Growing the best tomatoes
It’s great to have a go at these fruit – there are many many varieties too and everybody has their favourite ones.
But there are some problems that can occur, whether you’re raising them in an open garden bed, or in a glasshouse/tunnelhouse.
Tomato (potato) thrips: These are a nuisance interloper in NZ. They go here a few decades ago and will attack Solanaceous plants (potatoes, tomatoes, nightshades, poroporo, you name it). I used to get heaps of them when growing tomatoes in Auckland, but in Christchurch they seem to be prevalent only in autumn.
In my tunnelhouse. and in my open garden, I rarely get them now, simply because I am fanatical about pulling up nightshade weeds. I reckon the thrips overwinter on these weeds, so removing them meticulously helps a lot to keep your patch clean. Sprays with insecticides need to commence well before you see the first psyllids; it keeps their populations down too.
Finally: regular neem sprays will keep them down. Aim for the newer leaves/growth on the tomato plants.
Blossom End Rot: This has always been translated as a deficiency of calcium. Apparently that is a myth in itself; it has more to do with the inability of the plant to transport calcium through the plant. Gibberellins appear to be playing an important role in that job and most NZ soils are not deficient in calcium; so: try some fertilisers with gibberellic acid (Seafood Soup/Seaweed Tea!)
Often the first tomatoes of the season show some Blossom End Rot. With settling temps and regular fertilisation/watering these symptoms often disappear.
Watering: I’ve noticed that by slightly underwatering the tomatoes, their fruit become a lot sweeter and more intense in flavour; It pays to treat the tomato plants MEAN!
Early Blight and Late Blight: This can move pretty quickly through the plants. Here comes the watering again - only water the soil, NOT the leaves. Remove the lower leaves as soon as practicable, so they don’t drag on the moist soil and get infected. Underwatering also helps in this matter: keep the area drier and make sure the wind/air movement can dry the plants and stems quickly to avoid blight.
If you have persistent hassles, keep a regular fungicide treatment going, especially on the lower parts of the plant and very much so before wet, humid weather is forecast. Some of these sprays are systemic (taken up by the plants and giving a built-in immunity); some are protectant fungicides like copper and sulphur. These last two are also “organic” or natural compounds that resist fungal spores from entering the plants.
Hygiene: Maybe plant tomatoes in a new part of the vegetable garden (no history of fungal tomato diseases nearby). Dispose of diseased material ASAP. Do NOT compost that stuff – chuck it in the green bin to be taken away!
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