Pole bean leaf problems - Ask Extension
All of my pole beans new leaves have become mottled and a bit curled like this pictured, along with some of my calabash leaves. Can you help identify ...
Knowledgebase
Pole bean leaf problems #872328
Asked June 09, 2024, 8:57 PM EDT
All of my pole beans new leaves have become mottled and a bit curled like this pictured, along with some of my calabash leaves. Can you help identify the problem?
Montgomery County Maryland
Expert Response
Both a viral infection and herbicide exposure can cause these kinds of symptoms. More information may help us narrow-down which is more likely, though unfortunately neither is treatable. (Viral infections are incurable, though sometimes herbicide injury is temporary, but it can depend on the dosage and type of exposure.)
Has any weed killer been applied nearby (either by you or maybe a neighbor, unless there is a farm upwind nearby) that could have drifted into this planting area? If not, was new compost (especially of manure origin) been used in the garden? (Sometimes it can be contaminated with herbicide that did not break down with the animal's digestion.) Are any plants other than the bean and gourd affected? Were the beans planted from seed you purchased, or saved from a prior planting?
Miri
Has any weed killer been applied nearby (either by you or maybe a neighbor, unless there is a farm upwind nearby) that could have drifted into this planting area? If not, was new compost (especially of manure origin) been used in the garden? (Sometimes it can be contaminated with herbicide that did not break down with the animal's digestion.) Are any plants other than the bean and gourd affected? Were the beans planted from seed you purchased, or saved from a prior planting?
Miri
Thanks for the response!
The seeds are our own, saved from last year. We recently used Scott’s weed and feed on some grass— we thought we had kept it further away from the garden but I guess maybe it blew into it?
Is there anything we should do now to try to help the plants recover? Some leafy greens (Chinese watercress) seem to be affected a little bit but not significantly. The beans are in the worst shape.
Karen
Hello Karen,
Although there may be several different formulations of the weed-n-feed product you mention, we looked up the active ingredients and see that it may contain 2,4-D and dicamba. Dicamba is often responsible for herbicide exposure damage on a variety of plants, including any nearby trees and shrubs. For the future, we don't recommend using weed-n-feed (regardless of the current contamination issue) since such products don't allow you to address any fertilization and weed treatment needs independently, or at the ideal time for each action. Additionally, Montgomery County (all but one municipality, anyway) has restrictions on herbicide use on lawns, with non-organic products being prohibited. You can learn more in the linked county government page. The state of Maryland also has a lawn fertilizer law that must be taken into account when anything that applies nutrients to the lawn is used, so the yearly total of nitrogen does not exceed the law's limits. Phosphorus is also not permitted to be used on lawns unless a laboratory soil test indicates a deficiency, so we mention this as well just in case you're unaware.
Given the appearance of symptoms on several unrelated vegetable plants, this implies the damage is due to herbicide exposure, not a virus, since the latter is unlikely to have coincidentally infected such a diverse range of species. Unfortunately, neither viral nor herbicide damage is something that can be treated or cured, and rarely does a plant grow out of either damage to resume normal growth if its symptoms are prominent. Plants with minor leaf distortion or yellowing might recuperate and can be left to do so at their own pace (no intervention is possible), but any with more dramatic symptoms, like the bean pictured, would probably need to be replaced.
It's hard to say if any herbicide residues were airborne (evaporating after application, especially on a warm day) or carried into the bed with runoff water (if a sprinkler system ran or it rained after application, for example), and therefore it's hard to predict how long any residues will remain active. If you want, you can do a germination test in that bed's soil to see if new seedlings emerge normally, and if they do, it's probably fine to replant with any replacement veggie plants.
Miri
Although there may be several different formulations of the weed-n-feed product you mention, we looked up the active ingredients and see that it may contain 2,4-D and dicamba. Dicamba is often responsible for herbicide exposure damage on a variety of plants, including any nearby trees and shrubs. For the future, we don't recommend using weed-n-feed (regardless of the current contamination issue) since such products don't allow you to address any fertilization and weed treatment needs independently, or at the ideal time for each action. Additionally, Montgomery County (all but one municipality, anyway) has restrictions on herbicide use on lawns, with non-organic products being prohibited. You can learn more in the linked county government page. The state of Maryland also has a lawn fertilizer law that must be taken into account when anything that applies nutrients to the lawn is used, so the yearly total of nitrogen does not exceed the law's limits. Phosphorus is also not permitted to be used on lawns unless a laboratory soil test indicates a deficiency, so we mention this as well just in case you're unaware.
Given the appearance of symptoms on several unrelated vegetable plants, this implies the damage is due to herbicide exposure, not a virus, since the latter is unlikely to have coincidentally infected such a diverse range of species. Unfortunately, neither viral nor herbicide damage is something that can be treated or cured, and rarely does a plant grow out of either damage to resume normal growth if its symptoms are prominent. Plants with minor leaf distortion or yellowing might recuperate and can be left to do so at their own pace (no intervention is possible), but any with more dramatic symptoms, like the bean pictured, would probably need to be replaced.
It's hard to say if any herbicide residues were airborne (evaporating after application, especially on a warm day) or carried into the bed with runoff water (if a sprinkler system ran or it rained after application, for example), and therefore it's hard to predict how long any residues will remain active. If you want, you can do a germination test in that bed's soil to see if new seedlings emerge normally, and if they do, it's probably fine to replant with any replacement veggie plants.
Miri
