NDSU Extension Service - Cavalier County

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6/27/2014

Wheat Development/Leaf Stage
Seed Date                            Stage

4/21                                        Boot
5/1                                          Flag leaf Emerged
5/15                                        7 leaf-flag tip emerged
5/20                                        6-6.5 leaf – jointing
5/26                                        5-6 leaf – jointing
5/31                                        4 leaf – tillering
6/5                                          3 leaf +

Soybean Iron Deficiency Chlorosis (IDC)
Additional comments from Dave Franzen your NDSU Extension Soil Specialist

To have IDC, the soil must have free lime (carbonates- calcium carbonate, magnesium carbonate, sodium carbonate or a mixture of two or three at once). The pH of these soils is always above 7. If a soil has pH below 7, then IDC is not possible and the cause of yellowing is something different. If a soil has carbonates, the next causal factor is soil moisture. Especially in our region, soil water must be sufficient to dissolve the more easily soluble salts, like chlorides, magnesium sulfate and gypsum, before the carbonate is dissolved. When carbonate dissolves, the resulting bicarbonate has the property of being able to neutralize the acidity the soybean root forms around itself to enable the activity of an iron ion reducing substance to transform Fe+3 to Fe+2, which makes iron a trillion times more soluble than it naturally occurs in an oxygen rich environment. Without the acidity around the soybean root, iron uptake is terribly restricted, and the characteristic interveinal yellowing occurs.       

In his studies on IDC, Dr. Goos at NDSU has stated that if a soybean plant exhibits any IDC symptoms one can lose 5 bushels per acre right off the top. As the condition persists, yield potential continues to decrease. In our region, under extreme perpetually wet conditions or with a variety with poor tolerance to our version of IDC, the soybean can be yellow the entire season. In my experience, soybeans rarely produce more than 10 bushels per acre if they are chlorotic the entire season.

Other environmental and soil conditions that contribute to greater IDC severity are soluble salts, cool temperatures, soil nitrate, and anything that stresses the crop even a little, including a herbicide application.  There is no cure for IDC that one could apply. An application of an iron foliar fertilizer may green up the leaves that are treated, but the iron is not mobile within the leaf or the plant. A recent foliar study by Dr. Goos included a Post-It note over half a soybean leaf. The exposed half of the leaf was green following treatment, but the half under the Post-It note continued to be yellow.

Make a note of the fields with problems. A high-resolution satellite image of the field or an aerial image (this may be one possible value for the use of a drone) will help define the area for future application of an ortho-ortho-FeEDDHA fertilizer in 2015 and beyond. Other methods to reduce IDC are to plant in row widths of 20 inches to 30 inches wide, and seeding a bushel per acre of oats or barley at soybean seeding to help dry the soil more quickly and use up excess soil nitrate.

For a more detailed explanation of IDC, see the 2013 NDSU circular- Soybean Fertility

Blackleg on Canola:  Blackleg of canola can cause severe yield losses on susceptible hybrids as some farmers experienced first-hand this past year though with the good canola year still had acceptable yields. The blackleg pathogen survives on canola stubble, and produces fruiting bodies that release large quantities of airborne spores which are capable of travelling several miles. These dark colored raised fruiting bodies can easily be seen with the naked eye. Higher levels of disease are associated with high levels of moisture and frequent rainfall events, particularly early in the growing season.  Infections often begin on cotyledons or the first few leaves, will progress into the stem, and may result in deep cankers or girdled lesions.  Damage to the lower stem early in the season may damage or kill the plant. Fungicides can be efficacious when applied at the two- to four-leaf stages so all canola is past that stage.

Weed Resistance!  Weather conditions have been very favorable for good weed control and occasionally some crop burn and yellowing.  Make a point to re-check all spray operations for control percentages in 7 -10 days after the herbicide is applied.  This is not only very important for efficacy of the herbicide but to identify possible weed resistance or late flushes.  Resistant wild oats are showing in very high levels in certain fields.  Only alternatives at this stage may be cutting those patches for hay or killing off with Roundup!  Some are trying to locate the old Avenge product which kills big wild oat plants.  The old Fargo herbicide appears to be doing a good job on all wild oats so will be a good option in 2015 where resistant wild oats have been found.

Scout for Diamondback Moth in Canola
Increased numbers of diamondback moth larvae are being found in canola fields in western ND but not locally. Mature larvae are about ½ inch long, light green with a forked posterior end. Larvae feed on buds, flowers, and pods and are economic when populations are at 25-30 larvae per square foot or 1 to 2 larvae per plant. Larval feeding during blooming to early pod development can cause aborted flowers, delayed plant maturity, uneven crop development and significant yield reduction due to loss of flowers and pods. Much of canola in north central region North Dakota is just starting to flower, so now is a critical time to scout – budding to flowering. Since this moth migrates up into North Dakota on southerly winds and then drops down by cold fronts, it is often found only in localized areas. It is not uncommon to see all of the life stages (adult, egg, larva, and pupa) present in the field due to multiple flights of these migratory moths. Diamondback moth larvae can be monitored in the field by pulling all plants from a 12-inch-square area. Beat collected plants onto a clean surface or into a white bucket and then count the number of larvae dislodged from plants. When disturbed, larvae thrash backward violently and often drop from the plant, suspended on a strand of silken thread. Repeat this procedure in at least five locations in the field to obtain an estimate of the number of larvae per square foot.

Aster Leafhoppers Low:  Aster leafhoppers were detected in only 29% of the canola field surveyed from June 16-20 and continue to be at very low densities (0 to 25 leafhoppers per 9 sweeps) in canola in North Dakota and Minnesota.

Sclerotinia Risk Forecast Program for North Dakota
Click on the following link to access the NDSU Interactive Sclerotinia Website: http://www.ag.ndsu.edu/sclerotinia/

April seeded canola is now just starting to flower:  The Sclerotinia Risk in Canola Forecast Program is a service of the Northern Canola Growers Association and NDSU. The Sclerotinia Disease Forecasting System is a regional guide to sclerotinia of canola disease risk. It is meant to be a management tool that canola producers can use in making a decision on the necessity of applying a fungicide to their canola crop for control of sclerotinia stem rot. It is not meant to be a field-specific recommendation for the application of fungicides for the control of sclerotinia. Other factors such as local weather conditions, seeding date, previous cropping history, and yield potential should be considered as well as the risk maps in making the final decision. The forecast maps show regions of North Dakota and Minnesota where environmental conditions are favorable for the germination of sclerotinia sclerotia, development of apothecia and release of spores. The degree of risk is shown as low, moderate and high coded green, yellow and red.

These risk maps are for the specific location where data is taken from.  Your farm units, may be receiving entirely different precipitation levels.  For white mold to occur, two events are necessary.  The soil moisture level in the top two inches has to reach capacity to wet and germinate the sclerotia and about 10-14 days later the sclerotia has to eject ascospores that land on the canola flower under condition that they will germinate. 

By its use, you agree to release the Northern Canola Growers Association and its employees and project collaborators from any and all claims, demands, actions or liability for material used or relied upon by you through this service. All results, statements, technical information or recommendations herein are believed to be reliable, but their accuracy or completeness is not guaranteed.  The project collaborator and developer is Dr. Luis del Rio, Plant Pathologist, North Dakota State University.

Sponsors are the Northern Canola Growers Association and the National Sclerotinia Initiative. Weather data and technical assistance: North Dakota Agricultural Weather Network NDAWN.

Wheat scab potential is very high for any wheat flowering (winter wheat).  See the enclosed page for timing of fungicides and on the reverse side is the agenda for Field Day.   

BEST STAGE FOR APPLYING FUNGICIDES FOR SCAB CONTROL IN WHEAT AND BARLEY
(pictures were included on hard copy but did not copy over to web page, please contact our office to request)
Timing of fungicides for Scab Control in Wheat and Barley

Early planted barley is approaching the stage of greatest risk for Fusarium Head Blight infection (scab). Spring wheat is not far behind.  High humidity during this critical stage increases the risk of scab development, so the recent wet weather has increased the likelihood that scab will develop. Refer to the small grains disease-forecasting model for further guidance on determining the risk for scab development for your particular area as your crop approaches heading. If conditions are conducive for scab development, recommended fungicides can be effective in reducing scab development, particularly if applied at the appropriate stage of development. If wet conditions continue, there is a high likelihood that fungicide use will be profitable. Given that we are approaching the optimum stage for fungicide applications for the management of scab, we have felt it would be useful to review information on the most effective stage for applying fungicides for the control of scab. This is a revision of an article previously published.

Timing in wheat – The optimum time to apply recommended fungicides for FHB control in wheat (winter, spring and durum) is at early flowering. Applying fungicide at this stage helps to protect vulnerable florets from Fusarium damage during fertilization and early grain-filling. The center spike in the accompanying photo (Right) is at the ideal stage for applying fungicide. The spike on the left has emerged from the boot, but has not yet started to flower (there are no visible anthers extruded from the glumes) and will likely be at the optimum stage in about two days. The spike on the right is past the optimum stage; the anthers are bleached and dried, unlike the turgid, yellow anthers in the center spike. The period between head emergence and flowering is usually about three days. Since not all spikes emerge at the same time, I recommend applying fungicides when most of the main stem and first tiller spikes have reached early flowering. Furthermore, experience has shown that it is better to apply fungicide too early rather than too late.

Timing in barley – Flowering in barley begins just before the spike emerges from the boot, so barley florets are not overly susceptible to scab infection. Scab infections do not generally impact yield in barley. The scab fungus, however, is able to infect the glumes of barley and produce DON which impacts its market value, particularly if it is being sold for malt. The malting and brewing industry is sensitive to very low levels of DON. The optimum stage for applying fungicides to protect the glumes of barley from FHB infection is when the spike is fully emerged from the boot. In the accompanying photo (Right), the spike third from the left demonstrates the optimum stage for treating barley with fungicides, with those further to the left too early and the one on the right too late. With barley the appearance of the first spikelet from the boot is a good indication that the best stage for spraying is only a few days away.

NDSU Langdon Research Extension Center & Northern Canola Growers Association Annual Field Day Thursday, July 17. 

 

 

 

 

 

 

 

 

 

 

 

 

 

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