Lane County Extension Service Master Gardener John Fischer here with KLCC's Good Gardening.
For many garden pests, I prefer to wait until I see the trouble maker before trying to reduce their damage. Not much point in putting out the biological cabbage worm control BT before you see the white butterflies that lay eggs on your broccoli plants.
But other critters need year round control because they are now year round pests. Slugs and snails can make holes in your big lettuce plants, but during the early season, they'll take the entire seedling before it can mature and get to the table - so starting slug control before putting out seeds can really help with plant survival.
That's partly because decades of gardening in the same spot provides a predictable food supply, and partly because they stay alive and active all winter now instead of just during the summer months.
Fortunately, an old organic slug control strategy has been revised, and it is more effective than even toxic, animal dangerous, chemical products containing metaldehyde. Fresh yeast, flour, and water mixed together will attract slugs in the same way that beer used to - before most beer had the yeast filtered out of it.
Researchers at Oregon State University have found that the yeasty dough concoctions outperform chemical attractants, and last longer too. Just mix a cup of flour, a cup of water and a teaspoon of active dry yeast together, let it get bubbly for a few hours inside, and put it in slug traps. I make sure the mixture is soupy enough to drown the invasive imports.
You can make a thicker doughy mixture and pick off the slugs as they feast if you prefer. If you're a home brewer, or have a friend who is, the leftover yeast at the bottom of the fermentation vessel can be used in traps too.
Here are links to the OSU research article, and plans for a plastic bottle homemade slug trap.
Now one of my favorite foods - bread - can protect one of my other favorites - salad.
I'm John Fischer with KLCC's Good Gardening.
