Tomatoes are among the most popular edible plants to grow at home. Whether you choose to grow them in containers or an expansive garden plot, tomatoes usually give you a good harvest and often taste much better than what you can find in the store. However, diseases like leaf spots and blights can pop up and ruin your garden party. Don’t let these potential problems scare you away, though. Fortunately, there are steps you can take to prevent and treat most of these problems
12 diseases caused by poor cultivation habits, bacteria or fungi
1. Blossom end rot
The tomato plants appear healthy, but as the tomatoes ripen, a black patch appears on the bottoms. The cause – your plants aren’t getting enough calcium.
Lime and gypsum may be added for calcium, but they must be added in the proper amounts depending on your soil’s condition. That’s why a soil test is necessary. Adding crushed eggshells to your compost pile can also boost calcium naturally when you add compost to the soil. A foliar spray containing calcium chloride can prevent blossom end rot from developing on tomatoes mid-season. Apply it early in the morning or late in the day — if sprayed onto leaves midday, it can burn them. Water plants regularly at the same time daily to ensure even application of water.
2. Blossom drop
Flowers appear on your tomato plants, but they fall off without tomatoes developing. Tomatoes need night temperatures between 55 to 75 degrees F in order to retain their flowers. If the temperatures fall outside this range, blossom drop occurs. Other reasons for blossom drop on tomatoes are insect damage, lack of water, too much or too little nitrogen, and lack of pollination.
The weather is out of your control, however you can make sure the rest of the plant is strong by using fertilizer for tomatoes and drawing pollinators.
3. Fruit cracks
Cracks appear on ripe tomatoes, usually in concentric circles. Hot, rainy weather causes fruit crack. Plants may take up water rapidly after the first heavy rainfall, which swells the fruit and causes it to crack.
What you can do about this is to water tomatoes evenly during the growing season. This prevents them from being so thirsty that they take up too much rainwater.
4. Sunscald
As tomatoes ripen, yellow patches form on the red skin. Yellow patches turn white and paper-thin, causing poor taste. The sun is the only culprit.
Sunscald usually occurs on staked plants that have been too-vigorously pruned, exposing many of the tomatoes to the sun. Leave some foliage and branches for protection.
5. Catfacing
This is the only one of the diseases that causes deformities. The cause for this problem is when plants are pollinated during cool evenings, when the temperatures are about 50 to 55 degrees F. Blossoms fall off when temperatures drop too low. If the flower is pollinating before the petals begin to drop off, some stick to the developing tomato. This creates catfacing tomatoes.
If possible, plant tomatoes a little later in the season. Make sure the weather has truly warmed up enough to support proper tomato development. Using black-plastic spread on the soil can help. As the plastic heats during the day, it releases the heat back towards the plants at night. Black plastic can be used as a temporary measure until the temperatures warm up enough that it’s no longer needed.
6. Leaf roll
Mature tomato plants suddenly curl their leaves, especially older leaves near the bottom. Leaves roll up from the outside towards the center. The cause – high temperatures, wet soil and too much pruning.
Even though leaf roll doesn’t look nice, it won’t affect tomato development.
7. Bacterial canker
Bacterial cankers start as yellow dots on ripening red tomatoes. If you look carefully at the spots, you’ll see a dark, birds-eye-type rim around each of the yellowed spots. This is what distinguishes bacterial canker from cloudy spot disease. It is caused by a bacteria called Clavibacter michiganensis. The bacteria occurs naturally but can be brought into the garden on infected plants or tools. Once it gets into the soil, rainwater splashes it up onto the plants.
Remove the infected plants immediately and do not plant tomatoes again in that soil for at least three years. Rotate your crops regularly to prevent these and other diseases from taking hold in the soil.
8. Anthracnose
As tomatoes ripen, a dark, bull’s-eye circle appears on the blossom end or bottom of the tomato. The spot is sunken and mushy to the touch. When you slice into the tomato, there’s a black mushy spot underneath that looks like rot. This is caused by a fungus called Colletotrichum phomoides. The fungus loves hot, moist weather and is often spread by overhead irrigation.
Switch your watering methods so water drips on the roots, not the leaves of the plants. Harvest tomatoes when ripe, since overly ripe tomatoes tend to contract the fungus.
9. Early blight
Brown spots on tomato leaves, starting with the older ones. Each spot starts to develop rings, like a target. Leaves turn yellow around the brown spots, then the entire leaf turns brown and falls off. Eventually the plant may have few, if any, leaves.
Crop rotation prevents new plants from contracting the disease. Avoid planting tomatoes, eggplants or peppers.
10. Fusarium wilt
A fungus called Fusarium oxysporum f.sp. lycopersici that attacks the vascular system of the plant, roughly equivalent to a human’s veins is the cause. The fungus destroys the xylem tubes, which transport water and nutrients up from the roots and into the leaves.
Rotate your crops so tomatoes aren’t planted in the same section of the garden each year to prevent diseases. Purchase wilt-resistant varieties if you’ve lost tomatoes to wilting diseases in the past, since the fungus can overwinter in garden and lawn soils.
11. Verticillium wilt
Yellow blotches appear on the lower leaves. As the blotches spread, the veins in the leaves turn brown. After the leaves turn brown, they fall off. The disease progresses up the stem until the plant is stunted. It is caused by a fungus that lives in the soil, Verticilliurn albo-atrum, attacks the roots and travels up the xylem tubes with water.
Once plants are infected, there isn’t much you can do to treat Verticillium wilt. Rotate your crops, because the fungus can live for long periods in the soil and even live among weeds such as ragweed.
12. Powdery mildew
You might find white spots on tomato leaves or even the stem. If you let the fungi thrive it will turn your tomato leaves yellow and then brown. Powdery mildew on tomatoes is more common in greenhouses than an outdoor garden because of the lack of air flow and high humidity.
The best way to prevent powdery mildew on tomato plants is to use a preventative spray formulated with sulfur.
Source: www.saferbrand.com
