Wednesday, October 7, 2009

Attack of the Aphids!!!

Something wicked has been awakened by the recent rain and cool weather. In all my years in the garden business, I have never seen an explosion of aphids like we’ve seen in the last couple of weeks. Just the other day, I saw several free flying aphids in the middle of a parking lot. I was at least 50 feet from any plant, surrounded by asphalt.

So what can we do about these critters that have suddenly left everything sticky and covered in sooty mold? To start, keep an eye out for the source of the sap. In my yard, it is my pecan trees. I can park a freshly washed car in the drive and within two hours, it is covered in a sticky film. Unfortunately, there isn’t much you can practically do about large trees like this. Just keep an eye on any understory plants. Be sure the aphids are not spreading to these plants and keep an eye out for sooty mold (more on that in a minute). If the aphids are on lower plants, small trees, shrubs, and perennials, you can treat them in several very effective ways.

One of the first ways to go after the aphids is simply to blast them with high pressure water. Products such as the Bug Blaster help to create a spray that is strong enough to remove the bugs but not enough to hurt plants. This is always my first line of defense. If blasting doesn’t seem to be effective, there are a number of great organic products that are very effective on aphids. Insecticidal soap is by far the safest product you can use. It is a very simple soap that is very harmless to people, plants, and animals. Another product I really like is Orange Oil. It is a natural insecticide, miticide, and fungicide. It works really well on aphids and many other insects, but a little care needs to be take when it is used. Never spray an oil in the middle of a sunny day. Be careful of plants in the mint family, including all the salivas, as they will not tolerate oils. If in doubt, test your plant before covering with oil.

Not only will the soap or Orange Oil kill the aphids, they both help to break down the sooty mold. You see, many insects (aphids, scale, mealy bugs) suck chlorophyll from plants. Chlorophyll is a complex sugar made by the plant. Their simple digestive system processes these sugars a little, but what they secrete is basically sugar water called Honey Dew. When Honey Dew accumulates on a surface, especially plant leaves, it can begin to mold. It will turn black and become what is known as Sooty Mold. Enough Sooty Mold on a plant can great hinder that plant’s ability to do photosynthesis and continue to prosper.

Also, before spraying, look for beneficial insects that may already be doing your job for you. There are pictures above of both ladybug larvae and green lacewings. These are both voracious aphid eaters and we would highly encourage you to leave them and let nature take care of the invasion.

Still have questions? Feel free to click on the “Contact Us” link or call the nursery for more info.