QUESTION:I just moved into the area from Southern California and don't understand why everyone hates blackberries so much. What a treat ... to have delicious berries everywhere? What's the problem with them? My neighbors are suggesting I get rid of the few plants I have along my backyard boundary. But I'd like to keep them for fruit.

ANSWER:The most prevalent and aggressive blackberry species you see on roadsides, in vacant lots and along wetland edges are not native here in the Pacific Northwest. The more common exotic species are the Himalayan blackberry (Rubus discolor) and the evergreen blackberry (Rhubus laciniatus).

Both are native to Europe. They were brought to this country for fruit and for erosion control. They are notorious for taking over yards, gardens and vacant lots in the western part of Oregon and Washington.

Nonnative blackberries choke out native vegetation (including our native trailing blackberry Rhubus ursinus). They often form a barrier along stream corridors that may prevent animals from getting to sources of water.

One mammal that does do well in blackberries is the nonnative black rat (Rattus rattus) also known as roof rat. Birds and mammals eat blackberry seeds and pass them through their digestive tracts, spreading them everywhere. Blackberry thickets can produce 7,000 to 13,000 seeds a square meter. To germinate, blackberry seeds require 90 days of warm temperatures, followed by 90 days of cold-typical conditions in Western Oregon. Seeds can remain alive in the soil for several years. Young seedlings require strong sunlight to grow and cannot penetrate into areas with much less than 50 percent full sunlight.

Once established, these blackberry plants almost can "walk." Their canes grow as much as 20 feet in a single growing season. Most canes can sprout and grow at the tips as soon as they bend over and touch the ground. The side branches can sprout and establish new plants this way as well. And short pieces of stalks or roots can grow into plants, so the potential of these plants to spread all over is mind boggling.

Unfortunately, they are here to stay, despite our best efforts. They do not belong in grasslands, wetlands, riparian areas or other areas. I encourage you to remove them now before they set fruit again. Cut them back and grub out the roots. You may have to do this repeatedly for several years until they stop sprouting.

You can replace blackberries with native plants that can provise the food and shelter for invertebrates, reptiles, birds, and mammals, such as the native thimbleberry or salmonberry or plant some nice domestic raspberry or boysenberry canes in their place-the berries are less seedy and they aren't as rampant. Your neighbors will be grateful.

If you want to see what the Himalayan blackberry looks like, look in a plant book such as "Plant of the Pacific Northwest" by Pojar and McKinnon. Or there are photos posted on the Web, including: http://tncweeds.ucdavis.edu/esadocs/rubudisc.html