Credit: Steve Garner, Flikr.

An immense amount of rain has fallen across California in recent weeks. While rain is incredibly beneficial, in excess it can cause serious problems. The continued wet conditions opens the door for many pests, so see the list of dos and don'ts below for common wet weather pest prevention tips.

DO

• Check for snails and slugs. These critters thrive in moist environments and can often be seen on sidewalks and driveways after rain. Their feeding causes irregular holes on leaves and flowers, and they'll leave behind a slimy trail. Pesticide sprays and dusts will not be effective under such wet conditions and therefore, should not be used. Instead, hand pick them or trap them using a wooden board trap.
• Remove weeds and unwanted plants. When the ground is wet it is much easier to pull weeds and remove unwanted plants from your garden or landscape. Use this time to your advantage by catching up with any winter annual weeds, like oxalis, nutsedge, and groundsel. Be on the lookout for more in the coming weeks.
• Dump standing water. As the weather warms, any areas left with standing water will be a breeding zone for mosquitoes. This wet winter is already favoring a big mosquito season, so do your part to reduce habitat around your home. This can include dumping flowerpots and saucers, wheelbarrows or buckets, and cleaning clogged storm drains or gutters.
• Continue to conserve water. During the fall and winter months, adjust your irrigation schedule to reflect the increase in rainfall. Consider purchasing a rain sensor for your sprinkler system to avoid irrigating while it is raining. Overirrigating your plants during this time can lead to root rots and other water-borne pathogens so do what you can to reduce excess water.
• Be on the lookout for ants, cockroaches, and earwigs. These insect pests may invite themselves into your home when flooding or heavy rains make it unfavorable for them outside. Seal any cracks or openings in your home to prevent them from coming indoors. Use weatherstripping and door sweeps, and place sticky traps near entryways. Keep food sealed tightly and maintain a clutter-free environment to prevent these pests from establishing indoors.
• Remove mushrooms. Wet weather encourages the growth of above ground fruiting bodies of fungi. While not harmful to your garden or lawn, you may want to remove mushrooms to prevent children and pets from consuming them.

 DON'T

• Fertilize your garden, lawn, or outdoor potted plants. Any fertilizer applied now will likely be washed off the ground or rapidly leached out of the soil and into our waterways. Wait until the winter storms have passed and there is a stretch to time between days with rain.  
• Use pesticides (sprays, dusts, drenches). Similar to fertilizers, these products are more likely to just contaminate waterways than control any pests. Pesticides applied to foliage as sprays will be washed away quickly with daily rainfall and those applied to the soil as a systemic drench will likely not be taken up by the plant in waterlogged soils and instead will become runoff. Pesticide dusts need to remain dry to be effective, so now would not be the time to use those outdoors either.
• Prune plants. Unless necessary to remove damaged limbs or branches from the recent windstorms, avoid pruning plants under wet conditions. Pruning at this time can make plants vulnerable to pathogens and easily spread disease from one plant to another. Apricots, cherries, and olives should never be pruned during cool, wet conditions. 
• Worry about tiny piles of soil. Earthworm activity is increased during rainy weather, so if you are seeing piles of soil on top of landscape beds or the lawn, don't worry—it's just the earthworms coming out and getting some air. As they do this, they help aerate the soil. Earthworms deposit castings when they ingest soil and leaf tissue and emerge from the soil surface to remove fecal matter. Castings are rich in nutrients and organic matter and can provide some benefits to turfgrass plants.
• Compact your soil. Avoid driving or excessive walking on soft ground and keep heavy machinery off wet soils. Compacted soils make lawns, trees, and shrubs more susceptible to diseases, drought, and insects as they restrict oxygen and water from plant roots.   

For year-round actions to keep landscape plants healthy, reduce pest problems, and prevent future issues, see the Seasonal Landscape IPM Checklist to find monthly activities specific to your county or region.