Twisty, Narrowed, Thickened Leaves and Other Weedkiller Damage

New growth on tomato made weird by persistent herbicide in manure.

Cabbage growth stunted and warped by persistent herbicide in manure.

There seems to be a lot of weedkiller damage in gardens this year. I've seen twisty, narrowed leaves on rose bushes (from two different yards) that were probably exposed to 2,4-D before the plants even leafed-out in spring; I've seen shortened, odd growth on hydrangeas (same cause); and I've seen vegetable plants whose growth has been stunted and made odd by a group of herbicides that persist in hay, grass clippings, and manures.

Cupped, Twisty, Weird Tomato Leaves: Herbicide Damage

I have seen, in the past couple of weeks, several examples of tomato and pepper plants that show signs of damage from weed killers. The leaves are variously cupped, twisty, fanned, excessively pointy, and otherwise just plain weird. The gardeners whose plants these are have not been using weed killer in their gardens, nor have they applied any manures (another source of herbicides), but they have used weed killers (or employed a lawn care company that used them) on their lawns.

K-State has a great little "Problem" page about accidental herbicide damage, and this sentence is especially eye-opening: "Some broadleaf herbicides such as 2,4-D are volatile, especially during hot weather, and may drift across the yard or even adjacent yards in concentrations sufficient to cause injury."

Twisty, weird tomato leaves with unusual vein pattern.

This means that even carefully applied lawn herbicides can cause unintended damage in the vegetable garden.

Those of us who have "freedom lawns" (random-weed-and-turf-grass mixes) rather than monoculture lawns typically don't suffer from herbicide damage, because we never use any, but there are plenty of gardeners in urban/suburban areas who live in neighborhoods that demand botanical uniformity in lawns. Vegetable gardeners in these neighborhoods may be stuck "between a rock and a hard place."

Persistent Herbicides, OR, Manure Isn't What it Used to Be

Pepper plant affected by persistent herbicide in Cobb County, GA. PHOTO/Amy W.

I have a friend who has been farming for a very long time, and his life experience has told him that Manure Is Good.

He has friends - owners of stables of horses - who offer to provide him with enormous amounts of composted manure, and he accepts.

Even though he has had trouble with manure before (a couple of years ago), he spread it on some of his planting beds again this year, and the tomato-family plants, not too surprisingly, have become twisty and weird.

The leaves from before the spreading of the compost look fine, but all the growth since the application looks pretty bizarre.

The North Carolina State Univ. publication about Herbicide Carryover explains that the chain of herbicide-treated hay to horse to compost needs to be very clear. Unfortunately, in the casual exchanges of small-plot farmers, the information chain can become a little vague. That can be a problem for garden-farmers who are hoping to produce healthful food from their land.

For any of us who have always thought that manure can be a great amendment to the soil for their vegetables, it is good to remember that times have changed, and that not all composted manures are what they used to be.

When 'Organic' Gardening Goes Horribly Wrong

I have a friend who's had some trouble with his tomatoes and peppers this year. I never seem to have a camera handy when I'm out at his garden/farm, but I can say that the leaves on most of the tomato and pepper plants in most parts of his garden are narrow and twisty with weird pointy parts.

At first, I thought the problem might be a virus (it definitely wasn't a fungal or bacterial infection), but it seemed that the problem might also be caused by herbicide residues in the soil. My friend uses horse manure, but he was a little doubtful when I said that I thought herbicide residues might be causing the problem. He ages that manure in huge piles for a full year, and he's never had this problem before (in more than 20 years of using manure as his main source of organic matter in the soil).

To find out for sure, I did the experiment described in various places online. I took some of his soil home with me, mixed it half & half with potting soil, then divided that into three pots. I did the same thing with soil from my own garden so I'd have a control to compare the results to.

Then I went to one of those big box stores and bought a four-pack of Big Boy tomatoes. I planted two in his pots, two in mine, and planted bean seeds (five each) in the other two pots.

In the bean pots, four germinated in my pot and only one in his, but they seemed to be mostly ok after coming up.

After three weeks, this is what the leaves on my tomato plants look like:



And these are the leaves on his tomato plants:




I'm pretty sure this means that herbicide residue is the problem, and it turns out that the problem showing up most often at the County Extension office this year is this exact problem -- damage from herbicide residues. In most instances, the damage is worse because people have used grass clippings from lawns sprayed within the last month or so right on their gardens as mulch. At least my friend's source of herbicides has sat around for a full year, giving it more time to break down and disappear.

The real frustration here is that people are trying to do the right thing -- using local amendments to improve their soil (my friend) or local mulches (others) to reduce evaporation from the soil, saving water, and to reduce the need for weeding. These uses also keep organic matter out of the landfill.

I brought my experiment to an organic gardening class I was co-teaching with the leader of the Plant-a-Row-for-the-Hungry garden, and it turned out that one person who showed up had already had the damage-from-grass-clipping problem.

Another had bought some hay to use as mulch in her garden that has always been managed using organic-approved practices and never had any big disease problems. She and her husband had brought leaves (thankfully in plastic bags, so spores weren't getting loose all over the place) from plants in her yard to show several disease problems that seemed to have arrived with the hay.

They had been told that the hayfield had never been sprayed, and I had a huge moment of doubt about that, but after more thought this seems totally possible. If the field hadn't been sprayed, it probably had a lot of weeds in it. Some of those weeds were probably in the same families as the now-infected garden plants (including the tomatoes). Weeds could easily be carriers of diseases that her garden had never before been exposed to.

This is all one big cautionary tale. I am now thinking about ways to get more organic matter into my garden without actually bringing it in from the outside, because the outside is looking pretty untrustworthy. I've grown winter cover-crops before. The vetch that I grew wasn't especially attractive, or all that easy to dig back into the soil in spring, but I am thinking about trying that again.

I've also read in Dick Raymond's "The Joy of Gardening" that in plots where he had experimented with growing two crops of edible legumes (beans, peas, not vetch) in the succession with other crops, the soil was great. He had dug in all the crop residues from the two legume crops. His method calls for growing a lot of peas.