Weevils feast on roses

I was quite sure that it was in one of your columns recently that I read about a pest that lives in the ground around the roots of roses during the day and then emerges at night to chew the poor leaves down to nothing. I didn’t save the column, and now I’m sure I have the little rascals. They attack my more tender roses, not the hardy old roses.

Jayce Keeling

The column you probably are thinking of was one on sowbugs and pillbugs. Unfortunately I think you have black vine weevil. The adults are a quarter- to a half-inch in length and black or brown. But the ones that do the real damage are the larvae. They overwinter in the ground and feed on roots if the weather is mild – like last winter. From April to June, the larvae turn into adults and emerge to feed on leaves. The adults live in the soil or debris at the base of the plant during the day and climb up to feed each evening.

To start controlling these critters, cultivate the soil around the affected plants to turn up adults, eggs and larvae through the summer and fall. Pick off any adults you happen to see on the plants late in the evening.

The adults can be controlled by using sprays of Neem extract (derived from an Indian tree related to the chinaberry, which works as a natural pesticide) or Orothene, starting in late May and June. Larvae can be controlled with a beneficial nematode soil drench applied to the soil in the fall. Nematodes are tiny bugs that will infect the larvae. Ask at your local garden center and follow all label directions carefully.

Local soil has good pH levels

Is it really necessary to get a soil test for its pH rating? Some things I’ve read and had people tell me indicate that it is a waste of time and money. What are your feelings about this? I usually till in the shredded maple leaves from the yard along with the lawn clippings that accumulate throughout the year.

Dennis Baslington, Spokane Valley

For the home gardener with an average garden patch that has been producing well, a pH test is usually not necessary. Commercial growers and some gardeners do use them if there is a great need to maximize crop production or they have a plant that needs certain levels of pH. Blueberries and rhododendrons are examples of this.

In the garden, the term pH refers to levels of acidity or alkalinity in the soil and is ranked on a 15-point scale: One is very acidic, and 15 is very alkaline, with a neutral point at about 7-7.5. Most soils in the Inland Northwest tend to be about 6.5 to 7.5, right around neutral – a good thing.

By adding the maple leaves and grass clippings back into your soil, you are replacing the nutrients used up by the plants. The overall health and pH of your soil should be good.