|I live in Everett Washington. I moved here 2 seasons ago from SD. I have since killed most of the morning glories, blackberrys, and moss. But I still have problems with the grass getting rusty colored and in some areas it takes on a white, dead appearance. I have power raked, reseeded, fertilized once early this spring, still the problem persists. My blade on the mower is sharp???????????????|
|What you describe sound like the fungal diseases rust and powdery mildew. Both are common in the Pacific Northwest, both are caused by cultural/environmental conditions and both are self-limiting in that they go away when the weather warms up in the summer. It sounds as though you've already put in lots and lots of time on your lawn so I know how exasperating it can be when the lawn doesn't respond in a positive way! Let's backtrack a little. You mentioned moss, which is a clue as to how your lawn is doing, and the immediate environment. Moss is a symptom of several things: too much shade, poor drainage, compacted soil, acidic soil. If you can address each of these causes, you can eliminate moss from your lawn and you can discourage rust and powdery mildew, as well. If you have a lot of shade, grass won't grow well (except when first sodded) and will become thin and more vulnerable to weeds and moss. Limbing up nearby trees or thinning out the canopies might supply more sunlight to the area. Poor drainage is usually caused by clay soils or those that are compacted due to heavy foot traffic. Aerating every few years will give your lawn a better opportunity to drain well. Aeration can be done with a machine you can rent at most garden centers. The machine pulls 1/2" by 3" plugs out of the ground. You can leave the plugs where they lay and they will break down over a period of several weeks. After plugging you can sprinkle a thin layer of compost or sand on the lawn. The sand or compost will work its way down into the holes left from the plugs and will help improve the drainage and compaction problem. Acidic soils can promote the growth of moss so you might want to have your soil tested. If it is 6.0 or below you can spread lime over your lawn in the fall. It will break down over the winter months and help sweeten the soil. It's still early enough in the season to aerate your lawn. This fall you can address the problem with acidity by spreading lime.
Best wishes with your lawn!