pustules with every lesion (unlike bacterial pustule where only some lesions produce pustules) (Figure 10). Pustules can be observed through a hand lens by rolling the leaf around a finger (Figure 11). Must be confirmed in a laboratory.

Favorable conditions: Soybean rust must spread from the South, and as of August 15th, the furthest north soybean rust has occurred this year is in Mississippi and Alabama (Figure 12).

 Management: Not necessary in North Dakota.

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Sam Markell

Extension Plant Pathologist, Broad-leaf Crops

Hans Kandel

Extension Agronomist Broadleaf Crops


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Growers Successfully Managing Cercospora Leaf Spot Control in Sugarbeet (08/17/17)

Growers are working around the clock utilizing ground rigs in dry weather conditions and amply supported by aerial applicators to apply fungicides in a timely manner to manage Cercospora leaf spot (CLS) in sugarbeet.

Growers Successfully Managing Cercospora Leaf Spot Control in Sugarbeet

Growers are working around the clock utilizing ground rigs in dry weather conditions and amply supported by aerial applicators to apply fungicides in a timely manner to manage Cercospora leaf spot (CLS) in sugarbeet. CLS, caused by the fungus Cercospora beticola, is currently the most damaging foliar disease of sugarbeet in North Dakota and Minnesota. Conditions favorable for CLS include warm days above 77 F, warm nights above 60 F, and leaf wetness from dew or rainfall.

In southern Minnesota, environmental conditions favorable for CLS started in July and continued into August. Growers at the Southern Minnesota Beet Sugar Cooperative (SMBSC) have been diligent in their timely use of fungicide mixtures to control CLS. In Minn-Dak (MD) and American Crystal Sugar Company (ACSC) factory districts, CLS disease severity was low in July. Rain and dew in August have resulted in more favorable conditions for CLS and disease severity has increased significantly over the past two weeks, especially in inoculated research trials. Growers at MD and ACSC also have done a great job of containing CLS.

Growers need to continue applying fungicides to control CLS until at least mid-September or when night temperatures consistently fall below 60 F. In fields currently too wet for ground rigs, aerial applications should be used, especially in mid- to late-August because of the favorable environment for disease development coupled with the current high inoculum density.

Figure 1 below shows that CLS will cause economic damage if not controlled. Figure 2 shows that fungicide mixtures used in a rotation are controlling CLS under high inoculum pressure at Foxhome, MN.

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Mohamed Khan

Extension Sugarbeet Specialist

NDSU & U of MN

701-231-8596

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Planting Winter Wheat – 2017 (08/17/17)

Currently there is a large spread between the price of winter wheat and spring wheat.

Currently there is a large spread between the price of winter wheat and spring wheat. Never the less, winter wheat might still be a viable option for some farming operations in North Dakota. Winter wheat spreads out the workload because of when it is planted and harvested and it can provide important green cover this fall and early next spring for fields that were hayed earlier this year due to drought. Furthermore, winter wheat can have a significant yield advantage over spring wheat. As an example, even with the very dry conditions in southwestern North Dakota, the winter wheat trial at Hettinger averaged 82 bu/acre this year. In addition to the issue of price, winterkill and greater susceptibility to several diseases are challenges to successful winter wheat production. The following are some suggestions that might help mitigate the risks associated with planting winter wheat.

1-   When possible, plant winter wheat into standing stubble. Survival of winter wheat during the winter is enhanced when it is covered with snow during the coldest months of the year. Standing crop residues can effectively retain snow. Tall, erect flax and canola stubble works best, but any erect stubble that retains snow is recommended. Planting winter wheat into wheat stubble is not ideal for disease reasons, but as long as disease management is planned, wheat stubble can be an acceptable residue.

2-   Plant a winter hardy variety, especially if you are not planting into a standing residue. Based on the North Dakota Winter Wheat Selection Guide (A1196-16) Accipiter, Decade, Flourish, Moats, Peregrine, Radiant, WB Matlock are the most winter hardy varieties in recent tests. Varieties developed in Canada, North Dakota, Montana and South Dakota usually have good winter-hardiness and, in most years, will survive the North Dakota winters adequately. For availability of certified seed refer to the seed guides in North Dakota and South Dakota. Winter wheat variety trial results from 2016 are summarized in the A1196-16 and results from trials conducted in 2017 can be found at https://www.ag.ndsu.edu/varietytrials.

3-   Plant in September: The optimum planting date for the northern half of the state is September 1-15 and for the southern half, September 15-30. In recent years, plantings during the first ten days of October have largely been successful. The last practical date that winter wheat can be planted will depend on the weather but there must be enough moisture and growing degree days so that the seed can germinate and the seedling vernalize by spring. Larger seedlings will over winter better than smaller ones. Target the earlier portion of the recommended planting date range if planting into bare, fallow ground.

4-   Plant 1 to 1.5 inches deep: Adequate moisture for establishing winter wheat is often a concern as the soil profile is usually depleted of moisture in the fall. If there is little or no moisture in the soil’s surface, planting shallow (1 to 1.5 inches deep) and waiting for rain is recommended. Furthermore, these relatively shallow planting depths allow for faster emergence when temperatures are rapidly declining.

5-   Seed about a million seeds per acre: Generally, a seeding rate of 900,000 to 1.2 million viable seed per acre is adequate. The higher seeding rate may be appropriate if planting late or when planting into poor seedbeds. Since winter wheat tends to tiller more profusely than spring wheat, 1.2 million seeds per acre is the upper end of the recommended seeding rate. Excessively high seeding rates can result in more lodging by harvest time, particularly if you are using a taller variety (like Jerry).

6-   Break the green bridge. Breaking the green bridge is critical to reducing the risk of infection of the Wheat Streak Mosaic Virus. This disease is vectored by a tiny mite that moves from green tissue to green tissue by wind. Breaking the green bridge is particularly important when winter wheat is planted early. The green bridge is broken by controlling volunteer cereal crops and grassy weeds in a field, two weeks prior to planting winter wheat. A two-week window of not having a host present assures that the mite has gone through its lifecycle and died before finding a host to feed on and transmit the virus.

7-   Avoid varieties that are highly susceptible to scab. Scab is not always a problem in winter wheat, but there were significant losses due to scab in 2014 and 2015 (no reports yet about the 2017 crop). Check the recent Selection Guide for the level of scab resistance in currently available varieties. The following rated as the most resistant: Emerson, Lyman, Moats and Redfield.

Joel Ransom

Extension Agronomist for Cereal Crops

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Weather Forecast (09/14/17)

The September 14 through September 20, 2017 Weather Summary/Outlook

Temperatures so far this month have been running above average across most of the North Dakota Agricultural Weather Network (NDAWN). Much of this is due to the well above normal temperatures of the past few days as the first week of September temperatures were mostly below normal. The recent warmth is about to end, as beginning today (Thursday) we will be trending cooler and by this weekend temperatures will be 10° to 20° below average. In fact, on Saturday, some parts of the region may record maximums only in the upper 40s.

1

Our recent warm weather has come with no moisture, as the rain that has fallen so far in September at some NDAWN stations occurred during the cooler weather earlier in the month. Rain is expected with the transition to cooler temperatures in the next several days. There will be at least some scattered precipitation in the area today, but a more widespread rain event is expected on Friday with some lingering lighter rain during the weekend.

2

Most of this growing season the upper level wind flow has been out of the northwest, meaning a flow from Canada. This flow does not allow for much moisture to be advected into the northern plains from the Gulf of Mexico, leading to the the dry conditions that most of North Dakota and northwestern Minnesota recorded this summer. The storm system expected in the next couple of days will come in from a more southerly direction. It is storms along that track that have historically brought the most abundant moisture, meaning that although not everyone will get the same amount of rainfall, there is much more potential for a more widespread rain in the next couple of days than we have experienced most of this year.

The projected growing degree days (GDDs), base 32°, 44° and 50  for the period September 14 through September 20 is presented below.

3

The very cool August has resulted in the maturity development of corn and soybeans to be behind schedule. Using GDDs based 50° the graphic below shows that many parts of eastern North Dakota and northwestern Minnesota are 200 to 300 GDDs behind the pace of last year. The coolness of the next several days will come with very few GDDs, but some warming is expected toward the middle of next week with maximums in the 80s for a least a couple of days.

4

Using May 10, 2017 as an average planting date, the number of corn growing degree days (Base 50°) accumulated through September 12 is depicted below. The exact numbers based on your actual planting date(s) can be found here: https://ndawn.ndsu.nodak.edu/corn-growing-degree-days.html

5

Using a planting date of May 1, 2017, the number of wheat growing degree days (Base 32°) accumulated this season through September 12 is given below. The exact numbers based on your actual planting date(s) can be found here: https://ndawn.ndsu.nodak.edu/wheat-growing-degree-days.html

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Daryl Ritchison

Meteorologist

Interim Director of the North Dakota Agricultural Weather Network

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South Central ND (8/03/17)

Information from the South Central region of North Dakota.

The region’s NDAWN stations indicate July rainfall ranging from 2.5 inches (Pillsbury) to 0.4 inch (McHenry). Total rainfall from April 1 to August 1 ranges from 10.5 inches (Cooperstown) to 4.2 inches (Wishek). Estimated daily water use by corn and soybean during the past week (July 26-August 1) averaged 0.25 inch/day. Additional soil moisture is needed throughout the region with our row crops being in critical growth stages - moisture stress having major impact on seed yield.

Winter cereal, barley and field pea harvest is in progress and spring wheat harvest is pending. Preliminary reports indicate average or less yield but good quality. Corn planted mid-April through the first week in May is in the blister stage (R2). Based on NDAWN growing degree day units accumulated from a May 1 planting date to August 1, the region’s corn ranges from -80 units (Marion) to 170 units (Wishek) compared to the long-term average. Soybean are in the pod formation stages (R3-4); dry bean in the pod to early seed formation stages (R3-6); and sunflower is blooming (R5).

Continue monitoring soybean fields for aphids, dry bean fields for rust, and sunflower fields for seed-infesting insects.

 

Upcoming Carrington REC crop tours:

 

*Barnes County corn – Fingal: August 10 (8 a.m.)

*Corn, dry bean, soybean and sunflower – Carrington: August 24

*Field Day – Oakes: September 7

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Greg Endres

Area Extension Specialist/Cropping Systems

NDSU Carrington Research Extension Center

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Northeast ND (8/03/17)

Information from the Northeast region of North Dakota.

Barley swathing has started in the region. Winter rye harvest is starting. Spring wheat is color changing. Some growers are intending to move away from glyphosate desiccation this year. This action is to reduce glyphosate resistance pressure. Soybean aphids continue to be the big pest management concern in the northeast. Scout for soybean aphids regularly and re-scout fields after insecticide spray to check for possible resistance or reduced performance of insecticides.

Most of the canola has finished flowering. Now through swathing is a great time to scout for blackleg, sclerotinia or clubroot infections because the tan dead spots contrast the surrounding green plants. In the last week, white mold was found in canola fields.

Last year, a clubroot field survey was done by LREC plant pathology program in seven northeast counties. Cavalier County remains the only county with known clubroot infections. Swathing is a perfect time to look for clubroot on your farm. Check plants which do not cleanly shear off during swathing for clubroot. Pull up roots and inspect for decaying clubs. The clubroot phytoplasma needs water as a part of its lifecycle. Since it’s been dry in 2017, lack of moisture may have reduced the spread of this soil-born pathogen.

Lesley Lubenow

Area Extension Specialist/Agronomy

NDSU Langdon Research Extension Center

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Northwest ND (8/03/17)

Information from the Northwest region of North Dakota.

Strong scattered thunderstorms rolled through parts of NW ND last Wednesday and Thursday. Southern Williams County recorded 1” or more with the Williston REC NDAWN station reporting 1¼”. Rain also fell in northern McKenzie and southeastern Mountrail. Small areas of Divide and Burke picked up a ½” or less. The rain will benefit late-season crops like soybean and sunflower, but was too late to be used by most small grains and pulses. Any rain will help forages and pasture recover, but more is needed as most places are still at a moisture deficit.

Small grain harvest is underway and some early-planted pulse crops are coming off, too. Here at the WREC, some of the first dryland spring wheat to come off has yielded in the mid-20 bushels per acre. Thankfully, the rain has reduced the risk of fire during harvest, but still use caution if you are working in an area that did not get much of last week’s rain. Temperatures for the up-coming week are predicted to be milder than the past few weeks with highs in the 70’s to mid-80’s.

Clair Keene

Area Extension Specialist/Cropping Systems

NDSU Williston Research Extension Center

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North Central ND (8/03/17)

Information from the North Central region of North Dakota.

Hot and dry conditions are allowing small grains to dry quickly across the region. Some growers in the North Central region have already begun small grain harvest. Some fields of canola are rapidly maturing as well. Some areas of the region were lucky enough to receive some needed precipitation while weren’t so lucky over the last week. Minot was an example that missed out on many of the storms as they rolled just south of the area (0.08” are the NCREC). Bottineau (0.38”) and Garrison (0.78”) were the big winners over the last week. The forecast is showing a bit of a cool down and some chances of precipitation. Some of the longer season crops could still benefit from any additional moisture we could receive.

Thistle caterpillar continues to be found in the region in soybean and in canola. Please fall back to the July 6th issue of the Crop & Pest Report for more information.

                Upcoming events:

The NCREC we will play co-host with the NRCS for a field day focusing on good bugs within an agricultural setting. Please note, registration is limited to the first 80 participants. Lunch will be provided. The registration cost is $40. This will cover your educational materials and meal. A block of rooms has been set aside at the Astoria Hotel in Minot for those who would like to travel to this event. Registration and event information can be found on the NCREC website. Registration will close on August 11th.

TJ Prochaska

Area Extension Specialist/Crop Protection

NDSU North Central Research Extension Center

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Grain Drying and Storage System Planning Includes Automation, Safety (8/03/17)

On-farm grain drying and storage have changed significantly as the capacity of equipment used and the amount of grain being handled and stored on farms have increased.

Grain Drying and Storage System Planning Includes Automation, Safety

On-farm grain drying and storage have changed significantly as the capacity of equipment used and the amount of grain being handled and stored on farms have increased.

Safety has become even more crucial in system design and operation because too many people are trapped in grain, get tangled in auger flighting, or develop respiratory problems from exposure to grain dust and mold particles.

Here is some advice on how to stay safe while working with grain:

 

* Never enter a bin while unloading grain or to break up a grain bridge. Flowing grain will pull a person into the grain mass, burying the individual in a few seconds. A wall of grain can collapse without warning and cover a person.

 

* Never enter a grain bin without stopping the auger and using the "lock-out/tag-out" procedures to secure it. Use a key-type padlock to lock the auger switch in the "off" position to assure that the equipment does not start automatically or someone does not start the equipment accidentally.

 

* Even low-level exposure to dust and mold can cause symptoms such as wheezing, a sore throat, nasal or eye irrigation and congestion. Higher concentrations can cause allergic reactions and trigger asthma episodes and other problems.

 

The minimum protection should be an N-95-rated facemask. This mask has two straps to hold it firmly to the face and a metal strip over the nose to create a tight seal.

These and other tips have been added to the latest edition of "Grain Drying, Handling and Storage Handbook." The publication focuses on planning a new grain facility or expanding an existing one. Many farmers can do themselves what used to be done at a local elevator.

The "Grain Drying, Handling and Storage Handbook" contains chapters on planning guidelines for drying, handling and storage; locating and developing a grain center; safety and health; automation and control; and basic principles of equipment used for grain drying; handling; and storage.

The publication is useful to help farmers planning an upgrade in their infrastructure to educate themselves on the various aspects to consider and options before meeting with a design team. The handbook can assist farmers to obtain a system that efficiently meets their current and future grain drying, handling and storage needs.

The publication includes tables with information on various types of grain storage facilities. This information is cross-referenced to downloadable spreadsheets. Producers can recalculate the capacities to meet the needs of their grain facilities. In addition, the publication contains numerous figures, illustrations and photos.

To obtain the publication, contact MidWest Plan Service at Iowa State University by email at mwps@iastate.edu or by phone at 515-294-4337, or visit its website at https://www-mwps.sws.iastate.edu/.

 

Kenneth Hellevang

NDSU Extension Agricultural Engineer & Professor

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Dicamba Injury to Soybean (8/03/17)

There has been significant inquiry about the possible causes of plant growth regulator symptoms on soybean.

Dicamba Injury to Soybean

There has been significant inquiry about the possible causes of plant growth regulator symptoms on soybean. Verification of symptoms from Extension publications or material is a common request. We have discovered an excellent Extension publication authored by Dr. Chris Boerboom, our most illustrious NDSU Extension Director, while he was working as an Extension Weed Specialist at University of Wisconsin. This was written in 2004 long before the invention of dicamba resistant soybean. He addresses spray drift, dicamba vapors, contaminated spray, injury, and yield loss. He also includes good photos of dicamba symptoms on soybean.

http://ipcm.wisc.edu/download/pubsPM/dicamba2004.pdf

There are other points to consider on soybean affected by dicamba drift:

- Dicamba damage on soybean is generally worse in drought situations.

- Depending on the plant stage when affected the impacted plants may show flower, pod, seed abortion/malformation in addition to cupped leaves.

- Most research from dicamba drift on soybean yield does not address repeated exposure to dicamba. Research summarizes single doses applied at different times and concentrations.

- In summary, yield losses cannot be predicted before harvest because drift exposures may have occurred at multiple times and in concentrations that are not known.

 

 

Rich Zollinger

Extension Weed Specialist

 

Andrew A. Thostenson

Pesticide Program Specialist

 

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