New research on potential organic insecticide

While it’s popular to bash seemingly frivolous tax payer funded scientific research, I think most people would agree that a vast majority of research is worth while.

There is some really interesting research happening over at the US Department of Agriculture that may have the potential to spill over into the organic gardening area. A naturally occurring chemical called methyl bromide may turn out to be a safe, effective, natural insecticide suitable for organic growing.

If methyl bromide sounds vaguely familiar, it’s because you’ve probably seen it on a list of food ingredients on the package of one of your favorite foods or beverages. It’s often listed under one of many different names such as methylbenzoate, benzoic acid, methyl ester and others.

Methyl benzoate is found naturally in the flower aromas of daffodils, tuberoses, kalachoe, snapdragons, petunias, and many others. These flowers produce methyl benzoate as part of their fragrance to attract bees and other insects. This substance contributes to the flavor of bananas, cherries, cloves, allspice, mustard, coffee, black tea, dill, kiwi and other plant foods. It’s used in the food industry for its nutty, cherry-like flavor and fruity, flowery scent.

As it turns out, this chemical, when isolated or as part of a formulation, can repel or even kill many insect pests. Plus it leaves no long term residue that can build up on food or in the environment. All of this is still in the early stage of research, but if it turns out that a methyl benzoate formulation is effective, it probably won’t take long for it to gain governmental approval.

Many insect pests are developing resistance to current pesticides this may help to fill the void left by insecticides that are no longer effective. Also, organic insecticides are not always good at killing certain types of pests. If it works, methyl benzoate will be a valuable addition to the organic insecticide arsenal.

As a side note, methyl bromide is scent drug sniffing dogs are looking for. Methyl benzoate is produced when cocaine is exposed to the moisture in the air.

Bob

Near organic apples

Regular readers of this blog know that I like to talk about the idea of growing near-organic apples.

With the near-organic method, you spray as little as three times early in the season when the apples are still very small — starting when they first begin to grow. Then two more sprays are applies spaced about ten days to two weeks apart. If it is rainy during that time period, then another spray may be needed. After the third spray application, you stop spraying. By the way, I sometimes do a very early pre-blossom spray.

I use a general, all-purpose orchard spray mix, one with both fungicide and insecticide in the formula.

The reason why this technique works as well as it does is because it takes advantage of the life-cycles of orchard pests. Generally, the insects that cause the most damage to apples emerge early in the season. The spray knocks back the population of pests. Then once the spraying is over,the population of beneficial insects begins to grow and help keep pests in check. At least that’s one theory I’ve heard.

Minor cosmetic surface blemishes were the only problem with our near organic apples.
Minor cosmetic surface blemishes were the only problem with our near organic apples.

Through the season, as the apples grow in size, pesticide residue is washed off with the rain and breaks down in the sunlight, hence the name “near-organic”.  There is no official term as “near-organic” but it helps to describe how the apples were grown.

The apples often have some discoloration due to harmless fungi on the outside surface of the skin. I just wash off what I can (or rub it off on my shirt) and eat the apple whole.

I’ve been using this method for many years and have had great success with it. It’s not a guarantee that it will work in your situation but it would be worth a try if you are aiming to reduce your use of pesticides while still having half way decent apples.

I certainly would not recommend it for someone who’s livelihood depends on their apple crop, but for a few trees in the backyard, it may be worth trying.

Bob

Powdery Mildew on Squash

Growing pumpkins and squash has changed sine the early days early days of my career. Back then, pumpkins rarely had any problems whatsoever. You could just plant some seeds, keep the patch weeded and you were pretty much guaranteed a fine crop.

This year demonstrates how times have changed. In addition to the squash vine borer and squash bug that I talked about the last couple of weeks, we are now seeing powdery mildew on our pumpkins and squash.

Powdery mildew shows up as a white powdery-looking coating on the surface of the leaves. It eventually cause the leaves to turn yellow and die. Under certain conditions it will eventually kill the entire plant.

We’ve had textbook weather conditions for the development of powdery mildew. This type of mildew is a fungus that thrives when daytime temperatures are high and nighttime temperatures are low enough to form morning dew.

Unlike most other fungi, powdery mildew does not need liquid water to infect a plant and grow. High humidity within the leaf canopy provides the environment powdery mildew requires.

We do not see much powdery mildew during rainy years. As a matter of fact, one non-chemical approach to controlling powdery mildew takes advantage of this. Spraying the surface of the leaves with overhead irrigation will wash off much of the infection. It also will cause existing spores to absorb so much water that they burst, greatly reducing the source of new infection. This method only works if the area is well drained, otherwise you will end up causing other problems due to excess water.

Some varieties are more resistant to powdery mildew than others. Here two different squash varieties growing side by side.
Some varieties are more resistant to powdery mildew than others. Here two different squash varieties growing side by side.

Commercial chemical and organic formulas are available on the market to control this disease. I’ve been using a homemade concoction that has been working pretty well for me. I mix one table spoon of baking soda and two tablespoons of Murphy’s Oil Soap to a gallon of water. Spray it onto the leaves no more than every seven to ten days. It’s important to use this ratio, a stronger solution will damage leaves.

The spores from the species of powdery mildew that infects the squash family of plants does not survive Michigan winters. Spores are blown in to Michigan on southerly winds each spring to start a new cycle of disease.

Powdery mildew is very species specific, meaning each species of plant is infected a specific strain of fungus. For example, the powdery mildew that infects lilacs cannot spread over to squash and vice-versa.

This, I hope, will be the last problem we’ll have to deal with on our vine crops this year.

Bob

 

 

Some Organic Pesticides Used in the Garden

Someone asked me the other day, “do you spray your garden?” and “what sprays do you use?”  I gave her a short list of materials that I found useful in my garden.  Most people agree that these materials are OK for organic gardeners.

I have been a fan of Bt (Bacillus thuringiensis) since I started gardening in the 1970’s.  It is an insecticide made of naturally occurring bacteria found in garden soil.  Only surface feeding caterpillars like cabbageworms are killed by it.  Bt must be eaten by the caterpillars in order to work.   It does not harm beneficial insects.

Spinosad is another insecticide derived from soil bacteria.  The bacterium was discovered in the soil at an abandoned rum distillery, so the story goes.  This insecticide kills a wide range of insects.  It too must be eaten in order to be effective.  This reduces the likelihood that the Spinosad would kill a beneficial insect.

 

Pyola is a mixture of canola oil and pyrethrins.  This effective insecticide has the potential to kill any insect good or bad so be on the lookout for honeybees or other helpful insects before you spray.

For disease control, I use a liquid copper fungicide.  The other material I’ve used with mixed results is potassium bicarbonate.  Potassium bicarbonate is chemically similar to sodium bicarbonate or baking soda.

You can make your own homemade garden fungicide by mixing one tablespoon of baking soda and one tablespoon of liquid dish soap together in one gallon of water.  Just make sure your plants have had plenty of water to drink before you spray this mixture.