The NCAP published the Journal of Pesticide Reform and works to educate the public about the dangers of pesticides. Go to their Publications section to download information on alternative solutions to pest problems, pesticide fact sheets, and special reports about issues of pesticide reform.
Keyword: Insect pests--Control
National Sustainable Agriculture Information Service pest management
A series of publications that offer a wide array of techniques and controls to effectively reduce or eliminate damage from insects, diseases and weeds without sacrificing the good of the soil, water, or beneficial organisms.
Cypress tip moth
My Leyland Cypress is browning and has Cypress tip moth signs. I’m worried about the brown spots, and wonder if it can survive this attack? How can I control the pests, if it might survive?
From what I can determine, your Leyland cypress (x Cupressocyparis leylandii) trees are probably going to
survive this attack unless they are weakened in some other way.
x Cupressocyparis leylandii in California survive the Cypress tip moth, though they can be unsightly. Since California is a bit too dry for this tree, the conditions are
not identical, but Natural Resources Canada does not
indicate that infestations are fatal. Because you said you found
evidence of tip moth (Cypress tip moth = Argyresthia cupressella), I will
assume that is what the problem is, but a bit of browning, even in
conifers, is not unusual right after trees are planted. Be sure that you
are not overwatering, as one effect of that is the same as underwatering
(i.e., tip die-back or yellowing) because too much water prevents the
plant from taking water and oxygen into the roots.
The Organic Gardener’s Handbook of Natural Insect and Disease Control
(ed. by Ellis and Bradley, 1996, p.183) says about pine tip moth
(Rhyacionia frustrana):
“Handpicking works if only a few caterpillars are present. Pruning off
and destroying infested tips in winter is a very effective control.”
I would recommend a prune-and-wait-and-see approach. April is a bit late to
prune (and puts root establishment in competition with shoot regrowth),
but you may be able to slow the infestation down, so go ahead and do
it. Watch the trees this season and then prune again in the winter next
year. Be sure to destroy (burn or bag and put in the garbage) the
debris so you don’t reinfect your tree.
A good gardening resource is the UBC Botanical Garden Forum. Personal
testimony/experience is valuable, especially if it’s regional. (You
might find it useful in the future.) Several people commenting about
x Cupressocyparis leylandii note that it is not a very desirable tree; one of its
parents, the Cupressus nootkatensis, also called Callitropsis
nootkatensis or Chamaecyparis nootkatensis, or, for that matter, plain Nootka cypress) is better. One person
recommended planting small trees in the beginning, since they grow very
fast. This might save you some money, should you have to replace your
trees. The site does not need a password; just click on “Search” in the upper right
corner.
Below is some additional information from Oregon State University about cypress tip moth. This site recommends pesticides, but from everything I read, they are not
effective without multiple treatments. Since this pest is generally not
fatal to the trees, it is probably not worth it to use chemicals which would be dangerous and time-consuming to apply. If you know something about the
life cycle of the pest, your observations will yield more information and any
manual control attempts are more likely to be effective.
Controlling mountain pine beetles
What is the latest method of eradication for the mountain pine beetle, Dendroctonus ponderosae, that is rampant in western Canada?
In the northwestern U.S., USDA Forest Service states that the focus has shifted from using pesticides to taking preventive measures:
Excerpt:
Control methods have shifted away from direct control (e.g. spraying, felling, burning) and towards prevention of outbreaks. This course of action was chosen after thoroughly exploring direct control measures for nearly a century and arriving at a simple conclusion: They don’t work. It is possible to prevent infestation with penetrating sprays on individual, high value trees such as those in campgrounds and near houses, but they need to be applied before the tree is infected and the cost of such treatments is prohibitive for any large-scale application.
Once a mountain pine beetle outbreak begins to spread, it can be stopped by thinning the stand ahead of the edge of the outbreak. This is because outbreaks expand on a tree to tree basis where the incoming beetles switch their attacks from a recently attacked-stem to the next largest tree. More importantly, infestations can be prevented by thinning stands before crown closure, an operation that not only increases the vigor of the residual stand, but also prevents the spread of an outbreak if individual trees have been attacked.
Mountain pine beetles are a natural part of western ecosystems, and for this reason will never be completely eradicated (nor should they be, as they serve to create small stand openings which are important for biodiversity of both flora and fauna). As such, the death of a few trees on your property doesn’t necessarily mean an epidemic is getting started; check your trees for root disease symptoms. To maintain mountain pine beetles at their normal levels, predisposing factors for outbreak must be removed. Some of these, such as environmental stresses, are not possible to control. However, many stresses are related to stand management practices. First and foremost, two situations need to be addressed: root disease centers and overstocked stands. More details about treatment for root disease centers have been given in other WSU Cooperative Extension “Forest Health Notes;” in summary, they need to be identified and planted with resistant species. Overstocking causes trees to compete for water, light and nutrients, and thus weakens their defenses against bark beetle attack. To minimize stand stresses and maintain vigorous growing conditions, stand managers should: (adapted from Berryman: Forest Insects, 1986).
Natural Resources Canada has a task force on the mountain pine beetle. You might want to contact them for the latest update. Go to their mountain pine beetle website and follow the links for additional information, including how to contact CCoFI.
Lemon tree, leaf loss, and scale
I have a lemon tree that is actually not dead yet, but it’s not looking good. I had to bring it in late last year as Florence [Italy] was due to have frost for a few days. Then we had horrendous winds and heavy rains. After a few weeks inside, (on a nice sunny indirect-light window sill) it started to drop everything: leaves, blossoms, tiny lemons, and now it is utterly bare. Maybe this is why? On clearing the leaves off the dirt I noticed little blister-like spots on some of the branches. I scraped them with my fingernail and they peeled off, but left sticky stuff behind. Is this a disease? Can I wash the stems? With what? I trimmed the tips of the tiny branches; they are green inside so not dead. I did fertilize with a high-nitrogen liquid, over the leaves and in the pot, a couple of times a month. I have a feeling that spider mites are doing the mischief. Is there hope?
Sorry to hear of your bare lemon tree! The loss of leaves could have been a reaction to the wind, and once the leaves are gone, the tree can become susceptible to waterlogging, pests, and diseases. It is good that you moved it inside, and that it has good light. The blister-like spots on the branches sound like a kind of scale insect, to which Meyer lemons can be prone: California red scale (Aonidiella aurantii). I do not think it would be spider mites, because they would cause stippled, yellowed leaves, and might leave telltale webs. Scale can defoliate and kill a tree. There are beneficial Aphytus wasps that can be used to control scale, but they have to released regularly to be effective and, of course, you would not do this while your tree is indoors. A good reference about scale insects and how to manage them is Pests of the Garden and Small Farm by Mary Louise Flint (University of California Division of Agriculture, 1990)
Here are two recommended books on growing citrus:
Citrus: Complete Guide to Selecting & Growing More than 100 Varieties by Lance Walheim (Ironwood Press, 1996)
Success with Citrus Fruit by Sigrid Hansen-Catania (Merehurst Ltd., London: 1998)
controlling rose sawflies
I think my rose leaves are being devoured by rose sawfly, and I was wondering if spraying ‘Rose Defense’ on them would help.
Rose Defense is a Scott’s product that contains Neem (as well as other ingredients). There is some evidence that Neem is effective against sawfly larvae. As with any pesticide, you should follow the directions on the package carefully (and note that this product may be harmful to humans, domestic animals, bees, and the environment, depending on the route of exposure).
You might want to start out with the least toxic approach first, that is, handpicking and spraying with water. Once larvae are knocked off the roses, they will not climb up again. If this doesn’t seem to be helping, then you could choose a Neem-based spray or insecticidal soap, keeping in mind that the Neem product is toxic to bees, and should not be applied when bees are active.
According to University of Minnesota Extension, sawflies are best controlled when young. You can simply pick them off by hand or dislodge them with a stick or a stream of water. If using water be sure to spray early enough in the day for the foliage to dry by sunset. This will prevent favorable conditions for fungal development. Horticultural oil, insecticidal soap and azadirachtin (sometimes called neem), are among the less toxic insecticides to treat young sawflies. Azadirachtin is slower acting. Bacillus thuringiensis (Bt) is effective on young lepidoptera caterpillars but NOT on larval sawflies.
Cornell University’s Resource Guide for Organic Insect and Disease Management also discusses the uses of Neem. Here is an excerpt:
“Neem products are generally sold as emulsifiable concentrates. Neem oil soap is sold as a water-soluble liquid concentrate. While Copping (2001) reports no known incompatibilities with other crop protection agents, phytotoxicity may be a problem when combining neem oil or soap products. Read labels for specific application guidelines including determination of re-entry interval and pre-harvest interval. Range of efficacy will depend on the susceptibility of species in question and environmental conditions at time of application. However these are points to follow:
Make multiple applications. Frequent applications are more effective than single sprays because neem does not persist well on plant surfaces. Like most other botanically derived materials, it can be rapidly broken down by sunlight and washed away by rain (Thacker 2002).
Use against immature insects. Azadirachtin-based insecticides act on immature stages of insects more effectively than on eggs or adults. To reduce a build up of populations it is important to make treatments to crops targeting insects in an early stage of their life cycle. For instance, neem would likely have little effect on an infestation of striped cucumber beetle adults; however if applied to potato plants early in the season, it has been shown to greatly reduce larval activity of Colorado potato beetle.
Begin applications before pest levels are high. Antifeedant and egg-laying repellant effects show best results in low to moderate pest populations.
Neem is reported to work best under warm temperature conditions (Schmutterer 1990).”
There are quite a few different species of sawfly, and I would guess that the rose sawfly is so named because rose bushes are its primary feeding ground. If you aren’t sure what is eating your roses, you may want to take samples of the affected leaves to your local county extension agent before you begin to treat the problem. You may find the images on the self-described Buggiest Rose Website (now archived) helpful in comparing with the leaf damage you are seeing.
controlling root weevils and whiteflies
I have a line of Ward’s ruby azaleas. The three weakest ones have a lot of tiny notches in the leaves. I seem to remember the notches from the root weevil as being larger than these. Are the tiny notches from something else?
I also noticed that some of my dahlias have splotched leaves and that when I disturb the leaves, white-looking insects fly off the leaves. These flies apparently have spread to tomatoes as well. Are these whitefly? Will they disappear after the winter or is there some control I should use to prevent them from taking over?
First you need to get an accurate diagnosis of your problems. If you are in King County, you can bring samples to a Master Gardener Clinic. For information about Clinic hours see their website (Plant Clinic Schedule).
Oregon State University offers this information about root weevils and Rhododendron (which includes Azaleas). It describes using beneficial nematodes as a control.
According to Washington State University Cooperative Extension’s publication, How to Identify Rhododendron and Azalea Problems (1984), root weevil damage to foliage is not usually a serious problem. You can check for weevils with a flashlight at night to confirm that they are the source of the notches you are seeing. There are some Neem oil-based products that may be helpful, but they must be used at the correct times of year. See WSU’s HortSense page.
As for the dahlias and tomatoes, it is important to determine exactly what the insects are before proceeding with treatment. If they are whiteflies, you can put yellow sticky traps around the plants to trap them. University of California, Davis’s Integrated Pest Management site has other recommended control methods, including reflective mulch. You may not want to use insecticidal soap:
“Insecticides have only a limited effect on whiteflies. Most kill only those whiteflies that come in direct contact with them. For particularly troublesome situations, try insecticidal soap or an insecticidal oil such as neem oil or narrow-range oil. Because these products only kill whitefly nymphs that are directly sprayed, plants must be thoroughly covered with the spray solution. Be sure to cover undersides of all infested leaves; usually these are the lowest leaves and the most difficult to reach. Use soaps when plants are not drought-stressed and when temperatures are under 80 degrees F to prevent possible damage to plants. Avoid using other pesticides to control whiteflies; not only do most of them kill natural enemies, whiteflies quickly build up resistance to them, and most are not very effective in garden situations.”
insect pests in the garden
Is it normal to have many different insect pests in one garden? Is it a sign that I am not taking care of my plants well? Everything looks fine except for one infestation after another!
As far as I am concerned it is perfectly normal to have all of these pests (because I also have many)! But some gardeners are more ruthless than I am. They would rip out the plants. Others would assault their garden with chemicals. I prefer the middle ground of tolerance of some damage and using low-toxic controls.
The mantra these days is RIGHT PLANT RIGHT PLACE and HEALTHY SOIL = HEALTHY PLANTS. For further information (and support) go to the Seattle Public Utilities website, which has a number of great publications on Natural Lawn and Garden Care.
There are lots of links to browse.
There is also information about Natural Pest, Weed, and Disease Control.
Other good resources are Toxic-Free Future (formerly known as Washington Toxics Coalition) and Northwest Center for Alternatives to Pesticides.
Plants that repel mosquitoes
Is there really a plant that will ward off mosquitoes, and if so, what is the name and is it available in the Seattle area?
There is disagreement about the extent to which certain plants repel mosquitoes. Below, please find some web sites that highlight some plants that may work.
There are eleven plants generally thought to repel mosquitoes:
Citronella, Eucalyptus, Pennyroyal, Rosemary, Rue, and Wormwood. Milder ones (in our experience) include Basil, Bay, Lavender, Sage and Thyme. With even the smallest of herb gardens, or access to a supermarket selling freshly-cut herbs, the leaves of such plants can simply be rubbed on pets and people to temporarily ward off insect attacks.
(Source: Janette Grainger & Connie Moore. Natural Insect Repellents for Pets, People & Plants. 1991, p.11.)
According to Donald Lewis of the Department of Entomology at Iowa State University, citrosa, lemon thyme or citronella grass may help repel mosquitoes, but you have to crush the leaves and rub them on your skin to make them work.
According to the MadSci Network, citronella oil may be more effective at repelling mosquitoes than the plant itself.
Lastly, Colorado State Cooperative Extension recommends scented geranium, lemon grass and a host of other plants.
There are many local nurseries which may carry the plants mentioned above, but since inventory changes frequently and they do not list their inventory online, it is best to give them a call to find out if plants you are seeking are available.
Because of the ongoing concern about West Nile Virus, there is a lot of information available on ways to control mosquitoes. See King County Public Health’s resources on this topic.
on the safety of using horticultural oils on edible plants
I have some insects on my bay laurel, which we use for seasoning. Someone told me to spray it with horticultural oil. I wondered, though, if it would still be safe to use the leaves in cooking. Is horticultural oil petroleum based?
As you suspected, horticultural oil is petroleum-based. U.C.Davis provides information on Integrated Pest Management for the plant I am assuming you mean, the usual source of culinary bay leaves, sometimes called sweetbay, or Laurus nobilis. (Just to be clear, I don’t think you are referring to the plant known as California bay laurel, Umbellularia californica, which has leaves that are aromatic and reportedly edible, but not commonly used for seasoning.)
They also note that “…specially refined petroleum products, often called narrow-range, superior, or supreme oils. Some botanical (plant-derived) oils are also available.”
When referring to plant-derived oils, I believe they are referring to Neem oil, as described in this information from U.C. Davis Integrated Pest Management. Additional information from the Cornell University Resource Guide for Organic Inesct and Disease Management about Neem and human health is excerpted here:
Studies of azadirachtin mutagenicity and acute toxicity have shown that it likely does not pose a significant risk to human health. However, some people have exhibited skin and mucous membrane irritation from neem seed dust (Weinzierl and Henn 1991). Note that most studies have been done on azadirachtin, and may not show the
effects of a whole neem product. Neem is used in some commercial human hygiene products.
Another long excerpt on horticultural oil from Colorado State University Extension suggests the following:
Essentially all commercially available horticultural oils […] are refined petroleum products also known as mineral oils. Impurities in the oil that are associated with plant injury, such as aromatic compounds and compounds containing sulfur, nitrogen or oxygen, are removed. Filtration, distillation and dewaxing complete the production of the finished base oil. Final formulations of horticultural oils are normally combined with an emulsifying agent that allows the oil to mix with water. This mixture usually is used at about a 2 percent dilution.
Vegetable oils also can be used as insecticides, although the type of oil can greatly affect its activity. Cottonseed oil is generally considered the most insecticidal of the vegetable oils. Soybean oil, the most commonly available vegetable oil used in cooking, has often provided fair to good control of some insects and mites.
Extracts from seeds of the neem tree, Azadirachta indica, have recently attracted attention as a source of pest management products. Several neem-derived insecticides have been developed. A number of compounds found in neem seeds, notably azadirachtin, have proven useful as insecticides. However, the oil fraction of neem seed extracts, which is mostly free of azadirachtin and related terpenoid compounds, also has demonstrated effects as a fungicide and insecticide. At least one product currently on the market, TrilogyR, consists of a largely azadirachtin-free oil fraction of neem seed extracts. It is formulated with an emulsifier and mixed with water at a concentration similar to horticultural oils (0.5 to 2.0 percent). Many over-the-counter products sold in nurseries that mention neem contain the oils of neem seed extracts.
If you know the insect on your bay tree, Peaceful Valley Farm Supply is one commercial supplier which carries less toxic, of not organic, products to control specific pests. That does not necessarily mean they are safe enough to spray on leaves which will be harvested for cooking.