Posts Tagged ‘small grains’

Thoughts on Planting Soft Red Winter Wheat Early

Friday, September 14th, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

With corn harvest proceeding much earlier than in ‘normal’ years, many growers could be considering whether to go ahead and plant their wheat or barley crop in the next few weeks. The recommended or suggested planting date varies from county to county based on the Hessian fly-free date. (For more information on Hessian fly see the article by Joanne Whalen “Agronomic Crop Insects – September 7, 2012” in issue 20:25 of the Weekly Crop Update) The fly free dates are Oct. 3 for New Castle County, Oct. 8 for Kent County, and Oct. 10 for Sussex County.

For barley, we have conducted planting date studies in Sussex County comparing early-planted (September 26) barley with a close to suggested planting date (October 7). Our results indicated a fairly consistent 5 percent reduction in yield with September planted barley as compared with the October 7 planting date. Winter weather in the years the study was conducted did not result in significant visual winter injury to the barley so the impact appeared to be more of a general nature. Barley planting was dramatically affected by late planting unlike wheat. Delaying barley planting by just one week to October 15 resulted in a (four year average) yield reduction of over 15 percent and delaying two weeks to October 25 resulted in an over 20 percent yield reduction. Delaying planting barley until November increased the yield potential reduction to over 40 percent.

For winter wheat, experience has to be our guide with respect to planting date. We have evaluated the ideal planting date versus later planting dates but not against a September planting date for wheat. However, we can use both past experiences and basic agronomic knowledge to evaluate the risk involved with early planting wheat.

Since September planting dates are before the Hessian fly-free date for all our counties, we can surmise that the risk of lodging during grain fill will be increased versus planting after the fly-free date. You do need to keep in mind that the fly-free date is based on temperature averages and during warmer than normal falls fly emergence and egg-laying activity can extend past the listed dates. Larval activity can cause lodging, stunting, and yield loss since wheat tillers can be severely injured. In past variety trials, we have seen significant injury and yield reductions on susceptible varieties. Early planting of wheat can increase your risk of an infestation especially if wheat is planted in fields with wheat stubble or in fields next to one with wheat stubble.

For wheat that is planted following dryland corn, the greatest risk this year likely is due to excessive soil residual nitrogen (N); or, if the fall weather is warm and moist, to fall N mineralization from the high levels of nitrate in the dryland corn residue. High fall N availability can lead to excessive growth that will be more susceptible to winter kill or injury if we have a cold, open winter. In past years, we have had many growers asking what they could do about all the excessive top growth that occurs when wheat is planted in September and fertility levels are high. In some areas of the country, the extra foliage is used to graze cattle or sheep but most Delaware farmers do not have this option. The option tried has been to mow off and sometimes remove the excessive top growth. This has at least in part been successful in reducing winter injury but there are significant costs associated with the practice.

Another concern that again depends on fall weather conditions as well as insect populations and a residue of disease inoculum is the development in September planted wheat of disease or insect problems. In particular, barley yellow dwarf virus, which is transmitted in the fall by aphids feeding on the lush growth, can cause more severe injury than spring infections. The lush growth of early planted wheat could be more of an attractant for aphids but certainly will have a longer exposure to the risk of infestation.

All these cautions are not to say that you should never plant wheat or barley before the fly-free date only that you should be aware of the possible consequences and make a decision on when to plant and how many acres to plant from a position of knowledge.

Considerations for Small Grains Weed Control

Friday, September 7th, 2012

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

For no-till fields, a non-selective herbicide needs to be used prior to planting. If grasses are present glyphosate is a better choice than paraquat. Fields worked with a vertical tillage implement for residue management still need a non-selective herbicide. These implements are not weed control tools.

There are few effective herbicides labeled for preemergence applications. Sharpen is labeled but we have limited data in the region to recommend it for either residual weed control or crop safety. Valor can be used at 1 to 2 oz with the burndown application, but there must be a 30 day period between application and planting wheat due to concerns with crop safety.

A few products can be used shortly after the crop has emerged. Axiom and Prowl H2O can be used at crop emergence (Axiom at the spike stage and Prowl H2O at 1 leaf stage); however they need to be tankmixed with other herbicides or followed by postemergence herbicides to provide a broad spectrum of control.

Products that provide postemergence control include: Harmony, Harmony Extra, Starane Ultra, Osprey, PowerFlex, Axial XL, 2,4-D, or dicamba. Others labeled with a limited fit include metribuzin, Finesse, and Maverick.

Review of Barley Yellow Dwarf in 2012

Thursday, August 2nd, 2012

Phillip Sylvester, Kent Co., Ag Agent; phillip@udel.edu, Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu and Nancy Gregory, Plant Diagnostician; ngregory@udel.edu

As we approach the upcoming small grains planting season, it is a good time to discuss barley yellow dwarf management. Barley yellow dwarf (BYD) can be found most years in a few wheat fields in Delaware. It is not uncommon to see a few infected plants, primarily in the spring. In 2012, the number of fields with infected plants appeared to be generally higher compared to most seasons. Impact on yield was variable, though it was estimated that some fields experienced a 5% yield loss. The dry spring weather in Delaware had a larger impact on yield, therefore it was difficult to estimate the true impact of BYD. It is important to understand the causal agents, symptoms, and disease cycle in order to best manage BYD. Barley yellow dwarf is the most widespread virus disease of cereal crops worldwide and can infect other crops such as rye, barley, oats, and corn, though the greatest concern in our area is in wheat.

Causal Agents
There are numerous virus types that actually cause BYD. While the taxonomy of BYD can be complicated, it’s important to note that some strains are more severe than others. The ones that are of greatest concern in our area are (in order from least severe to most severe): BYDV-MAV, BYDV-PAV (severe strain), and CYDV-RPV. CYDV-RPV, cereal yellow dwarf, was named and then later found to be a related strain of BYD. Both CYDV-RPV and BYDV-PAV were confirmed in the samples submitted this past spring from wheat fields in Delaware.

Vector
The BYD viruses are limited to the phloem and can only be transmitted from plant to plant by aphids which have piercing/sucking mouthparts. The infection occurs after aphids feed on infected hosts, such as wild grasses, and then move into and feed on wheat fields. The wild grasses may be infected yet show no symptoms. It can take as little as 12-48 hours from the time aphids feed on the infected grasses until infection has occurred in wheat plants. This can occur anytime that aphids are actively feeding, which would typically be in the fall and spring months when the weather is warmer. Since the spread of barley yellow dwarf depends on aphids, management of the aphids may be helpful in fields with known problems of barley yellow dwarf in the past. Remember that the viruses causing BYD are only transmitted by aphids and are not known to be seed-borne. Read the Aphids Prevention and Barley Yellow Dwarf Management article in this issue of WCU for more on management.

Symptoms
Symptoms include leaf discoloration (Figures 1- 3), shortening of the internodes, and general stunting of the plant. Leaf discoloration typically has a characteristic purple to yellow color. Symptoms become exacerbated by cool weather and high light intensity. Hot spots (cluster of infected plants) may occur near field borders, field corners, or near woods depending on how the aphids moved. To further complicate matters, the plant’s reaction to the infection may vary depending on when the plant was infected and the variety of wheat. Fall infections usually result in more stunting and less tillering while spring infections tend to discolor the flag leaf and are thought to cause little yield loss. Other viruses such as wheat spindle streak and/or wheat soil-borne mosaic virus may infect the plant causing additional symptoms (see Figure 4). The other viruses are not transmitted by aphids. To learn more about the other viruses we encounter in Delaware, read Bob Mulrooney’s article on Viruses in Winter Wheat at: http://agdev.anr.udel.edu/weeklycropupdate/?p=2745.  It’s difficult to identify viruses in the field and samples should be submitted to a lab for testing to confirm virus infection.

Figure 1. Wheat plant infected with barley yellow dwarf (BYDV-PAV).

Figure 2. Wheat plants infected with barley yellow dwarf (BYDV-PAV).

 Figure 3. Wheat plants infected with barley yellow dwarf (BYDV-PAV).

 Figure 4. Wheat Plant infected with BYDV-PAV, CYDV-RPV, wheat spindle streak mosaic virus, and wheat soil-borne mosaic virus.

Figure 5. Close up of wheat infected with BYDV-PAV, CYDV-RPV, and wheat spindle streak mosaic virus.

Small Grain Harvest Began Early

Friday, June 1st, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Believe it or not, a number of growers have begun to harvest barley around the state and our winter wheat crop is advancing in maturity very rapidly. This is the earliest that I can remember growers beginning barley harvest and if wheat comes on as early as I think it will we also will have a record early harvest season for wheat. Although the very much shortened growing season for the small grains could signal lower yields for barley and wheat, I think we will find that double-cropped soybeans will have at least the potential for excellent yields. Weather and/or irrigation availability will determine the final yield potential for the double-crop soybean crop but with as much as a two week longer growing season, the soybeans could help make up for any shortage in the small grain yield.

So the message here is to not feel that you don’t need to plant soybeans as soon as possible after the small grain crop is harvested. Although the extra time may seem as if it gives you the opportunity to not be as pressured to plant soybean quickly, there is the possibility of a substantial reward for remaining aggressive in planting the soybean crop as soon as possible after removing the small grains. With the current price of soybeans, that reward could mean a significant return to you come this fall.

Wheat Disease Update – April 27, 2012

Thursday, April 26th, 2012

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

BYDMV
We have had several more reports and a sample of Barley yellow dwarf mosaic virus in wheat. Irregular patches of varying height reductions, yellowing and purple flag leaves indicate BYDMV infection. Since this virus is aphid transmitted there are no controls at this time.

Fusarium Head Blight
With the much needed rain that came and the forecast for more Thursday and possibly Saturday as well some have been asking about the possibility of head blight or scab appearing. The forecast at the present time is the probability is low. The corn residue on the surface needs to be wet for a long time before spores are produced that can infect the wheat at flowering and the temperatures need to be in the mid-70s for significant infection to occur. The temperatures have been and are too low now for infection. As long as the wheat flowers between now and next Wednesday when the forecast is for warmer temperatures the wheat will no longer be in a susceptible stage of development for scab to infect. I think the risk of scab it very low and specific sprays for scab control are unwarranted at this time.

Keep up to date with scab by visiting the website and using the 2012 Predictor. http://www.wheatscab.psu.edu/ This will be important if we should get more rain later in the week.  Make sure the predictor says 2012 across the banner. For some reason my browser is going back to the 2011 site. If you run into the same problem here is the 2012 link http://www.wheatscab.psu.edu/riskTool_2012.html

Leaf Rust & Stripe Rust
More of a possibility is the occurrence of some late season leaf rust and stripe rust. There has been stripe rust reported in NC earlier in the week and now a report of leaf rust and stripe rust from Mt. Holly, VA in university test plots. These reports are fairly close and after a big rain event like we had with some more possibly on the way we may see some develop within the next two weeks. If growers have a variety that is susceptible to leaf rust or stripe rust, there is a chance that we could see more rust two weeks from now depending on the temperatures. Again that might justify application of a fungicide at flowering if you have rust present now or are growing a susceptible variety. With the lack of water there may be undetected leaf rust in the lower canopy and with the recent rain there could be spread to the upper canopy. Be sure to get out and check the wheat before making a spray decision. Prosaro plus a non-ionic surfactant can be applied to wheat until 30 days before harvest; for scab control it needs to be applied at early flowering in 5 gal/A if applied by air. Tilt can only be applied until full head emergence. With the low risk of scab, strobilurin fungicides such as Headline and Quadris could also be considered for protection against leaf and stripe rust as well as tan spot, and the Septoria complex if those diseases are present, which have not been seen because of the dry weather. Be sure to check labels for application restrictions. Our past experience has shown that diseases that appear late (after flowering) usually do not have time to infect the upper leaves that are important for grain fill and reduce yield. If diseases are present in the canopy at flowering there is more of a risk of diseases reducing yield and/or quality of the grain.

Some information from Dr. Christina Cowger from USDA at NC State Unversity indicates that the following varieties are susceptible to stripe rust and might warrant spraying especially if any rust is present now. There are some gaps in our knowledge about susceptibility to stripe rust, so this is a very limited list of known susceptibility for varieties that are grown in the Mid-Atlantic:

Coker 9436, DG Shirley, NC Cape Fear, NC Neuse, NC Yadkin, P26R12, SS520, SS560, USG3209, USG3592, USG3665, SS8404

Freeze Injury
We just received a wheat sample from Kent County, DE with random bleached awns as well as tips of some heads. If you see some irregular bleaching of heads don’t panic about scab. We suspect at this point since no fungus appears to be present on this sample that the damage is from freezing. From spike emergence through flowering, freezing can cause symptoms that range from minimal bleaching of the awns to severe grain yield loss, depending on the duration and degree of freezing.(See Photo 3 in the article by Richard Taylor, “Another Risk of Frost on the Small Grain Crop”, which is in this issue of WCU) If normal kernel development does not occur, then freeze injury can be suspected.

Small Grain Disease Update

Thursday, April 12th, 2012

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

The dry weather and low humidity has been very unfavorable for diseases at the present time. There are still some fields of barley with powdery mildew and leaf rust. If they needed treatments they should have been treated by now. Wheat is looking a bit better in that powdery mildew levels are low and except for some barley yellow dwarf mosaic virus in some areas the crop looks good. Rainfall is desperately needed. The risk for Fusarium head blight or scab is low at the present time. To keep track of the threat of scab be sure to check the website http://www.wheatscab.psu.edu/.

Dry Spring and Small Grain Irrigation

Thursday, April 12th, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Available soil moisture is becoming a critical issue in small grain fields across the entire state. For producers fortunate enough to have the means to irrigate small grain fields, now is the time to replenish the top and subsoil moisture supply, especially for winter wheat. Barley is much further along developmentally (most has already headed out) and matures earlier in the year than does winter wheat. Although I might hesitate to spend the money to irrigate barley that is already past flowering, I would not hesitate to irrigate wheat, which, for the most part, has not reached the heading stage as yet. In some irrigation work we did on wheat a number of years ago, we found that irrigation after head emergence tended to decrease yield potential, although only by a small amount and this decrease may have been related to disease pressure encouraged by higher humidity conditions created when irrigating. My preference for small grain irrigation is to apply enough water before heading to build the topsoil and subsoil moisture levels back to near field capacity. This should provide the water the crop needs to mature since wheat and barley are excellent at using available soil moisture.

As a side benefit, irrigation can help with emergence in the crop following the small grain crop. Without adequate early irrigation, it can prove difficult to rewet the soil, and especially recharge the deeper layers of soil, with enough moisture to adequately support the second crop if the dry weather continues.

Frost Injury on Small Grains

Thursday, April 5th, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Several weeks ago frost damage was identified on several barley fields, although it appeared to be limited to leaf tip burn (see Photo 1). Since that time, a number of other fields of both wheat and barley have shown similar symptoms and at least at this time the long-range weather forecast indicates a continuing risk for frost in the state and region. Barley fields have begun to head out and are quite susceptible to frost which can kill the pollen in the anthers preventing successful pollination and subsequent grain fill. Many times the only way we can determine if this has happened is to wait and see if the crop develops blank heads as maturity approaches. In the most recent issue of the Mid-Atlantic Regional Agronomist Quarterly Newsletter (March 2012), Dr. Wade Thomason from Va Tech wrote a review article entitled ‘What’s The Risk? Development of the 2012 Small Grain Crop and Potential for Spring Freeze Injury’. The article, as well as one I wrote for Weekly Crop Update April 13, 2007, gives the risk of injury from frost and the expected impact on wheat yield potential.

The Mid-Atlantic Regional Agronomist Quarterly Newsletter is posted on several web sites. Among these are the following locations: http://sites.udel.edu/equine/fact-sheets/forages-hay-and-pastures/ (look for the March 2012 issue) or http://www.grains.cses.vt.edu/ (look for Mid-Atlantic Regional Agronomy Newsletter) or www.mdcrops.umd.edu (click on Newsletter).

Photo 1. Leaf tip burn on barley from freezing temperatures (Kent County Delaware)

Small Grain Weed Control

Friday, March 2nd, 2012

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

With the mild winter that we have had, small grain fields should be scouted for weeds, and applications should be made before the weeds get too large.

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.

Be sure to consider your rotation after small grains when you select your herbicides. Harmony Extra is very flexible for vegetable rotations; and Starane Ultra and Axial may require up to 120 days; while Osprey and PowerFlex cannot be rotated to vegetables for 9 to 12 mos. The most restrictive are Finesse and Maverick, which cannot be rotated to vegetables and require use of STS soybeans.


First Split Nitrogen Application to Small Grain

Friday, March 2nd, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Many wheat and barley fields that were not fertilized with manure or poultry litter last fall have looked poor for much of the winter. Even those fields that received some fall nitrogen (N) fertilizer but as commercial fertilizer have been yellow since mid-winter or earlier. Recently, the date when spring fertilizer can be applied was moved to earlier in February to help those with wheat that was showing signs of N stress and was trying to start spring growth. Since then, some cooler weather has settled over the region and slowed greenup in small grains.

For those who have not yet applied the first shot of N to their wheat, it is time to apply it. In fields that did receive fall manure or litter, the need is not as critical. In wheat, we have often seen about a 5 to 7 bu/acre yield increase when N applications are split into early greenup and then just before or at Feekes growth stage 5 when the first node is visible or can be felt above the soil surface. In work that Bob Uniatowski and I conducted a number of years ago, this response to splitting N applications was fairly consistent across locations and years. The largest response to a split application comes when significant rainfall occurs between the two splits causing some of the applied N to be loss either through leaching or denitrification. We also found that if all N was applied at one time, the early application date was the best choice although if the wheat had adequate tiller numbers in early spring even a Feekes growth stage 5 single application could produce excellent yield potential.

For those who may be growing barley, we did find that this crop is very sensitive to the rate of N applied because the straw strength seemed to be most affected at high rates of N. Whenever we applied much more than about 80 pounds of N per acre, we started seeding significant lodging which can not only make harvest difficult but can cause yield reductions, especially when lodging occurs early in the grain fill period.