Defoliation of sunflower plants - Ask Extension
My sunflower plants are 24-30 inches tall. The last 2 days, just since the rain over the weekend, something has been eating the leaves. In a few cases...
Knowledgebase
Defoliation of sunflower plants #839082
Asked July 05, 2023, 1:28 PM EDT
My sunflower plants are 24-30 inches tall. The last 2 days, just since the rain over the weekend, something has been eating the leaves. In a few cases, the leaves are reduced to just the veins, no green material left. I cannot see any bugs or worms on the plants.
Eaton County Michigan
Expert Response
The two most common "dine and dash" insects that might do this are climbing cutworms and grasshoppers. Grasshoppers will leave very little trace, but the cutworms drop a very distinctive frass pellet. These will be dark green and soft when fresh, and after drying out they are hard and almost black.
It would be unusual for either one to eat enough of the leaf area to be a major concern to the plants, especially if they are growing well.
It would be unusual for either one to eat enough of the leaf area to be a major concern to the plants, especially if they are growing well.
How should I treat either one of these pests? Some of the plants have been almost completely stripped of leaves. If I don't solve the problem quickly I fear they won't survive.
I saw a few kinds of bugs on the sunflower plants today, but only one or two of each. My cousin said it looked like deer damage to her.
I saw a few kinds of bugs on the sunflower plants today, but only one or two of each. My cousin said it looked like deer damage to her.
Two more possible suspects
Photo ending in 951 is a small scarab beetle, these could cause a little of the defoliation. Photo ending in 229 is an immature katydid. These are close relatives of grasshoppers, they feed mainly at night, and they do eat quite a bit of foliage per insect. Standard garden insecticides like carbaryl or orthene would likely work against these. Deer are also a possibility, especially in places where they are numerous or very bold about coming into yards and gardens.
Here are some more possible suspects which I discovered yesterday. 
On Fri, Jul 7, 2023 at 3:53 PM, Ask Extension<<personal data hidden>> wrote:
I'm sorry that I did not comment on all of the earlier photos. Image ending in 713 is a leafhopper. These can only suck sap out of leaves, they cannot chew away pieces. Image ending in 006 is an fly, also not a defoliator. In the most recent set of photos, the first image shows a lace bug. Again, just a sap feeder, not able to chew off parts of leaves. Other photos are small spiders, all predators.
