Since the weather has not been cooperating, we have not received many samples in the clinic so far this season. It's still pretty cool and moist. We have received several samples of turfgrass with Necrotic Ring Spot already this spring. As soon as soil temperatures start warming up, we expect to see more. Information on control can be found here: http://www.ext.colostate.edu/pubs/garden/02900.html. There are both cultural and chemical controls, but be advised that NRS is a difficult disease to cure.
We have also received a couple of samples of wheat with Tan Spot (Pyrenophora tritici-repentis). This disease can show up anytime April-June and appears as small brown, oval lesions with tan centers usually with a yellow halo around the lesion. It is always a good idea to get confirmation of this pathogen before deciding to spray as magnesium and chloride deficiencies can mimic tan spot. This disease overwinters in old wheat stubble and germinates in early spring after a prolonged wet period (usually 24 hours or more). Asexual spores are spread by wind and keep the disease cycle going, infecting new leaves. North Dakota State University has an excellent fact sheet on control measures that can be found at http://www.ag.ndsu.edu/pubs/plantsci/pests/pp1249w.htm.
With the recent moisture we can also expect to see Gymnosporangium rusts, most often Juniper-Hawthorn rusts. This disease will manifest first as orange, gelatinous masses on juniper causing some discomfort for homeowners. These brightly colored galls often look like some alien being has landed in the landscape. After they dry, the galls become dark brown and will stay on the junipers but will not generally harm the plant, only causing aesthetic damage. Cooperative Extension Plant Talk has a script on this disease that can be found at http://www.ext.colostate.edu/ptlk/1450.html.
Recently planted vegetables will be set back a bit with this cooler weather. Be patient with your landscape as the roots need some warm soil temps to really get your plants going.