Posts Tagged ‘barley powdery mildew’

Small Grain Disease Prevention

Friday, September 23rd, 2011

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

Be sure that you plant wheat and barley 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 fungicide that will protect them from early infection.

Small Grain Disease Update – May 27, 2011

Friday, May 27th, 2011

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

Barley
The most prevalent diseases that can still be seen in areas where the barley has not returned yet are the spot blotch form of net blotch and powdery mildew. After checking the barley varieties today near Sandtown in western Kent County I don’t believe that net blotch will be affecting yields, but powdery mildew on unsprayed ‘Thoroughbred’ will reduce yields if the flag leaf is infected. There is some scab infected barley in Kent County.

Wheat
The wheat in the Kent County variety trial has tan spot moving in rapidly on some varieties. Most of the varieties are in the watery ripe stage of development and will not likely be adversely affected. Leaf rust was easily seen on a public variety ‘Rumor’. Powdery mildew in general was low in most varieties but was in the upper canopy on SS8302, Milton, Bravo, and USG3770. There is a low level of scab in the trial as well. If scab is going to appear it should be evident now or very soon depending on location. Low levels of scab (less than 1% of the heads infected and most of the infected heads were only partially infected) were present in 8 out of 45 varieties (around 18%).There is some sort of physiological spotting that could look like a disease but is probably a resistance reaction by the variety in response to a fungal infection. This spotting was evident on the following varieties at this Sandtown location: Merl, Sunburst,USG3665, USG3409, USG3251, and Grow Mark FS627.

 

Scout Barley for Disease

Thursday, April 15th, 2010

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

Scouting barley regularly is important to monitor for diseases such as powdery mildew and spot blotch, especially in ‘Thoroughbred’. This variety has great yield potential but is very susceptible to powdery mildew and the disease has been yield limiting. Fungicide applications may be warranted if enough disease is present and yield potential is high. Most other varieties would not likely respond to fungicide control of powdery mildew and/or spot blotch unless disease occurrence was very high.

Small Grain Diseases

Friday, April 18th, 2008

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

Barley
We have had reports of increasing amounts of powdery mildew on barley. Looking at my evaluations of the barley variety trials that Bob Uniatowski conducts yearly, ‘Thoroughbred’ looks to be the most susceptible in the trials but there has never been enough disease present to warrant spraying. 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 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.

Barley Powdery Mildew

Powdery mildew on barley

Wheat
This week the diagnostic lab received more wheat samples with virus symptoms. The first results have come back and the virus detected was soilborne wheat mosaic virus. SBWMV is a virus that is transmitted to the wheat in the fall by a soil born fungus called Polymyxa graminis. Symptoms range from mild green to prominent yellow leaf mosaics and streaking. Stunting can be moderate to severe. In this region the symptoms are found on plants in areas that are generally wet or poorly drained. Virus symptoms often diminish when the weather gets warm and symptoms are confined to the lower leaves. Symptoms on the upper leaves can look identical to wheat spindle streak mosaic virus. Planting resistant cultivars is the best solution for fields with a history of SBWMV.

I would suggest waiting until early head emergence before applying fungicides to wheat if disease levels do not warrant spraying now. Delaying until head emergence is the last opportunity to apply most fungicides and that application can carry the crop through harvest if glume blotch, tan spot, or rust should appear at or after heading. Another benefit is sooty mold control if we have poor weather during harvest. In most cases disease levels are low in wheat except where high nitrogen carry-over or over fertilization has occurred. That has resulted in more powdery mildew.