deformed and curled tomato leaf problems - Ask Extension
I have 16 large tomato plants (4-6 ft tall; half Big Boy Hybrid Heirloom and half Kellogg's Breakfast) in a row in my garden on a lower-and-lean trell...
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deformed and curled tomato leaf problems #873668
Asked June 18, 2024, 4:47 PM EDT
I have 16 large tomato plants (4-6 ft tall; half Big Boy Hybrid Heirloom and half Kellogg's Breakfast) in a row in my garden on a lower-and-lean trellis system that I have grown from seed earlier this year. About half of them in the row have some sort of disease (?) resulting in curled and radically deformed leaves and emaciated-looking plants. No yellowing of leaves. See picture #1 and #2. Picture #3 shows left-most three Big Boy plants afflicted with this problem right next to a healthy Big Boy plant...the difference in leaf vigor is visible (all plants are same age). Healthy plants in the entire row of 16 are mixed randomly with emaciated plants with deformed leaves, so it's not all-or-nothing. I water these plants regularly, so it's not water stress, and I have surface fertilized a few times with a mix of 1/3 bone meal + 1/3 kelp meal + 1/3 cottonseed meal (and mixed this stuff in the soil when originally planting seedling outside). They are south-facing and have full mid-day and afternoon/evening sun but filtered morning sun. I've applied no herbicides in the area other than neem oil spray to the plants directly earlier in the spring to prevent insect damage (but not within the last month or so). The problem has been getting worse over the past month. Plants show no insect damage at all. What is wrong and how do I fix it? Thanks!
Howard County Maryland
Expert Response
Unfortunately, the damage pictured looks like classic herbicide injury, a type of phytotoxicity. If you are not applying any type of weed killer in the yard, perhaps a neighboring property (or farm upwind) has. Tomatoes are notorious for being highly sensitive to herbicide drift, at least with certain chemicals that act like plant growth hormones. Was the sprayer used to apply neem used for any herbicide prior to the insecticide? If so, residues may have remained in the sprayer and contaminated the spray, directly affecting the plants. Otherwise, differences in variety tolerances, individual plant vigor or exposure, and other environmental conditions may explain why some individuals are showing more severe signs than others.
Herbicide damage cannot be reversed. If the exposure was minimal, sometimes new foliage can grow normally, but usually (especially with tomatoes), the exposure is too great and the impacts are permanent; the plant never grows out of the damage, and as you noticed, it might even worsen. Plants showing herbicide injury need to be replaced.
Was any manure-based compost used in this planting bed? If so, sometimes herbicides used in pastures are not broken-down by the animal's digestive system, and those chemical residues persist in the manure and finished compost, and can then affect plants put in after it is incorporated. Was any mulch used that could have contained herbicides? (A few brands of bagged mulch include a pre-emergent herbicide to combat weeds. The bags should be clearly labeled with the pesticide info., though, since this is otherwise not a normal treatment of mulch.)
Miri
Herbicide damage cannot be reversed. If the exposure was minimal, sometimes new foliage can grow normally, but usually (especially with tomatoes), the exposure is too great and the impacts are permanent; the plant never grows out of the damage, and as you noticed, it might even worsen. Plants showing herbicide injury need to be replaced.
Was any manure-based compost used in this planting bed? If so, sometimes herbicides used in pastures are not broken-down by the animal's digestive system, and those chemical residues persist in the manure and finished compost, and can then affect plants put in after it is incorporated. Was any mulch used that could have contained herbicides? (A few brands of bagged mulch include a pre-emergent herbicide to combat weeds. The bags should be clearly labeled with the pesticide info., though, since this is otherwise not a normal treatment of mulch.)
Miri
Miri,
Thanks so much for that response....news I was not wanting to hear. I know that I have not applied any herbicides, but I don't know about my neighbor whose lawn is adjacent to my garden. There is another neighbor's horse pasture behind my garden, but I highly doubt they applied any herbicides. There are no other signs of damage on any plants in the rest of my garden. I applied plain old bags of shredded hardwood mulch from the garden center below these tomato plants this spring, but I have no reason to believe that they contained any herbicides.
My only thought might be Roundup. I applied Roundup spray last fall several times on my lawn before any freezes to kill the grass in the area of my new expanded vegetable garden where I planted these tomatoes. Early this spring (in February) I tilled that new garden area with a tiller to till under the remnant turf. I always thought that Roundup has a short "half-life" in the soil, so I did not worry about it. Could that potentially be causing this tomato damage? How long does Roundup last in the soil? Thanks.
Richard
The autumn Roundup application is probably not the culprit, though there are different formulations of that brand, using different herbicides or herbicide combinations. You are correct about glyphosate not lasting long or remaining active once in contact with soil, but it's hard to say where the other presumed herbicide exposure came from. You could do an experiment to see if residues are present in the soil in that bed by trying to germinate seeds in it, to see if they too either don't emerge or emerge with deformed stems/foliage. When tomatoes succumb to herbicide exposure, though, it's often through airborne drift, not soil contamination.
Is the lawn visible through the deer fence the neighbor's property? If so, that strip of what looks like dead vegetation just next to the netting is suspect, as it looks like it might have been sprayed with herbicide to kill the grass or any weeds that might have been there, rather than killed by other means (digging, flaming, etc.).
Miri
Is the lawn visible through the deer fence the neighbor's property? If so, that strip of what looks like dead vegetation just next to the netting is suspect, as it looks like it might have been sprayed with herbicide to kill the grass or any weeds that might have been there, rather than killed by other means (digging, flaming, etc.).
Miri
Forgot to add: the National Pesticide Information Center has a fact sheet on glyphosate, the active ingredient in most, but not all, Roundup formulations. Information about longevity in the soil is found under the heading "What happens to glyphosate in the environment?" near the bottom of the page. The NPIC's technical fact sheet is more, well, technical, but includes more detail about its environmental fate.
Miri
Miri
