Anchorage Daily News

The warm weather and lack of rain thus far this season has resulted in quite a sticky situation in Southcentral. These are the ideal conditions for aphids, those 1/8-inch, pear-shaped insects that suck the sap and juices from plants and excrete a sticky goop. While they appear every spring, this year numbers appear much greater and some readers are reporting "rain drops" of honeydew that are coating decks, cars, lawns and everything else underneath trees.

Click to enlarge

Gardening calendar (6/18/09)

Potatoes: Hill them. Pile soil or mulch around the growing stems. Leave the top three or four inches above it all.

Thin: Carrots, radish, beets, lettuce. Eat the thinnings in a salad.

Lawns: Mow high and less when it is dry as it has been. Remember one inch of water per week between you and Mother Nature.

FAIR: The Annual Alaska Botanical Fair is this weekend out at The Garden at Tudor and Baxter. This is a must-attend event for the entire family and guests! Saturday and Sunday. For more information go to www.alaskabg.org.

Story tools

Comments (0)

E-mail a friend

Print

Share on Facebook

Digg this

Seed Newsvine

Send link via AIM

Follow on Twitter

Font size : A | A | A

You really get a handle on the amount of aphid honeydew that has been falling when you discover the window washer fluid tank is empty and you just filled it last week. Whether called plant lice, as some do, or just aphids, normally they don't cause damage because they merely suck juices (they don't have any chewing mouth parts).

It takes a few years before aphids can damage a tree. Not so, of course, when it comes to more tender annuals and perennials.

Unfortunately, the honeydew is a carbon source for a fungus some call "sooty mold" because it is black and sooty looking. This is why older white birch trees are more like gray or dapple-black in color and why the decks and furniture can turn "dirty." It really doesn't harm anything, but it is not appreciated.

Many people think that this honeydew comes from two tailpipe-like structures that sit on the top of the back end of aphids. For the curious, these are called cornicle (or siphuncle) and are not the source of the dew, but rather can emit volatile substances used for protection.

Aphids have an interesting natural history. Some species are all female, that is no males have ever been found. The ones making the mess here hatch in the spring from eggs laid just before winter. These eggs produce only females and in a matter of weeks they bear from five to 100 or so, live and fully functional additional females. Several generations appear throughout the spring and summer.

When populations become high, a winged generation of females is produced and these fly off to find new plants. In the fall, males are born and fertilize females so they can lay eggs for the following year.

The best defense to aphids is to make sure that plants can fend for themselves. That means ample water, non-compacted soils, no damage to bark or stem. High nitrogen fertilizers, in particular, need to be avoided because they cause fast, more susceptible, growth.

When you have them, a spray of cold water will knock aphids to the ground. This works on trees as well as perennials. Since most don't have wings, they will have to make the long trek by foot.

Some perennials really aphid up. One popular plant, Thalictrum, meadow rue, can attract hundreds upon hundreds to a flower bud. These can be squished off as well as washed off. If you have lot of meadow rue, then you may consider cutting the bud off. Look for aphids on flowering vegetables, especially in indoor greenhouses.

Some folks use a soap mix with a bit of spreader sticker oil. This smothers the aphids. I have even heard of folks rubbing stems of plants (like meadow rue) with garlic as a deterrent to aphids. If you do this, the remedy to the smell lingering on your fingers is to rub them on the flat side of a stainless steel knife or on the sides of a stainless steel bowl.

Aphids have many natural remedies ranging from tiny, parasitic wasps, to crab spiders, green lacewings and ladybugs. I am not a big believer in releasing the latter into the yard as they usually fly away. Using them in a greenhouse is a better idea.

If we have to make a choice between high aphid populations and warm, dry weather, I am pretty sure all of us would take the warmer weather.

We can live with a few less meadow rues and a bit more sooty mold if the sun shines as well.

Jeff Lowenfels is a member of the Garden Writers Hall of Fame. You can reach him at teamingwithmicrobes.com or by calling 274-5297 during "The Garden Party" radio show from 10 a.m. to noon Saturdays on KBYR AM-700.

ADVERTISEMENT