Discovered different insects damaging dahlias yesterday.

15 years ago

It kinda started with my Zinnias. I planted Zinnia seeds back in late May when I planted the first 3 Dahlia tubers from SI. After the zinnias were about 4 weeks old, I came out one morning and noticed that the top half of a zinnia was laying on the ground. It was actually sheared off in 2 pieces. The place where it was cut was perfectly straight, like done with a pruner. I looked around, and noticed these green bugs, about 5mm long, narrow, but tall with a ridge on their backs. Then I noticed brown ones too. They were eating a perfect circle around the stems, then the stems would fall off.

So, a friend came over and we looked for something to spray them with after removing the bugs. We found some natural Lemongrass oil, and she said it would work well. So I diluted it 50%, and sprayed it on. After she left, I went back outside 5 hours later, horrified that the zinnias looked as if someone had poured acid on them! The leaves were hanging like rags, and they were thinner and translucent!

So I dug up the zinnias, planted new ones and kept an eye out for those bugs, but they never came back.

Then yesterday, I was fertilizing my dahlias, when I noticed a leaf that was turned upside down, and I saw a brown bug about 5mm long, that was eating the central vein that runs through the leaf, and it was turning brown where he was biting it. Then I looked under other leaves and started finding LOTS more of these bugs! I also noticed that there were usually ants hanging around these bugs. But then I also noticed what I guess are spider mites on about 2-4% of the undersides of the leaves in groups.

So, I had no liquid insect control, so I got the hose, put on a shut off valve that can be adjusted to spray out a light stream, and I washed off all the spider mites, then picked off all the other bugs.

I had some new granular insect control(Spectracide-Gamma cyathrofluthrin or something?), and I broadcast it all around the garden, even getting some on the dahlia leaves. The idea was to stop the insects from crawling back over to the dahlias. But I noticed that the brown stem eating bugs actually hopped. So I had to pick them off again!

But today, I dont see anymore on there.

If I had not discovered them yesterday, they wouldve done some major damage in a hurry! But now the leaves look fine, and show almost no signs of damage on the tops.....

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Comments (2)

nerak
15 years ago
Highlander,
This yr. 1/2 of the dahlias I planted,(a little weird)do have spider mites on them. They are planted in my garden that has a bridge in the middle of it going to the pool. So the dahlias are planted on both sides. On 1 side they have spider mites, growth is stunted but they are still blooming. The leaves are all mottled looking. Going out now to spray w/ Hot pepper wax insect repellent. The mites are spreading and I want to stop this. I used this repellent on my tomato's for white fly and it worked for about 2 wks.
It did not hurt the plants or change the taste. But we had a lot of rain and the fly;s are back! Spraying again/bought concentrate and more organic.

Last yr. my front yard were I plant orange dahlias were doing great then all of a sudden they looked like they were dying. I dug them up and they had wire worm. I treated them w/Triazicide-concentrate and they came and bloomed all summer in to fall when I dug them up/ treated them and put away for the winter in cellar. This yr they are doing fine, no wire worms. Don't know what the other bug is. Did you go on the bug finder on this site, it is helpful. That is what got me going on this site. Lots of pictures. Good luck

karen
highlandernorth
Original Author
15 years ago
Yeah, I ended up applying Triazide about 3 days after I posted this thread, and its worked well so far.

I got lucky in that I discovered the problem almost immediately after it had begun, so you really cant even tell that there was any damage.

As far as the brown bugs I mentioned, they have like a camels hump looking ridge on their high backs, with 2 humps.

I just brought a few of them that I had found on my one sunflower to the cooperative extension for identification because I cant seem to find them on any dahlia site. So now, considering how long it usually takes for the cooperative extension to get back to me, I should know something by the end of the millennium! They are suppose3d to contact you within 3-5 days, but it took 3 weeks one time last year! The messed up thing, is that whenever I go there, there arent hardly any other samples left by other people in the basket there, so they shouldnt be all that busy........
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