Posts Tagged ‘barley’

Small Grain Disease Update

Friday, April 22nd, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Barley
We are getting more reports of powdery mildew in ‘Thoroughbred’ barley. This variety is very susceptible and growers have been spraying fungicides to control the disease and protect their yields. Tilt or other labeled triazole fungicides work well along with strobilurin combination products like Quilt, Stratego, etc. Folicur, which is a triazole or sterol-inhibiting fungicide, does not have powdery mildew control on the label for barley or wheat. Folicur (tebuconazole) is now available as a generic as Monsoon, Orius, Embrace, Tebustar and others. When small grains are followed by soybeans there are no plant back restrictions but if you are planting processing or fresh market vegetables be sure to check the label for what can be planted if a fungicide is used in barley or wheat.

Wheat
Disease activity has been light so far. Another sample of wheat spindle streak mosaic virus was received this week. See the article titled Viruses in Winter Wheat in WCU 19:2 for more information. The one control option for wheat spindle streak is planting resistant varieties. Seed company literature and web sites can provide that information. The University of Maryland has some ratings for disease resistance from their variety trial plots. Dr. Arv Graubaskas revised the MD list last December and it is online at: http://agdev.anr.udel.edu/weeklycropupdate/wp-content/uploads/2011/04/MDWheatDiseaseRatings2010.pdf.

 

Manganese Deficiency Can Worsen with Spring N Applications on Small Grains – Part 2

Thursday, April 14th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu and Phillip Sylvester, Kent Co., Ag Agent; phillip@udel.edu

Last week, we discussed the possibility that either the starter fertilizer or knifed in nitrogen solution from the previous year’s corn crop might be responsible for the row-like pattern to manganese (Mn) deficiency that we had observed in barley recently fertilized with broadcast nitrogen (N). We took soil tests within the rows where barley was alive and vigorously growing (good area) and between the rows where barley plants were dead or growing very poorly (Photo 1). The soil samples have been analyzed and support our original conclusion (Table 1).

 

 

Table 1. Soil test analyses of good and bad barley areas in field showing barley surviving on 30-inch row spacing.

Barley Area Sampled

Sample Depth (inches)
0 to 4 4 to 8 8 to 12
Water pH Mn lb/A Zinc lb/A Water pH Mn lb/A Zinc lb/A Water pH Mn lb/A Zinc lb/A
Bad barley 6.1 15.1 8.5 6.6 9.0* 2.9 6.6 5.0* 1.0*
Good barley 6.2 16.3 8.7 6.3 10.8 3.2 6.5 6.3* 1.3*

*Deficient soil test level

Photo 1. Barley rows generated following renewed spring growth and nitrogen application showing effect of last year’s fertilizer (either starter band or knifed in nitrogen solution). Barley between corn rows was either severely Mn deficient or had died while barley on rows 30 inches apart grew vigorously.

Another interesting factor showed up on the soil test results. While the visual symptoms resembled traditional Mn deficiency on barley, the soil test indicated that at the deepest (8 to 12 inch) sampled layer zinc was also deficient. For any crop planted after barley (soybeans by tradition), the grower should conduct a tissue analysis mid-season before the crop begins to bloom to determine if tissue zinc levels indicate the possibility of a hidden zinc deficiency that could reduce yield potential. In addition, the grower should scout the crop for obvious zinc and Mn deficiency symptoms so that foliar zinc or Mn can be applied as early as possible.

Zinc deficiency symptoms on soybean include the following:
· Soybean yields are considerably decreased in zinc deficient soils.

  • · Deficient plants have stunted stems and leaves with chlorotic interveinal areas.
  • · Later on the entire leaves turns yellow or light green.
  • · Lower leaves may turn brown or grey and may drop early.
  • · Few flowers are formed and the pods that are formed are abnormal and slow in maturity.

Manganese deficiency symptoms on soybean include the following:
· Manganese deficiency commonly occurs in plants in well drained, neutral and alkaline soils.

  • · Interveinal areas become light green to white and the veins remain green.
  • · Necrotic brown spots develop as the deficiency becomes more severe.
  • · The leaves drop prematurely.
  • · Soybean yields can be significantly reduced by Mn deficiency.

Both micronutrient deficiencies can be reduced or eliminated by either a soil application of the sulfate or oxide compound of the micronutrient at 15 to 25 lbs per acre or by a foliar application of either the chelated form of the micronutrient or the sulfate form of the micronutrient at 1 to 2 lb of the nutrient per acre.

 

Manganese Deficiency Can Worsen with Spring N Applications on Small Grains

Friday, April 8th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu and Phillip Sylvester, Kent Co., Ag Agent; phillip@udel.edu

Over the years, with respect to soil pH and manganese (Mn) deficiency, we have found that barley seems to be if not the most sensitive then close to the most sensitive small grain. When soil pH approaches the mid 6 range where we would expect it to be optimum for corn and beans, we often see Mn deficiency symptoms on barley, especially in certain areas of the state where the native Mn levels are low. During late fall and winter, the symptoms can often be confused with winter injury, wind burn, or other problems. However, the confusion usually clears after nitrogen (N) fertilizer is applied in the spring. Unfortunately, clearing the confusion often means that partial or entire stands of barley are lost.

The impact of spring N can vary depending on the soil acidity profile. If the Mn deficiency is severe or if the deeper soil layers are higher in pH, the N applied can cause barley plants to quickly die or, as frequently described, the barley appears to go backwards in appearance. The N stimulates rapid growth and if Mn is not available either as a result of soil pH levels or just low native Mn levels in the soil, the plants suffer significant damage.

This has been the case in several fields in southwestern Kent County over the past couple of weeks. Of particular interest is a field shown in the photographs below. The field developed striping across it on 30-inch centers (Photos 1, 2, and 3). In some areas, plants between the “rows” died and disappeared (Photo 4) and in other areas plant growth was slower other than in the “rows”. As can be seen in the photos, the rows are very straight and on 30-inch centers. We think the pattern follows where starter fertilizer was applied next to the corn rows last year since the lines are very straight. Rather than residual nutrients, the effect is very likely due to the slight acidulation of the soil that surrounded the banded starter fertilizer. The slightly lower pH in these areas has increased Mn availability just enough so that the plants were healthy enough to survive until the field received foliar Mn about a week before the photographs below were taken. Between the ‘rows” where banded starter did not affect Mn availability, the plants were so stressed for Mn that the N application caused them to die.

This week we took additional soil samples to investigate whether we can detect the small pH differences expected and we will report on the results in a future issue of Weekly Crop Update.

A concern that the grower may have is whether the Mn deficiency will show up in double-cropped soybeans if they are planted after the barley. First, the foliar treatment on the barley will not have any effect on a future crop. Second, a soybean crop is subject to Mn deficiency but whether the soil Mn levels are low enough for symptoms to appear is still in question. Barley seems to be more sensitive than soybean so visual symptoms may not been seen in the soybean plants. However, there is a strong possibility that the soybean crop will suffer from what is often referred to as “hidden hunger’. This occurs when the soil Mn availability is not quite low enough to stimulate visual symptoms but is at the critical range where yield potential is lowered without visual symptoms appearing. Our recommendation is that either the grower should consider a broadcast application of Mn (usually for a broadcast application 30 lbs actual Mn is applied per acre) so that soil Mn levels are increased above the critical range or the grower should plan on a foliar Mn application around the fifth leaf stage (V-5) when enough leaf area is present to adsorb adequate Mn from a foliar application. One to two pounds of actual Mn is the suggested rate for a single application. This rate is suggested since application costs are more than the cost of the product and so a single application will be the preferred method.

Photo 1. Barley rows generated following renewed spring growth and nitrogen application showing effect of last year’s starter fertilizer.

Photo 2. Barley between corn rows was either severely Mn deficient or had died while barley on rows 30 inches apart grew vigorously.

Photo 3. Wide view of barley field with old corn rows showing vigorous barley growth.

Photo 4. Between the “rows” barley Mn deficiency symptoms following spring N application were severe.

Barley Frost Damage Hits in Kent Co.

Friday, April 8th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu and Phillip Sylvester, Kent Co., Ag Agent; phillip@udel.edu

While checking out a barley field for possible manganese (Mn) deficiency problems, we discovered that the field had recently been damaged by freezing temperatures. Photos 1, 2, and 3 below show the typical whitening or bleaching of the leaf when temperatures drop below the critical level for barley at its current development stage. Photo 2 and 3 show the typical leaf tip bleaching but also show how freezing temperatures affect leaves differently depending on the stage of emergence of the leaf involved. Some leaves were affected only at the leaf tip while others were damaged around mid leaf leaving a whitened area in the middle of the leaf and green leaf at the tip and base of the leaf blade.

The question we can’t answer at this point with 100% certainty is whether the low temperatures caused pollen sterility in the developing seed head. The plants appeared to be at the Feekes 5 growth stage when the first node is just visible above the soil surface. We think that at this early stage damage will be limited to the leaf bleaching symptoms we observed. We won’t be able to know for sure until after heading when the anthers extrude from the florets and we can detect whether pollen release occurs. If pollen viability is impacted, the heads will not set grain and the heads will appear blank.

In the areas where Mn deficiency was observed, the leaf damage from the freezing temperatures was much worse causing significant injury to the barley plants (Photo 4). These plants will likely recover but yield will be much reduced.

Photo 1. Generalized tip burn on barley subjected to freezing temperatures following renewed spring growth and nitrogen application.

Photo 2. Leaf tip burn and mid-leaf frost injury showing stage of leaf emergence at the time of freezing temperatures.

Photo 3. Close-up view of leaf injury caused by freezing temperatures on barley. The growing point is just above the soil surface at this stage of growth.

Photo 4. Close-up view of severity of frost damage on Mn deficient plants.

Barley Leafspot Diseases

Friday, April 8th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

As you scout your fields at this time of year it is often easy to find scattered brown spots in barley. Sometimes in wheat and rarely in barley, a minor disease called Ascocyta leafspot can be found on winter damaged tissue that can resemble Septoria leafspot but the plants grow out of it once warm weather arrives. The other brown spot that can be seen now is the early symptoms of net blotch. This is a very common leafspot of barley in our region. Severity is determined by the weather (it likes cool and wet) and the susceptibility of the variety. High nitrogen fertilization early will also favor development. Spot blotch rarely gets severe enough here to warrant fungicide applications. The symptoms that develop on barley can vary depending on the variety of the fungus present (there are several forms or isolates of this fungus) and the barley genetics. Later in the season we see the spot blotch form of net blotch (two leaves on the left) more frequently than the classic net blotch symptom seen on the two leaves on the right in the picture below.

Two leaves on left- spot blotch form of net blotch, on the right classic net blotch symptoms

Sometimes the only symptom development is a small brown spot or fleck that never enlarges or blights a leaf. This is thought to be the barley resistant reaction to the fungus infection.

The picture above, taken two days ago, shows the early symptoms on leaves before jointing has occurred. Typically, as the season warms the older infected leaves at the base of the plants will die and the new leaves may or may not develop more symptoms depending on the weather.

Small Grain Weed Control

Friday, March 11th, 2011

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Be sure to read the herbicide label carefully because some products can be tankmixed with nitrogen but only if the nitrogen is no more than 50% of the spray solution (nitrogen is mixed 1:1 with water). A few specifics:

● Osprey cannot be applied within 14 days of nitrogen application

● Harmony Extra can be applied with nitrogen, but use of surfactant differs depending on concentration of nitrogen and targeted weed species

● Axial XL and PowerFlex can only be applied with nitrogen if it is mixed 1:1 with water; also PowerFlex cannot be applied with nitrogen if the amount is more than 30 lbs of N/A

Axial XL and PowerFlex are two herbicides that are effective on annual ryegrass. Both of these can be double-cropped with soybeans. However, PowerFlex will injure vegetables planted after harvest.

There are reports of fields with poor chickweed control due to resistance to Harmony, Harmony Extra, or Finesse. If you are in that situation, your alternatives are quite limited. Most other small grain herbicides do not provide acceptable chickweed control. One product to suggest is Starane Ultra (from Dow AgroSciences). This product is labeled for wheat and barley and has good crop safety and fair to good chickweed control. However, it will not control other key species such as wild garlic. Starane Ultra can be tankmixed with Harmony Extra to broaden the spectrum of control. Starane Utra by itself does not need an adjuvant and can be applied in nitrogen. Be sure to read and follow label directions.

Finally, a reminder on timing restrictions for small grain herbicides. The timing restrictions are based on crop safety.

2,4-D – up to jointing stage (pre-jointing)

Banvel/Clarity – up to jointing stage (pre-jointing)

Osprey – up to jointing stage

Buctril – up to boot stage

Harmony Extra or Harmony GT – up to flag stage (pre-flag leaf)

Starane Ultra – up to flag leaf emergence

PowerFlex – jointing

Axial XL – prior to boot

Will Your Crop Suffer from Sulfur Deficiency this Cropping Year?

Friday, March 11th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Past and recent emphasis has been placed on reducing sulfur (S) emissions from power plants, diesel vehicles, and other industries. The question of whether the Clean Air Act and other programs run by the Environmental Protection Agency are accomplishing their objectives can be answered by the farm community with respect to sulfur emissions. The answer growers would likely give is that yes the air quality programs have worked, but so well that their crops are increasingly showing sulfur deficiency symptoms, especially when grown on sandy, low organic matter, non-manured soils.

Why is S critical for maximum economic yields (MEY)? Sulfur is needed by a crop when making certain amino acids such as cystine and methionine that are vital components of many proteins. The entire factory output (yield) of a crop is dependent on proteins that make up the chlorophyll molecule, all the plant enzyme systems, the plant’s genetic material such as DNA, the assimilation function of legume rhizobia, and all the inter-related metabolic activity in the plant. The ideal nitrogen (N) to sulfur ratio in a plant is 15:1. Above that ratio, the S concentration is not adequate for MEY.

Sources for S include commercial fertilizers, atmospheric deposition, and manures or biosolids. The movement away from the old superphosphate (16 to 22% P2O5 and 12 to 14% S) to triple superphosphates in the late 1900s and then more recently to ammonium phosphates and ammonium polyphosphates (DAP, MAP, and others) has reduced the amount of S fertilizer applied without us consciously being aware of the trend. With the success of the Clean Air Act, atmospheric S deposition had dramatically decreased even before the very recent change over to ultra low sulfur diesel fuel. In addition, the emphasis on nutrient management planning to reduce manure application rates due to phosphorous buildup in the soil and the development of programs to help move poultry manure to areas without manure resources has also contributed to reduced S application rates.

Who should be concerned about the potential for S deficiency on their crops? The answer is that probably everyone but especially those growers with coarse textured soils, with soils low in organic matter, or with soils that have received enough rainfall or irrigation water to leach S below the crop rooting zone should be concerned. For shallow rooted crops such as wheat and barley, it is especially critical to ensure that adequate S is available during tillering and early growth and development. Growers should consider adding enough ammonium sulfate to their normal nitrogen application to provide from 20 to 30 lbs of S per  A in the first N application split in the spring.

If there is adequate S accumulation in the soil clay subsoil as determined with a deep soil test, S fertilization may not be a yield limiting factor on deep rooted crops such as corn. However, this does not mean that early season growth won’t be improved with the early season addition of some type of sulfate fertilizer. Even in high yield irrigated environments, such an application could help improve yield potential or at least not limit yield.

Some growers will want to rely on soil test results to make a decision on whether to add S fertilizer. These growers should be aware that the normal soil test depth of 0 to 6 or 0 to 8 inches is not as good an indicator of soil S status as it is for phosphorus and potassium. Sulfur is taken up by plants as the sulfate (SO42-) ion and as an anion (negatively charged ion) in the soil that is similar to nitrate. It is subject to loss via leaching and anaerobic conditions (similar to denitrification).

Sulfur deficiency symptoms vaguely resemble those of N except that S, unlike N, is not mobile in the plant so symptoms occur first on new growth. Sulfur deficiency is most often described as stunting with general yellowing or chlorosis of the plant. For examples, please review the photos at the end of this article.

The choices available for fertilizing with S include ammonium sulfate and potassium magnesium sulfate (K-PoMag) plus ammonium thiosulfate, calcium sulfate (gypsum), magnesium sulfate (Epsom salts), potassium sulfate, and elemental sulfur. Sulfate is immediately available for plant uptake whereas elemental So must be oxidized by the soil bacteria (requiring warm soil temperatures and adequate moisture) into sulfate before plants can absorb the S. Organic sources (manures, crop residues, biosolids) must undergo mineralization into inorganic sulfate before being available for plant uptake.

Other by-products such as derivatives from battery acid are sold as S sources but should be evaluated carefully by the grower to be certain that potential problems such as heavy metal contamination, non-available S forms, or injurious compounds are not present. Even then the S form in some by-products will need to be converted into plant available forms by the soil microorganisms and if S is needed immediately or if soil conditions are not favorable for this conversion yield potential could be impacted negatively. Certainly, any form other than the sulfate form is not appropriate in-season when deficiency symptoms indicate the immediate need for S.

Photo 1. Induced sulfur deficiency in corn grown in sand culture. Note reddening of lower stem, general chlorosis or yellowing especially of new growth, and stunting of the plant.

Photo 2. Field corn showing stunting and general chlorosis or yellowing, especially of new growth on sandy soil in southern Delaware.

Photo 3. Sulfur deficiency in barley grown on a very light sandy soil low in organic matter in Sussex County, Delaware. Note general chlorosis or yellowing especially of new growth and severe plant stunting.

Photo 4. Sulfur deficiency in wheat grown on a very light soil low in organic matter in Sussex County, Delaware. Note general chlorosis or yellowing especially of new growth and severe plant stunting.

Agronomic Crop Disease Updates – September 17, 2010

Friday, September 17th, 2010

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Corn
Corn harvest is underway so be sure to check corn fields for lodging potential by squeezing the lower nodes or pushing on the stalks. A simple way to do this is to walk through the field and, keeping your hands at chest height, push stalks 8-10 inches from vertical. If 10-15% of the stalks lodge, schedule the field for early harvest before a strong wind results in severe lodging. Drought conditions during grain fill put substantial stress on corn plants. In many fields, it is likely that the corn crop responded by cannibalizing stalk reserves to fill the grain. This results in a weakened stalk and greater susceptibility to stalk rot.

Small Grain
Be sure that you plant wheat varieties with high levels of disease resistance. Select varieties with high levels of resistance to powdery mildew, leaf rust and stripe rust. Seed should be treated with Baytan, Raxil, Dividend or other labeled product to protect plants from loose smut and common bunt. Varieties that are susceptible to powdery mildew should be treated with Baytan, Dividend or other seed treatment that will protect them from early infection.

Soybeans
Do not ignore soybean cyst nematode. Soil sampling after harvest before any fall tillage is recommended for fields to be planted next season to soybeans following this year’s crop. Do not plant SCN susceptible varieties without soil testing first. Soil sample bags are available from the county Extension offices for $10/ sample bag.

Soybean Rust Update
Nothing new has developed north of the North Carolina find on August 30. Florida had its first soybean rust detection on soybeans on September 14. Needless to say, soybean rust is not going to be an issue in most of the US this season.

Fusarium Head Blight Forecast and Alert System

Friday, May 14th, 2010

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

The risk of Fusarium head blight or scab is low for the next several days. There is some rainfall in the forecast for Friday and early next week with warmer temperatures, but until now there has not been enough moisture to produce spores for infection. Most of the wheat by next week should be past flowering and therefore not at risk unless it is very late. There are scattered reports of low levels of leaf rust on Delmarva so scouting should continue.

I just became aware that wheat growers can sign up for scab alerts. See the following information:

Producers, crop consultants, grain processors and others can sign up for the alerts by going to the following web site address: http://scabusa.org/fhb_alert.php. The alerts will be sent out to one’s cell phone or email, depending upon the user’s preference. Frequency and timing of alerts will depend upon a given area’s risk for severe scab – which can vary widely, depending on environmental conditions.

The purpose of the alert system, is to give growers and affiliated industry personnel better advanced notice of potential outbreaks and the risk of scab in their area, thus allowing for timely treatment of fields with fungicides. “We are aware that many farmers do not have easy or convenient access to the Internet, but most of them carry a cell phone,” says Dave Van Sanford, USWBSI co-chair. “We wanted a system that would send an alert to their cell phone, prompting them to take an appropriate action – such as going to the USWBSI website, checking with their county agent, chemical dealer or consultant, or simply looking at their crop to check its stage of development. Our hope is that the alerts will lead to some action that will reduce the impact of head scab on the crop.”

The alert system is tied in with the Fusarium Head Blight Risk Assessment Tool hosted by Pennsylvania State University, Kansas State University, Ohio State University and the U.S. Wheat & Barley Scab Initiative. This web site – www.wheatscab.psu.edu/riskTool_2010.html – provides detailed, daily updated information on scab risk in various U.S. small grain production regions. The FHB Assessment Tool is supplemented by commentaries from various state university plant disease specialists regarding environmental conditions and the presence of scab (or lack thereof) in their state. These commentaries provide the content behind the FHB alerts.

Small Grain Disease Update – April 30, 2010

Thursday, April 29th, 2010

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Keep scouting wheat for foliar diseases. Stripe rust is still a concern and is present in the South. Warmer weather will favor the Septoria, Stagnospora complex that causes speckled leafspot and glume blotch as well as common leaf rust and tan spot.

Last week I inadvertently did not include Twinline fungicide from BASF as another choice for powdery mildew control and other diseases on wheat and barley.