Dial-a-Garden Message

for the Week of Monday, September 7, 2009

Susan Rose, Horticulture Education Specialist
Colorado State University Extension Tri River Area

Thank you for calling Dial-a-Garden. This message was recorded on Tuesday, September 8, 2009.

The evapotranspiration rate for the last seven days is 1.2 inches in the Grand Valley, for cool-season lawns such as Kentucky bluegrass or perennial ryegrass. As the precipitation in the area has been anything but uniform, please check to see whether your lawn needs watering by digging down into the soil with a trowel or probe. If it penetrates easily to 6 or 8 inches, you don’t need to water yet.

On Friday, September 18, we will be holding an open house at our new Ute Ethno-Botany Learning Garden, located behind the Extension office on the Mesa County Fairgrounds. Public events begin at 2:00 p.m. and include a talk on Ute archaeology in Western Colorado and traditional songs by members of the Ute Indian Tribe of the Uintah and Ouray Reservation. Following these events please tour the garden and learn about how the Utes utilized the native plants. A donation of $2.00 per person or $5.00 per family is requested to help support the garden.

The weather conditions are perfect right now for the development of powdery mildew. This easily recognizable fungus appears as patches of grayish-white powder, and is most often seen on the upper surfaces of leaves. We’ve been seeing it on squash, pumpkins, lilacs, roses, and bindweed. Unfortunately, it doesn’t kill the bindweed though it does slow it down. Powdery mildew is a unique fungus that does not thrive in the presence of standing water, but what it does require is high humidity. It occurs readily in crowded plantings and in damp, shaded areas, and preferentially attacks young succulent plant tissue. Powdery mildews are host specific and will not spread, for example, from roses to grasses.

To manage powdery mildew, avoid overhead watering. Fall sanitation - the removal of all infected leaves - greatly reduces the overwintering of the disease. Don’t compost this material, as home composting units are unlikely to get hot enough to kill this disease. Thin out crowded plant material to help reduce humidity, and don’t apply nitrogen fertilizers at this time to avoid the production of succulent plant material. Powdery mildew may be treated with fungicides; one to try is potassium bicarbonate which is non-toxic. Read the label of any fungicide to determine how, how much and when to apply it to your specific plants, and observe the pre-harvest interval if you’re applying it to food crops.

Wasps are abundant right now. They generally will mind their own business if not disturbed too much. If they are a real nuisance, look for a product specifically labeled for managing them, which will contain a chemical for a quick knockdown. Spray at night or early in the morning, when most of the wasps are on the nest. A fact sheet with more information on Nuisance Bees and Wasps is available at www.ext.colostate.edu/pubs/insect/05525.html or give the Master Gardeners a call at 244-1836.

Another insect we often encounter in the late summer and fall is the red velvet ant, Dasymutilla magnifica, which is actually a solitary wasp. The female is wingless and has a distinctively red furry abdomen. The sting of this wasp is notoriously painful so do treat it respectfully; it moves around rapidly and covers a lot of territory but it is not aggressive and feeds primarily on nectar.

Some spiders and insects try to move into the house as the weather cools, seeking shelter. They are generally not seeking food, but are looking for a safe place to spend the winter. They may be attracted to water, so fix any drips in the plumbing. Check and repair any cracks or torn screens, and use weather stripping around doors to help prevent entry.

Another commonly seen nuisance insect that we see in the fall is the fruit fly, which has a life cycle that coincides with ripening fruit. Disposing of any peels, cores, etc. right away can help minimize the number of these insects you’ll have to deal with. I’ve had some success with leaving a small glass of wine sitting out overnight. The fruit flies become immobilized by the wine and can be washed down the drain in the morning. If you don’t have wine available (or prefer not to waste it) you can make a similar trap using vinegar. The vinegar doesn’t knock them out like wine does, so you’ll need to cover the glass or jar with foil and punch small holes in it with a toothpick. The fruit flies are better at getting in than getting back out.

Give us a call with your yard and garden questions and we’ll do our best to help. Master Gardeners are available in our Delta and Montrose offices through September, and year round in our Mesa County office. Our number in Delta is 874-2195, in Montrose, 249-3935, and in Grand Junction we’re at 244-1836.

Thank you for calling Dial-a-Garden. This message will be updated next week; have a great week!