Dealing with the insects that come with rainy weather
First comes the rain, then comes weeds, then comes gophers, rabbits and insects. If you can control the weeds, you can reduce the rest of the problems. But if you cannot control the insects, here are some possibilities.
The five most common organic insecticides are insecticidal soap, pyrethrum, horticultural oil, neem oil and bacillus thuringiensis. Almost all insecticides sold today (organic or inorganic) that you spray on plants are considered contact, which means that they kill only what they touch, and as soon as it dries, they are no longer toxic to insects.
This can be beneficial to the environment, but it means you need to spray more often. Most insects need to be sprayed at least weekly if you have an outbreak. Less and less insecticides are absorbed by the plant, and when the insect eats the plant, it is controlled. This can be a great way to control insects, but it can be hazardous to both us and other animals that may eat the plant.
These five basic insecticides may be sold already mixed with water and often called ready to use, or RTU. You can often find these pesticides as a concentrate, in which you add the pesticide to water in a sprayer. Concentrate is cheaper, but RTU is more convenient.
Insecticidal soap is one of the safest pesticides available and will work very well for controlling soft-bodied insects. Common insects that are controlled by insecticidal soap include aphids, thrip, mealy bug and cottony cushion scale.
Insecticidal soaps are based on fatty acids that kill soft-bodied insects, but do not affect humans, mammals and birds. This fatty acid dissolves the exoskeleton (the outside of the insect), and the insects dry out and die.
Too much soap can also dry your skin. Avoid using insecticidal soaps during the heat of the day and in full sunlight; it could burn your plants. In fact, insecticidal soap is used as an herbicide when applied according to the directions at a high concentration. It should be applied in the morning to be the most effective. They are very toxic to bees.
It is best to purchase insecticidal soap and not make your own out of household soap. Household soaps can contain other products such as perfumes and oils, which can damage your plants.
If you believe all soaps are the same, check your cabinets, you may have hand soaps and face soaps and dish soap and laundry soap. Would you substitute laundry soap for face soap if it were cheaper? Using household soaps and making your own insecticides would not be considered organic if you wanted to be a certified organic grower.
Pyrethrum is an organic pesticide and is considered completely safe for humans and animals. It is made from a variety of chrysanthemum and stops most insects but breaks down in sunlight in a few hours. In fact, pyrethrins are used in flea shampoo for dogs and cats. Often flea shampoo is the most common form that I can find pyrethrum.
It can also be found in many aerosol insecticides used in homes. They can kill almost any insect, but they work better on soft-bodied insects, mosquitoes, flies and gnats. They are also very toxic to bees. Synthetic pyrethrins are called pyrethroids and are more commonly found in most household insecticides. They are also toxic to cats.
One of the best pesticides is horticultural oil, which is highly refined petroleum oil. It kills all insects by suffocation. It can also kill eggs and larvae of insects. It can be used on any insect including scale and other difficult to kill insects. However, it can kill beneficial insects as well, like ladybugs. Insects cannot build up immunity to horticultural oil.
As great as horticultural oil sounds, it has some major drawbacks. A lot of plants are also sensitive to it. The oil can burn, damage or even kill some plants. You should check the label and make sure oil is safe to use on the plant you want to spray, or you need to test a leaf or two, checking after a day or two to make sure the plant is not damaged. Using horticulture oils may burn your plants, especially if the temperatures are above 90 degrees.
Heavier types of oils are called dormant oils and are used only on deciduous trees during the winter, suffocating eggs, larvae and insects hibernating on the branches. On evergreen plants, we use light or summer oils.
Very similar to horticultural oil is neem or neem oil. Neem is a vegetable oil made from the seeds of the neem tree. Neem prevents insects from molting or growing larger, so it works best on young insects. It is slower acting than most of our organic insecticides and it breaks down in sunlight.
The last great organic insecticide is bacillus thuringiensis, also known as B.t. It is an insect pathogen, which means it makes the insect sick and finally kills it. B.t. is considered completely safe to all people and animals. It is also considered an organic pesticide. It kills most all caterpillars on any plant, including tomato hornworm on tomatoes and grape leaf skeletonizers.
When using an insecticide, be sure that it is labeled to be used on plants and controls the insects you are trying to control. Apply the insecticide only according to the label. Remember, if the label says to use 1 teaspoon per gallon of water, 2 teaspoons per gallon is not better; it may damage your plants. Follow the directions completely, including time of day and correct temperatures to spray.
Buy your organic pesticides at the nurseries. Making your own from recipes on the Internet or from friends is risky at best. They are often effective at killing insects, but often they can hurt your plants or pets.
There are a lot of insecticides on the garden shelf, but more of you are turning to organic types of pesticides. They are still considered pesticides, and you must follow the federal and state rules that apply to pesticides.