Archive for pesticide

Alternatives to Toxic Insecticides

Alternatives to Toxic Insecticides

By George Giltner, Adv. Master Gardener, MS Biology

A third study now validates results of earlier research of associations between autism and prenatal exposure to agriculture chemicals (www.ehp.niehs.nih.gov/1307044/).  “Women who are pregnant should take care to avoid contact with agricultural chemicals whenever possible” says author, Janie F. Shelton who is now a consultant with the U.N.

Three groups of common pesticides were studied that included organophosphates (chlorpyrifos, acephate, diazinon, and others), pyrethroids (esfenvalerate, lambda-cypermethrin, taufluvalinate, and others), and carbamates (methomyl, carbaryl, and others). The organophosphates were associated with an elevated risk of autism spectrum disorder, especially chlorpyrifos applications in the second trimester. Pyrethroids had a moderate association with autism spectrum disorder immediately prior to conception and in the third trimester. Carbamates were associated with developmental delays.

The present rate of autism is now at 1:68 births according to estimates from the CDC.  Also about 1 in 6 children in the United States had a developmental disability in 2006-2008. In the birth year of 1992, the prevalence of Autism Spectrum Disorder was 1 in 150, which has steadily increased to 1 in 68 in the 2002 birth year.

Therefore as gardeners, we should always use the least toxic chemicals, read labels, follow all safety precautions, and keep up with the latest research concerning pest control.

The good news is that more and more information is available on less toxic pesticides.  Clemson Cooperative Extension has an outstanding article on “Less Toxic Insecticides” which conscientious gardeners should print out (www.clemson.edu/extension/hgic).  “Most essential oils used as pesticides work by disrupting an insect neurotransmitter that is not present in people, pets, or other vertebrates.” The EPA no longer requires approval for use as pesticides due to minimum risk to uses of these essential oils (cedar, cinnamon, citronella, citrus, clove, garlic, mints, rosemary and others).

Microbial insecticides include Bt (Bacillus thuringiensis) for caterpillar control.  Milky Spore (Bacillus papillae and lentimorbus) is used against June bug larvae – grub worms. Spinosad, Saccharopolyspora spinosa is a treatment for fire ants, caterpillars, thrips, whiteflies, aphids, and even borers of fruit trees. Beneficial nematodes are the good nematodes that control clearwing borers, cutworms, sod webworms, mole crickets, and grub worms.  However nematodes are difficult to get started due to humidity, moisture, shipping, and temperature issues.

Bacillus subtilis and pumilus combat downy and powdery mildews, rust, bacterial spot, blight, botrytis and multiple other mildews on veggies, fruits, ornamentals, trees, and shrubs.

Minerals like boric acid acts as a stomach poison which causes the insects to die from starvation.  Diatomaceous Earth controls slugs, millipedes, ants, cockroaches, and soft-bodied insects like aphids. However use the “natural grade”, not the swimming pool filtering-agent that poses an inhalation hazard.  Sodium Fluoaluminate has sharp edges which punctures insect (caterpillars, sawflies, beetles, etc.) gut cells from consuming leafy material, however beneficial insects are not affected since they are not leaf eaters.  Iron phosphate is used as an organic slug and snail bate.  It is not poisonous to cats and dogs.

“Organic Farm and Garden” 2013, Vol.1, 2nd Ed., lists Biological Control Options which incorporates predator and prey functions in every ecosystem.  Plant nectar sources attract beneficial insects, and allow them to lay eggs near this food source.  Plant small flower favorites like dill, parsley, fennel oregano, cilantro, and thyme.  Also include annuals like sunflowers, cosmos, amaranth, alyssum and statice.  Perennials like yarrow, tansy, daises and angelica can be inter-planted within your garden.  Your beautiful garden will buzz with beneficial insects, and will have an ecological balance of predator and prey bugs.

“Louisiana Gardener”, Feb. 2015, has a super article, “What’s Bugging You?” by Cindy Shapton.  She puts emphasis on learning good bugs and bad bugs. Numerous recipes for repellants to easy to make sticky-traps are highlighted.

“The Naturally Bug-free Garden”, 2012, by Anna Hess is now available at Amazon.  It focuses on the worst garden pests that we have here and in Texas, and gives organic control measures.  Good bugs and good animals are reviewed and used to make your garden a living balance of natural defenses.  Resistant varieties, row covers, companion planting, and plant nutrition are tools for helping plants resist insects.  This is a good book to assist the beginner and young gardeners in learning about organic gardening.  It is a treasure!

So this year, learn, read, and experiment with organic chemical-free gardening to avoid potentially dangerous chemicals that are used in commercial agriculture.

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Leafcutter Bees – Holes in Roses

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Leafcutter Bees – Holes in Roses

By George Giltner, Advanced Master Gardener

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A leaf cutter bee in action on a rose. Photo: itsnature.org

The rose enthusiast may recognize nearly circular, up to ¾ inch holes in rose leaves and petals that are cut at first glance, by what appears to be a fly.  The bug may also be observed going into pruned, thick rose piths.  Wait! Put down the bug spray.  This may be the leafcutter bee, a solitary beneficial bee.

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The leaf cutting bee has large jaws or mandibles. Photo: D. Almquist and David Serrano

Leafcutter bees can be identified by their stout, black bodies with light bands on the abdomen.  Pollen is not transported on the legs like typical honey bees. Instead the underside of the abdomen has thick, yellow hairs (scopa) for carrying pollen. The size is varies from 1/5 inch to one inch depending on which of the 60+ species is viewed.  Also note that flies have two wings, but bees have four.

The value of these bees is as with honey bees, they are important pollinators of fruits (blueberries, etc.), vegetables (onions, carrots, etc.), and many wildflowers.  Alfalfa and blueberry crops are commercially pollenated with Osmia species.

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Nesting house for Leaf cutting Bees. Photo: US Forest Service, Beatriz Moisset

Leafcutter bees are literally “holed up” nesters.  They make their nests in cylinder cavities, by excavating in rotten wood to soil to straw cavities (rose piths).  A bee house can be made for the garden by drilling bee-sized holes in driftwood.  The nest will occupy several inches of depth with a sawdust or leaf plug at the entrance.  Multiple egg cells are laid in the leaf-lined tunnels, each packed with a larval food supply of pollen and nectar. A single female will lay up to 40 eggs in its two-month life span.

 

Roses seem to be the preferred broadleaf for constructing nests, however green ash, lilac, Virginia creeper, azaleas, redbud, crepe myrtle bougainvillea and other plants with smooth thin leaves are also used by leaf-cutting bees.

 

If the leaf-cutting is a problem, the recommended control is to simply lay cover cloth over your prize ornamentals.  Normally, the leaf damage is minimal, and the value of this important pollinator compensates for its cut-out leaf circles.

 

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Residue Problems with Herbicides in Gardening

Residue Problems with Herbicides in Gardening

By George Giltner, MS Biology, Adv. Master Gardener

 

A recent Mercola interview with MIT research scientist, Dr. Stephanie Seneff has raised the awareness of human health problems with glyphosate (Roundup) that has entered the American food supply by genetically modified organisms (GMO’s which include wheat, corn, soybeans, etc.).

 

Everyone has heard the sales pitch of how “biodegradable”, “environmentally friendly”, and “clean and inert” it is for years.  Now biochemical research is painting a different picture that looks more like an evil villain.  Mounting evidence according to Dr. Seneff pictures glyphosate as “the most important factor in the development of multiple chronic diseases and conditions that have become prevalent in Westernized societies”.

 

These chronic diseases are the result of nutritional deficiencies and systemic toxicity caused by glyphosate. Strangely, the mechanism of harm is through intestinal microbes.  Beneficial gut bacteria are preferentially affected (as weeds), causing disruption in microbial functions and lifecycle.  Pathogens flourish and then inflammation causes disease.  For a better description of the mechanisms, please view the hour-long interview: www.articles.mercola.com./sites/articles/archive/2013/06/09/monsanto-roundup-herbicide.aspx.  Note: Some terms are scientific, however concepts are simplified by an interviewer.  Discussions involve biochemical mechanisms related to autism, allergies, gastrointestinal diseases, diabetes, cardiovascular disease, etc.

 

When you do use Roundup at home treat it with respect. Wear PPE, bathe, wash clothes, and do not inhale spray droplets.  Keep the kids away from spray area and don’t let the dog roll in grass sprayed that will be rubbed off by petting at a later time.  Remember that the half life of glyphosate ranges from 1 to 174 days as water and bacterial action are required for degradation.  In ponds the half life is about 2 weeks to 10 weeks.

 

Another herbicide commonly used is “Sledgehammer”, halosulfuron-methyl. For controlling pesky nutgrass this herbicide will work by systemically destroying the nut tuber and stem.  The question always comes up – “Can I use it in my Vegetable Garden?”  The answer is emphatically “No” or “No Way”.  The reason – The EPA states that it can persist at toxic levels to plants for months or years.  Therefore if you have a garden area that was sprayed with this chemical, and it has not produced vegetables for years, it may be due this persistent chemical herbicide.

 

Yet another herbicide, Tordon (picloram) is commonly used to rid property of tallow trees or to destroy regrowth from stumps. The problem with Tordon is that it also persist for a long time, like several years.  Trees in the vicinity of a treated tree may also be killed as the chemical can be easily absorbed by nearby roots.  Broadleaf crops can be damage for up to two years.  Extension recommends use of Roundup for stumps and root sprouts.  Tordon should not be used for backyard usage.

 

These are just three examples of herbicides with residual or human health effects. Before you use any chemical for gardening, do like our county agent says, “Read everything on the herbicide label”.  Also be sure to wear PPE, and above all keep updated on new research and herbicide safety.

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Battle of the Bugs: Spider Mites of Summer

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Spider Mites of Summer

By George Giltner, Adv. Master Gardener, MS Biology

In the hot and humid Summer months, a common pest problem is spider mites which infect tomatoes, snap beans, roses, lantana, maple, redbud, blackberries, strawberries, blueberries, squash, cucumber, and about 200 other species of plants.  The most common spider mite throughout the U.S. is the two spotted spider mite, Tetranychus urticas . 

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Spider mites at various life stages. Photo by LSU AgCenter.

Symptoms appear similar to a graying of the leaves which is caused by destruction of chlorophyll containing cells by the piercing mouth parts of the mites.  One may think that the plant is undergoing some type of heat stress or fungal disease, but close observation of the leaves reveals small webs that all spider mites produce.  A magnifying lens with 10x power will reveal the presence of a minute (1/50th inch) spider mite with 8 legs.

The best chance of control is early in the infestation. Miticides are available in garden stores, however most are not effective on eggs.  Therefore plan on multiple applications. After continuous use, most acaricides  become ineffective as the spider mites built resistance to chemical sprays.  If no control measures are taken, populations can spread rapidly to completely defoliate the leaves or to impair plant flowering and fruiting.

Insecticidal soaps, commercially available natural predators, and oils are options that are friendly to nature and less toxic to humans.  Note that oils and soaps may burn plants, especially at higher rates.  Natural predators can be purchased from internet sites, but they are delicate forms of life that can be destroyed during shipping, especially in summer.

Important natural predators include lady bugs, predatory mites (Metaseiulus, Amblyseius, and Phytoseiulus), minute pirate bugs, lacewing larvae, big eyed bugs, and thrips (Leptothrips).  Therefore use of broad spectrum insectides can destroy these predators, making your problems much worse.

Spider mites are difficult to control.  For home gardeners persistence of treatment is the most important aspect of control.  If the infection becomes too difficult, consider eliminating affected plants by bagging and burning during calm periods of the day.  Spider mites are like spiders.  They use their webs to spread in the wind.

The entire life cycle (eggs to larva to two nymphal stages to adult) can be completed within five days, but can be extended with lower temperatures to 20 days.  Adult females can live 4 weeks while producing several hundred progeny. Continuous generations are produced though summer.

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Battle of the Bugs: Citrus Leafminer & Natural Control

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Battle of the Bugs: Citrus Leafminer & Natural Control

By George Giltner, Adv. Master Gardener, MS Biology

If you have planted Satsuma’s or other citrus within the past 3 years, chances are that the leaves have been mined by the citrus leaf miner, Phyllocnistis citrella.  Close observation of the distorted wrinkled leaves will show the twisting larval tunnels, larval frass trail, and possibly the live larvae itself.

When the larvae are near the leaf marginal edge, use a fingernail to extract one.  Then you have successfully controlled one leaf miner, needless to mention that several hundred that may be ready to hatch from recently laid eggs by the 2 mm long adult female moths.  The singly laid eggs hatch after 4 to 5 days, then begin their mining operations for over a month, usually from midsummer to early winter.  The leaf distortions and curls are caused by the destruction of upper and lower cellular tissue.

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The larva of a leafminer feeding between the top & bottom surfaces of a citrus leaf. Photo by UFL Extension.

As you review the entire citrus plant, notice the pattern of infestation.  New fast growing and tender leaves are infected, but the hardened thicker leaves are resistant to leaf miners.  Therefore activities that stimulate rapid plant growth like pruning, vertical water sprout growth, and heavy fertilization actually make your citrus more favorable to citrus leaf miners.  Also notice that older (4+ years) trees are not impacted like younger trees.  The aged and hardened older leaves cannot be penetrated and mined like fresh leaves.

Commercial products containing imidacloprid, a systemic insecticide, have been used during periods of flushing (rapid growth) of young citrus.  These soil or irrigation treatments can protect the plants for up to 3 months.  However, there is concern over the use of this insecticide and its effect on bees.  The systemic insecticide will be inside plant tissues, pollen, and nectar.  Experts report that use of this chemical is one of the many possible causes of bee decline and colony collapse disorder (CCD).  The European Food Safety Authority (Jan. 2013) stated that neonicotinoids (imidachoprid) pose an unacceptably high risk to bees.

If you are an internet user, some suggestions for leaf miner control are absolutely hilarious.  One suggests using moth balls.  The response was to take good aim at the moths to be effective.  Another was to use Sevin, but the larvae is tunneled and protected by the waxy leaf cuticle.

Biological control can be the most effective means of control.  Worldwide, 39 parasites of CLM have been identified.  14+ natural enemies (many wasps) have been identified within the U.S.  Since the initial identification of CLM in Homestead, Florida (1993), it has spread throughout the South into Louisiana and Texas.  It is now a common pest.  However recent research has shown up to 90% mortality due to endemic beneficial insects.  The message from researchers is to not use wide range killing insecticides (malathion, carbaryl, and pyrethroids) that destroy beneficial predators of citrus leaf miner.  Better control with less environmental impact can be obtained by using spinosad formulated products like Conserve, Green Light Spinosad, Success, Leafminer & Tent Caterpillar Spray, etc.

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Adult Leafminer. Photo by Florida Extension

Gardeners and homeowners of citrus may choose to not treat citrus for citrus leaf miners.  That is correct – do nothing and let nature take its course (Dr. Malcolm Manner, UFC) .  Young citrus will be infected and look ugly for several years.  Nature will begin to supply CLM predators without the use of harmful insecticides.  The mature hardy thick green leaves develop.  Then the citrus tree matures into its round dark green form.

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Spittle Bugs – the Mystery Foam Source

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Spittle Bugs – the Mystery Foam Source

By George Giltner, Master Gardener

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Two lined Spittle bug (Prosapia bicincta), Clemson University Coop Extension Service photos

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Spittle (bubbly froth mass with larvae), Clemson University Coop Extension Service photos

From the name, spittle, you know what to look for – a spit-looking mass on vegetation.  This frothy mass is excreted by yellow-brown nymphs mainly on grasses and ornamentals as defensive protection against predators and desiccation.  Below the froth, the nymphs insert piercing mouth parts into the plant consuming large amounts of plant juices.  They go through 4 instars before reaching adulthood.  Populations expand during wet humid climate periods and retract during drought.

In Louisiana, they can be found on grasses like St. Augustine, centipede, rye, Johnson, coastal Bermuda, and small grain crops.  Usually spittle bugs are not a problem, unless large populations develop under wet environmental conditions.  Pyrethroids can be used for control.  Also look for them in vines like honeysuckle and morning-glory and in ornamentals like holly, aster, and redbud where their feeding results in white blotches on the leaves.  They are most active in the morning to avoid the heat and drying conditions of hot afternoons.

The common two-lined spittle bug adults look like large black leafhoppers.  They are easily identified with two large red or orange stripes across their triangular-shaped body.  If you get close enough, notice the small red eyes.

The adults only live for three weeks, with females laying eggs during the last two weeks of their lives.  Eggs laid in the fall, overwinter in grass sheaths and ground debris.

The Pecan spittlebugs, Clastoptera achatina, are more of a problem insect, especially where pecans are grown.  The nymphs become active after bud break in the spring by feeding on young buds and later on tender shoots and nutlets.  Heavy populations can cause terminal bud death and immature nut shedding.  Infections can be recognized by white bubbly masses on terminal buds to dried yellowish masses on young nuts.  The adults are small, 4 to 5 mm, and yellowish brown in color.  Therefore they are hard to detect in pecan trees.

So the next time that you see those frothy masses on your plants, shrubs or trees, look for the larvae spittlebugs underneath.  At least you will know the source was not a rabid animal or from human origin.

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Winter Burweed Should be Treated Before It’s Too Late

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Winter Burweed Should be Treated Before It is Too Late
Keith Hawkins, LSU AgCenter, Beauregard Parish

     As a County Agent for the AgCenter, I strive to help homeowners with their lawn question and provide the best research-based information available. However, in my own yard, my attitude towards turf is more lax. I mow the yard and treat for fire ants, and that was it as far as lawn maintenance was concerned. I regard my yard as more of a botanical collection and have learned to identify St. Augustine, Bermudagrass and bahia grass. My yard is also a training lab in learning lawn weeds such as annual bluegrass, henbit, dichondra, carpetweed, and other weeds.

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Lawn Burweed in the Winter. Image by LSU AgCenter

      I have been very tolerant of lawn weeds until I walked barefoot one spring a few years ago and encountered stickers. The stickers became so bad that Gracie, our female Maltese dog, would not walk on the yard. After attending Dr. Ron Strahan’s Master Gardener classes on turf and on weeds, I learned that I have lawn burweed, or stickerweed.

     When the stickers are felt, it is too late to treat. The trick to treating burweed is timing. I have already seen burweed in my yard this month of January so I will be treating soon to prevent the stickers.

     Last February I used an herbicide with the active ingredient call Atrazine and where I applied it in accordance with the label, the treatment was an overwhelming success. I did not treat the whole backyard, but there was enough burweed-free yard that Gracie could comfortably visit the lawn and conduct her business.

      One treatment worked well for me, but sometimes another treatment may be necessary. Here are the suggested products labeled to control lawn burweed:
o Atrazine 1.5 oz. / gal. water per 1000 sq. ft.
o Weed B Gone 3 oz. / gal water per 1000 sq. ft.
o Ferti Lome Weed Free Zone 1.5 oz./ gal. water per 1000 sq. ft.
o 2,4D 1.5 oz./gal. water per 1000 sq ft.
o Bayer Advanced Southern Weed killer 2 oz. /gal. water per 1000 sq ft.
o Trimec 2 oz. /gal. water per 1000 sq. ft.
o Spectracide Weedstop 2 2oz./gal. water per 1000 sq. ft.

     These products are safe to use as labeled. If you use these or any pesticides off-label then you can expect damage. Also, these products are labeled for turf and could harm broad-leaf plants such as ornamentals, trees and shrubs.

     The “take home” lesson for the homeowners is to find lawn burweed, a winter weed, early and treat it as soon as discovered. When you or your family feel the stickers, then it is too late to treat, and you will have to wait a year for the next chance to deal with this weed.

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