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Latest posts by Italophile

Tomato leaf problems - help

Posted: 09/07/2012 at 15:58

No, spraying for the deficiency won't hurt. I think it's about 20g ES per litre of water. Spray in the mornings to let the foliage dry out during the day.

Spraying against fungal problems has become a tad controversial these days. Most of the common fungicides are chemicals and many are reluctant to use them and with good reason. They poison foraging insects amongst other things.

The most common organic treatment is a copper sulphate spray. Very popular here in Italy. You see tom plants everywhere with bright blue leaves. But, while it's organic, it's also a metal, it can eventually build up in the soil, and doesn't do foraging insects much good either. I don't use it because I don't like metal building up in the soil.

The very best treatment I ever came across - and used when I was back in Australia - was a chlorothalonil-based spray. It comes under various brand names - Daconil, Bravo, etc. It's synthetic, a chemical, but harmless to foraging insects. It will kill fish if you pour it into a fish pond. So I didn't pour it into any fish ponds. It's very widely used in the US - the home of heirloom tomato growing - and even by many organic growers. They acknowledge that it's not organic, but (a) it doesn't harm the garden wildlife; and (b) it's stunningly effective.

Problem is, it's hard to come by outside the States for domestic use. In fact, in Australia, it was only available in bulk for farm use. So a group of us tomato growers all chipped in, bought a container, and divided it up. It worked brilliantly.

A week or so ago someone posted in this forum about spraying with milk against fungal problems. Some people do, and swear by it, but there's no scientific evidence that it works. At best, it's thought that the milk might amend the pH of the leaf surface to a figure less sympathetic to the spores.

The principle of spraying against fungal problems isn't that you kill the spores. You can't. You spray preventively - before the spores arrive - and coat the leaves (on both sides) efectively stopping the spores getting a grip. Normally you would start spraying just after planting out and about once a week thereafter. If it rains, obviously, you have to respray. It's not always failsafe - though I found the chlorothalonil was - but it's the best you can do in terms of taking positive action.

I don't spray here in Italy but only because I can't get chlorothalonil here. I just do all the basic housework and hope for the best. I get Early Blight and Septoria Leaf Spot - the two most common fungal problems in the home garden, and they're pretty inevitable - but nipping off affected leaves as soon as the symptoms appear keeps things under control.



Tomato leaf problems - help

Posted: 09/07/2012 at 14:36

Gard, a pH of 6 is ideal for toms. They prefer it slightly acid. A homemade mix might well explain some nutrient deficiencies, but I haven't seen those sorts of lesions before as a result of, especially, magnesium deficiency.

In terms of limiting the chances of fungal problems - if you don't want to spray, you just have to adopt all the housekeeping practices mentioned above. And, in a greenhouse, most of all, great ventilation.

You will never escape fungal spores. They're airborne, they're everywhere, and effectively invisible. All you can do is create an environment that gives them the least sympathetic conditions.


Courgette 'Parador F1 Hybrid' surprising!

Posted: 09/07/2012 at 12:41
Dovefromabove wrote (see)

Butternut squash but tiny, no flowers yet (flippin' weather).  Nothing else likely to fertilise them and next door's courgettes aren't flowering yet.  No other veg patches nearby either.

I have two Parador plants in a raised bed, both are behaving exactly the same and each of them have three 11cm courgettes with the flowers still attached, and we ate four the same size a few days ago.  The first male flower has opened today.

Well, something's fertilising them!

Unless, of course, you have a case of - ahem - Virgin Birth.

Courgette 'Parador F1 Hybrid' surprising!

Posted: 09/07/2012 at 11:24

What else do you have growing nearby?

Tomatoe plants with no flowers !

Posted: 09/07/2012 at 07:56

As Geoff says, avoid the temptation to feed them. In fact, don't feed them at all and keep watering to an absolute minimum. Regardless of the weather, they are more likely to produce flowers - the first step to reproducing themselves - if they think they're struggling for survival.

Tomato leaf problems - help

Posted: 09/07/2012 at 06:59

Good one, Bob. I've never had Leaf Mould problems but then I've never grown in a greenhouse. You hardly ever see it on outdoor crops.

Gard, LM is about the most common fungal problem for greenhouse toms. As Bob says, it's down to air circulation, the enclosed environs of the greenhouse effectively turning it into an incubator. You have to aim for as much ventilation as you can to keep introducing fresh air from outside. A friend of mine used an electric fan on low speed to help the process.

Rain can be one of the enemies of outdoor tom crops because of the wet foliage. Unless you spray preventively against fungal diseases+, all you can do is (a) keep a sufficient distance between plants - at least 3 feet - to help air circulation; (b) avoid letting clumps of foliage develop both on individual plants and between adjacent plants - hindering air circulation - by judiciously thinning foliage; (c) plant in a sun trap, a position that will let the sun dry the foliage as soon as possible; and (d) observe basic housekeeping practices like watering in the mornings, avoiding wetting the foliage, and maintaining a safety gap between the lowest branches and the soil.

+Even if you spray preventively you still need to observe the same fundamentals.

Unfortunately, for some reason, tomato growing seems to have been turned into a complicated process with a lot of misinformation circulating. For example, I read on a dedicated tomato website that a plant that wilts is ruined. Which is rubbish. Outdoor toms will wilt in the heat of the day. The key is to check the plant's condition after the sun goes down. If it has perked up again, no problems. If it's still drooping, it's an indicator that it's time to water. But the plant isn't ruined. This sort of misinformation is predicated on the notion that toms are delicate, sensitive plants. And they're not.

Tomato growing is a relative simple process. Observe basic cultural practices, don't pamper them, keep them alive, and let them get on with reproducing themselves.

Tomato leaf problems - help

Posted: 08/07/2012 at 17:07

Spot on, Bob - and I use the term advisedly in light of Gard's problems - humidity is an invitation to fungal problems. As is any sort of moisture on the leaves, especially overnight. It's always best to water in the mornings.

I helped a friend just outside Cortona set up her vegie garden. She installed an overhead sprinkler system. I told her she was in for trouble. Sure enough, her tom plants - and quite a few other things - are plagued by fungal problems.

Also, fungal spores can and will drop onto the soil under a plant and can be splashed back up again when watering. I maintain a gap of about a foot to 18" between the lowest foliage and the soil to help guard against same.

Tomato leaf problems - help

Posted: 08/07/2012 at 13:07

Gard, I think it's probably one of the Leaf Spot diseases, and Dove might be onto something with the added deficiency problem. As I said earlier, there's nothing you can do to treat fungal problems once they're established. You can only remove foliage, trying not to remove more than about 30%.

Apart from that, I'd cut back on both the watering and feeding. To hark back to the watering situation: regular watering just means watering to a pattern and the pattern is dictated by the plant's needs. Simply, if the mix is damp, the plant doesn't need water. The trick with containers is to poke your finger as deeply into the mix as you can. The surface might appear dry, but it's the first thing to dry out, along with the outer edges of the mix. So test the mix as deeply as you can towards the middle of the container. Any dampness at all means water isn't needed. Continually watering already damp roots just means a plant with wet feet and few plants - least of all toms - prosper with wet feet. If it takes three days for the mix to dry out, regular watering, in your case, would mean every three days. And, when you water, water well. Then let the mix dry out again. And so on. I have to say I would be enormously surprised if a container that size, in that position, needed water more than every three days. Look at the example of my neighbour's plant - in a container, in 6 hours of direct sun, with the temps around 35C - not needing water more than every two days.

Cut back the feeding to once a month. Dove is right in that potassium-rich fertilisers can impact on the mix's nutrients. And the simple fact is that toms don't need that much fertiliser. As I suggested earlier, an over-watered and over-fertilised plant isn't a happy, healthy one. It's bloated and vulnerable. Less is much preferable to more in terms of both water and food.

Change the regime, give it a few weeks, and let's see how things look.

Tomato leaf problems - help

Posted: 08/07/2012 at 10:50

No, they look like pretty classic disease-based lesions. It's a matter of which one. For example, Early Blight lesions are made up of lots of little concentric rings. Septoria Leaf Spot's lesions have wee tiny spots at their centre.

It's also rare for a tomato to suffer from deficiencies once it's established. It would have to be the poorest of very poor soils to lack, for example, enough magnesium. Deficiencies mostly occur when the plants are at the early seedling stage and growing in sterile or very basic potting mix.

Tomato leaf problems - help

Posted: 08/07/2012 at 10:08

No, there are definitely lesions on the leaves, particularly in the photos of the plant. The photos of the removed leaves show whatever it is has progressed. Magnify the photo and you can see very crusty lesions on the edges of the leaves in the second of the removed leaves photos. It's hard to tell some of the fungal diseases apart without a very close look at the lesions themselves. Even magnifying the photos isn't showing the image clearly enough.

Gard, can you have a good look at the lesions - those individual brown spots, like blisters - on the leaves? Check whether they have a light halo around them? Whether the blisters themselves are made up of concentric rings? You might even need a magnifying glass. And is there any sign of damage to the plant stems?

If it is fungal, and I think it is, all you can do is remove the affected leaves. Spraying doesn't help once the problem is established. Spraying is only useful as a preventive measure. Fungal spores are everywhere in the air, it's virtually impossible to avoid them. Unless you spray preventively, all you can do is provide plenty of air circulation and avoid getting the leaves damp or leaving them stay damp.

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