What are all those holes in the middle of the leaves and flowers of my plant? Why are mostly the edges chewed off the leaves? How do I get rid of the bugs that are damaging my flowers? Are all holes in leaves made by ‘bad bugs’? We’ve all had these questions at one time or another. Either we plant new baby plants or we wait and wait for our plants to bloom and seemingly overnight the plants are either eaten completely or progressively chewed to death! Then we begin our search for answers and that can be confusing!
First, it's important to know what is causing the damage to your plant in the first place.* Identifying the pest will help you decide how to tackle the problem. For aphids many times just blasting the pests off the plant with water every few days will be enough to manage them. Whiteflies love hot, dry, and dusty conditions. Making a change in the environment from dry and dusty to watered more often along with yellow sticky traps will lower and perhaps eliminate the population. If these measures don't work it may be time to try a product. Years ago, many gardeners just reached for the super toxic pesticides and killed everything! Today, we have some great choices of less toxic products.
Insecticidal soap can be very effective on mealybugs, aphids, or any pest that is just sitting there, sucking the juices out of the plant, but the soap needs to land on the pest to kill it. Insecticidal soap will kill beneficial insects also, so be mindful to spray only the insects you mean to eliminate.
If the leaves of a plant have the edges chomped it may be a type of caterpillar (like petunia bud worm) or grasshoppers. Spraying insecticidal soap on the leaves will not kill these, since once the soap dries it is ineffective. For the caterpillars and grasshoppers there is a product called BT or Bacillus thuringiensis (organic approved). The BT stays active after you spray the leaves, so when the chewing starts again the insects ingest BT and die off within days. Butterflies go through a caterpillar stage so proper identification helps you make sure you are killing off only the pest you mean to kill.
Some leaf damage is acceptable in The Gardening Tutor's Demo Garden. For instance, when there are perfect cutout circles from the rose leaves there is no need to take any action. The circles are made by leafcutter bees; the bees use the leaf parts to make their nests.
Of course, this article could go on and on about different pests and their management and encouraging predator insects to the garden but this is a good start to get you thinking through your choices. The main point is to identify the pest before you start your counter attack. To find the culprit you may need to go out into the garden with a flashlight late at night or really early in the morning (make sure to check under the leaves where many insects hang out) but it will pay off in the end when you defend your plants by making a well informed decision about how to take care of the problem. Creating the healthiest environment for your plants will help them be strong and less attractive to pests. Also, start with the least toxic action, like the repeated applications of a strong water spray to knock pests off the plant. If the water doesn't fix the problem, then step up to insecticidal soap and then perhaps you'll need Neem oil.
When you're ready to learn more about pest management contact Mary for an appointment.
*Please, whenever you have a sample of a pest or pest damage that you want to take to your local nursery for help identifying the issue, put the plant parts and/or pest in a sealed plastic bag. Keep the bag out of the sun or it will sweat and make it hard to see what's inside.