Watch For Tan Spot

Now that we have received significant rainfall and considerable acreage of wheat has been planted in to wheat stubble, there is concern about the crops susceptibility to leaf diseases. Certainly winter wheat fields planted last fall into wheat stubble should be watched carefully for such diseases, especially tan spot.

There is a number of fungicide products registered for tan spot control, including products in the Strobilurin class and the Triazole class. There are also combinations of these products available. Fungicides for this purpose are rated for efficiency (not price) in the 2012 Wheat Fungicide Efficiency table found in a link at http://www.ag.ndsu.edu/extplantpath/.

Keep in mind that fungicides for this use are generally applied at half the full label rate in mixtures with herbicide applied at the three to five leaf stages. Also, if the fungicide is applied with herbicide, an additional adjivent for the fungicide should not be included. Some product combinations have been shown to cause leaf burn, especially if temperatures soar into the high 80s after application.

As long as I am on the issue of diseases I want to call attention to a special program of extension services in North Dakota, Minnesota, and South Dakota that will alert growers of Fusarium head blight (FHB). These alerts can be sent to either a mobile phone or to your email. Sign-up directions are found at http://scabusa.org/fhbalert.php. Updates on other wheat and barley disease risks also may be provided. Currently, states in winter wheat producing areas to our south or east have indicated relatively low FHB risks so far this year.

Tree of the Week

Oh, how we love these white-barked trees. But, they sure can break the heart of a homeowner. The birch trees prefer moist sites and most do not tolerate prolonged droughts. The biggest problem with birch trees is their susceptibility to the bronze birch borer after the tree has been stressed, usually by environment conditions.

There are several types of birch trees growing in the area. The most common seem to be the Asian White Birch (Betula platyphylla) and European White Birch (Betula Pendula).

The hardbook “Trees and Shrubs for Northern Plains Landscapes” lists three varieties of Asian White Birch – Dakota Pinnacle, Japanese White Birch and Prairie Vision. Dakota Pinnacle and Prairie Vision are both NDSU developed varieties. The handbook recommends Prairie Vision because of its higher resistance to the bronze birch borer.

The Paper Birch is a native tree that does best on loamy or sandy soils that are well drained. It requires cool, moist sites and will not tolerate prolonged droughts. By comparison, it is similar to aspen in water needs.

The European Birch (Betula pendula), at one time, was the most popular white barked birch because the bark develops at an early age and many of the varieties have gracefully pendulous branches. It is easily stressed making it very susceptible to the bronze birch borer. My observations indicate it is more prone to iron chlorosis and often times I see trees of Betula pendula with as many dead branches as there are branches with leaves.

Birches can withstand our winters provided they are not stressed during the growing season. They tend to be shallow-rooted and subject to soil compaction caused by humans and pets.