Snails, Slugs Update

The UC IPM Online Program has updated their information on snail and slug control in the garden. Here's the complete report. 

The report reinforces much of what you already know about snails and slugs, as well as how to control them. But there are some interesting twists, including:

Copper Sulfate repels snails and slugs.

"Instead of copper bands, Bordeaux mixture (a copper sulfate and hydrated lime mixture) or copper sulfate alone brushed onto trunks will repel snails. One treatment should last about a year. Adding a commercial spreader or white latex paint can help the Bordeaux mixture remain effective for two seasons."

There are snail and slug-resistant plants!

"On the other hand, many plants resist snail and slug damage including begonias, California poppy, fuchias, geraniums, impatiens, lantana, nasturtiums, and purple robe cup flower as well as many plants with stiff leaves and highly scented foliage such as lavender, rosemary, and sage. Most ornamental, woody plants, and ornamental grasses also aren’t seriously affected. If you design your landscape using snail and slug resistant plants, you are likely to have very limited damage."

And these are the plants they enjoy the most: 

"Because they prefer succulent foliage or flowers, they primarily are pests of seedlings and herbaceous plants, but they also are serious pests of ripening fruits that are close to the ground such as strawberries, artichokes, and tomatoes. They also will feed on foliage and fruit of some trees; citrus are especially susceptible to damage. Look for the silvery mucous trails to confirm slugs or snails caused the damage and not earwigs, caterpillars, or other chewing insects."

"Some plants these pests will seriously damage include basil, beans, cabbage, dahlia, delphinium, hosta, lettuce, marigolds, strawberries, and many other vegetable plants."

Another reason to turn off the sprinklers and turn on to drip: 

"Switching from sprinkler irrigation to drip irrigation will reduce humidity and moist surfaces, making the habitat less favorable for these pests"

Shopping for snail bait? The advice remains the same: Choose iron phosphate over metaldehyde.

"Baits containing the active ingredient metaldehyde are most common; however, metaldehyde baits are particularly poisonous to dogs and cats, and the pelleted form is especially attractive to dogs. Don’t use metaldehyde snail baits where children and pets could encounter them. Avoid getting metaldehyde bait on plants, especially vegetables. Some metaldehyde products are formulated with carbaryl, partly to increase the spectrum of pests controlled such as soil- and debris-dwelling insects, spiders, and sowbugs. However, carbaryl is toxic to earthworms and soil-inhabiting beneficial insects such as ground beetles, so it is better to avoid using snail baits containing carbaryl."

"Iron phosphate baits—available under many trade names including Sluggo and Escar-Go—have the advantage of being safe for use around children, domestic animals, birds, fish, and other wildlife, making them a good choice for an integrated pest management program in your garden. Ingesting even small amounts of the bait will cause snails and slugs to stop feeding, although it can take several days for the snails to die. You can scatter the bait on lawns or on the soil around any vegetable, ornamental, or fruit tree that needs protection. Iron phosphate baits can be more effective against snails than slugs overall and more effective than metaldehyde during periods of higher humidity. Snails and slugs tend to hide before they die, so you won’t see scattered empty shells or dead snails and slugs as you would if treating them with metaldehyde."

"The timing of any baiting is critical; baiting is less effective during very hot, very dry, or cold times of the year, because snails and slugs are less active during these periods. Irrigate before applying a bait to promote snail activity, and apply the bait in the late afternoon or evening. Sprinkle bait around sprinklers, close to walls and fences, or in other moist and protected locations, or scatter it along areas that snails and slugs cross to get from sheltered areas to the garden."

FROST PROTECTION PLAN FOR PLANTS

The following are highlights from a Fair Oaks Horticulture Center Workshop presentation by Master Gardeners Caroline Hathaway and Cathy Coulter. Also see the UC/ANR publication, "Frost Protection for Citrus and Other Subtropicals."

Before a frost:

1. Identify cold spots in landscape by monitoring with thermometers. 

2. Identify plants at risk: citrus, succulents, tender perennials, tropical and subtropical plants.

3. Have supplies ready: sheets or frost cloths, lights, wraps for trunks, thermometers, stakes or framework to hold covers off foliage.

4. Prepare tender plants: avoid fertilizing and pruning after August to minimize tender new growth.

5. Rake away mulch to allow soil to warm up during the day and radiate heat at night into plant.

6. Monitor weather forecasts and note how low temperatures will be and for how long. 

Some terms you might hear:

Local frost: clear, dry nights; but, it usually warms up during the day.

Hard freeze: temperature inversion or Arctic front, can last for days/weeks, very damaging.

When a frost is forecast:

1. Move potted plants to a warmer spot next to house or under patio cover, especially on south side.

 2. Check that plants are well watered since dry plants are more susceptible to damage, and moist soil retains heat better than dry soil.

3. Cover plants before sunset to capture ground heat radiating upward at night, but remove covers daily if it is sunny and above freezing to allow soil to absorb heat.

4. Add heat by using outdoor lights: hang 100 watt drop lights or Holiday string lights to interior of plant. Use the old C7 or C9 large bulbs, not new LED lights which do not give off heat.

5. Wrap trunks of tender trees if hard freeze is expected, using towels, blankets, rags, or pipe insulation.

6. Harvest ripe citrus fruit. Generally both green and ripe fruit are damaged below 30 degrees, but there is some variation by species (refer to the chart in UC/ANR Publication 8100, "Frost Protection for Citrus and Other Subtropicals).

After a frost:

1. Identify damage: dark brown or black leaves and twigs.

2. Wait to prune out damage until after danger of frost is past, and new growth begins in spring.

Birds, Bees and Beneficials

One of my favorite blogs is Bill Bird's "Sacramento Vegetable Gardening". Bill is a jazzman with words. His blogs have a rhythm comparable to a Gene Krupa drum solo.

In one recent post, Bill waxed rhapsodic about a certain rose in his yard, Our Lady of Guadalupe.

      As I was reading this post about the trials and tribulations of growing this rose (and actually, the blog is more of a love letter to his wife, Venus), I was wondering how he was going to bring it back around to, if you will excuse me for being a stickler, "Sacramento Vegetable Gardening". 

     Bill did not disappoint. He tied into a neat little package at the end, exclaiming: "Our Lady of Guadalupe attracts a number of beneficial insects to the garden, including bees..."

     This is a subject we have tackled on these pages, as well: the benefits of having a wide variety of beneficial insect attracting plants in your yard to help you do battle against the bad bugs.  And, it's a topic covered more in depth at farmerfred.com.

    But Bill's apian accolade got me wondering: what other beneficial insects are attracted to roses? And, are there any beneficials that use roses for more than a source of food (housing, for example)? For that answer, the "go-to" guy has to be Baldo Villegas, an entomologist for the state of California, past president of the Sacramento Rose Society and Sierra Foothills Rose Society, as well as being a consulting rosarian.

     "Roses produce a lot of nectar, some more than others," explains Baldo. "Single-petaled roses are best for seeing what attracts insects both good and bad. Some of the best beneficials that I see are syrphid flies, tachinid flies, as well as numerous wasps, both parasitic and predatory. Among the parasitic wasps are the braconid and ichneumonid wasps and predatory wasps that are mainly those in the family Sphecidae. Then there are a lot of different types of bees such as honey bees, andrenids, halictids, megachilids (aka leafcutting bees), and anthophorids (including small carpenter bees). The only ones that use roses for housing and for prey gathering are two predatory wasps in the family Sphecidae. One of these wasps preys on aphids and the other one on flies."

For pictures and more information about these garden good guys, visit the UC Davis IPM Online Natural Enemies Gallery.

Dog vs. Drip Irrigation

I'm not sure what the attraction is, but dogs and water find each other, wayyyyy too often. We've had more than one sprinkler mangled by our dog. Probably a combination of thirst, playfulness and boredom. Our sprinkler solution: put a tomato cage around the sprinkler head to keep a few inches separation between nozzle and muzzle.

     Les in Gold River has his own doggone water issue:

     "We are dog sitting my in-law's dog for awhile," Les writes. "I was thinking of re-doing my drip irrigation this year, but now my in-laws' dog has done my thinking for me by ripping up sections of the drip line. So before I try to put something back in place, is there something that you can recommend that I try that does not encourage dogs to chew it up?"

     You mean other than blame the psychoses of your in-laws for screwing up the dog? Nah, that's too easy. Other than burying the line, I can't think of any other deterrent; installing an enclosed dog run in another part of the yard, perhaps. You may want to check with the Dripworks website to see if they have any dogproofing ideas.

     The Dripworks catalog is a great resource for anyone tackling the problems associated with drip irritation...uh, irrigation. Just thumbing through the catalog can give you several "Aha!" moments for improving your own yard watering procedures. And the Dripworks online site has helpful tips and videos that can help beginner and pro alike solve their drip irrigation and yard watering woes. (note: I was not compensated for this endorsement, damn it.)

     And that includes a helpful staff. I sent a copy of Les' e-mail to Cathie Nicolaus at Dripworks. And she responded:
     "I experienced my lab puppy doing the same thing, she liked the emitters the best because of the water spraying out. I had to redo my entire system on the deck! Here is something to try: Get a spray bottle and mix cayenne pepper powder and warm water and spray on the area that the dog is going for. You may have to make a small offering of tubing for the dog to get the idea, but he should rather quickly. For squirrels, we have in the past recommended petroleum jelly and cayenne pepper mixed together if you need to have it last longer on the tubing. In retrospect for our dog situation, I would have used the petroleum jelly/cayenne pepper mix around the emitters (being careful not to plug any holes) and tubing, since the water from the emitters was attracting the dog."

  

Cold Weather Houseplant Care

        

As the weather turns cooler, we begin to pay more attention to horticultural chores in the great indoors. Houseplants need a bit of TLC right now, as they adjust to the change of seasons. Houseplants tend to slow down their growth cycles now, so their food and water requirements are less.

        Many houseplant aficionados won't even feed their houseplants now, and won't resume a monthly fertilization until next spring. And because houseplants use less water now, change your irrigation habits. 

     Poke your finger or a moisture meter into the soil of a houseplant to make sure that the top few inches have dried before you add water. Another way to determine if your houseplant is in need of water: lift the pot. If it is as heavy as it was when you last watered, wait. When the soil has dried, that pot will be a lot lighter, a good sign that it's time to pour it on.

        During fall and winter, the sun is lower in the horizon. Help your houseplants cope with this lower level of light by moving them a bit closer to a sunnier window.

        There are some indoor plant pests that may be moving into your house this time of year. Aphids, spider mites, whiteflies, fungus gnats and scale are among the pests that are taking up residence with you, especially if your houseplants have spent any time recently outdoors or are new purchases. A couple of good books about houseplants, including lots of pictures of plants and pests, are "The Complete Houseplant Survival Manual" by Barbara Pleasant and "Successful Houseplants" by Ortho Books.

        And one reader is wondering about how to control another common houseplant pest. From the garden e-mail bag, Cynthia writes: "I have an indoor coleus plant in my bathroom, which gets indirect sunlight. All was well until yesterday when I discovered little oblong or rectangular-shaped, white, fluffy somethings on the plant. What are they and how do I eradicate them?"
        

     Those "fluffy somethings" might be mealybugs. These soft-bodied sucking insects are about one-eighth of an inch long, and are covered with a whitish, cottony wax. They especially like to congregate on the backsides of the leaves of houseplants, where the leaves meet the stems.

        There are several steps you can take to control mealybug populations on your houseplants. Step One: wash off the plant, especially the underside of the leaves, in the sink with a forceful stream of lukewarm water. Doing this once or twice a week for a few weeks may take care of the problem. Step Two: Dip a cotton swab in rubbing alcohol and remove the mealybugs by hand. Tweezers can help dislodge the ones you can't reach  with a cotton swab. If those two techniques don't do the job, apply insecticidal soap or a narrow-range horticultural oil to the infested plant area. But be careful: make sure your plant won't be damaged by the soap or the oil by testing it on a small, out-of-the-way part of the plant first. According to Lori Ann Asmus of Emerald City Interior Landscape Services in Sacramento, scrape away and replace the top inch of soil in the potted plant. That can help eliminate future mealybug populations.

What NOT To Do in the Garden Now

     In the interest of easing your garden workload as the busy holiday season approaches, here are some yard tasks you don't have to tackle this time of year:

• Don't deadhead your roses. Many Northern California rosarians are now advising rose growers to let those fading October flowers remain on the plant. This will force the rose bush to form hips, which helps the plant slow down in preparation for the January pruning season. Because cold winters are not a certainty here, roses have problems entering complete dormancy in our area. Not pruning roses now tells the plant, "Time to take a nap!"

• Don't prune your shade trees until the last leaf has fallen. Then, it will be easier to gaze up into the canopy of the tree to decide which branches need to be trimmed or removed. Good reasons for pruning trees include removing or cutting back branches that are rubbing each other or the house. Low branches that impede foot traffic or suckers emanating from the base can be removed at that time, too. If you think you won't remember the dead branches that will need to be removed when all the leaves are gone, go ahead and mark those branches now with ribbon or green tree tape.

After the Storm: Inspect Your Trees!

      The day after a major rain and wind storm is not necessarily the best day for the backyard gardener to tackle the hazardous task of cleaning up the remnants of trees, shrubs and other plants that took a beating. If wind and rain is still in the forecast, the prevalence of slippery conditions and the chance of more falling debris should limit your cleaning chores to dragging broken branches away from the scene of the crime. It is not a good day to be climbing ladders or scrambling into trees while balancing a chain saw. Leave that to the professionals. 

     Sacramento-based arborist Analisa Stewart of Arbor Entities offers this good piece of advice for those surveying the fallen aftermath of a major storm: "Limb failure is largely a product of poor tree maintenance over time," says Stewart. "Take care of your trees, or they may take care of themselves in ways you won't appreciate."
     According to the University of California publication, "Inspect Your Landscape Trees for Hazards", a nice day in autumn (or winter, spring or summer, for that matter) is the time to take an inventory of any possible future tree damage before you, your house or your car becomes the next victim of a falling tree or branch.

Leaning Trees: Are your trees not as upright as the result of recent heavy winds? Can you see newly upheaved roots or soil around those trees? Then, immediate action is required: call in a professional, certified, bonded and insured arborist to do an onsite inspection and offer a solution. Newly leaning trees are an imminent hazard. If you have a tree that has leaned for a number of years, that tree can still be a hazard during wet, windy weather. Taking periodic photographs can help you determine if a greater lean is developing.

Multiple Trunked Trees: This co-dominant condition can result in breakage of major tree parts during storms. Usually, these trunks are weakly attached. Inspect the point where the two trunks meet; if you see splitting beginning, call in an arborist.

Weakly Attached Branches: Trees with many branches arising from the same point on the trunk are prone to breaking during wind storms. Prune out any split branches. Thin out multiple branches.

Hanging or Broken Branches: If you see storm damaged branches hanging from the tree, remove them as soon as possible. This includes removing any completely broken branches that may be resting elsewhere in the tree's canopy.

Cracks in Trunks and Branches: Measure the depth of any cracks with a ruler. If those cracks are more than three inches deep, call in an arborist to determine the best course of action.

Dead Branches: Branches that have completely died are very likely to fall off in a storm. Dead branches are most noticeable in the summer when the tree is in full leaf.

Cavities and Decay: Large, open pockets where branches meet the trunk, or at the base of the trunk, can mean big trouble. The presence of mushrooms on the bark or on exposed roots may indicate wood decay. Call in an arborist.

The Arbor Day Foundation website has this animated guide to proper pruning techniques.


Also:
Tips for Hiring an Arborist.