Meran
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Chard disease / pest?

Hello, I've been having trouble growing chard in my new house, I tried in summer and had this problem, then again in winter in a different bed (I'm in Australia in a subtropical climate, things like this generally grow best at this time when it's not so hot), but having the same problem.

Things start off great, but then the leaves start curling and getting smaller (like the outer leaves on this plant), and that just gets progressively worse (like the newer inner leaves). I've grown various varieties and they all do the same. I've got kale, cabbage and tatsoi growing in this bed with ample spacing, and they're doing great, it's only the chard that is suffering.

I've been searching but without really knowing what I'm looking for, and I haven't managed to find what the problem is, which makes it hard to fix.

Can anyone identify what might be causing this? It's very frustrating not being able to grow this leafy green which in the past has been such an easy and productive thing for me to grow.
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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

Although there is tendency to group them together, Chard is beet family and cultural needs are slightly different, still it might be good to let us see the rest of the plants and see if we all agree they are doing as well as you think.

Lookin at the Chard

- Have you checked under the leaves for possible sucking pests?

- Fist thing I thought of is pH — I have acid native soil and I have to apply serious amount of Dolomitic lime in beds where I intend to grow beets and chard — if I see lambs quarters/goosefoot/Spinach/amaranth growing well, then I can be satisfied.

- What about micronutrients? Try spraying with liquid kelp or kelpmeal tea. This year, I’m trying to see if boron deficiency explains some of my problems - and am particularly boost boron for the leafy crops including broccoli, cauliflower and Brussels sprouts, as well as strawberry and melon by applying a sprinkling of borax. They should form larger heads/fruits if successful.

imafan26
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I have similar problems. It turned out to be thrips curling the leaves. When the damage was minor, I could just cut off the leaves, but some of the plants stunted so badly, I had to pull them out and plant new ones in a different location.

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applestar
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Hah it’s those thrips again. (...this is a sort of an on-going “comedy” — I’m not very familiar with them since thankfully we don’t get many of them here, if at all)

Meran
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Thanks for the replies. I'll have a look into thrips.

I'm aware of chard being of a different family, I just wanted to grow some and thought they would be ok in the same bed. This is my first planting in that bed so there were no previous crops to consider in crop rotation.

I can take a photo of the rest of the bed when I get home from work. The kale (opposite side of the 1.5m wide bed) looks very healthy to me, and the leaves regularly top 70cm in length with a good width. The tatsoi and cabbage had a bit of a problem with something eating them at the stem as seedlings and didn't have a good survival rate, but the surviving ones aren't showing any obvious signs of disease or pest problems, still fairly small since they were planted later.

I have not seen many obvious pests. I get the odd little group of aphids on the kale, but very scarce and easily removed. Also the odd grub, but again very scarce.

I'll try the liquid kelp.

imafan26
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I do have to move the chard when the thrips are around. Even if I grow chard where it has been successful before, I will get this kind of damage on chard if the thrips find it. It is worse when the weather is hot and dry. A good rain usually lessens the problems with thrips. I live with them, since they have so many hosts, especially the Western flower thrip. I don't spray much of anything except water for pest control and I do have thrip magnets like plumeria, orchids, roses, gardenia, and jasmine sambac. I am not planning to get rid of any of them.

Since I don't spray, I do preserve the predators and if I just hose down the problem plants regularly with water and get rid of the weakest ones, everything will survive. Chard is happier in more neutral conditions and will do ok if it gets a lot of water and air circulation in summer. I will sometimes use alcohol or 3 in 1 spray if I get desperate, but it is better to plant the chard farthest away from the thrips favorite plants or give them something else to attack like marigolds and use it as a trap plant in the locations where the thrips are a problem. I have more problems with thrips on peppers than on Chard. I usually have to cut them back severely to get rid of thrips and (mites) since the weaker plants will be continuously attacked.

Mites also show up around the same time as the thrips do as they both like hot, dusty conditions. Mites are usually also diagnosed based on the damage they do as they are very hard to see. Spider mites are the most common and they cause bronzing on the underside of the leaves and you can see their webbing with heavy infestations. Broad mites also cause curling of the leaves like the thrips and are also hard to see. I usually have broad mites on my peppers. For me, whether it is thrips or broad mites, it does not matter, the control is the same. Get rid of the worst infected plants and don't plant the same kind of plant there. I usually plant crackerjack marigolds as a trap plant. I have a lot of saved seeds and I use Crackerjack for nematodes and to invite predators. Hose down the plants, especially the undersides every time I water. Cut back the plants that are infested but worth saving.
I rarely treat anything, but the best thing to use is still sulfur. It cannot be used if it is approaching 90 degrees, but sulfur will kill mites. Horticultural oil would be my second choice. It has the same issue using it in hot weather and cannot be used within 2 weeks before or after sulfur. Spinosad can only be used 4 times a year and you have to get a max kill when you do use it so everything will need to be sprayed not just the problem plants. It is best to follow up spinosad with another max attack with either horticultural oil or sulfur a week later. Horticultural oils will preserve some predators but will kill the predatory mites and thrips which control the bad ones. Sulfur will also kill good bugs. Neither persists for long.

Neem oil is favored by a lot of people, but it gives me a headache so I avoid it. Sulfur has been around for literally thousands of years and as long as you avoid breathing and getting it on your skin, by wearing long sleeves, covering up and mixing it properly with a spreader sticker, it is of very low toxicity. It also works as a fungicide and miticide and is usually paired with copper or pyrethrins to enhance the effectiveness on other pests.

https://npic.orst.edu/factsheets/sulfurgen.html
https://www.bookstore.ksre.ksu.edu/pubs/mf2922.pdf
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7405.html

Meran
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Well, it's not hot, daytime max lately has been low-mid 20's Celsius, lows in the low-mid teens Celsius, and hasn't been overly dry either.

I had a look at one of the badly curled leaves very closely, and there were small white specks on it, upon looking with a magnifying glass for a bit I noticed a few of them moving, I'm guessing mites.

I have some Neem oil, but the only stuff I've found around here says not to use on edible plants. I'll give your other suggestions a go, thanks imafan26.
I've only been in this house just over a year, with the garden beds newer than that. I have no idea if I have thrips around here or not. I do have another flowering plant (scaevola) in a pot elsewhere which definitely looks like it has a mite problem, with the fine webbing and such.
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imafan26
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Location: Hawaii, zone 12a 587 ft elev.

Mites are harder to kill. Use 3 in 1 spray it contains sulfur and pyrethrins. If you can get sulfur with a wetting agent that will also work. Sulfur is the ingredient that is active against the mites. Since you are not approaching 33 celsius, it should be fine. Do not use sulfur within 2 weeks before or after any oil or the plants will burn. Keltane is better but it was voluntarily taken off the market by the supplier because of low demand for the product. The newer miticide contains abamectin. It is more expensive and does not have the range that kelthane had and has more side effects.

I don't have as much problems with spider mites. The mites that I have issues with are broad mites. They attack the peppers and some of the leafy vegetables like the chard. Sulfur works on both kinds. Broad mites are smaller than spider mites and they don't cause bronzing.

https://nevegetable.org/insect-and-mite-management
https://www.tnstate.edu/extension/docume ... heet-1.pdf
https://www3.epa.gov/pesticides/chem_se ... 940401.pdf



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