This blight is a true plight! Early blight covers tomato plants with black spots, and even makes the fruits inedible. From trying to avoid in the first place, to treating it with natural treatments, discover how to deal with this disease while using only completely organic techniques!
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Early blight is a fungal disease. This means it’s caused by a type of mushroom. The culprits are: Alternaria solani (for the tomato specifically) and Alternaria alternata ! As is the case for all fungus, they tend to appear when the air is warm and moist. Although this disease most often infects tomato plants, it can also impact potato, red beet, fruit trees, cabbage, carrot and eggplant. These particular mushrooms stay dormant in the soil, and they easily survive winter colds. They spread through various means: rain, wind, contact with contaminated soil, sick plants or infected seeds. When the air become loaded with warm moisture, spore germinate and quickly infect tomato plants.
Black spots in the shape of round rings form on stems, leaves and fruits. On the fruits, these spots lead to rot: they’re not edible anymore. Early blight is distinct from downy mildew! In the case of mildew, yellow spots appear that then fade to brown. Keep an eye on the weather forecast, since this disease takes hold during warm spring days. If it rains a lot, risk of developing the disease increases, but sometimes simply morning dew followed by a warm afternoon is enough to trigger early blight.
Avoid wetting the leaves when watering. A good idea is to use a cut plastic bottle as a funnel, stuck into the ground near the foot of the plant. That way you can water without getting water on the leaves.
Choosing a resistant variety is one of the cheapest defences you can put in place, since the fungus is always waiting in the soil. These are widely sold cultivars bred or selected for blight tolerance.
| Variety | Fruit type | Blight resistance | Plant habit |
|---|---|---|---|
| Crimson Crush F1 | Large slicing fruit, 180-200g | Bred specifically for blight resistance | Indeterminate (cordon) |
| Mountain Magic F1 | Small cocktail fruit, around 50g | Resistant to both early and late blight | Indeterminate (cordon) |
| Mountain Merit F1 | Round slicer, around 200g | Late blight resistance with early blight tolerance | Determinate (bush) |
| Ferline F1 | Beefsteak-type, around 150g | Good blight tolerance, plus fusarium and verticillium | Indeterminate (cordon) |
| Defiant PhR F1 | Medium slicer, 150-200g | High late blight resistance, intermediate early blight | Determinate (bush) |
| Legend | Large round fruit, 250g and up | Tolerant of late blight, early ripening escapes disease | Determinate (bush) |
| Juliet F1 | Elongated grape fruit, 30g | Good general foliage disease tolerance | Indeterminate (cordon) |
Still more prevention is possible to offset the disease’s appearance: fermented tea, weed decoctions and plant infusions will reinforce plant immune systems, help them develop strong roots, and will boost growth and fruit formation.
This natural fungicide is sprayed on vulnerable plants. Never use it pure: you’ve got to dilute it to a 10% mix (9 volumes water for 1 volume pure tea). Use it to water the plants, once or twice a month. It’s easy to prepare yourself, but you can also find it in garden stores nowadays.
Garlic has both antifungal and antibacterial properties. Use it to prevent fungal diseases such as early blight. Prepare a batch of garlic infusion yourself at home, all you need is a large cooking pot.
This bacteria is used to colonize space on leaves and thus keep Alternaria alternata fungus from taking hold. It’s a bacteria that also secretes anti-fungal compounds that block spore germination.
There are no curative treatments against Alternaria solani fungus, the one that impacts tomato. Regarding the other species – tomato, red beet, and citrus species, there is a treatment that helps eradicate Alternaria alternata. It’s actually another fungus called Aureobasidium pullulans that competes directly with Alternaria for space and nutrients. As for infected tomato plants, there’s no choice but to eliminate diseased specimens and carefully apply all the preventive measures to keep the disease from spreading any further.
