Trial summaries for applied research on field crop disease and nematode control conducted in Virginia in 2015 are now available.
Applied Research on Field Crop Disease Control in Virginia, 2015
Category Archives: Small Grains
2016 Wheat and Growing Degree Day Accumulation
Previous work in VA has demonstrated that we “normally” accumulate around 1350 GDD from planting to jointing in wheat in Virginia. The warm weather this year has been anything but normal and so I don’t think we can follow that guidepost this time.
Our wheat varieties require at least 30 days of temps less than about 42 degrees to vernalize. In most areas we made that threshold of at least 30 days between what I considered to be a normal planting date for the region and the end of the year. For example near Richmond a crop with planting date of Oct 20 would have experienced 31 days with lows below 42F before January 1. Other researchers have reported that wheat requires around 700 GDD after the vernalization threshold has been reached. This seems pretty reasonable for use in VA. When comparing to the 30 year average temperatures for central VA, 700 GDD accumulated from January 1 predicts a jointing date of March 20. I believe this matches well with historical observations for the crop
Below is a figure showing GDD accumulated at 3 sites in eastern VA since January 1, 2016.
Yep – it’s been warm. About 40% greater GDD accumulation at this point in the year compared to the long term average. Normally we are accumulating about 5.75 GDD/day this time year. This year it’s over 8.
I honestly don’t what this means for us in terms of wheat development.
If the temperatures return to the 30 year average tomorrow the warm weather thus far would have relatively little impact. Instead of predicting a jointing date of March 20 (700 GDD) we would get to 700 GDD on about March 15.
The 14-day forecast I’m looking at has us continuing to stay warmer, however.
If we stay near the current trend through jointing, it’s possible we will be 3 weeks ahead of the long term average.
I won’t pretend to be able to forecast the coming weather, but I think it’s likely that things may begin to happen very quickly with the crop.
This may impact our ability to split N applications as driving over wheat that’s already jointed damages the growing point. I suspect weeds, insects, and disease are also responding to these warmer temperatures. Small weeds are going to get to be big weeds sooner this year. Diseases like powdery mildew have already been found in the crop in some places. Scouting early and often may prove a valuable investment.
26th Annual Eastern Shore of Virginia Ag Conference & Trade Show
The Eastern Shore of Virginia Ag Conference & Trade Show is on! We are snow free, and looking forward to a great event on January 26 and 27, 2016. The event will take place at the Eastern Shore Community College Workforce Development Center in Melfa, VA. The full program can be found at: http://issuu.com/esarec/docs/flipbookfinal/1. We have been approved for Certified Crop Adviser (CCA) CEU credits (details at: https://www.dropbox.com/s/f34f3spg4quni7a/CCA_Credits_Handout_2016.pdf?dl=0), Virginia Nutrient Management Credit (1 credit), and Virginia Pesticide Recertification credits (information in the program). See you there! Directions can be found at: http://es.vccs.edu/about/mapdirections/.
Eastern Shore Ag Conference & Trade Show
Join Virginia Tech, Virginia Cooperative Extension, the Virginia Association of Potato and Vegetable Growers, and Industry to hear updates, research information, and innovative products for grain, oilseed, and vegetable crops important to Virginia’s Eastern Shore on January 26 and 27, 2016. This event is free and open to the public. Announcements concerning conference updates, weather delays and/or closings, etc. will be made at: https://www.facebook.com/EasternShore.Soils. Highlights of the program can be found in the attached flyer.
Eastern Shore AREC Specialist Day
Join us next week, November 17th, at the Eastern Shore AREC (33446 Research Drive, Painter, VA, 23420) for Weed Science Specialist Day. Topics will include new herbicide technology and control of herbicide-resistant Italian ryegrass in wheat. The event will begin at 10:00am and conclude at 12:00pm. Lunch will be served promptly following the meeting. Please RSVP to Ursula Deitch (ursula@vt.edu) or Theresa Long (tmjlong@vt.edu) by Friday if you are interested. See the below flyer for more details.
Specialist Day will be held at the Eastern Shore AREC on Tuesday Nov. 17th.
Herbicide-resistant Italian Ryegrass
With harvest in full swing, it is hard not to forget about weed control in wheat. Primarily of concern is herbicide-resistant Italian ryegrass. In the past, ACCase- (Hoelon) and ALS-inhibiting (PowerFlex and Osprey) herbicides provided control of this weed. However, Italian ryegrass biotypes resistant to these products have developed, but that is not to say these herbicides will no longer work in your area. For example, Osprey is still effective throughout most of Eastern North Carolina, but once you move into the Piedmont, ryegrass control by Osprey is hit or miss. In areas with known ALS-resistant Italian ryegrass, Zidua is suggested delayed-preemergence. Delayed-preemergence means 80% of germinated wheat seeds have a shoot at least ½-inch long. If applied prior to this stage, injury may occur. Zidua is a seedling-shoot inhibitor and will not control emerged weeds, therefore, it is important for fields to be clean prior to application. Axiom applied spike (applied preemergence, Axiom can cause severe injury) also controls Italian ryegrass if a timely activating rainfall is received following application. Another option on no-till or minimum-till fields (where stubble from previous crop has not been incorporated) is Valor SX applied preplant. Valor must be applied at least 7 days prior to wheat planting and should be applied in combination with either paraquat or glyphosate to control emerged weeds. Tillage should not be performed after Valor SX is applied. Italian ryegrass control by Finesse is variable and growers should expect only suppression. If Finesse is applied, plant only STS-soybean following wheat harvest. Postemergence options for Italian ryegrass include Axial XL and Osprey. Although most Italian ryegrass is Hoelon-resistant, Axial XL (also an ACCase-inhibiting herbicide) still seems to work in most areas. Osprey may also control Italian ryegrass in areas yet to develop resistance and will also control small bluegrass.
Ryegrass in the non-treated control. Received glyphosate 14 days preplant.
Ryegrass control by Valor SX plus glyphosate applied 7 days preplant
Wheat seeding rate and drill calibration, 2015-16
Based on previous research we know we need at least 70-80 heads per square foot to reach optimum wheat yields. That typically requires a seeding rate of 30-35 seeds per square foot, which is equivalent to 20-22 seeds per foot of row in 7.5 inch rows. The reason we advise seeding based on actual number of seeds per seed lot, and not on a pound per acre basis is that seed size varies considerably among wheat varieties and over years for the same variety. The number of seeds per pound is determined both by genetics and by environment. A few of the entries in our state wheat variety test are listed below and it’s obvious that a range of 30% or larger exists among varieties within a year. The consequence of not calibrating grain drills to deliver the optimum seeding rate can vary. If too little seed is planted, yield potential may be compromised. Overseeding increases seeding cost and in a year with smaller profit margins in wheat, we certainly need to avoid both. This management activity is an investment of time, but spending that time can result in greater profit.
|
2016 |
2015 |
2014 |
Mean |
% Dev. |
|
|
———–seed/lb———– |
|||||
| Massey |
13046 |
12371 |
10318 |
11912 |
23% |
| Jamestown |
13472 |
14277 |
11762 |
13170 |
19% |
| Shirley |
11100 |
10861 |
9722 |
10561 |
13% |
| Pioneer Brand 26R20 |
12825 |
14157 |
11378 |
12787 |
22% |
| Pioneer Brand 25R32 |
13593 |
13488 |
13353 |
13478 |
2% |
| Featherstone 73 |
14099 |
12304 |
11436 |
12613 |
21% |
| VA10W-119 |
10993 |
11756 |
9578 |
10775 |
20% |
| Pioneer Brand 26R10 |
10509 |
12587 |
11073 |
11390 |
18% |
| Pioneer Brand 26R41 |
11979 |
10682 |
10913 |
11192 |
12% |
| Pioneer Brand 26R53 |
11671 |
11988 |
11947 |
11869 |
3% |
| Avg. by year | 12329 | 12447 | 11148 | 11975 | |
TriCor Receives Registration for use in Wheat and Barley
The herbicide TriCor, a metribuzin product from United Phosphorus Inc., has received 24(c) registration (special local needs) for use in Virginia for control of Harmony and Harmony Extra (group 2 herbicides) resistant common chickweed. The supplemental label is here: TriCor DF Herbicide 24(c) VA label. This is good news for small grains growers.
Research by Drs. Scott Hagood and Michael Flessner indicate that TriCor at 2 oz/a results in excellent common chickweed control when applied in fall or spring, with no significant injury to wheat. However, wheat injury can be a concern. Using crop oil concentrate or vegetable oil surfactants with TriCor increases the risk of crop injury, as well as when applying with fertilizer in combination with TriCor. Growers should select wheat and barley varieties that are tolerant of metribuzin if planning on using TriCor as certain varieties are more sensitive to metribuzin than others. Seed dealers may have information regarding metribuzin tolerance. Additionally, preliminary nonreplicated wheat variety sensitivity research by Drs. Wade Thomason, Carl Griffey, and Michael Flessner is included in this publication: https://pubs.ext.vt.edu/CSES/CSES-129/CSES-129-PDF.pdf. See pages 99 to 101.
Always make sure to read and follow the product label. Also note that TriCor is the only stand-alone metribuzin product legal for this use.
Example of wheat variety differences in sensitivity to metribuzin. Thomason 2015.
Preliminary 2015 Hulled and Hulless Barley OVT results posted
The 2015 barley OVT trial data have been posted to the Corn and Small Grain Management website. By-location, 2015, two and three year data are summarized in Excel format. The links can be found on the website:
http://www.grains.cses.vt.edu/
Or by using these direct links to the excel files.
http://www.grains.cses.vt.edu/Testing_results/barleytables2015.xlsx
http://www.grains.cses.vt.edu/Testing_results/hullesstables2015.xlsx
The Value of Straw
Farmers are busy in the fields harvesting barley and wheat. Often, farmers opt to bale the straw themselves or allow custom balers to come in and remove the straw from the land. What is the nutrient value of this straw being removed? Check out this publication to figure out what fertilizer nutrients are being removed to help gauge whether the straw should be baled or not. Straw_Value_17June2015