Walls of water, grasses & raspberries

Last year I started my tomato plants in walls of water. The walls did protect my plants from cold temperatures, so that I had earlier tomatoes than usual. But one of the walls fell over. By the time I noticed, part of the tomato plant had been smashed under the wall. The plant recovered but never grew as big as the others. Have you ever heard of this happening? Yes, occasionally. It happened to me once, when I first was using walls of water but never again. Let me pass on a few tricks for keeping the walls upright: Before setting a wall in place, level the ground. Be scrupulous about the circle of dirt where the wall will sit. Make certain that it is smooth, level and void of pebbles.

Once the walls are in place, take a quick look every day to be sure that all the tubes are full; even a pinhole leak can empty a tube overnight. The walls are stable in wind only when all the tubes are full of water. I have patched leaky tubes with plastic tape and I have used the available repair kits, which consist of single tubes to insert in leaky ones. Both systems work and my walls have seen many years of use.

I consider setting the wall on level ground critical to its stability. My garden is in a windy spot. Being fussy pays off for me.

We planted some ornamental grasses and we like the way they look in winter-at least until heavy snow smashed some of them. Should we cut them down now or can we leave last year's stems? I strongly recommend cutting the grasses down now, before the new stems are mixed in with the old. It will not be an easy job. I use heavy scissors on my grasses but some gardeners use a power saw. If you discover the ideal tool for the job, please let me know.

Try to cut the stems an inch above the ground. As the clump of grass gets older, growth at the base of the stems becomes denser and it will be possible to cut only two or three inches above the ground. Eventually the grass clump will need to be thinned.

A mixture of new stems and dead ones is not attractive, so it is worth the work of cutting out the old growth every spring.

What caused some of my raspberry canes to leaf out in the spring and then die during the summer? Some years back, the problem would have been cane borers but that epidemic seems to have run its course. Hardly anyone has seen cane borers in the last 10 years. To be sure that borers are not killing your raspberry canes, try pulling a dying cane out of the ground. A cane infected with borers will pull easily and it will be hollow near the ground. You may even expose a white grub-the borer itself.

If you have cane borers, their two-year life cycle makes them difficult to kill. You are better off to dig out all your raspberries and replant fresh stock in a different place.

Chances are excellent, though, that what you are seeing is a minor problem. If only a few canes die, they may have been injured in cultivating or weeding. They may have a disease, although raspberry diseases are rare in Montana.

If berry production on the remaining canes is decreasing, if some berries are drying up before they mature, the raspberries probably have a virus disease. Again, the only cure is to dig out the plants and replant in fresh ground. There is no way to kill the virus.

Raspberries with tips which die probably are being eaten by the grubs of raspberry sawfly. Newly unrolled leaves also will have parallel slits eaten out of them. Immature sawflies look like small green caterpillars. Spraying the leaves with Bt can kill them but you may not want to bother. Unless the sawfly outbreak is huge, damage to the crop will be minimal.

Hackett welcomes reader questions related to gardening, pest management, plants & soils. Submit questions to mhackett@centric.net, call 406-961-4614 or mail questions to 1384 Meridian Road, Victor, MT 59875.