First, you need to make it difficult and less desirable for larger mammals such as rats and rabbits to get to the garden. To deter rabbits, make sure the area is fenced, with the bottom of the fence at least 6 inches below ground. To discourage rats, remove all garbage or store it in a closed, animal-proof can.
Pick up and discard all fallen fruit or nuts. Clear away all hiding/nesting places such as low-growing branches and stacks of firewood; trim shrubs and foliage to at least a foot off the ground. Remove all sources of standing water: buckets, flower pots, bins, lids, and old tires. Keep your barbeque clean, as rats are attracted to leftover food and grease. If you are composting, don't add eggs, greasy food or meat and make sure you have a metal mesh barrier beneath to prevent them from coming up through the bottom.
My garden is fenced; I am growing only in raised beds and I have removed all standing water. As an avid animal lover, I don't wish harm on any living thing, not even a spider (most of which are extremely beneficial). However, last year, we lost nearly half of our tomatoes, lots of leafy greens and all but two or three of our persimmons to rats and rabbits. This spring, all of my sugar snap peas and most of my chard and kale were eaten down to the stems. And when something starts messing with your tomatoes it's time to take action!
We hired a trapping service, and it has been very effective so far. We have caught several rats, a handful of rabbits and even a few gophers and voles. There are several licensed services in the Bay Area that can legally trap and remove the animals from your property. My one remaining chard plant has now made a full recovery, there are hundreds of tomatoes on the vine that are just weeks away from ripening, and the persimmon tree (so far) is loaded with fruit.
Much smaller pests you may be seeing now include an array of aphids, beetles, worms, stink bugs and grasshoppers.
Aphids are tiny pear-shaped bugs that suck the sap from plant leaves, causing them to curl and drop. They leave honeydew, which promotes viral disease and sooty mold. Blasting your plants with a strong stream of water will wash away most of the aphids. Planting plants such as white alyssum, yarrow, and fennel will attract ladybugs, lacewings and other beneficial insects that devour aphids.
There are lots of beetles to look out for. Both the spotted and striped cucumber beetle have been prevalent this year. They do most of their damage before you even know they are there. Larvae attack the roots just as the plants are getting started. Adults will continue to wreak havoc, so hand-picking or vacuuming them off is important. They will attack not only cucumbers, but pumpkins, melons and all squash as well. Using row cover for seedings will help, but you need to remove it as soon as the flowers appear to allow the pollinators to do their job.
Caterpillars and worms can do lots of damage very quickly. You need to inspect the underside and inside of curled leaves thoroughly, as many blend in quite well with green leaves. Although it may be “yucky”, the best nontoxic pest control is to handpick and squish them.
Grasshoppers are one of the most difficult pests to control. If you see only a few, you can again handpick and discard them. Row covers can help. But if the population is high they can chew right through the cloth. Some gardeners have been successful in planting a row of tall grasses and other lush plants around the garden to divert their attention.
When all else fails, and you need to resort to a chemical solution, please bear in mind that the good bugs will be killed off alongside the bad ones. So use this as a last resort!
by UC Master Gardener Rebecca Jepsen
Photo from the San Jose Mercury News
This article first appeared in the July 22, 2018 print issue of the San Jose Mercury News.