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Archive for May, 2013

It will forever be known as the Great Shrubaggedon of 2012. It will go down in infamy and my family will all recount where they were the day two of our lush, vibrant burning bushes lost their luster and turned a bedimmed burnished color. I was beside myself, thinking my notorious brown thumb had claimed yet another victim. Hippie Husband and I wracked our brains. We weighed our options. One evening, he turns to me and nonchalantly says, “hey, I think it’s spider mites.” And then the googling began. Furiously, I typed and searched images. There it was, the answer to our flora whoas.

The tiny answer we were looking for.

The tiny answer we were looking for.

I soaked up the information and learned that spider mites (Family: Tetranychidae) are classed as a type of arachnid, relatives of insects that also includes spiders, ticks, daddy-longlegs and scorpions. Spider mites are small and often difficult to see with the unaided eye. Their colors range from red and brown to yellow and green, depending on the species of spider mite and seasonal changes in their appearance.

Many spider mites produce webbing, particularly when they occur in high populations. This webbing gives the mites and their eggs some protection from natural enemies and environmental fluctuations. Webbing produced by spiders, as well as fluff produced by cottonwoods, often is confused with the webbing of spider mites. Upon further inspection, there was indeed small strands of webbing all throughout our affected bushes.

Interestingly, most spider mite activity peaks during the warmer months. the outbreak occurred over a blazingly hot August week here in Ohio. The mites can develop rapidly during this time, becoming full-grown in as little as a week after eggs hatch.

This is an up close picture of the damage caused by the mites.

This is an up close picture of the damage caused by the mites.

After mating, mature females may produce a dozen eggs daily for a couple of weeks. The fast development rate and high egg production can lead to extremely rapid increases in mite populations. When I say it happens fast, I mean it. It took precious little time for the shrubs to start showing their plight.

One thing that allowed the mite’s population to take over was that we rarely water our landscaping. We prefer to conserve water whenever possible, however adequate watering of plants during dry conditions can limit the importance of drought stress on spider mite outbreaks. Periodic hosing of plants with a forceful jet of water can physically remove and kill many mites, as well as remove the dust that collects on foliage and interferes with mite predators. Disruption of the webbing also may delay egg laying until new webbing is produced. Sometimes, small changes where mite-susceptible plants are located or how they are watered can greatly influence their susceptibility to spider mite damage. Ooops. At least we know better this year.

Healthy leaf vs damaged leaf.

Healthy leaf vs damaged leaf.

Spider mites feed with long, needle-like mouthparts that are inserted into plant cells. Contents of the individual cells are extracted resulting in decreased chlorophyll content in the leaves with many small white or yellow dots called, “stippling.” Chlorophyll is essential to plants because it is the substance in the cellsthat converts sunlight into energy for the plant. When it is removed, the plant literally starves. In addition, the mites absorb the excess water in the cells as well, causing a drought- like conditions where the leaves will droop and in severe cases, like ours, begin to fall off.

After our initial diagnosis the next step was to research our treatment options. Pesticides are a no-go at our hippie homestead. I was on a mission to find holistic options to rid my bushes of their infestation. I wanted something that would be safe AND effective. I came across an answer that was even better. Not only was it safe, it was seriously inexpensive. What I needed was some dish soap, a spray bottle and water. Lucky for me I save my spray bottles to reuse them for things all over the house and garden.

Soaps have been used to control insects for more than 200 years. Recently, there has been increased interest in and use of these products. This change is due to a better understanding of how to use soaps most effectively and a desire to try insecticides that are easier and safer to use than many currently available alternatives.

How soaps and detergents kill insects is still poorly understood. In most cases, control results from disruption of the cell membranes of the insect. Soaps and detergents may also remove the protective waxes that cover the insect, causing death through excess loss of water.

The amounts I used were 2-3 teaspoons of water to a spray bottle of water. Make sure to add the soap to the water and not vice versa, I learned this lesson the hard way. I applied the mixture liberally to the affected area of the two bushes and over sprayed to cover some of the healthy growth, hindering the spread of the mites now that I had them on the run. Apply the solution in the early morning or evening. During these times it will take it longer to dry and the remedy is most effective while wet.

The soap solution has to directly reach the mites to kill them, so I sprayed both the top and underside of the leaves and as much of the branches as I could. I also noticed some webbing at the base of the plants, so those were doused with the mixture as well. I did this over the course of three weeks, spraying every four mornings or so.

The plants never regenerated, but they also didn’t get any worse. Nor did the infestation and damage spread to any other shrubs in flowerbed. I wouldn’t know the extent of the damage until next spring and waiting through the fall and winter was pretty intense. With the first buds of spring, which couldn’t come fast enough, however, my mind was put at ease. At the end of April, the leaves of my bushes finally emerged into their full, green, lush glory.

This shows the extent of the damage- photo was taken in the evening so please excuse the poor lighting.

This shows the extent of the damage- photo was taken in the evening so please excuse the poor lighting.

Healthy, full burning bushes.

Healthy, full burning bushes.

So what did I learn over the past nine months?

  • Spider mites infestations can happen quickly especially if conditions are right. Prolonged heat, drought, or not watering plants.
  • Spider mites drain plants of essentials such as water and chlorophyll, causing, “stippling,” brown, yellow, gold leaves that are dry and eventually fall off.
  • The signs of mites are webbing around the leaves, stems, and branches, small bumps on leaves, “stippling.”
  • Mites can be controlled by watering the plant and hitting the leaves with jets of water to knock eggs and mites off the plant.
  • If an infestation occurs a solution of 2-3 teaspoons of dish soap to a full spray bottle of water applied every four to five days over the course of a few weeks will eliminate the infestation.

I hate that I had to learn this lesson, but I am confident that in the future I will be more prepared when our plants are under siege by a tiny army of plant cell sucking miscreants.

Happy, healthy spring,

Lauryn

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