This spring has brought two problems for our client’s lawns. Clark County has been invaded by Poa Annua, a native, highly invasive grass, and leaf spot, a common fungal disease.
Poa Annua is an annual blue grass, easily identified by the small, white seeds it prodigiously produces throughout the spring and early summer (see picture right). Poa will produce seed at any mowed height, but will usually stop seed production by mid-July, making it much less noticeable.
These seeds germinate in the fall, when soil temperatures drop below 70 degrees and can remain viable for several years, germinating when conditions are favorable.
In practical terms, it is not economically feasible to control Poa. This grass will out-compete any other type of grass in our unique, northwest climate, and has quickly invaded almost every lawn we service. If it is found in small patches, it can be treated with Glyphosate (Round Up) and the areas reseed or resodded.
Because Poa is so wide spread and persistent, managing it, i.e. blending it into your lawn, may be your best solution. It is usually most noticeable in your turf for a 6-8 week period in the spring, when it is producing heavy seed populations. The majority of the year, other than a “patchy” effect, Poa blends well (compared to most other invasive grasses) in most turf settings.
Leaf spot is a common fungal disease that can be found year round, in almost all of the lawns in Clark County. However, when conditions are favorable; the disease pathogen is present, coupled with temperatures 75 degrees and above and available moisture, leaf spot can progress to the destructive melting out phase. (see photos right and left).
This disease first appears as light green or purplish, unevenly growing areas in the turf. These patches will, over the course of a few days, fade to a tan color and then straw color. As the disease progresses, it forms irregularly shaped dead spots with circular spots of healthy, green grass. This “frog eye” effect is highly characteristic of the disease.
If your applicator sees this condition in your lawn during your regularly scheduled service, he will leave a green, informational sheet will your invoice with more detailed information and a quote for a fungicide application, which will stop the disease. If you suspect this disease may be present in your lawn between visits, you should call our office.
Because fungicide applications can be expensive, we also want to offer our valued clients the option of treating this disease themselves. Immunox, a ready to use fungicide concentrate can be purchased at Home Depot. As with all pesticides, it is very important to carefully read and follow the label to achieve safe, effective results.