Why are these leaves curling?

Question: Hello, I am wondering what is wrong with these plants. There are healthy plants around them. They are in a bed that has several inches of mulch. The stem of the poppies starts to curl. Can you identify the problem and suggest a solution? Many thanks, Patty Donovan

responder: An Ask Extension Expert Replied June 12, 2023, 10:05 AM EDT
response: Patty,  Thank you for your pictures and question.  Please identify all of the plants. We received Poppy. What are the other two plants?

responder: The Question Asker Replied June 12, 2023, 5:21 PM EDT
response: Hello, I think the 1st one is Tansy. The other is a new lilac. Many of my lilacs have begun to curl upon the ends of the leaves. It is happening to plants in different areas of the yard. I have not used any weed killers or fertilizers in a few years. I have been keeping about 4-6" of mulch around all of my gardens. I do not see any insects.

responder: An Ask Extension Expert Replied June 14, 2023, 12:09 AM EDT
response: Thank you.   When puzzled by curling leaves on plants in your garden or landscape, you may need to do some detective work to figure out the cause. Curling leaves can be caused by many problems, including insect damage, disease, abiotic disorders, or even herbicides.  Since you have explained that herbicides have not been used and you have not seen any evidence of insects we might suggest the following;   Insects - Take a closer look. Really inspect the plants. Use a magnifying glass or hand magnifying lens.  There are several insect pests that cause leaves to curl when they suck plant juices of new or young leaves that are still growing. These include aphids, thrips, and whiteflies.  Abiotic damage. Leaf rolling in vegetable plants like pepper, eggplant, and tomato is very common during wet spring conditions. This isn't caused by a disease, and no action is necessary.  Please take a moment to inspect your plants closely and let us know what you find.

responder: The Question Asker Replied June 15, 2023, 10:06 AM EDT
response: Hello, Thank you for helping me with this plant issue. I looked carefully for any sign of insects but did not see anything (ants and a mole cricket} even with the magnifying glass.  I do not think it is from too much rain because I had this problem last year. It gets worse as the growing season continues. I did not mention that it is worse on my Maximillion perennial sunflowers. (Aploogies for not know the correct names of my plants.} I hate to spray for insects if I dont have to.

responder: An Ask Extension Expert Replied June 17, 2023, 10:46 AM EDT
response: Patricia,   Your pictures all point to insect damage if you, or your neighbors have, in fact, not sprayed any herbicide. The one research-based factor for poppy leaves and stems that curl and twist is that aphids are present. Also, distorted, deformed leaves on sunflowers is caused by aphids.   Below is a link from University of California Agriculture and Natural Resources regarding aphid management.   https://ipm.ucanr.edu/PMG/PESTNOTES/pn7404.html  Also, side note: Apply most mulches, including wood chips and pea gravel, to a depth of 3 to 4 inches. More is not better! You mentioned you are keeping 4-6 inches. Mulch that is too deep can weaken trees, shrubs, plants and prevent water and air from reaching the soil.