Chlorisis

Question: Is my plant experiencing chlorisis? If so, what’s the best DIY way to treat it?

responder: Weld County Colorado Master Gardeners Replied July 20, 2023, 2:27 PM EDT
response: Hi, this is Steve and thank you for your Ask Extension question. I would like some follow up information in order to give a better answer. Can you identify the tree? And can you send a picture of the entire tree? Thanks

responder: The Question Asker Replied July 20, 2023, 2:56 PM EDT
response: Steve,I think it’s some sort of locust. It does have thorns on the branches and doesn’t flower if that helps. I’ve attached pictures of multiple of these plants yellowiThanks  - Alex Hebbert On Jul 20, 2023, at 12:27 PM, Ask Extension <<personal data hidden>> wrote:﻿

responder: Weld County Colorado Master Gardeners Replied July 20, 2023, 3:18 PM EDT
response: Thanks for the quick response. I had thought it was a locust and overall they appear healthy except for the yellow leaves. I don't believe it is chlorosis which usually only affects newly planted locust. When I zoom in on your first two pictures, I think I see small white insects which would be aphids. Aphids have sucking mouth parts which pierce the leaves and draw out the "juice" in the leaves. You can determine if you have aphids by holding a sheet of paper under various leaves and shaking the leaves to cause the aphids to fall onto the sheet of paper. If this is the case, here is a fact sheet on aphids and various management ideas: https://extension.colostate.edu/topic-areas/insects/aphids-on-shade-trees-and-ornamentals-5-511/  It can be difficult for a homeowner to apply chemicals on larger trees and you must follow label directions when using. Thank you for your question and don't hesitate to reach out again for this or any other issues.

responder: The Question Asker Replied July 20, 2023, 3:36 PM EDT
response: ﻿Steve, I've sprayed roundup (I know bad stuff) on weeds near these plants and some others. Could this cause yellowing of the leaves? I confirmed the aphids are on the locust plants could it be on some of the other trees/bushes as well? Seems like I have a lot of yellowing in my yard plants/trees. I’ve attached one more picture of the locust as reference. What’s the prognosis for these plants if the aphids are left untreated? In your expertise what’s the best way to treat?  Thanks for the help. Thanks,On Thu, Jul 20, 2023 at 1:18 PM Ask Extension <<personal data hidden>> wrote:

responder: Weld County Colorado Master Gardeners Replied July 20, 2023, 3:51 PM EDT
response: Alex, this does not look like herbicide damage. Yes, you could have aphids on many other plants, they generally are not plant specific. If plants are well cared for, good water, etc., they can generally withstand a lot of pressure from insects. The affected leaves will likely drop prematurely, and other leaves may become affected. The size of the trees make it difficult to treat for a homeowner, but if you can find an insecticide that attaches to your garden hose, you might reach high into the trees. Good coverage is key and you need an insecticide effective on aphids - not all are. You can also choose to do nothing and that's a viable choice.