Type your question here!

Saturday, October 8, 2011

Treadle Pumps When Water for Irrigation is Near But Unavailable

What are treadle pumps?

Do you have water available to you with less than a 20 foot vertical lift and no electricity? Then this foot-powered piston pump might be the answer. The treadle pump works off of human leg power (similar to walking, a treadmill or Stairmaster). By simply walking using this device human power can be used to lift water from shallow wells or storage devices for irrigation purposes.

Here are two short videos demonstrating a treadle pump and hand pump that I taped at an Ag Fair in Harare, Zimbabwe.

Too expensive? How about a bamboo treadle pump?

Paul Polak from IDE on Treadle Pumps

Buy Your Fruit Trees, Vegetable Transplants and Seeds in Arizona

Of course this is a bit of tongue-in-cheek for residents outside of Arizona but Arizona's law that allows its residents to buy fruit trees, vegetable transplants and seeds for personal use to be tax exempt makes alot of sense. It is food on your table (hopefully). If you are an Arizona resident, print this out and take it with you the next time you go to buy fruit trees, vegetable transplants or seeds at an Arizona garden center.

TPR 93-12
This substantive policy statement is advisory only. A substantive policy statement does not include internal procedural documents that only affect the internal procedures of the agency and does not impose additional requirements or penalties on regulated parties or include confidential information or rules made in accordance with the Arizona administrative procedure act. If you believe that this substantive policy statement does impose additional requirements or penalties on regulated parties you may petition the agency under Arizona Revised Statutes § 41-1033 for a review of the statement.
Sales of seeds and plants.
Arizona Revised Statutes (A.R.S.) § 42-1310.01.A.35 provides an exemption from the transaction privilege tax under the retail classification for the gross proceeds of sales or gross income from sales of seeds, seedlings, roots, bulbs, cuttings and other propagative material to persons who use those items to commercially produce agricultural, horticultural, viticultural or floricultural crops in this state.
A.R.S. § 42-1310.01.A.15 provides an exemption from the transaction privilege tax under the retail classification for the gross proceeds of sales or gross income from sales of food.
A.R.S. § 42-1381.3 defines "food" to mean any food item intended for human consumption which is intended for home consumption as defined by rules and regulations adopted by the department pursuant to A.R.S. § 42-1387.
A.R.S. § 42-1387.B.3 provides that the department shall include, in the definition of food, seeds and plants used to grow food for personal consumption.
A.R.S. § 42-1301 defines "person" or "company" to include an individual, firm, partnership, joint venture, association, corporation, estate or trust, this state, a county, city, town, district other than a school district, or other political subdivision and any other group or combination acting as a unit, and the plural as well as the singular number.
Retail sales of seeds or plants to commercial producers of plants, flowers or food crops in this state are exempt from transaction privilege tax under A.R.S. § 42-1310.01.A.35.
If seeds or plants, which were purchased for commercial production, are taken from inventory and used by the producer for a noncommercial purpose, the seeds or plants are subject to the use tax. For example: seeds are purchased to grow commercial sod. The producer uses a portion of the seed in landscaping the company's own property. The cost of the seed used by the producer is subject to the use tax.
Sales of seeds and plants to individuals to grow food for personal consumption are exempt from tax under A.R.S. § 42-1310.01.A.15. For example, the sale of an orange tree to an individual for growing fruit for his own consumption is exempt under this provision.
Sales of seeds and plants to persons for non-commercial use are subject to transaction privilege tax if the plants or seeds are not used to grow food for personal consumption. For example, the sale of flower seeds and decorative plants to an individual or to a company for home or business landscaping is taxable.
Harold Scott, Acting Director
Signed March 15, 1993

Tuesday, October 4, 2011

Maxwell Norton Gives Table Grape Pruning Tips at UNCE Orchard

Back in 2005 Maxwell Norton, Farm Advisor in Fruit Production for the University of California Cooperative Extension in the San Joaquin Valley in California gave a pruning presentation and demonstration at the UNCE Orchard in North Las Vegas to Orchard volunteers and the general public. It was recorded and is presented here as a supplement for your own attempts at pruning grapes at home.

Monday, October 3, 2011

Extremehort Visits Ped's Farm In Laguna, Philippines, and His Giant Passionfruit and Fish Farm

While in the Philippines I visited the farm of another member of the Rare Fruit Society of the Philippines where we learned about growing Giant Passionfruit and his sustainable fish farming practices.

Extremehort Visits Dr. Coronel and His Duku Lanzones and Chempedak

While visiting in the Philippines with the Philippine Rare Fruit Growers they invited me to Dr. Roberto Coronel's house which is also his nursery and grounds for plant trials. I sampled a delicious variety of lanzones called 'Duku' which slips off the seed easily and has a wonderful citrusy and sweet flavor.

Sunday, October 2, 2011

Getting To The Root of the Problem With Desert Trees and Water Use

Deep tree roots are important for large trees. We know that these roots help to stabilize large trees, keeping them anchored during high winds, and we know that it is important to get deep rooting established in landscape trees when transplanted into urban residential environments. Early research at the University of Arizona traced deep roots of native mesquite to depths below 200 feet. More recent research suggests that these deep roots are important for other reasons.

Mesquite roots called sinkers in the Sonoran Desert
in Jerez, Mexico, near a river
that periodically overflows
Global research which surveyed maximum rooting depth of plants (trees, shrubs, perennial grasses) in natural settings (290 observations, 253 species) found a range in average maximum rooting depths from one foot (plants growing in northern tundra regions) to over 200 feet in deserts like the Kalahari; 194 species had roots at least six feet deep, 50 species had roots fifteen feet or more and 22 species had roots more than 30 feet deep.

When the researchers grouped these plants by similar natural habitats, they found the average maximum rooting depth to be 6 feet for cropland, 30 feet for deserts, 12 feet for conifer forests, and nine feet for deciduous forests. When plants were again regrouped into three groups based upon growth habit, then trees had an average maximum depth of 20 feet, shrubs 15 feet and herbaceous plants (nonwoody) 7.5 feet. This research showed that deep rooting is quite common in woody and herbaceous species in natural habitats, far deeper than the traditional view held up until now.

Deep rooting is suspected, and research supports it, to be more important than just structurally anchoring plants in the landscape. Research supports that they could be very important for moving and releasing nutrients and water, both up and down, and redistributing water and nutrients among different soil profiles. Water movement up roots into drier surface soils may affect water use estimates trees and other plants growing in their vicinity.

Many woody plants utilize deep roots for water uptake, particularly when surface soils are dry, but how they do this is not well understood. It was thought to be a combination of water “pulled” up through the tree by evapotranspiration and capillary action (like a soda straw) and little understood process called “root pressure” (like a submersible pump). Measuring water moved from deep in the soil by roots has always been difficult without disturbing the roots and accessing these roots.

However a plant process for moving water deep in the soil profile to upper soil profiles through plant roots has been identified more recently. Research found that during periods without rain, upward flow through deep roots was continuous during both day and night using a plant process researchers call hydraulic lift. Researchers identified that this process contributed up to 20% of daily water movement from that depth with no evidence of nighttime transpiration and no water storage inside the plant.

Research done in Texas on tree roots of two native trees found that roots growing at 20 to 60 feet below the soil surface contributed 20 – 50% of daily transpiration, depending on the water content of surface soils. As surface soils dried, more water was taken from deeper sources. All of this water from deeps soils was attributed to the plant’s hydraulic lift. Large quantities of this water are lifted at night. When hydraulic lift occurs at night then it is termed nocturnal hydraulic lift.

The question then becomes, if available water is moved from deep sources through deep roots during nighttime, when the plant is not transpiring for transpiration the next day, then where is this water stored? Other research indicates that water lifted from the deep soil profile is redistributed to dry, shallower soils where it is stored and used in the future. Deep root water transport varies with changes in the environment. When shallow soils become wetted again due to rain and/or the plant’s need for water decreases, hydraulic lift stops or is reduced dramatically.

Hydraulic lift is the passive movement of water from roots where water is more available to roots or root compartments where the soil is drier. It does not require plant energy. While the majority of documented cases for hydraulic lift are in native plants in desert or arid climates, recent studies (such as those in the Northeast with Sugar Maple) indicate that hydraulic lift is not restricted to desert or arid species or regions.

Release of water into the upper soil layers has been shown to benefit plants neighboring roots responsible for hydraulic lift. Because soils tend to dry from upper soil profiles downward and nutrients are usually more plentiful in the upper soil layers, lifted water may provide moisture to dry surface soils and enhance mineral uptake, beneficial microorganism growth such as mycorrhizae, and uptake of nutrients by feeder roots which typically occupy shallow soils. Some researchers feel that this is a form of plant parasitism and may have been the primary selective force in the evolution of this process. Hydraulic lift may also prolong or enhance root hair activity by keeping them hydrated.

The direction of water movement in deep roots may be upward, downward or horizontal depending on where soil moisture is more limiting. The transfer of water downwards by root systems, from lets say roots growing in wet shallow soils to dry deep soils, has been termed downward siphoning or inverse hydraulic lift; the reverse of hydraulic lift.

Such downward movement through the root system may allow growth of roots in otherwise dry soil at greater depths, permitting more rapid establishment of some plants. The amounts of water stored deep in the soil are not likely to be significant contributions if plant drought is severe. However, downward transfer of water may be important to plant establishment and the reduction of waterlogging in certain soil types. Inverse hydraulic lift may facilitate root growth into deep soil layers and transfer water away from neighboring, shallower-rooted competitors.

In addition to hydraulic lift, where water is redistributed from moist depths to dry topsoil, or inverse hydraulic lift which transfers water downward, the process of "hydraulic redistribution" includes the transfer of water horizontally, from areas that are moist to areas which are drier. In some locations and at some times of the year the subsurface transfer of water through roots may actually represent more water than the amount needed for transpiration.

How much water can this represent? Researchers aren’t really sure but field measurements of hydraulic lift in sugar maple in the Eastern U.S. have put these estimates as high as 25 gallons per night but other studies indicate much higher values. It is suspected that there is a great deal of competition for this water by neighboring plants.

Cultural Differences Influence Tree Selection for Urban Landscapes

It is well known that urban forestry and the planting of woody plants in urban communities provide substantial benefits to these environments. Trees reduce summer temperatures by providing shade and evaporative cooling. Trees also reduce atmospheric pollution by capturing or sequestering or capturing carbon as they grow and reduce the demand for air conditioning.
Trees can add needed shade to a desert
environment but is one this large needed for shade?

Appropriate tree selection can provide valuable wildlife habitat and protect the species diversity to urban dwellers. In most developed countries urban forests were considered almost entirely on the basis of aesthetics. More recently, environmental and economic benefits that these urban forests provide are being given closer scrutiny. In other parts of the world factors may drive plant selection such as the need for food, fuel, cultural heritage and shelter.

Historically the role of forestry was seen as guaranteeing a supply of industrial wood products for a variety of uses that was harvested much like an agricultural crop. But the role of forestry has broadened dramatically over the past few decades to help address a variety of environmental issues such as biological diversity and amelioration of global climate change as well as a new area of forestry coined 'social forestry".

Our cultural heritage may play a large role in how we view urban forests, plant selection and the composition of our urban forest. In a recent research article Canadian researchers surveyed community members representing three different cultural heritages; British, Mediterranean and Chinese; to find out how much actual influence cultural heritage has on the in residential component of Toronto's urban forest.

Researchers found dramatic differences in residential components of Toronto's urban forest and influenced by cultural ancestry. In order to understand where these differences emerge from it is important to understand their historical and cultural evolution.

Residents of Toronto from British origins valued primarily aesthetic landscapes composed of large trees. The researchers proposed that this was primarily due to Britain's demand for English oak used to build wooden ships for their military navy and merchant marine. British landowners also supplied lumber for firewood and maintained their properties for producing wild game for the privileged.

Prior to the industrial revolution, wood produced for shipping was valued and grown on properties owned by the aristocracy. This wood was harvested, sold to the government and provided a significant revenue to these landholders. Large trees were viewed as a sign of wealth, power and prosperity.

Wealthy industrialists emerging later in Britain's history viewed the landscape aesthetics of large mature trees as a sign of wealth and status. This was coupled with a backlash reaction to the industrial revolution that romanticized the world of nature. These views influenced the English school of landscape architecture toward greenspace planning and heavily influenced the evolution of the Garden City Movement in Britain and the United States.

The Garden City Movement was founded in 1898 by Sir Ebenezer Howard in the UK. In his view, garden cities were to be planned and self-contained communities surrounded by greenbelts with a careful balance between residential, industrial and agricultural development. The Garden City Movement had an impact on the landscape development of New York's Central Park and the downtown central core of Washington, DC among others.

Much of the native vegetation in the Mediterranean region has been lost or dispersed for centuries and replaced by small scale agriculture. Cities in the Mediterranean region, beginning in the middle ages, lacked greenspace and forests but were surrounded by small scale intensive agriculture focused on the growing of fruit trees, grapes and vegetables. The Renaissance villa was intended to be an agricultural center owned by wealthy landlords. From this villa rich landlords could view the pastoral countryside and visitors could admire well manicured gardens.

Villas weren't renowned for their self-sufficiency where owners drank their own wine and pressed their own olive oil. Later the term villa was extended to describe any freestanding suburban home surrounded by a landscape, much of it secured for the growing of food. Mediterranean immigrants continued this agricultural tradition in their new homes of North America which was dominated by the emerging northern European aesthetic of urban forests.

Very little greenspace existed in Chinese cities and what did exist was under the control of the government. Chinese citizens had very little direct influence on urban landscapes outside of their own home. The typical Chinese home, which has changed little in 3000 years, generally consists of several buildings belonging to an extended family. These buildings would all face one or more courtyards separated by family dining areas and communal gathering spots.

This communal home was typically surrounded by a wall which closed the family off from the rest of society and was also used to bring the outdoors into the family's private compound. Inside the compound landscape design was abstract and featured primarily water, stone and buildings with trees playing a less significant role. North American parks with large trees and expansive lawns might seem uninteresting to a Chinese immigrant.

Researchers point out that three concepts play the largest and role in Chinese landscapes: private courtyards, abstract designs with little emphasis on plants, and a lack of involvement in landscape design outside of their courtyards.

It was not surprising then that those surveyed who are from British origin were the most likely to plant shade trees while the Italian, followed by the Portuguese, had or would plant the most fruit trees. Chinese favored the least number of trees. When shown computer generated images of urban landscapes, the British reacted more favorably toward landscapes dominated by trees and shrubs while Chinese tended to favor brick and lawn dominated landscapes.

In backyards, Mediterranean respondents tended to have the largest vegetable gardens while British had the smallest. In the Mediterranean group, Italians tended to plant more fruit trees in backyards than Portuguese which was still more than British which favored shade trees. Chinese was the only group which included untended space in backyard designs.

In front yard designs the researchers found no significant differences in the proportion of vegetable gardens, lawns, flower gardens and patios and driveways or the types of trees. However, those surveyed from the Mediterranean community did not like landscapes dominated by trees which concealed the front of the house while those of British origin preferred it because it had greater privacy than more open landscapes.

Culture also influenced preferences in urban park design. All three groups favored playing fields but differed in recreational use and aesthetics. As would be expected, those from a British background was alone in favoring hiking trails while the other groups or more receptive to flower gardens.

The largest percentage of trees in North American cities grow on private property. Cultural heritage plays a huge role in the selection of plant materials and designs that impact our urban forest. The British were far more interested than other groups in the planting of large ornamental shade trees. The Mediterranean and community, with its history intertwined with agrarian society com was far more interested in producing food in our urban landscapes than aesthetics.

Bugs and Roly Polys Can Be A Problem in the Garden

Q. My biggest question is how to rid my raised vegetable beds of the abundance of bugs of all sorts who have made their home there over the past couple years. I love the little “roly poly” bugs but have a thousand of them in my gardens causing problems. Is there an organic pesticide that you would recommend? I have just begun planting fall veggies and would really like to catch this problem now.
Picture of pillbug from Texas A and M
A. It is hard to determine what went wrong with your garden this past year. It could be a number of things but we generally use soap and water sprays about three times a week just to keep the vegetables free of bugs as much as possible.

Roly-polys generally like decaying debris on the soil surface so keeping the soil clean and free of debris is always suggested to keep their numbers down. Not letting soft fruits touch the ground helps and keeping them trellised. Roly polys can’t fly or climb so elevating them off the ground helps.

Cutting Back Tomato Plants in the Fall

Cutting back tomatoes in the hoophouse in July and August
Q. I have ripe tomatoes on my vines right now in July but I want to know when should I cut them back for a fall garden? How high above the ground should I cut them back?

A. You don’t have to cut them back. They will begin to produce again as the temperatures cool this fall. However, if they have gotten too large or you want to reinvigorate them then you can cut them back. In our hot desert tomatoes stop producing when temperatures climb over the mid 90's or so. The ones that have set will continue to develp and ripen but no new fruit will set until cool weather sets in.

Whatever you use if you cut them back make sure it is clean and sterilized. You can cut back about 1/3 plant just above some side branches. Cutting the plants back will cause them to begin to grow vigorously as they tried to reestablish their tops to the existing root system. Do not cut them back to stems only or they most likely will just die.

If there is fruit still on the vine that you want to harvest and cutting the vine means removing the fruit than you might wait until after you finish harvesting. Then go ahead and cut.

Once you have trimmed the plant back then lightly apply some foliar fertilizers that focus on fruit production. Do this in the early morning hours. Apply this fertilizer in the early morning hours while it is still cooler and the sunlight is not so intense. This would mean a fertilizer high in the middle number or phosphorus and lower on nitrogen.

You want to stimulate some new growth but you want the nitrogen in the fertilizer to begin to fizzle out in a couple of weeks as daytime high temperatures cool into the lower nineties. I’m guessing that this will be toward the end of September but I am no weatherman.

You can apply a fertilizer to the soil but these generally last too long and can cause your tomatoes to grow excessively before they bloom again. Foliar fertilizers are usually short lived and you will get flowers sooner after an application. Try mixing it at half the label rate.

Whenever you are growing vegetables you should be applying light applications of fertilizer whenever you are harvesting. You are taking away from the plant so you need to give something back to it to help it recover from harvesting. I hope this helps.

Line Trimmers Can Cause Tree Dieback

Q. My purple plum has branches that are dying on one side of the tree. The leaves are all brown and crunchy while the other side seems healthy. Please help.

A. It is important to try and find out what the problem is if possible. From your description 1/3 tree has leaves that are dead or dying. These leaves are brown, dry and withered and possibly dead. Something is causing water not to reach the side of the tree that is withered and appears dead.

This means there is damage to the limb or trunk below that area. Please inspect the larger limbs and trunk below it for wounding or bark that is peeling away from the trunk. If the tree is in a rock landscape, which is really not good for this tree, make sure that water is getting to that side by turning on the irrigation system and making sure water is coming out.

You might try putting a hose at the base of the tree and a soaking the area around the tree slowly over a couple of hours. Do this once a week along with your normal irrigations and see if this makes a difference. But my best guess is that something has damaged the tree below the problem area. You still have time this year to help get it recovering from this damage before leaf drop.

Response from reader:
 Yu are correct. I just inspected the tree, which is not in a rock landscape, and found several wounds at the base of the truck near the ground. There are places on the truck where the bark is peeling away. Additionally, the branch that did not produce many leaves has a ½ inch split in it; the wood looks dry. The only reasonable explanations for this problem that I can come up with are (1) the gardener may have damaged the tree with his mower or lawn edger, or (2) borers may have damaged the tree before I treated it for insect infestation. There is no well around the tree; the grass grows around the base of the truck. I am watering my tree now and praying for its recovery.
My response to reader:
Good detective work! You are right, if the damage goes a considerable way around then this could be the root (pardon the pun) of your problem. Let’s determine if it is weed whacker or borer damage, shall we? Pull any loose bark away from the trunk. Look for accumulations of sawdust in channels that run parallel with the bark but just under it. A pen knife might work well to see if this sawdust “frass” located in the exposed tunnels just under the bark indicates a borer problem or not. If this is weed whacker damage (can be very likely and a common problem when grass is allowed to grow right up to the trunk) then there will be no frass or elliptically shaped exit holes about 3/8 inch long. Regardless of the outcome, remove the grass out a distance of two feet from the trunk. Can be a circle if you want but doesn’t have to be. If you want to be creative make it a square or even a trapezoid! But get the grass away from the trunk so the weed whacker doesn’t damage it.

Grape Damage May Be Due to Intense Sunlight Not Black Rot

Picture from reader most likely sunburn on the berries

Q. My husband and I attended your seminar earlier this year regarding growing grapes and making wine. It was very interesting and helpful. We have been growing the Thompson "tasteless" for about four years now and they are doing quite well, however, our second year wine grapes, Cabernet and Black Spanish, appear to have black rot according to the internet pictures. Can you tell me if this year’s crop can be saved?

A. We don’t have this disease west of the Mississippi to my knowledge. That is an East Coast grape disease problem. We have very few grape disease problems in our climate due to our very low humidity and geographical isolation. It is more likely to be sunburn. From the picture you sent me the discoloration is typical of sunburn and it seems to be facing the sides toward the sun.

Make sure when the berries are developing that they are in the shade of the canopy as much as possible during the heat of the day. They should have as much indirect light as possible to help in color development (which also helps in the color of the juice or wine).

Grape trellis with parallel catchwires on the top
to "catch" the new growth and provide shade
to the berries
When you trellis the grapes you want to make sure that the bunches are shaded from direct light as much as possible by the overhead canopy of the vines. We use a catchwire about 18 inches above the cordon wire to do this so that the fruit remains protected but still allows for plenty of indirect light. The fruit needs sunlight to develop good color and antioxidants.

They should also have plenty of air movement around bunches so that the few disease problems we have are minimized. We sometimes pull leaves off of the vine surrounding the bunches to increase indirect light and air movement.

Grapes berries usually turn color (called veraison) in July through September depending on the variety being grown. Most of our wine grapes are ready for harvest in late July and into most of August. Veraison will also turn the berry a different color as it spreads through the berries but from your picture this is not what I am seeing.
Our wine grapes entering into veraison
at 115F (46C) daytime temps

Not all the grapes will be turning color at the same time nor will bunches be ready for harvest all turn at the same time. In the extreme heat of July and August color development can be very spotty through the bunches with some much further along than others.

I have attached a picture of our wine grapes entering into veraison with some berries totally dark while others are still green and yet others turning color.

Attack of the Desert Snail Monsters

Q. Do you have any idea how to get rid of snails? I have a factory! There are literally hundreds throughout my grass andplanters. They are very small and we rarely see the large ones so not sure if they are regular snails or what. But I’d like to get rid of them because they grab onto the kids shoes which can bring them in the house.

Picture of the snail culprit from the reader.
Out, out, dam ned snail!
A. Snails are not usually a huge problem here due to our lack of moisture and sparse plant growth. However in a garden situation where there is plenty of water and debris on the ground they can get established, usually being brought in on nursery or garden materials.

The basic strategy is to minimize water by using drip irrigation whenever you can and clean up ground debris to remove hiding and egg laying places. Traps can be put out which is basically used so that you have some central locations where you can find them and kill them.

Usually once you get these traps established and conduct raids daily for about two weeks you will lower their numbers substantially. Then once or twice a week is all that is necessary to maintain lower numbers.

There are some devices such as copper barriers and diatomaceous earth that can be used to keep them out of specific places. Then there are the chemical baits containing metaldehyde and Sevin, an insecticide.

The following I copied verbatim from the University of California IPM website a couple of months ago. But check to make sure the information is current at their website located at

Snails and slugs are among the most bothersome pests in many gardens and landscapes. The brown garden snail, Cornu aspersum (formerly Helix aspersa), is the most common snail causing problems in California gardens. It was introduced from France during the 1850s for use as food. Another troublesome snail is the white garden snail, Theba pisana. It currently is established only in San Diego County but has been found in Los Angeles and Orange counties as well.

Several species of slugs also cause damage including the gray garden slug (Deroceras reticulatum,formerly Agriolimax meticulatus), the banded slug (Lehmannia poirieri), the three-band garden slug (L. valentiana), the tawny slug (Limacus flavus), and the greenhouse slug (Milax gagates).


Both snails and slugs are members of the mollusk phylum and are similar in structure and biology, except slugs lack the snail’s external, spiral shell. These mollusks move by gliding along on a muscular “foot.” This muscle constantly secretes mucus, which facilitates their movement and later dries to form the silvery “slime trail” that signals the presence of either pest.

All land slugs and snails are hermaphrodites, so all have the potential to lay eggs. Adult brown garden snails lay an average of 80 spherical, pearly white eggs at a time into a hole in the soil. They can lay eggs up to 6 times a year, and it takes about 2 years for snails to mature. Slugs reach maturity after about 3 to 6 months, depending on the species, and lay clear, oval to round eggs in batches of 3 to 40 beneath leaves, in soil cracks, and in other protected areas.

Snails and slugs are most active at night and on cloudy or foggy days. On sunny days they seek hiding places out of the heat and bright light. Often the only clues to their presence are their silvery trails and plant damage. In areas with mild winters, such as southern coastal locations, snails and slugs can be active throughout the year.

During cold weather, snails and slugs hibernate in the topsoil. During hot, dry periods or when it is cold, snails seal themselves off with a parchmentlike membrane and often attach themselves to tree trunks, fences, or walls.


Snails and slugs feed on a variety of living plants and on decaying plant matter. They chew irregular holes with smooth edges in leaves and flowers and can clip succulent plant parts. They also can chew fruit and young plant bark.

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.


A good snail and slug management program relies on a combination of methods. The first step is to eliminate, as much as possible, all places where they can hide during the day. Boards, stones, debris, weedy areas around tree trunks, leafy branches growing close to the ground, and dense ground covers such as ivy are ideal sheltering spots. It won’t be possible to eliminate some shelters such as low ledges on fences, the undersides of wooden decks, and water meter boxes, so make a regular practice of trapping and removing snails and slugs from these areas.

Locate vegetable gardens or susceptible plants as far away from snail and slug hiding places as possible. Reducing hiding places allows fewer snails and slugs to survive. The survivors congregate in the remaining shelters, where you can more easily locate and remove them.

Switching from sprinkler irrigation to drip irrigation will reduce humidity and moist surfaces, making the habitat less favorable for these pests. Choose snail-proof plants, such as those listed below, for areas where snails and slugs are dense. Copper barriers can be useful for protecting especially susceptible plants. Though baits can be part of a management program, it is better to use them in conjunction with other habitat modification, especially in gardens that contain plenty of shelter, food, and moisture.

Plant selection can greatly affect how difficult your battle with snails and slugs will be. Because snails and slugs favor seedlings and plants with succulent foliage, you will need to vigilantly protect these. Some plants these pests will seriously damage include basil, beans, cabbage, dahlia, delphinium, hosta, lettuce, marigolds, strawberries, and many other vegetable 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.


Handpicking can be very effective if done thoroughly on a regular basis. At first you should look for snails and slugs daily, paying careful attention to potential hiding places. After the population has noticeably declined, a weekly handpicking can be sufficient.

To draw out snails and slugs, water the infested area in the late afternoon. After dark, search them out using a flashlight, pick them up (rubber gloves are handy when slugs are involved), place them in a plastic bag, and dispose of them in the trash. You also can put them in a bucket with soapy water and dispose of them in your compost pile after they are dead. Alternatively, crush captured snails and slugs and leave them in the garden. Another option for killing slugs you have collected is to spray them with a solution of household ammonia diluted to a 5 to 10% solution in water.


You can trap snails and slugs beneath boards or flower pots that you position throughout the garden and landscape. Inverted melon rinds also make good traps. Construct wooden traps using 12- by 15-inch boards (or any easy-to-handle size) raised off the ground by 1-inch runners. The runners make it easy for the pests to crawl underneath. Scrape off the accumulated snails and slugs daily and destroy them; crushing is the most common method. Don’t use salt to destroy snails and slugs, since it will increase soil salinity.

Some people use beer-baited traps buried at ground level to catch and drown slugs and snails that fall into them. Because it is the fermented part of the product that attracts these pests, you also can use a sugar-water and yeast mixture instead of beer. However, these traps aren’t very effective for the labor involved. Beer traps attract slugs and snails within an area of only a few feet, and you must replenish the bait every few days to keep the level deep enough to drown the mollusks. Traps must have deep, vertical sides to keep the snails and slugs from crawling out and a top to reduce evaporation. You can purchase this type of snail and slug trap at garden supply stores.


Several types of barriers will keep snails and slugs out of planting beds. The easiest to maintain are those made with copper flashing and screen. It is believed that copper barriers are effective because the copper reacts with the slime that snails and slugs secrete, causing a disruption in their nervous system similar to an electric shock. When erecting vertical copper screens, it is best to use ones that are at least 4 inches tall, so you can bury a portion of it a few inches below the soil to prevent slugs from crawling beneath the barrier.

Copper foil (e.g. Snail-Barr) wrapped around planting boxes, headers, or trunks will repel snails for several years. When banding trunks, wrap the copper foil around the trunk, tab side down, and cut it to allow an 8-inch overlap. Attach one end or the middle of the band to the trunk with one staple oriented parallel to the trunk. Overlap and fasten the ends with one or two large paper clips to allow the copper band to slide as the trunk grows. Bend the tabs out at a 90° angle from the trunk. If the bands tarnish, you can clean them with a vinegar solution.

When using copper bands on planter boxes, be sure the soil within the boxes is snail free before applying them. If it isn’t, handpick the snails and slugs from the soil after applying the band (but before planting new plants) until the box is free of these pests. Solarizing the soil—a technique that uses clear, plastic tarp and the sun’s heat—is a good way to kill eggs in raised beds.

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.

Barriers of dry ashes or other abrasives heaped in a band 1 inch high and 3 inches wide around the garden also can be effective. However, these barriers lose their effectiveness after becoming damp, making them difficult to maintain and not very useful in most garden situations.

Natural Enemies

Snails and slugs have many natural enemies including ground beetles, pathogens, snakes, toads, turtles, and birds, but most are rarely effective enough to provide satisfactory control in the garden. One predator found in some California gardens is a large Staphylinid beetle called the devil’s coach horse, Ocypus olens. However, this beetle, which is more than 1-inch long, also will feed on ripening or decaying fruits and vegetables.

Domesticated fowl—such as ducks, geese, or chickens—kept penned in infested areas can be effective snail predators that significantly reduce problems. Be careful, though, as these birds also can eat seedlings.

The predatory decollate snail, Rumina decollata, has been released in Southern California citrus orchards to control young brown garden snails and is providing very effective biological control. It feeds only on small snails, not full-sized ones. Because of the potential impact of the decollate snail on certain endangered mollusk species, it can’t be released in California outside of Fresno, Imperial, Kern, Los Angeles, Madera, Orange, Riverside, Santa Barbara, San Bernardino, San Diego, Ventura, and Tulare counties. Decollate snails can feed on seedlings, small plants, and flowers and can be a nuisance when they cover the back patio on a misty day. Because snail baits will kill decollate snails, you shouldn’t use them where these predators are active.


Snail and slug baits can be effective when used properly in conjunction with a cultural program incorporating the other methods discussed above. However, baits alone won’t effectively control snails or slugs. Baits are toxic to all snails and slugs, including the predatory decollate snail and native species.

Several types of snail and slug bait products are available. 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. Metaldehyde baits containing 4% active ingredient are more effective than those containing only 2%; however, they also are more toxic to dogs and wildlife. 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.

Baits containing only metaldehyde are most reliable when temperatures are warm or during periods of lower humidity. When it is sunny or hot, these baits cause snails and slugs to die from desiccation or dehydration. The pests usually die with one day of ingesting the chemical or getting it on their foot. If cool, wet weather follows the baiting, they can recover if they ingest a sublethal dose. Don’t water heavily for at least 3 or 4 days after bait placement, since watering will reduce effectiveness. Most metaldehyde baits break down rapidly when exposed to sunlight and high irrigation; however, some paste or bullet formulations (e.g. Deadline) hold up somewhat longer in these conditions.

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.

Sprinkle baits in areas that snails and slugs regularly frequent such as around sprinkler heads. Placing baits repeatedly in the same areas maximizes control, because mollusks tend to return to food source sites. Never pile bait in mounds or clumps, especially those products that are more hazardous, because piling makes bait attractive to pets and children and is not as effective as sprinkling. Thick, liquid baits might persist better when it is rainy or in areas that receive sprinkler irrigation.

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.