Dealing with Daylily Aphids

I grow a lot of daylilies, I have grown a lot of daylilies for years. This year I have had an infestation of daylily aphids. This has never happened before, I’m not sure why I was spared previous years, or hit this year. I think maybe the high rain earlier in the summer allowed the foliage to get high and lush, which provided a better more sheltered eating environment for the aphids down deep by the crown, but I’m not sure.

That rain was earlier in the year, lately it has been hot and dry. I noticed weeks ago a section of my “Happy Returns” daylily hedge lying down. I thought at first maybe an animal, or a toddler, had done it. It resembled what you’ll find in the grass after a deer has bedded down for the night. There was also then some yellowing, so I thought maybe it was the drought.

Finally, when watering heavily did not help at all, I thought maybe it was a pest. So I dug down underneath the foliage and found tons and tons of aphids. They had been eating from lower on the leaves causing them

to lack vigor and strength and fall over. Some of the plants looked nearly dead.

I immediately got out my duster and filled it with some diatomaceous earth. This is a white powder substance to us, made up of ground up ancient seashells. But to small soft bodied insects it is like razor blades, and it is a non-chemical way of killing them. So I injected the dust all on the row.

But the foliage was very thick, and I worried I couldn’t get coverage, so later I then cut the most affected ones back to better get at the lower growth. There was so little green left that they really did look dead, and I don’t think they’ll recover yet this year, but daylilies have such strong roots that I’m sure they will be back next year.

Then, next time I was at Lowes, I got a systemic pesticide. If I had caught it earlier my initial efforts may have been enough, but this was a full blown infestation, very progressed, and I had to not only treat the affected plants, but protect the ones not yet attacked. A systemic product doesn’t kill bugs on contact, instead it is taken up by the plant, and then the bugs who eat the plant injest it. A indiscriminate pesticide could kill bees or lady bugs or other beneficial insects, but a systemic one should only get the bad ones, the ones that eat the plant. It was a Bayer product and it says it lasts for 30 days in the plants, providing long term protection that should hopefully get rid of my aphid problem.

Aphids can often be treated without chemicals. When on trees or roses or other plants that stand up straight, you can often blast them off with a hose, use a soap based product, or the diatomaceous earth as I used. However with these daylilies they were really down in deep where they couldn’t really be sprayed away or accessed well with any sort of spray. There was too much daylily foliage providing coverage. A systemic pesticide was really the best solution as I did not need to worry about spraying all the aphids, but only all the affected plants.

In the future, if this happens again, I will know what to look for and hopefully be able to head it off before it gets this bad.


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