Posts Tagged ‘barley powery mildew’

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/.

Small Grain Diseases

Friday, March 2nd, 2012

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

Powdery Mildew on Small Grain
Be on the lookout for powdery mildew on ‘Thoroughbred’ barley and wheat. Powdery mildew has been seen on both within the last several weeks. ‘Thoroughbred’ barley is very susceptible to PM as you know and if the stand is thick and lush you will more than likely see it. Does it need to be controlled this early in the season? I think it depends on how many times you are willing to spray it. Dr. Arv Grybauskas did a trial last season looking at fungicide applications at jointing (GS6), flag leaf emergence (GS9) and flowering (GS10.5) Tilt (4.0 oz/A) was applied at GS 6 or 9 and Prosaro (6.5 fl. oz/A) was applied at GS 10.5. While all treatments gave a positive yield response in two trials, only the later applications gave a significant yield increase. It confirms what we have been saying about the importance of keeping the top two leaves free of disease and the positive relation to grain fill. This is true in wheat and susceptible barley like ‘Thoroughbred’. If you spray to control mildew at jointing you may have to come back again later because the control will not last season-long. Disease control later is more important for protecting the yield potential of the crop.

For powdery mildew on wheat, check areas of rank growth first to see if the disease is present in the field then revisit to see if it spreads. It is too early to consider control of powdery mildew (PM), but if it is present, keep scouting. Unless the variety is very susceptible the mildew does not move fast depending on the weather.

Rank areas, like the one pictured here that was infected with powdery mildew, should be checked often.

Close-up of powdery mildew as it looks now

Rust on Small Grain
Everyone has been wondering about the possible consequences of the warm winter and one consequence might affect wheat. Both leaf rust and stripe rust have been found in the South this winter. It has been mild and relatively moist depending on the location. This scenario is conducive for rust infections that get started in the southern production regions and blow north as the season progresses. With the early appearance down south, the mid-Atlantic area may see rusts early enough to be a threat. Keep your eyes open as the season progresses.

Agronomic Crop Disease Update – May 13, 2011

Thursday, May 12th, 2011

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

Barley
Powdery mildew on ‘Thoroughbred’ is the most common disease at the present time. Fields with the top two leaves with mildew will have some yield reduction. After looking at the variety trials in Sussex County on Tuesday I could also find small amounts of leaf rust, barley scald and the spot form of net blotch. None of these should impact yield.

Wheat
Wheat is looking very good at the present time. There is very little disease present. A few unsprayed varieties have some powdery mildew that is confined to the lower leaves and leaf sheaths. A small amount of leaf rust was also spotted on one unsprayed variety on the lower leaves. Most of the wheat that I saw has flowered and with the dry weather in most of the southern parts of the state, it looks like head scab should not be a problem. In the northern areas of the state if we get showers this weekend we may have some opportunity for infection if wheat is flowering.

Barley scald

Soybeans and Soybean Cyst Nematode
It is still not too late to check for soybean cyst nematode especially if susceptible soybeans are going to be planted. Soil test bags with the submission form can be purchased at the Extension offices. If you need results quickly, test results can be sent via FAX or email if you provide the number or email address on the Nematode Assay Information Sheet. This information sheet can be found on the web at the Plant Clinic Website http://ag.udel.edu/extension/pdc/index.htm .

 

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.

 

Agronomic Crop Diseases

Thursday, April 22nd, 2010

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

Wheat
The first disease of the season on wheat is usually powdery mildew. In general, powdery mildew has not been a problem for several years. Once wheat reaches jointing (Growth Stage 6) it should be scouted regularly for powdery mildew. As always, planting the highest yielding resistant varieties is the best control strategy, but if mildew threatens to rob yields later, fungicide control is the best control measure. Tilt, Propimax EC, Stratego, Quilt, Proline, and Caramba (the new Group 3 triazole from BASF) are suggested for control when and if fungicides are needed. These fungicides are also very effective for control of tan spot and Septoria leaf spot and glume blotch. It is common for powdery mildew to infect the lowest leaves and remain there for some time. The critical time to scout for powdery mildew is GS 8-10 (when the last leaf just appears until head emergence) to determine if fungicides are needed.

Barley
We have had reports of increasing amounts of powdery mildew on barley. ‘Thoroughbred’ looks to be the most susceptible variety but others should be scouted as well. Regionally we have no data to evaluate fungicides for control of barley diseases because barley rarely needs to be sprayed for diseases and the cost has been prohibitive. Times have changed, and if the heads are emerging and the top two leaves are infected there may be some benefit to controlling powdery mildew on a susceptible variety such as ‘Thoroughbred’ if the weather continues to favor powdery mildew. Stratego, Tilt, Quilt (10.5 – 14.0 oz/A) would be suggested for control if necessary. A beneficial non-target effect will be brighter straw if straw is being baled.

Powdery mildew on barley.

Soybean Cyst Nematode
It is still not too late to check for soybean cyst nematode, especially if susceptible soybeans are going to be planted. Soil test bags with the submission form can be purchased at the Extension offices. If you have a fax machine and need results quickly, test results can be sent via FAX if you provide the number on the Nematode Assay Information Sheet. This information sheet can be found on the web at the Plant Clinic Website http://ag.udel.edu/plantclinic .