Tomato Health 101: Preventing Blight for Better Harvest

Is tomato blight putting a damper on your harvesting spirit? Every gardener enjoys healthy harvesting tomatoes from their garden. In this article, I’ll take you through some of the causes of tomato blight and how to avoid unsightly fungal infections.

Tomato blight is caused by a fungus called Phytophthora infestans. It spreads via airborne spores. This fungus requires poor airflow and hot, humid conditions to flourish. This fungus is responsible for late and early tomato blight.

Every type of fungus presents differently, allowing gardeners to distinguish between them. Early blight appears all over the plant, causing fruit to fall, and late blight causes fruit to turn brown and wither. Once a gardener identifies the specific spore affecting his plants, they can follow the six preventative measures I’ve put down in this article to safeguard future harvest.

2 tomatoes with blight

How Can You Identify Blight?

Let us take a closer look at what tomato blight is and how it is present in the plant.

Blight is a common fungal infection that causes many gardeners distress in different seasons. The disease can infect an entire farm of tomato trees resulting in untamable losses. Other parts of the tomato plant can be affected depending on the fungus you have.

While there is no cure for blight, there are ways to prevent it, and the first step is to know how to identify the disease in its different variations.

1. Early Blight

Both fungi types can cause early blight, Alternaria Tomatophilia and Alternaria Solani. This blight resembles rings, presents first on the leaves, and quickly progresses to the plant stem. The spots also show on the tomato, soon developing into large bruises. The affected fruits soon fall because the blight appears close to harvesting time.

This blight is the most disappointing for a gardener because the infection happens close to harvesting time. Luckily, this kind of blight treatment is simple and easy to implement.

This will not kill the whole plant but automatically affect the yield. Even though you can shift to resistant cultivars, you aren’t always out of the hook. That’s why we have listed some steps you can take to reduce the damage.

  • Keep the tomato leaves dry. Remember, wet surfaces favor most fungi diseases. So, keeping the leaves dry helps to prevent the disease.
  • Keep off plants and weeds in the tomato family, as they can also infect your tomatoes.
  • Support your tomato plants with sticks
  • Always check and get rid of the infected plants

2. Late Blight

This type of fungus causes pale green blisters on the leaves and stems. Many gardeners term this fungus the most destructive of the three types. The blisters quickly develop into nasty purple-black lesions that eventually encapsulate the stems. This fungus attacks tomato plants in the rainy seasons with cool night weather.

This fungus does not spare fruits as they present brown rings that become crusty patches and cesspools for rot. Any tomato gardener will tell you there is little hope for a good harvest once this fungus takes hold.

Here are some of the best tips that you can put in place to prevent late blight.

  • Always go for the right variety. Shop from a trusted dealer. You can also go for varieties that mature earlier before the late blight.
  • Ensure that your tomato plants are well-spaced. When you let every plant breathe and receive light maximally, it can fight and resist the disease.
  • Pay attention to the weather conditions. Remember, this disease is always favored by cool and wet weather. But dry weather tends to discourage it.
  • Avoid watering your tomatoes with a sprinkler or other overhead watering methods, and keep the foliage dry.

If you want to know more about blight, the video below covers it in more detail, along with other tomato diseases.

The Life Cycle of Blight Fungi

The blight spreads through spores that can germinate between forty-seven degrees and ninety degrees Fahrenheit. The spores also need free water and humidity greater than 90% to grow.

When the spore lands on a leaf, the first signs of infection will show after at least five days. There are different ways a spore can move around the farm. Some of the transference methods include human contact and water.

By nature, blight fungi will infect the lower leaves of a plant before advancing toward the fruit. Only an eighth of an inch in diameter of spores need to contact the plant for an infection to take hold. The pathogen can also be transferred from plant to plant, sometimes crossing from farm weeds to food crops. Once the fungi have infected a plant, the only cure is uprooting and disposing.

Six Ways You Can Prevent Tomato Blight

When you spot the fungus on the farm or garden, the first step is to uproot all affected plants and keep them as far away as possible from the healthy plants. The best way to dispose of the plants is to burn them or store them in sealed garbage disposal units. Because the fungus reproduces through airborne spores, you might want to cut the plants down gently without agitating their plant.

Using mulch around the base of your plants will help keep the blight at bay. You can use grass or wood chips to this end. The mulch creates a barrier preventing the spores in the soil from getting to the plant. If the blight is too widely spread, you can use a fungicide to stop the spread.

Prevention during planting

You can put a few measures in place while planting to keep blight at bay.

1. Crop rotation

The concept of plant rotation is quite common in farming. Using a different piece of land to plant tomatoes each season will reduce the risk of infecting your tomatoes. The potion of land you choose to grow your tomatoes next should not have any other member of the Solanaceae family plant planted there before. Plants in this family include eggplant, potatoes, and tobacco.

2. Choose the suitable tomato variety

There are tomato seeds in the market that will give you a crop resistant to tomato blight. The only way to know which sources to pick off the shelf is to read the fine print. If you pay close attention, you will notice the seeds that offer a blight-resistant crop; they might be a bit costly, but they are worth the extra coin.

3. Mulch Your Plants

tomato plant with green tomatoes and mulched with hay

After your plants have sprouted, you must ensure they are properly mulched. If you can, mulch your plants after planting the seed to give them a healthy start in life. Ensure that the plant base is well covered using whichever material you choose.

Suppose you are worried about your mulch turning white. It may be affected by Fungi. I wrote an article about what Fungi causes your mulch becoming white and how you will get rid of it. You can read it here.

4. Choose the Most Suitable Watering Mechanism

When watering your plants, ensure that you use a hose that reduces the amount of splashing. Using overhead sprinklers for your tomatoes is highly discouraged. Water on the leaves will only increase the chance of the fungus catching on and decimating your plants. I would recommend using a soaker hose.

5. First Action

If you rarely inspect your garden, you have little to no chance of catching the fungus at its earliest stages. I advise gardeners to examine their tomato plants as often as possible to increase the chances of spotting the first signs of damage and acting fast after that will save the rest of your crops from blight.

6. Choose the Right Fungicide

Some gardeners might not be open to using fungicides on their crops because of the perceived health hazards some people believe they pose. Some fungicides have been approved for use, which means they do not have any adverse health effects on the consumer. I like to use a fungicide to control the fungus spread in good time, especially when all other measures have failed to yield desired results.

Additional tips

1. Keep an eye out for the weeds

Since some weeds are also susceptible to the pathogen, all gardeners should focus on de-weeding the tomato plants. Some weeds that can contract the fungi include black and notorious nightshades.

2. Innovative mulching

When applying mulch, I advise gardeners to use plastic as it provides an extra effective barrier compared to other materials used around the farm. If you hope to get your tomatoes blight-free, you should also avoid working on them when the weather is humid, or the plants are wet from dew, rainfall, or irrigation.

3. Stake your tomatoes plants

Always use drip irrigation instead of overhead irrigation for the tomatoes. Most gardeners have advised that staking does a great job of drying out the plant base and reducing the contact between the leaves and spore-contaminated soil.

If you are wondering what staking is, it is a technique that involves inserting a stick beside the plant to provide support for it as it grows. The tomato plant needs this to flourish as it has a weak stem.

If you use chemicals to combat blight, ask your supplier to alternate between the chemical families as often as possible. This prevents the pathogen from becoming insensitive to chemical mixtures’ ingredients. How the gardener goes about applying the chemical is also crucial.

4. Keep up with the tech

Farming technology keeps advancing every day, so gardeners should always stay on their toes regarding the new ways their colleagues are running successful farms. There is always a chance to learn from each other. Gardeners should apply the chemicals when the environmental conditions are agreeable to the fungi. In other words, the gardener should apply the fungicides in hot and humid conditions for the best outcome.

FAQs on Tomato Health 101: Preventing Blight for Better Harvest

Can you eat a tomato with blight?
The good news is that late blight does not infect humans, so your tomatoes or potatoes should be okay to eat, depending on when you can rescue them. If you see blight lesions on your tomato or potato, clip them off and use them usually.

How do you kill the early blight in the soil?
Solarization, which uses the sun’s rays to heat the soil to a high temperature to kill the blight-producing bacteria, has proven effective and environmentally beneficial.

Will vinegar kill tomato blight?
Vinegar Solution of apple cider vinegar + 1-gallon water.
Fill a spray container halfway with the diluted solution.
Acetic acid will assist in the fight against fungus on your tomato plants.

How long does blight live in soil?
Blight spores can last three to four years in the soil. Tomatoes should only be planted in the same bed every three to four years, and tomato waste should be removed and burned in the fall.

Does blight die in winter?
Late blight cannot survive in the frigid winters of the northeast, but it may be able to survive in the center of a warm compost pile. The infection can survive as long as the plant tissue is alive.

Conclusion on what causes tomato blight

Tomato blight can affect other plants, too, such as potatoes and eggplants. It is also important to note that two types of fungi are responsible for causing blight in any plant, namely, Alternaria emetophilia and Alternaria solani.

Tomato blight can cause a gardener a bucket of stress, but these six measures are what every gardener needs to do. Observing these six measures will give you easier farming and a better chance at a bountiful harvest.

Tomatoes are great to grow, especially if you follow the basic rules and methods. I wrote a detailed article on growing tomatoes at home to ensure perfect results every time. Read that here.

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