Tan spot was the only wheat disease observed last week, with 1/3 of all wheat fields surveyed showing infection. The highest incidence and severity occurred in fields planted into wheat stubble. Some fungal leaf spotting also was observed in barley fields in the northwest region. Other wheat or barley diseases were not observed last week, and neither were insects, except for a very few grasshoppers in field margins. Field scouts in the southwest did report seeing leafhoppers in the fields.

Sam Markell

Extension Plant Pathologist

samuel.markell@ndsu.edu

Despite being very dry earlier this spring, we may begin seeing the effect of root rots in some row crops.

Cooler than average soil temperatures often mean seeds stay in the ground longer, increasing their exposure to root rotting pathogens present in the soil. Last week’s rain, although much needed in most of the state, may give some root rot pathogens a foothold on some broadleaf crops, particularly those recently planted (edible beans and soybeans for example). Although there is not much that can be done to manage root rots after planting, the observation of suspected root rot in a field (poor stand, young plants yellowing/wilting/dying) may influence management decisions for the rest of the season, as well as for future crops in the field.

If you see some suspicious patches in the field, take note for the future, it may be root rot diseases.

Rich Zollinger

Extension Weed Specialist

r.zollinger@ndsu.edu

• Do not graze livestock or harvest forage for hay from treated wheat and barley for a minimum of 30 days following application.

• Do not harvest grain for 60 days following application.

• Do not apply both Discover and Axial products to the same crop in the same season.

• Wheat and barley straw may be fed to livestock 60 days after application

Hans Kandel                                         R. Jay Goos

NDSU Extension Agronomist            NDSU Soil Scientist  

hans.kandel@ndsu.edu                      RJ.Goos@ndsu.edu

Soybean, dry bean, field pea, lentil, and alfalfa are important legume crops grown in North Dakota. Specific bacteria live in symbioses with legume roots and nodules are formed where atmospheric nitrogen is transformed in plant usable nitrogen. Nodulation is a good diagnostic tool to evaluate the relative crop condition. Stressed legumes will have limited nodule numbers. Severe stress after the nodules are formed may cause nodule sloughing and decrease the active number of nodules. There are several stress factors that can occur during the growing season. Excess moisture, drought, and unbalanced plant nutrition are the most common stress factors. As the legumes depend on the nodule growth for their nitrogen supply, stressed and reduced nodulation may lead to nitrogen shortages for the growing legume plant. Drought and nutrient stress may lead to low yields and early maturing of the crop.

Nodules develop on the tender root hair tissues rather than the older tissue of the root. Nodules can be already found a few weeks after the plant emerged. Nitrogen fixation kicks in, normally at about the 2nd trifoliolate stage. Active nodules, those producing nitrogen for the crop will have a nice pink or reddish color when the nodules are cut open.

If the legume seed was inoculated with an old source of inoculum (>2 yr. old) the bacteria count could be low, and therefore nodulation is lower than with new and healthy inoculants. If the inoculant (live bacteria) was exposed to heat or long periods of direct sun the bacteria count could be reduced, it only takes an hour to kill the bacteria if left in the sun. Also, if the seed was not properly and uniformly treated nodule numbers may be low. Some of the seed treatments (fungicide, insecticide or combination) may be antagonistic with inoculants (check the label.) Manufactures of products and seed suppliers can provide product compatibility information. Other stress factors that may cause low nodulation are root rot problems, wet and saturated soils, high pH and or high salt concentrations, and cold or dry soil conditions. It is important to diagnose why nodulation is low, so preventative measures can be taken next season to avoid similar problems.

Soil Science students researched the effect of nitrogen on early growth and nodulation of soybeans.

Four plants were grown per 2 kg pot of soil, amended with all nutrients except Nitrogen. The treatments were four N rates of 0, 50, 100 and 200 mg/pot by two inoculation levels; soil not inoculated and soil inoculated with a small amount of commercial inoculant. The soil was a Renshaw soil from Streeter, ND, with no history of soybeans. The data were averaged across four replicates. In Figure 1, the number of nodules was substantially higher when the seed was inoculated in soil with no history of previous soybean production. The soil was not sterilized, and a few scattered nodules were obtained per pot in the absence of inoculation. In Figure 2, the weight of the inoculated plants was higher than of the non inoculated plants. If nitrogen is available, the plant will use the nitrogen for plant growth. When plants can fix their own nitrogen in the presence of the right bacteria, NDSU does not recommend a N application for soybean.

Figure 1. Effect of Nitrogen treatment on the number of nodules per pot (four plants).

Figure 2. Effect of Nitrogen treatment on the fresh weight of the above – ground plant parts.

Roger Ashley

Area Extension Specialist/Cropping Systems

Dickinson Research Extension Center

(701) 483-2348 ext 106

Southwest North Dakota NDAWN locations reported having received various amounts of precipitation over the past two weeks. Past two week totals ranged from 1.24 inches at Beach to 3.07 inches at Hettinger. Producers have reported rainfall amounts greater than and less than those at the NDAWN locations. Wind and rain limited times when herbicide and fungicide applications could be applied, but recently applicators are getting into fields.

All crops are exhibiting a wide range of development in the area as well as within some fields. Germination was very uneven particularly on tilled fields and/or where high disturbance drills were used to put the crop in. Some producers with low disturbance drills had difficulty planting into last year’s heavy residue but many experienced operators adjusted their planting pattern to accommodate for the residue and produced some excellent stands considering how dry it was earlier this year.

Winter wheat that avoided severe winter injury has headed out in the area. However, winter wheat that was severely injured is in the boot to various stages of head emergence. Early seeded (late March to early April) spring wheat is in the boot or early stages of head emergence. Many alfalfa fields are in the bud to early bloom (less than 5%) stage and are ready for cutting.

Sunflower and corn has benefitted from recent warm conditions. Sunflower seeded May 25 is in the V2 stage of development. Several positive wheat streak mosaic virus (WSMV) and high plains virus (HPV) samples have been found in southwest North Dakota. The increase in WSMV and HPV samples indicate poor sanitation practices, early planting of winter wheat, and planting in close proximity to active "pools" (such as live field corn last fall) of mites and virus provided the green bridge needed by these pests to cause problems in this year’s crop. These viruses have also spelled over into the spring wheat crop too.