Master Gardener News Blog
Woolly Whitefly In The Garden
By Andrea Peck UCCE Master Gardener
I notice white flying insects on my orange tree, should I be concerned?
Leo V. Los Osos
It sounds like your citrus tree has become the landing pad for the woolly whitefly. When few in number, these pests will not hamper fruit production, but if the population increases dramatically, problems may soon follow. Found on all variety of citrus trees, guava and rarely ornamentals, the wooly whitefly tends to become a nuisance during late summer through early November.
This tiny insect (1.5mm in length) gets its name from the waxy, wooly-appearing filaments that protect it. The female lays her eggs on the underside of fully extended leaves in a circular or semi-circle shape. Newly laid eggs are pale white in color but darken to brown as time progresses. It takes 4-12 days for eggs to hatch, except when overwintering. The female whitefly is able to lay up to 200 eggs. Each egg is a diminutive 0.3mm. Good luck finding them without a magnifying glass.
In comparison to other whiteflies, the woolly variety is best described as indolent. When disturbed from its leafy post, it is likely to move slowly as it is forced from its cozy seat. The disgruntled creature will then, just as slowly, find another location to recline. These are not the high achievers of the insect world, but they are pests nevertheless and should be noted with caution. Searching for the woolly whitefly and its eggs may prove difficult based on their microscopic size, but there are other subtle hints that your plants have been invaded.
Woolly whiteflies obtain nutrients from the leaves of trees and plants. Leaf drop results which compromises the health of your tree. Additionally, these pests produce honeydew which creates a perfect environment for sooty mold and attracts ants. Sooty mold blackens leaves, limits photosynthesis and reduces fruit size and quality. Ants will protect whiteflies against natural predators.
Monitoring plants in the spring prevents the population from proliferating. During late summer and fall, the simplest control method for the home gardener is a strong spray of water to the underside of plant leaves. This will dislodge insects, eggs, and clean away harmful honeydew.
California Native Plants
By Leonard Cicerello UCCE Master Gardener
There are almost 5,000 California native plants to choose from. California has climactic zones that range from very wet to extremely dry; from coastal to alpine. There are evergreen trees including conifers, deciduous trees, flowering trees, shrubs; evergreens and deciduous evergreens. The flowering shrubs come in every color imaginable. There are ferns, wildflowers, vines, ground covers, succulents, and the list goes on. There is something to suit almost any need.
Until this current extended drought, native plants have been often treated as novelties rather than first choices. This drought has encouraged us to give up our long held love affair with water-thirsty lawns, to re-landscape wisely, and to use less water in our gardens. Besides the pride of planting native plants, another bonus is that they require less water than many of their non-native counterparts. Additionally, they do not need fertilizer. If you plant a native in an environment similar to its native environment, it should grow successfully, require fewer resources and less maintenance, saving you time and money.
If you love an abundance of birds, bees, and butterflies in your garden, native plants attract native wildlife. You can create a natural habitat for wildlife with groupings of native plants.
Other resources for native plant information are the California Native Plant Society. They are very active throughout the state, including a San Luis Obispo chapter, and they offer useful information on their website. A local nursery, Las Pilitas Nursery, includes a search feature to help home gardeners find the right native plant for their yard. Many local nurseries now offer a selection of natives well adapted to this region due to increased interest in natives. However It is important to do your research before purchasing to make sure the native you select will grow in your micro climate of San Luis Obispo County.
California Gall Wasps
By Tami Reece UCCE Master Gardener
What are the brown balls that look like fruit growing on my oak trees? Mary B. Atascadero
The apple size structures on the ground under your oak trees are probably oak galls caused by small wasps. These wasps are harmless to pets and humans and there are a variety of species of wasp species that commonly infest oak trees. Most galls are initiated by insects, but can also be caused by bacteria, fungi, or mistletoe.
Different gall wasp species form different types of oak galls on different areas of the tree, during different parts of the season. One of the most common in our region is the apple gall wasp (Andricus quercuscalifornicus). These wasps cause galls that start out green on the oak branch then turn reddish, brown, or sometimes black as they increase in size to as large as 4 inches in diameter. Your oak tree may have individual galls or dense clusters.
The lifecycle of California gall wasps alternate between sexual and asexual reproduction. The springtime generation consists of both males and females. The generation of the summer and fall consists of females only that reproduce parthenogenetically, or without male genes. The spring generation gives rise to galls forming in March and April and newly emerged adults in May through June. The summer and fall all female generations typically emerge as adults the following spring. There are hundreds of insects that use California oaks as a food source, many of which are gall formers.
As with other gall wasps, no control measure is necessary or recommended. The galls do not harm the tree or weaken it any way. Gall wasps and the gall itself are important host for other predators including parasitic wasps, birds, spiders, and lizards. Therefore, chemical applications would do more harm than good by disrupting this complex food chain.
On Saturday August 20, the Master Gardeners held their 10th Annual Tomato Extravaganza and Plant Sale. We would like to thank everyone who attended and announce the winners of the tomato and basil voting. The top tomato for taste was Brandywine. The second was Black Cherry and the third Yellow Pear. The top basil voted for taste was Sweet Thai with Lime Basil and Queenette Thai as a close second and third. See you next year!
By Leslie E. Stevens UCCE Master Gardener
Looper caterpillars get their name from their distinctive locomotion – arching their middle section by drawing up their back legs and inching along leaves and stems of plants. Unfortunately, this engaging trait belongs to some of the garden's more destructive pest families. Long before you spot one of these slinky critters, they'll have chewed the leaves of your prized plants into tatters overnight.
Cabbage loopers (Trichoplusia ni) are among the most common looper caterpillars. They're members of the noctuid moth family and cutworms and army worms. These green 1-1/2-inch-long larvae chomp their way through cabbage, broccoli, Brussels sprouts, cauliflower, kale and collards. They also have a taste for lettuce, spinach, beans, peas, celery, parsley, radishes, potatoes and tomatoes.
The adult cabbage looper – a brown, nocturnal moth – lays its tiny, domed-shaped eggs singly on the undersides of mature leaves. The pupa is enclosed in a thin cocoon attached to leaves in the plant's crown or in debris on the ground. The looper's lifecycle lasts between 23 to 95 days as long as temperatures stay above 50⁰F and below 90⁰F. The higher the temperature, the shorter the lifecycle. In our mild coastal climate, five or more generations may occur annually.
A host of other caterpillars share the cabbage loopers peculiar gait and voracious eating habits, but are otherwise unrelated. Commonly known as inchworms, geometrid relatives number in the thousands. They're about an inch long, many are green or brown with vivid markings. They feed on fruits, vegetables and ornamental plants, such as apple, avocado, oak and bougainvillea.
Prevention & Control
Despite the different lineage, management is similar for caterpillars of both families. As weather warms in the spring, watch for moths. Use row covers to protect your susceptible crops and prevent moths from laying eggs among your plants.
At the first sight of damage, inspect the undersides of leaves early in the morning for larvae and physically destroy them. Squish them or flick them into a container of soapy water. Avoid broad-spectrum and long-acting pesticides since they also kill beneficial predators such as spiders and wasps that help manage looper populations. If physical removal of loopers is insufficient, try applications of less toxic Bacillus thuringiensis.
Greywater Made Easy
By Lee Oliphant UCCE Master Gardener
Q. Where do I start in setting up a graywater system for my garden? Carol, Cambria.
Using greywater is an excellent way to reduce the waste of a valuable resource and minimize water that enters waste water collection systems. Greywater is used household water from sinks, showers, bathtubs, and washing machines. It does not include water from toilets, kitchen sinks (remember that raw chicken you rinsed), or dishwashers. Greywater should not be used on any edible plants in the garden.
While you can carry out buckets from your sink, shower, or tub, there is an easier (on your back and shoulders) way to use non-potable water for outdoor irrigation. A greywater system uses gravity to redirect wastewater from a washing machine to the yard, rather than to the sewer, and is called Laundry to Landscape Greywater System. A construction permit is NOT needed for this system as long as the system does not alter plumbing by cutting into pipes. A hose to the house exterior is attached to the washer hose and must follow the Health and Safety code 17922.12. This system requires a 3-way valve that allows you to switch between a greywater and sewer system. Water must be diverted to the sewer if used for dirty diapers, infectious contaminants or if it contains cleaning products harmful to plants such as bleach, softeners, and dyes.
According to chapter 16 of the California Plumbing Code, greywater cannot be stored and must be used within 24 hours from the time of collection. Immediate use minimizes the development of bacteria and other harmful pathogens.
There are other, more complicated systems than the Laundry to Landscape Greywater System. However, both require permits and plumbing alterations. It is always wise to check with SLO County and your specific city before beginning your greywater project.
Identify detergents that are safe for the environment before using the Laundry to Landscape Greywater System. Become familiar with plants that do well with greywater such as madrone, western redbud, coffeeberry, toyon, manzanita, rosemary, ceanothus, salvia, lavender, and penstemon. They will survive the alkaline environment created by greywater.
For more information on using greywater in the landscape, download Use of Greywater in Urban Landscapes in California: http://anrcatalog.ucanr.edu.