For better vegetables and flowers next year, do a good clean-up job in the garden this fall. Putting it off until spring may seem easier but it is not a good idea.

After cleaning up, dig up your garden as well. The soil will warm up more quickly next spring. Frost can leave a dark sun-absorbing, dug-up soil 10 days ahead of an undug garden insulated by light-colored crop residues.

Of course, the garden should not be dug if there is danger of considerable loss of soil by wind or water erosion. But if you do dig, lime and fertilizer should be applied first, so they will be down in the root zone next spring.

Many of the fungi, bacteria and other disease-causing organisms over-winter on or in dead leaves and other plant refuse. Removal and destruction of this material can help reduce infection of young plants in the spring.

Specialists recommend that dead plant parts suspected of being diseased be destroyed rather than added to the compost pile.

The iris borer and European corn borer are serious threats in many gardens. The iris borer overwinters in the egg stage on old iris leaves and other debris.

The eggs hatch in late April and early May. The borers (small green worms) crawl up on the leaves and make pin-point holes to enter them. They feed inside the foliage, working their way down into the roots, running them.

Pull off old leaves, rake up the trash and get rid of it all. This should eliminate most of the eggs. It is important to do so even if you haven't had a borer problem. Moths that lay the eggs can fly quite a distance.

The corn borer attacks corn, beans, dahlias, hollyhocks, asters, chrysanthemums and many other kinds of plants. They overwinter above ground in corn stalks and big-stemmed flowers such as dahlias. They can survive temperatures of 15 to 20 below without much protection. Only 5 to 10 percent usually survive the winter but that is enough to cause a lot of damage.

In the spring, they pupate, emerge as moths, and the females lay up to 400 eggs, which hatch in early June.

Old stems of phlox and peonies should be cut off about one-quarter inch below the soil surface and disposed of. This will help prevent leaf blight of phlox and botrytis blight of peonies next year.

Powdery mildew is one of the worst diseases for zinnias and phlox. The disease organisms can survive the winter on dead tops. Cut them off at the ground level and get rid of them.

All dead canes on roses should be cut off and removed. Do it before they lose their leaves because they are easier to identify.

Apply scab and cherry leafspot diseases overwinter on fallen leaves. Rake them up and get rid of them.

Old berries clinging to grape vines should be gathered and disposed of, as should leaves on the ground. This helps prevent several grape diseases, including black rot.