One of the benefits of growing your own food is that you are in control of the types of chemicals, both natural or man-made, used in garden beds and on your plants. 

The first consideration when designing your garden is creating a favorable soil climate, because a healthy soil supports natural disease and insect control. Whether you choose raised beds or in-ground gardening, take a soil test to find out what elements are in limited supply. Missouri University Extension has a good video that shows how to take a soil sample. You can find this at Missouri.extension.edu. 

When you submit your sample, you indicate what plants you plan to grow. The report results are sent to you with suggestions for what elements you need to incorporate into the soil bed for best results.

A couple of years ago I started a new 30×30 foot in-ground garden. I thought from just looking at it and digging around that the soil was not that great. After getting an analysis from Missouri University Extension, however, I found I only needed to add dolomitic limestone to address two deficiencies. I was very surprised. I’m so glad I didn’t just start adding a little of this and a little of that. It pays to get good advice!

In caring for our planet Earth, it is a good idea to do less harm to the environment, both above and below ground. Organisms live throughout the soil and work to turn elements into forms that our plants can take up. Nitrogen, potassium, phosphorus, magnesium, calcium, boron, zinc, sulphur, manganese, iron and copper are the main required nutrients that fuel new plant tissue growth and allow root function and flower/fruit formation. 

Organic matter content in the soil is important to maintain good soil structure and to supply food to the micro-organisms that make the whole system work. 

True organic gardening, by definition, rejects the use of all artificial agricultural chemicals, including pesticides used to control insects, diseases and weeds. I continue to try using a more organic approach to managing my garden beds. It is a transition and I’m not all the way there yet. I try to use as many naturally derived pesticide chemicals as possible.

Regular chemical applications can result in unintended transport through soil components into the water table.  Chemicals that persist in the soil below our garden plants may go on to kill beneficial insects and other organisms long after we have sprayed. Chemical labels on your garden pesticide include mixing and application instructions. When the instructions say, “Do not apply directly to soil,” that is a good indication that this particular chemical will persist in the soil and may move beyond your spray location.

Ten of the most common insects found in Missouri gardens are: cabbage loopers, aphids, stinkbugs, tomato hornworm, squash bugs, squash vine borer, cucumber beetle, blister beetle, corn earworm and flea beetles. I have had good luck controlling all but one of those with natural pesticides such as insecticidal soap, mineral oil, Neem oil and Bt. 

Beneficial insects such as lady bugs gobble up problem insects and we find they live all season long in the Barry County Community Garden. In order to do less harm to beneficial insects, it’s best to spray in early morning or late evening when the flower buds are closed. 

The early season plants that are flourishing in gardens right now are the brassicas like cabbage, broccoli, cauliflower, brussel sprouts, kale and collard greens. These are loved by cabbage moths who lay their eggs on the underside of leaves. 

These off-white moths are flying around all of those plants as I write this. When the cabbage moth larvae hatch, they devour the plant leaves. One natural compound, Bacillus thuringiensis, better known as Bt, is my go-to for controlling this pest. It was first discovered in 1911 in Germany and there are now several kinds of Baccillus that are used for controlling moth larvae, mosquito and black fly larvae, wax moth larvae, beetles and army worms. 

The bacterial spores kill the larvae by destroying the function of its gut. It is available as a powder or a liquid concentrate. This year we have been using the liquid concentrate on all of our brassicas at the Cassville Community Garden. 

Cabbage moths are flying around brassica plants this week, so it is time to start “scouting” for their activity. It is best to apply in late afternoon and to respray after every rain or reapply the powder. Bt is safe for humans and animals. Always refer to the label attached to your chemical bottle as it will tell you how much concentrate to mix in each gallon of water. 

It is also strawberry picking season, which started early again this year. I found a couple slugs helping themselves to my strawberries and grabbed my diatomaceous Earth to apply after the rain using a garden duster which allows even distribution. Diatomaceous Earth is a powder made up of the silicate skeletons of tiny marine creatures called diatoms which developed millions of years ago where large bodies of water once existed. 

It is not toxic if eaten but is irritating if inhaled. Therefore, wear a mask when applying it. It can kill spiders and beneficial insects as well so don’t overuse it. It can control other pests such as aphids, Colorado potato beetles, immature squash bugs or whiteflies. 

DE punctures the waxy coating all insects have and causes them to dry out. You can also try controlling slugs by inviting them to happy hour with trays of beer throughout your patch.

Insecticidal soaps are another tool in the gardener’s toolbox that have been found to be toxic to soft-bodied insects such as aphids, grasshoppers, leafhoppers, mealybugs, spider mites and whiteflies. Surprisingly, adult Japanese beetles are also susceptible. These soaps contain fatty acids that destroy the cellular membrane of insects on contact. 

Apply this soap when the air is still and be sure to cover both sides of leaves. Reapply after rain. Insecticidal soaps may cause leaf burn when applied during hot weather. Avoid spraying plants while the sun is shining directly on them. Spray early or late in the day.

Horticultural oils usually contain a processed oil and work by coating the insect and blocking the pores. This suffocates the insect. They are widely used in fruit and nut orchards to control aphids and spider mites. You must follow the labels carefully to avoid damage to the plant. 

Mineral oil can be applied to the emerged corn silks with a dropper to prevent corn earworm damage. It really does work!

Neem oil is derived from the seeds and fruits of the Neem tree which originated in India and has spread throughout southeast Asia. It can be applied as a fungal preventive spray on garden plants and as an insecticide. Neem oil also has anti-bacterial properties. It is best to spray it in early morning or the evening when flowers are not open. It is used medicinally and can be found in shampoos, skin care products and toothpaste.

Numerous recipes can be found on the internet for home brew recipes to control insects. One recipe combines 2-1/2 tablespoons of mild dish washing detergent plus the same amount of a vegetable cooking oil with one gallon of water. 

Sounds like insecticidal soap meets horticultural oil to me. I’m game to try something that sounds less toxic than some of the traditional full assault, kill-em-all cocktails on the market. 

All the great soil and carefully selected disease and insect controls only work if the plants get an adequate amount of water. Too little can cause an inability to thrive, resulting in slow growth or the loss of developing fruits. Too much water, particularly in clay soils, can cause fungal problems in the root system which leads to damping off and root death. Drip irrigation lines and drip hose paired with battery powered irrigation timers can automate the watering and reduce water use. 

It also prevents water going to areas where nothing is planted. Spraying water over the tops of garden plants can lead to more fungal diseases such as powdery mildew on squash, melon and cucumber plants. We have almost all our raised beds on drip irrigation at the University Extension Community Gardens behind Crowder College in Cassville. 

We are so thankful to Lincoln University and Missouri University Extension for donating grant money to fund our drip irrigation and other projects. A few of our beds are rented by individuals for their own gardening, but most are used to grow food that we donate to our local food panty and the Senior Center. 

Stop by and check us out!

Skip Easter is a forester with 44 years experience, certified arborist, member of the Barry County Master Gardeners and may be reached at [email protected].