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Master Gardener FAQ's |
The Most Frequently Asked Questions from our Hotline.... |
We receive phone calls from folks all over Orange County who have questions about a pest, a plant or some other problem. We have taken the questions that you ask most and placed them here.
If you don't find your question in this list, please call or email our hotline for assistance.
Questions and Responses listed below: |
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Q1: I don't have much space for gardening, but I have a patio. How do I go about gardening in containers? L.M., Santa Ana.
| A1: |
Container gardening is a wonderful way to enhance any setting where there is no ground for planting such as a patio or balcony. Containers can even be an interesting addition to an actual garden itself, adding texture, color and height. One of the advantages of container gardening is the ability to move plants around as you like. The same basics of landscape design apply to container gardening.
Consider the following when planning your garden:
CONTAINERS
There are no limits to the containers that can be used for planting. Everything from formal urns to classic terra-cotta pots, to a child's wagon or an old pair of shoes can be adapted to be used as a planter. There are just a few things to keep in mind when choosing the container:
-Be sure that the drainage in the container is adequate for the type of plants you will be using. Drilling drainage holes is best. If that's not possible, add a few inches of gravel or Styrofoam packing peanuts to the bottom of the pot.
-The bigger the container, the less often you will have to water and fertilize. A 24-inch barrel may only need to be watered once or twice a week, but a six-inch container may need to be watered daily.
-Realize that the container material will also affect how often you need to water. For instance, terra-cotta is porous and will require more frequent watering than a glazed container of the same size that doesn't breathe. Plastic needs to be watered the least often.
-Keep in mind the proportion between the container and the plant. In general, the container diameter and height should be about one third to one half of the height of the plant. Add vertical interest to a container in the way of trellises or decorations that are attached to a stake and inserted into the soil. Enhancements like miniature birdhouses or bird's nests are also fun to add.
PLANTS
Almost any plant can be grown in a container as long as it meets the plant's specific cultural needs. When deciding on plants remember these tips:
-Annual or perennial? Annuals will give you lots of blooms and lush growth quickly, but will need to be replanted two or three times a year as the seasons change. Perennials can live for years in the same container before needing to be divided, but will only have blooms for a portion of the year. Some perennials also die back at certain times of the year and won't look their best. You can move the pot to an inconspicuous spot when they are dormant or combine them with other plants that stay full throughout the year.
-Pay attention to color and texture. Coordinate the colors in the container the same way you would when decorating a room. Use a variety of flower color, foliage color and texture and plants of various heights.
-Do you want fragrance? Because most container gardens are on decks and patios, they are usually in close proximity to your house and seating areas. Make sure to keep this in mind when choosing plants so that the fragrance is an added enhancement and not overpowering or unpleasant. - Consider location before choosing plants. It is important to use plants that like similar exposure requirements. Don't plant shade loving plants with those that require full sun.
-Try grouping similar plants together for a common theme, such as all tropical plants, or all herbs.
-Groups of containers look better in odd numbers such as three, five or seven pots of varying heights.
-Choose plants of varying growth habits. In addition to upright plants, include plants around the edges that spill over the brims of the containers. SOIL There are many varieties of lightweight soils intended for use in containers that should be adequate for most needs. A few things to keep in mind:
-Plants with specific soil requirements, such as orchids or cactus, need the appropriate mixture for their specific needs.
-Don't use garden soil - it is too heavy.
-Consider adding water-saving soil polymers to potting soil, which hold water and release it to plants when needed. Be sure to soak the polymers before mixing them into the soil or they will push the soil out of the container when they expand.
-If a soil seems fine textured, add pumice to the mix to increase drainage.
-Leave room at the top of the container to allow water to soak in.
-Cover exposed soil with mulch to cut down on evaporation and make the overall appearance more aesthetically pleasing. Good choices include moss, stones, shredded bark or try an unusual mulch such as seashells or tumbled glass.
MAINTENANCE
-Establish an effective watering routine for the type of containers and plants in your garden. Consider installing a drip system if necessary.
-Fertilize regularly. Container plants need regular feeding because they have limited soil and the nutrients tend to get leached out quickly.
-Periodically check for roots that are coming out of the bottom of the pot which is an indicator that the plant needs to be transplanted to a larger container.
-Check for pest and disease problems regularly. Because plants in containers are under more stress than plants growing in the ground, they may be more subject to pest and diseases. Treat any problems quickly, before they spread.
-Grooming and deadheading is important since container gardens are typically viewed at a closer range than garden beds.
*Written and researched by University of California Master Gardener, Sheila Peterson, who lives in Laguna Beach. |
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Q2: What plants do well along the coast?
| A2: |
Gardening along the coast has its special challenges, including salt spray and windy conditions. Salt is extremely corrosive and many plants won't tolerate the salt air, which results in salt burn. Burned leaf tips are an indication of too much salt. There are plants, however, that tolerate very salty air, such as the aptly named saltbush (Atriplex). Many are desert plants and have a high resistance to salinity and alkalinity.
Windy conditions are also a problem on the coast. Plants that tolerate wind have small and/or waxy leaves that prevent the wind and salt air from damaging them and are able to reduce the rate at which they lose water.
Purchasing plants from a coastal nursery is advised, as they carry plants adapted for beach living. And it is best to start with small plants as they will adapt more readily to beach life than larger plants.
The following plants grow well on the coast, standing up to salt spray and windy conditions.
GRASSES
Bermuda grass (salt resistant) Kikuyu grass (salt resistant) Note: These grasses are very invasive and should be contained within borders.
PERENNIALS
Agapanthus (lily of the Nile) (salt tolerant) Armeria (Sea pink) Artemisia (salt tolerant) Asters Baccharis (Coyote brush) Capeweed (Arctotheca calendula) Ceanothus (wild lilac) Cotoneaster Cymbidium Echium (stands up to salt and wind) Gazania Geraniums Heather Ice plant Jade plant Lamb's Ears (salt tolerant) Lavender (salt tolerant) Lupines (salt tolerant) Penstemon (salt tolerant) California Poppies Salvia (salt tolerant) Santolina Succulents (aloe, cotyledons, Echeveria elegans (hen and chicks), euphorbia) (stand up to windy conditions)
TREES & SHRUBS
Acacia longifolia & redolens (good wind breaks) Artemisia Bottlebrush (callistemon) Monterey Cypress (good wind break) Escallonia Meyer Lemon Leptospermum laevigatum, scoparium (good wind breaks, salt retardant) Manzanita Melaleuca nesophila (takes wind and salt spray) Myoporum laetum (good wind break) New Zealand Christmas Tree (Metrosideros excelsus) Oleander Pittosporum (good wind break) Rosemary (salt resistant) Roses (some varieties) Saltbush (Atriplex)
VEGETABLES/FRUIT
Apple (Gordon and Beverly Hills only) Artichokes Bush Beans Blackberries Broccoli Brussels sprouts Cauliflower Culinary herbs Leafy vegetables (lettuce, spinach, swiss chard, mustard, kale, endive, arugula, cabbage, etc.) Peach Pumpkins Raspberries Root Crops (beets, carrots, garlic, onions, potatoes) Sugar snap peas Sunflowers Strawberries Tomatoes (varieties developed for cool and foggy areas) Zucchini
VINES
Bougainvillea Hardenbergia (vine) Honeysuckle Ivy Jasmine vines Lantana (vining shrub) Passion vine Potato vine (Solanum jasminoides) Sweet Peas (flowering) Trumpet vine |
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Q3: I heard that "killer bees" have become a menace in Orange County. What should I do to protect my family? C.R., Fountain Valley.
| A3: |
What many people call "killer bees," are actually Africanized honey bees (AHB). They were first sighted in Orange County in March, 1999. While they can be dangerous, they aren't exactly a menace. Fear of these bees should not prevent you from gardening or enjoying other outdoor activities.
According to Nick Nisson, the Orange County entomologist with the California State Agricultural Commission, all emergency services report serious bee stinging incidents to the Agricultural Commission. Thus far, none have been reported in Orange County. In fact, since AHBs first migrated across the Mexican border into the United States in 1990, less than ten deaths have been attributed to the AHB. So the risk of a serious bee attack is similar to the risk of being attacked by a bear, a shark or a mountain lion. Your best course of action is to learn about the habits of these bees and take reasonable precautions.
Until the arrival of the AHBs, the bee commonly encountered in Orange County was the domesticated European Honey Bee (EHB), which was bred for gentleness and good honey production. The EHB also plays an important role in pollinating garden plants and commercial crops.
AHBs were introduced to South America during the 1950s in the hope that they would adopt more readily than EHBs to warm tropical climates in the Americas. Unfortunately, AHBs are wild by nature, more easily upset than EHBs, and did not take to domestication. Nevertheless, in many ways they are very similar to EHBs. They cannot be told apart based upon appearance, and can be distinguished from EHBs only in the laboratory. Although there are important differences between the behavior of AHBs and EHBs, they are quite similar in many ways. An understanding of the habits common to both bees, and the habits unique to AHBs will help prevent stinging by either type of bee.
When bees are gathering pollen or nectar, they do not have time to bother people. There is little risk of being stung by these bees unless they are trapped or harmed in some way. Bees are often attracted to evaporative water coolers or to standing water in pets' dishes, birdbaths, or ponds, and may be attracted in large numbers. These bees, like foraging bees, are not likely to be aggressive unless harmed. Scent does attract bees, though, so if you do not want the close companionship of curious bees, it is best to avoid floral or citrus aftershave and perfume. The company of bees may also be discouraged by wearing light-colored clothing in the garden and on outings. Bees are more likely to attack dark clothing, dark hair, and dark skin.
In the spring and sometimes in the fall it is normal for one-half of the working force of a bee colony, and a queen, to separate from the mother colony and fly out (swarm) to search for a new home. Both AHBs and EHBs engage in this activity, although AHBs swarm more frequently than EHBs. Since they have no young bees to protect, swarming bees of both types tend to be mild mannered and are not likely to be a threat unless they are molested by rock throwing or similar activity. Usually a swarm will move on in a day or two.
Once bees establish colonies, they will defend them. The difference between EHBs and AHBs, is that AHBs defend a larger area around their nests, pursue intruders sooner and in larger numbers, and carry the chase further. AHBs may feel threatened by people fifty feet or more from their nests and they are sensitive to the vibrations of power equipment 100 feet or more from their nests. In fact serious stinging incidents often arise from the use of power equipment, such as mowers, weed-eaters, or chain-saws near colonies of AHBs. EHBs that become agitated will pursue an intruder as far as the length of one-half of a football field. AHBs will continue the pursuit even further, for one- quarter mile or more. As with EHBs, each bee can only sting once, and the sting of an AHB is no more potent than that of an EHB, but the aggressiveness of the AHB, their persistence, and the number of bees that join in attacks makes then more dangerous.
Unlike EHBs, AHBs establish colonies in small cavities and protected areas that would not ordinarily be used by EHBs, so their nests may be encountered in unexpected places. Colonies have been found in holes in trees, the space between the walls or buildings, underneath foundations, in sheds, in drain pipes, water meter valve boxes, abandoned appliances, holes in the ground, piles of junk, flower pots stored upside down, piles of rocks, underneath picnic tables and even in old tires. In wild areas there may be as many as ten to twenty colonies per square mile.
To avoid unpleasant encounters with AHBs, prevent the establishment of colonies near your house or garden. Fill in cracks and crevices around your house with steel wool or caulk. Cover openings greater than 1/8 inch in walls, and chimneys by installing 1/8 inch screen. Also cover drain pipe openings with screen. Remove junk, rock piles and wood piles. Fill holes in the ground and in water meter valve boxes. Secure doors to outside utility closets and sheds.
Be on the lookout for unusual bee signs. Watch for bees coming and going from a crack or a hole, and listen for a loud buzzing sound that may indicate the presence of a colony. Always examine areas where you plan to use power equipment, and inspect the area around campsites and picnic tables before children play. Stay aware of your environment when hiking.
Often, but not always, serious stinging incidents start with provocation such as a stone tossed at a colony, the vibration of power equipment, attempts to spray bees with the hose or an aerosol insecticide, or to douse them with chemicals. Avoid these behaviors, teach your children to avoid them, and when hiking, keep pets on a leash so they do not accidentally come upon a bee colony.
If you discover a bee swarm, or believe you have discovered a colony, the best advice is to stay away from it. According to entomologist Nisson, there are no public agencies in Orange County that remove bee swarms or colonies from private property. So, if you require bee removal you'll need to contact a commercial beekeeper or pest control company to arrange for its removal. In other counties, public assistance may be available; contact your local vector control district. Los Angeles county has an Africanized Honeybee emergency line at 1-800-233-9279.
What should you do if, in spite of your efforts, you do encounter angry bees? Bees frequently engage in defensive behavior before commencing an attack. So if groups of bees begin to fly at your face or buzz around your head, this is a sign that you are in danger. Do not further excite the bees by swatting at them; do not try to gather up your possessions; do not try to fool the bees by standing still. Withdraw immediately!
If bees begin stinging, flee, and remember that if shelter cannot be found, it may be necessary to continue for one quarter mile or more before the bees disengage. Also, remember that any person or animal who is not capable of sustained rapid movement is at serious risk once an attack begins. If you see someone else being attacked, call 911 immediately.
If attacked, don't flail at the bees. You will only leave yourself unprotected and further anger the bees. Cover the head and eyes with anything available, and if nothing is available, use your arms and hands to protect them. Stings to the chest, back, stomach, arms and hands are less serious than stings to the face and head. Try to get indoors as quickly as possible. If you are far from shelter and can do so, a run through brush may confuse and slow bees. Jumping into water is not recommended because AHBs will wait in the area for a considerable time.
If you are stung, evaluate the situation once you are in a safe place. The care for treatment of stings by AHBs is the same as care for stings by EHBs and wasps. When removing stingers, speed is most important. Try to avoid using tweezers or fingers to pull-out stingers as this may squeeze more venom into your wounds. Bee stingers should be removed by scraping sideways using fingernails, the edge of a credit card, or a knife. However, if none of these items are readily available, pulling them out quickly is more important than how you do it. Once stingers are removed, wash the stung area and apply ice packs to reduce swelling.
Ordinarily healthy people who are not allergic to bee stings are not killed by bee stings unless they have been stung hundreds of times. Elderly people and children are more at risk and may die from fewer than one hundred stings. If you have been stung fifteen times or more, know you are allergic to bee stings, or if you are having symptoms such as shortness of breath, swelling of the tongue, hives or dizziness, call 911, or seek medical attention immediately. In the case of symptoms described, unconsciousness may occur within twenty minutes.
Hopefully, with this information you will have the confidence to continue enjoying the outdoors and the drowsy humming of bees on summer afternoons. |
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Q4: I gardened inland for years, but recently moved near the beach. I've tried growing some things here that I grew without any problem inland, like tomatoes, but I haven't had much luck. Can you give me some pointers about coastal gardening? S.T., Huntington Beach.
| A4: |
As you have noticed, gardening along the coast is unlike gardening anywhere else. And although you aren't able to grow everything you grew inland, you'll be glad to know that gardening near the seashore can be much more pleasant.
Near the ocean you won't find the temperature extremes commonly found inland. Areas like Orange and Fullerton hit the nineties and even hundreds in the summer months, which make gardening uncomfortable and can kill certain plants. Seacoast weather, on the other hand, generally stays in the seventies and eighties, making gardening enjoyable. Weather is also milder in winter on Orange County shores. All of this creates a subtropical environment where many sometimes sensitive plants thrive. Banana, bougainvillea, ferns, hibiscus, begonia, fuchsia and impatiens are just a few of the plants that love coastal weather.
Coastal gardening does have its share of challenges, however, such as the one you mentioned. Growing certain plants that like high heat, such as tomatoes, can be difficult and sometimes impossible. In some instances, you will have to avoid certain plants or be very careful about the varieties you grow.
Although you can't grow large beefsteak types of tomatoes on the coast, you can successfully cultivate smaller varieties, such as Early Girl and cherry tomatoes.
In the case of citrus, it is hard to grow just about every variety, except for Meyer lemon, which actually does best along the coast.
Proper selection of other fruit trees, such as peaches and apples, is also important. These need a certain number of chill hours in the winter to produce well, so it's important to choose varieties that require low chill hours.
Some fruits and vegetables like cantaloupe and eggplant won't grow well, if at all, along the coast, but there are many other vegetables to choose from. Try zucchini, artichoke, pea, all leaf crops, all root crops, broccoli, cauliflower, culinary herbs, blackberries, strawberries and raspberries.
Many roses mildew and rust along the coast, but certain varieties will do well, as long as you pay careful attention to planting location. An iceberg rose bush will thrive in a sunny area next to a fence or shrub that gives it wind protection.
Other troubles common at the beach include salt spray and windy conditions, which can both wreak havoc on plants. Wind is a dehydrator and salt can cause poisoning, which entails browning at the end of leaves and a resulting dieback.
To protect plants from wind and the accompanying salt spray, create walls and canopies using plants that make good windbreaks, such as Acacia redolens, Myoporum laetum, Melaleuca nesophila and Australian tea tree (Leptospermum laevigatum).
Windbreaks are most effective if designed in a tier fashion. Small ground cover plants, such as native grasses, should be put closest to the ocean, with medium-height plants like shrubs and larger trees closest to the garden. Such a set-up will cause wind to sweep up and over the landscape, rather than hitting it vertically.
To minimize the salt spray plants receive, use spray irrigation for delicate plants to rinse the salts off.
Mulching and building the soil with a lot of organic material is also recommended as it creates air for the roots and will encourage healthy plants. Organic material also adds fertility and bulk to sandy soil found at the beach.
For a list of plants that thrive along the coast, see Question #2 above. |
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Q5: Aphids have appeared on my shrubs and roses. Is there anything I should do?
| A5: |
Aphids begin to show up in Southern California during the early spring, and in most areas they cease to be a serious problem after summer temperatures reach the nineties. Aphids are small, soft-bodied insects with long slender mouth parts which they use to pierce stems and leaves and suck out plant fluids. As they suck, they exude a sweet sticky substance known as honeydew, which is attractive to ants. Aphids may be green, yellow, reddish or black and are typically 1/8 inch or less in size, with pear- shaped bodies, long legs and antennae. Aphids give birth asexually to live young who resemble miniature adults and can multiply rapidly.
Limited numbers of aphids are not damaging to gardens, and a small number are actually a good thing, because they provide beneficial insects with a food source. A large population, however, may cause curling or yellowing of leaves, stunting of growth and damage to leaf and flower buds. A few species can cause galls (swellings of plant tissues within which the insect lives) or other distortions in growth. Aphids may also transmit viruses that cause plant diseases.
Often the honeydew that aphids create as they feed is more of a nuisance than anything else. This honeydew, which settles on plant leaves and underlying surfaces, such as walkways, is sticky and an airborne sooty black fungi often turns the sticky surfaces black. The honeydew also attracts ants.
There are a number of steps that may be taken to reduce the likelihood of aphid populations expanding to harmful levels in the garden. Consider the following:
* When selecting nursery plants, inspect the top and bottom of foliage for aphids and remove any pests found.
* Remove any build-up of weeds in the garden, which can harbor aphids.
* Encourage the presence of aphid predators--such as ladybeetles and lacewings--with plants that have nectar producing flowers, such as fennel, dill, lemon balm, nasturtium, scented gladiolus, lantana, parsley, honeysuckle and native plants. In addition to encouraging and conserving existing populations of aphid predators in the garden, it is also possible to introduce commercially available ladybeetles and lacewing eggs or larva.
Ladybeetles and their larvae are voracious aphid predators, but unfortunately upon release, they may not stay in your garden long enough to do any good.
Before releasing them, it is recommended that you spray them with sugar water, as purchased ladybeetles are often thirsty and hungry and more likely to scatter. It is also helpful to wet the plants and soil if the weather is dry. It is best to release them in the late evening on the ground or on lower branches of plants, as a climb seems to discourage flight. You can also discourage dispersal by chilling them for an hour or two in the refrigerator before release. Lacewings are generally purchased as larvae or eggs and they can be sprinkled onto dry aphid-infested foliage.
* Eliminating ants will make it easier for beneficial insects to control aphids. Trim trees and shrubs so that the only pathway ants may follow to foliage is the main stem. If a plant has a sturdy stem or trunk, then a sticky material such as Tanglefoot may be used as a barrier to the ants. When using sticky barriers, do not apply them directly to the bark of young or thin-barked trees or shrubs or to heavily pruned trees, as the sticky material may be toxic to the plants. Wrap trunks with fabric tree wrap and apply the sticky material to the wrap. Do not leave on indefinitely, as the wrapping material may cause damage as the plant grows.
* One of the easiest methods of controlling aphids is to wash them off with a strong spray of water. This also reduces the honeydew on foliage, and can be done on a daily basis, if necessary. Other options are to spray foliage with insecticidal soap or a fine horticultural oil spray. Or you can ask your local California Certified Nursery Professional (CCN Pro) for a recommendation. Do not use a soap or oil spray on any plant that is water- stressed or when the temperature is above ninety degrees.
* Because aphids are drawn to plant tissue with a high nitrogen content, it's also important not to overfertilize.
Written by University of California Master Gardener In training, Harold Pope, who lives in Irvine. |
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Q6: When is a good time to plant California poppies? Do they come in colors other than orange? How do I plant them? S.W., Santa Ana.
| A6: |
The state flower of California, the California poppy (Eschscholzia californica) is a short-lived perennial that is often treated as an annual, and now is an excellent time to plant them. These cheery flowers have lacy blue-green foliage, and naturally come in shades of orange or yellow, although after years of cultivation, you can also find other colors, such as pink, rose, red, cream and white.
The following are some available varieties:
-`Mission Bells': cream, pink, orange mix with semi-double blooms.
-`Ballerina': Semi-double flowers with frilled and fluted petals that come in shades of yellow, orange, rose and scarlet.
-`Monarch Mixed': singles and semi-doubles in yellow to cerise.
-`Silk Strain': striking, bronze-tinted foliage. Come in a full- color range with semi-double blooms. -`Apricot flambeau': creamy yellow petals with ruffled edges and rich orange highlights (Thompson & Morgan seeds).
-`Dalli': vivid deep orange blooms with yellow centers.
-`Maritima': clear lemon-yellow blooms, orange spotted-throat. Low mounder that makes a good border.
-`Mahogany Red': deep rust-red color.
-`Thai Silk': ruffled semi-double often available in single colors and a pink mixture.
The best time to plant California poppies is the same time you would plant other wildflowers and that is from late fall through early winter. Although you will see many people planting them in spring, November 15 through March 15 is optimum. California poppies germinate with winter rains, bloom in the cooler months of spring and set seed in late summer and then die. (Keep in mind that once established, exploding seed pods will distribute seedlings in places you might not want them.)
California poppies reach 12 or more inches in height and require very minimal care. They prefer full sun and some watering during the growing season. Sow where you would like them to grow, as they do not transplant well. Older plants tend to become leggy, so you should plant on giving them a severe pruning or start new plants.
Important guidelines to follow when planting California poppies and other wildflowers:
-Choose a spot in full sun. They look good growing in a natural grassland setting, on a sunny hillside or in the middle zone of a mixed country border. Try planting them with lupines, buttercups, deep red shirley poppies, scarlet flax, orange calendulas and with various bulbs.
-Control weeds.
-Carefully prepare the soil. Rake the soil to form shallow grooves. To assure even distribution of your wildflower seeds, you may wish to mix the seed with four times its volume of sand and then broadcast by the handful. Next rake the seed lightly into the top 1/2 inch or so of soil and tamp it down. Avoid casting the seeds under trees (especially pine, oak, walnut and eucalyptus), as the poppies will struggle, do poorly and be short-lived.
-Protect seeds and seedlings from birds. Bird netting is a good choice.
-Keep seeds moist until they sprout, which is especially during drying winds. After they sprout, water whenever the soil dries out to a depth of 2 inches.
-Fertilize properly. Feed twice during the growing season with a complete fertilizer.
-Give proper post-bloom care. When plants have dried and dropped their seed, cut them back to three to six inches high. Don't trim back before they've had a chance to set their seed.
Find seeds at a variety of locations, including the Theodore Payne Foundation, which also sells books on California wildflowers, 818-768-1802. Larner seeds in Bolinas, CA carries true wildflowers used by the Santa Barbara Botanic Garden, 415-868-9407, as does Tree of Life Nursery on Ortega Highway in San Juan Capistrano 949-728-0685. The Fullerton Arboretum has California Poppy seeds in individual packets, 714-278-3579. |
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Q7: My apples had worms in the fruit last year. What can I do to have worm-free fruit this year?
| A7: |
Worms in apples are most likely the codling moth, Cydia (Laspeyresia) pomonella. Codling moth adults are small with a wing span of 1/2 to 3/4 inch, about the size of a housefly. Their gray mottled appearance blends well with bark, making them difficult to detect. Codling moth adults can be distinguished from other moths by their dark brown wing tips that have shiny coppery markings.
The immature larvae or caterpillar stage is the one that damages fruit. When larvae penetrate fruit and bore into the core they leave brown-colored holes in the fruit that are filled with frass (larval droppings). Coddling moth is also a serious pest of pears and walnuts.
Sometime in late March or April the female codling moth will lay eggs on fruit, nuts or nearby leaves. After the eggs hatch, the young larvae seek out and bore into fruit. After completing larval development, they leave the fruit and drop from the trees to search out sites in which to pupate (transform into moths). Depending on the weather, there can be two to four generations produced a year.
Codling moth can be very difficult to manage, especially if its population has been allowed to build up over a season or two. In trees with low to moderate levels, codling moth can often be kept to tolerable levels by using several management methods. It is, however, important to implement these measures early in the season. Where populations are high and many infested trees are nearby, insecticide applications may be necessary to bring populations down to very low levels. However, insecticides are very difficult to time accurately, and the only highly effective material available is toxic to natural enemies and honey bees. In many backyard situations, the best course of action may be to combine a variety of nonchemical methods and accept the presence of some wormy fruit.
Methods for reducing population numbers that do not require the use of insecticides include sanitation, bagging the fruit, mass trapping and trunk banding. Pruning trees to a height where the canopy is easy to reach will also simplify management of this pest.
If a backyard tree or orchard has a very high moth population, it may take several seasons of diligently practicing the following control methods to reduce codling moth damage to about 10 to 20 percent per year. Also keep in mind that orchards or backyard trees within a half-mile radius that are infected with codling moth and have no control program in place can serve as a continual source of codling moths.
SANITATION.
If your trees are not isolated from other codling moth host trees and your neighbors do not also follow these sanitation practices, this method alone will only control a small percentage of the population.
A portion of the codling moth population will overwinter as pupae in protected areas on tree trunks and in rubbish around the base of a tree. Remove rubbish and loose bark in winter. Every week or two beginning about 6 to 8 weeks after bloom, check fruit on trees for signs of damage and remove and destroy any infested ones. Also, clean up dropped fruit as soon as possible. This will help reduce populations of the next generation, because dropped fruit and nuts may still have larvae in them. Cleaning up is especially important in May and June.
BAGGING FRUIT.
By enclosing fruit that are on the tree in bags, making them inaccessible to codling moth larvae, you can achieve excellent control of this pest. Bagging can be done on fruit over the entire tree, or on as many fruit as desired.
To bag the fruit, thin fruit to one per cluster. The best time to do this is when the fruit is from 1/2 to 1 inch in diameter. Use No. 2 paper bags (standard lunch bag size) that measure 7-1/4 inches by 4 inches. Cut a 2-inch slit in the bottom of the bag and slip this opening over the fruit to form a seal around the stem. Staple the open end shut.
While this technique does not affect the maturity or quality of the fruit, it may have an impact on the color development of red varieties. On the plus side, bagging fruit protects it from both codling moth and sunburn. In addition, thinning the fruit to one per cluster results in larger fruit at harvest.
PHEROMONE TRAPS.
Pheromone traps are baited with a synthetic sex attractant (pheromone) that mimics the chemical female moths use to lure males for mating. There are two ways home gardeners can use pheromone traps: (1) to mass-trap male moths in an effort to reduce the size of the mating population, or (2) to help determine the need for an insecticide treatment. Mass trapping with pheromones may help reduce populations, but the effectiveness of this method in backyards has shown mixed results.
Another mass-trapping technique which some backyard growers have reported success with is a homemade moth trap consisting of a 1-gallon plastic milk jug containing the following: 1 cup cider vinegar, 1/3 cup dark molasses, 1/8 teaspoon ammonia and enough water to make 1-1/2 quarts of liquid. Cut a 2-inch diameter hole just below the shoulder of the jug. Hang the jug in the tree using a wide strip of cloth to protect the tree branch. Use up to three traps per tree for large trees.
TRUNK BANDING.
A traditional nonchemical method for controlling codling moth is to trap mature larvae in a trunk band of Tanglefoot, burlap bags, or corrugated cardboard as they climb up the trunk to pupate under loose bark. Trapped caterpillars or pupae must be killed before they can emerge as adult moths that can lay a second generation of eggs. For effective control this method must be used in conjunction with other control methods.
Corrugated cardboard is preferred for trunk banding. Use a 4-inch wide strip of large-core corrugated cardboard (size Flute A 18-inch rolls) and wrap it around the trunk of the tree so that the corrugation tubes are vertical and the band is snug against the trunk. Staple bands to trees about 18 inches or more from the ground and reinforce the staple with duct tape; pick the smoothest part of the trunk.
Place these bands on trunks after bloom, just before the caterpillars drop from the trees to seek pupation sites. Generally this occurs by the end of May along the coast. The codling moth caterpillars will crawl up the tree and into the corrugated cardboard to pupate. Remove the cardboard bands before moths begin to appear (approximately the end of May or June) and destroy all caterpillars and pupae. To help control the overwintering generation, put new trunk bands up in August and remove and destroy them between November and January.
CHEMICAL CONTROL.
Proper timing of insecticide applications is critical if they are to be effective against codling moth. Chemicals must be applied just as eggs are hatching. Once the caterpillar has gone into the fruit or nut, it is protected from pesticides. In order to know when to spray, check fruit at least twice a week for entry holes or stings that indicate larvae have begun boring into fruit. Spray as soon as you see the first sting. Unless insecticide applications are properly timed, the nonchemical methods will probably provide more reliable control.
Only a few insecticides are available to home gardeners for managing codling moth. For a recommendation on the best insecticide to use in your area, consult your local California Certified Nursery Professional, the Agricultural Commissioner's office or the University of California Master Gardener hotline.
Other materials such as Bacillus thuringiensis, cryolite, and pyrethrin/rotenone combinations have not been found to be effective at controlling codling moth.
This information has been summarized from the UC Pest Management Guidelines. The full text and photos can be found at: http://www.ipm.ucdavis.edu/. |
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