Italophile

tomatoes

Is it too late to take a photo of the symptoms, Dipadee?

As I've posted before, it's impossible to avoid fungal spores, the pesky little things that cause these problems. They're invisible, they travel in the air, and they are everywhere.

Preventive spraying is probably the best means of preventing infection. The spray coats the leaves, creating a barrier between the fungal spores and the leaf surface, preventing the spores getting a grip and doing their damage.

Traditionally, the most common spray has been copper sulfate-based and you'll find it under various brand names in any garden centre. Technically it's organic because copper is a naturally-occurring substance. On the other hand, it's a metal, and some growers worry about a build-up of metal in the soil when the sprays drips to the ground.

Spraying is preventive, meaning it has to be undertaken before the spores arrive. It's no use spraying after the spores have arrived - that is, once fungal (or bacterial) symptoms are showing. Usually you start spraying a couple of weeks after planting out and continue to spray every week or 10 days. If it rains within that timeframe, you have to respray to recoat the leaves. Importantly, you have to spray every leaf, and both sides of every leaf.

Preventive spraying doesn't guarantee 100% that you will be fungus (or bacteria) free, but it gives you a huge head start. The only alternative to spraying is very diligent housekeeping - at least 3' between plants to aid air circulation, judicious pruning of branches and leaves to avoid great clumps of leaves which hinder air circulation, and keeping the foliage as dry as possible. Damp foliage is a fungal spore's playground. Finally, removing the lowest branches to keep a gap of at least 1' between the lowest foliage and the soil will help against the spores - that fall from the leaves to the soil - splashing back up onto the leaves when watering.

tomatoes

Potato Blight is the same disease as Late Blight in tomatoes. The pathogen is Phytophthora infestans. In toms, it certainly manifests on the stems, but also on the leaves. That is wasn't showing on the leaves still puzzles me.

tomatoes

Mmmm. About the only disease I can think of that might manifest on the stem before elsewhere is White Mould. I've only ever seen it a couple of times. It starts out as a lesion on the stem, a bit like a stain. Eventually, as the stem succumbs, it turns almost white.

EDIT. I just Googled White Mould for further info. Everyone spells it Mold. Whatever. It seems that it's most common on plants in flower and yours weren't flowering. Might be back to square one.

tomatoes

Ah, shame there's no evidence. Was there any sign of a  problem on the leaves? Most diseases manifest first on the leaves.

tomatoes

Coralie, "blight" has become a generic term for any fungal or bacterial problem. There are actually only two Blights - Early and Late - but there are many more fungal or bacterial diseases, some of which resemble Early Blight in particular.

Can you be more specific about the symptoms - or even post a photo - so we can try to work out what the problem is? And have the plants been indoors or outdoors?

But, in general, unless you spray preventively, all you can do is try to minimise the chance of infection via housekeeping practices. I say minimise because, without preventive spraying, you can't actually stop infection. Fungal spores are invisible to the naked eye, they travel in the air, and they're everywhere. You can't avoid them.

Housekeeping practices include: keeping plants well apart to aid air circulation; judiciously removing foliage to avoid great clumps of leaves to aid air circulation; keeping the foliage as dry as possible because damp leaves are the perfect incubator for the spores. It's also a good idea to remove the lowest branches in order to maintain a gap of at least a foot between the soil and the lowest foliage. Spores can and will fall from the leaves to the soil and can be splashed back up again onto the leaves when watering. The gap helps against this.

When you say well-watered, how often were you watering? Over-watered plants - and over-fertilised plants, for that matter - can be more vulnerable to disease.

Tomato leaf problems - help

Insomnia1973 wrote (see)

Cool. Just my toms that are sick then!

That's why I'd keep as much space between the lot of them as possible.

Tomato leaf problems - help

That's why I was wondering about insects. The spots don't look disease-related. Maybe scorch from droplets of water when the leaves weren't fully adjusted to the outdoors.

Tomato leaf problems - help

Gard, I used to live in Melbourne before I moved to Sydney before we came here to Italy. I know all about changeable weather. Melbourne has the infamous four different seasons in a day. The only real problem for toms in high temps is that they're reluctant to set fruit. Other than that they will cope providing you keep an eye on the moisture situation, which you're doing.

Yes, you need to harden off seedlings gradually. I've cooked a few in my time.

The problem with keeping things humid in a greenhouse in order to avoid one problem is that you invite other problems - like fungal disease.

Geoff, what do you reckon about Beck's pepper spots?

Tomato leaf problems - help

Insomnia1973 wrote (see)

Well, I've just checked, and not another mite in sight. Oh well. I'll see how or if it progresses. I've stripped all the tomato plants of fungal leaves, so nothing much more I can do for now. Sun is beating down already.

Thanks for taking a look at the pics Italophile.

All you can do is keep watch on the pepper leaves. If it's fungal or bacterial, the spots will change and develop.

Tomato leaf problems - help

Gard, toms will tolerate a lot higher than 25C, even in a greenhouse, but the sort of temp you're citing would be a problem. Outdoors it would be less of a problem - mine sit in a baking 40+C all day - but a greenhouse, even ventilated, can become effectively an oven. How likely is that your high-40sC will continue? You might need to look at erecting some shade cloth to keep the temp down.

Your watering routine is right. Requirements will vary with temperatures, etc. Water as and when required, not by rote.