Archive for the ‘Pest Control’ Category

Apocalypse

December 9, 2016

Is that too strong a word? It doesn’t feel like it.

In May, here’s what my Cleveland Sage and Apricot Mallow looked like:

may2016_clevelandsage

As of a couple of days ago, here’s what that part of the yard looked like:

dec2016_clevelandsage1

Now, the Apricot Mallow has been pruned back, and that’s not the problem. But I have lost half of my Cleveland Sage. Here’s another view:

dec2016_clevelandsage

And another:

nov2016_northeast

Note also that the Fragrant Pitcher Sage (Lepechinia fragrans) that was next to the birdbath is also gone — died. Here’s what it used to look like, only a few months ago (it’s the tall plant to the right of the birdbath):

Mar2016_PitcherSage

And on the west side, here’s what we had in May:

may2016_sagewest

may2016_westside

And here’s what we have now:

dec2016_westside

The Fuchsia in front has been coppiced, so that’s not the problem. But half the Cleveland Sage is gone, having died and been cut away.

And here is the culprit:

argentineant

This is an Argentine Ant, an invasive species that causes havoc with native California plants (and probably others as well). This ant cultivates scale insects and aphids, and milks them for their honeydew secretions. It also protects these pests from their natural enemies, ensuring that they continue to live on and do the maximum damage to their hosts. These sucking insects attach themselves to stems and roots and gradually kill the host plant if not eradicated.

This is exactly what happened to my Cleveland Sages, and also to my Pitcher Sage, and to a Ceanothus that died a couple of months ago, and which I removed, mistakenly believing that it had died of a fungus. It had been a fine specimen near my mound for several years. Here’s what it looked like just a few months ago (it’s in the middle foreground):

Feb2015_TowardWest

Now there is a blank spot there, which I filled in by extending the dry stream bed.

In retrospect, I realize now that it died from scale infestation. I have not seen aphids on my plants, but I have seen scale. Here is the evidence of scale infestation on my sages, and also on my Yankee Point Ceanothus, which is still alive, but which had several dead branches that I had to remove:

nov2016_sagewestscale

Sage

nov2016_scaleonsage

Sage

dec2016_ceanothusscale2

Ceanothus branches

dec2016_ceanothusscale1

More Ceanothus branches

The white spots and areas are scale insects — these  are insects which have lost their legs, even though they look like a fungus or something from the plant family. And they will kill your plants if you are not aware of them!

Here’s the hole in the Yankee Point Ceanothus where those removed branches used to be:

dec2016_ceanothus

Other changes have taken place that are probably not related to the ants (though I can’t be sure!). I had to remove my California Asters from the mound. Here they were in June:

jun2016_asters

But over the next couple of months they developed what looked like mildew on the leaves, and then the leaves gradually turned brown and died:

jun2016_asters1

Though the plants continued to survive and bloom, they looked so ugly that I cut them down to the ground in August. This is something I usually do in November or December, and by the spring they have come back with fresh shoots. The shoots did start to grow back with fresh-looking leaves, and I thought all was going to be well. But then the new leaves developed the same mildew and turned brown. So I finally made the decision to remove the asters from the mound. I am still not sure what did them in, but I would not be surprised to discover it had something to do with the ants!

I have replaced the asters with the following completely different plants:

dec2016_mound

(1) Three Monkeyflowers of varying colors (Diplacus), (2) two Coyote Mints (Monardella villosa), which will have lovely lavendar flowers in the spring (I hope!), and (3) four additional Seaside Daisies (Erigeron glaucus). Needless to say, the look of this area has changed profoundly. I trust it will fill in nicely and look perhaps even better than it did before!

Additionally, I finally gave up on growing milkweeds and raising Monarch butterflies. This I did with the heaviest of hearts, and only because I was losing almost all of the caterpillars to the dreaded Tachinid flies, which have apparently taken up refuge in my garden and persist from year to year. My garden did produce five or six butterflies that made it to adulthood, but many more, more than a dozen, perished either as caterpillars or chrysalises, showing the dreaded brown spots and white strings characteristic of an attack by these parasitoid insects. I felt I was doing the species a disservice by growing milkweeds when these dangers abounded. As such, I have replaced the milkweeds with a strip of succulents:

dec2016_succulents

(This picture also shows that my potted Woolly Blue Curls has, alas, reached the end of its days! Such a result is not surprising for this very hard-to-grow species.)

Dealing with the Ants

So back to the ants. How did this situation come about, after so many years of lush growth and no problems? After all, I have had ants for years in my garden — I often noticed them, and occasionally they would come into the house and cause havoc. But as long as they stayed outside, I was not the least concerned about them. There are always ants in a garden, right? The biggest problem they caused, as far as I could tell, was that they made it difficult for me to sit unmolested in my Adirondack chair. (I had to purchase a footrest to make it more difficult for the ants to crawl onto my feet.)

I have no idea why it took them this long to cause severe problems with my plants. Perhaps they have been colonizing scale for several years, and their efforts just finally reached a tipping point this summer. Or it could be that I had native ants for quite a while, and they were only recently displaced by these invasive Argentine ants.

It wasn’t until I hired a native plant specialist to prune my sages and other plants this fall that I realized what was happening. He pointed out the large amount of scale on several of my plants, and the many ants crawling on the stems and branches, including the dead Pitcher Sage.

I vaguely remembered reading warnings about invasive ants, but I had dismissed them, never believing that the ubiquitous ant could be truly dangerous. After my maintenance specialist pointed out the damage, these warnings came back to me in full force.

So what to do? I did some research and found some sources of information — the work of San Diego expert Greg Rubin was especially helpful. I immediately purchased some Advion Ant Baits from Amazon — one of the treatments recommended by Greg. As of this writing, the ants are very much under control — these baits are very good. However, I notice that there are still a few ants here and there in my front and back yards, and I think this effort will be an ongoing one for some time to come.

In the meantime, I have yet to decide what to do about the damaged Cleveland Sages and a replacement for the Pitcher Sage. I’m thinking of removing the sages entirely and planting new ones. Stay tuned.

And if you have a native California garden, please take this warning to heart: If you notice ants in your yard, check your plants very carefully!

 

 

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