How Do I Know If My Plants Have Diseases? Diagnosing Plant Health And Illness
One summer, we grew large, beautiful zucchini plants we were all so proud of and eager to eat! We saw their big flowers blossom and checked them every day to see how the plants progressed. But one day, our eyes fell upon a disappointing scene.
Our small baby zucchini were brown and mushy. The plant leaves were starting to get floppy as the stems lost their structural integrity. I remember feeling very discouraged as we were forced to pull out close to a dozen plants without harvesting any fruit from the plants.
All of us were confused until we cut one of the stems. There, nestled in the juice of the plant’s flesh, was a little white worm. In fact, there were several of them in a single stem, enjoying the zucchini plant. Unfortunately, their snacking was killing off our summer squash supply.
Another summer, our tomatoes suffered from a strange rot which started at the base of the tomato fruits. It looked like decay caused by overwatering, but when we stopped watering the plants as we did before, they began to droop and appear dehydrated.
What was going on?
Well, that’s what we’re going to explore together today! Keep reading and we’ll help you figure out what’s plaguing your plants and how you can save your harvest!
What Are Some Common Plant Diseases?
Powdery mildew is by far the most common plant disease and typically attacks plant leaves. Other common diseases include fungal spotting, stem rot, calcium or blossom end rot, and insect infestations can also hurt many popular garden plants. Treatment is advised in most cases and can usually save your harvest if you act fast and consistently.
Just like with any infection, the quicker you take action the better chance you have at getting better. The same rings true for your plants. We’ll dive a little deeper into the individual infections harming your crops, their causes, and how you can be proactive in preventing and treating them in the sections below.
Powdery Mildew
As we mentioned above, powdery mildew is one of the most common crop diseases. It attacks plants' leaves, creating a white, powdery coating over the top of the leaf. As the name indicates, it looks a lot like someone took baby powder and sprinkled it all over the surface of your plant’s leaves.
Causes: A fungal infection from the Erysiphaceae family is the most common culprit. It can spread very easily from one infected plant to another through contact or even the wind.
Susceptible Plants: In my personal expereince, powdery mildew seems to REALLY love my squash plants, including butternut, pumpkin, and zuchinni plants. However, it can infect almost any plant, including flowers like sunflowers, zinnias, and phlox.
Treatment: The good news is treating powdery mildew is pretty easy, affordable, and effective when treated right away. While there are several commercial powders and sprays which are effective, you can also use a mixture of baking soda, water, and non-detergent soap. Just spray it over the surface of your plant’s leaves and let it sit.
Impact: Powdery mildew can kill your plants by destroying the leaves and stems. However, most powdery mildew gets washed away in the rain, making it fairly ineffective at destroying a whole crop unless you ignore it and live in a very arid climate.
We always recommend treating your plants when they suffer. Powdery mildew can decimate a crop, especially when the weather is dry, since rain is good at washing the fungal spores off the surface of plant leaves and stems.
The spores can spread rapidly. If you find a plant with powdery mildew, treat it right away and be proactive in treating your other plants in order to contain the spread.
Blight
Blight is a blanket term for several types of fungal and bacterial infections that usually affect crops in the early stages of their life. Blight is usually categorized as early or late, which refers to the time frame in which these blights affect crops.
Late blight usually occurs in the autumn and is caused by cool-weather-loving fungi called oomycete Phytophthora. It typically attacks plants towards the end of their cycle and is thus often assumed to be a natural part of the plant’s life cycle since the weather is getting chilly.
Early blight usually impacts plants in the spring when the plants are still young. It is caused by the fungi known as Alternaria, which pose a bigger threat to tomatoes and other crops when they are still developing.
Causes: The most common cause of blight on crops is the fungus Alternaria and oomycete Phytophthora. This fungus usually spreads organically, either by contaminated soil or infected seeds.
Susceptible Plants: Most commonly, blight impacts tomatoes, potatoes, and apple trees. Although, blight can impact almost any plant, tree, and other crop.
Treatment: Treatment for blight largely consists of prevention. Practice crop rotation, proper tilling of the soil, and properly removing infected parts of plants. Never put an infected plant or infected parts of a plant in your compost pile. Ideally, burn the plant or plant parts, but if you don’t have a place to safely burn the infected plant, throw it away in your trash. However, you can also use certain anti-fungal powders and sprays to kill the infection, but it is not as effective as being proactive in preventing it.
Impact: Blight can kill your plants and even a whole tree if left unattented and untreated. If you can’t kill the infection with sprays or powders, or if removing the infected parts does not get rid of the infection, you should remove the plant and either burn it or dispose of it in the trash. By leaving it in the ground, you run the high risk of the infection spreading to other crops and trees and killing off most of your harvest.
Blight usually looks like small black or brown spots on the tips of your plant’s leaves. It initially looks pretty benign, and many either assume a lack of water causes it or that it is a natural part of the plant’s life cycle. Neither is true and if you choose to ignore it, it could permanently damage your trees or wipe out most of your crop.
Black Spots
Black spots most commonly occur on rose plants and are one of the most annoying rose-related diseases for avid gardeners. As the name indicates, the infection appears like small black spots, which usually begin to form along the edges of the leaves and spread to the interior of the leaves. While the spots are often mistaken for blight, black spots are usually caused by different types of fungi, including Asterina, Asterinella, Diplotheca, Glomerella, Gnomonia, Schizothyrium, Placosphaeria, and Stigmea.
Sadly, these fungi seem to especially love rose plants. These spots typically occur on the leaves of the plants, but they can also attack the flowers and stems.
Causes: The most common cause of black spots are various types of fungi (although Diplocarpon rosa is the most common for roses) infecting the stems, leaves, and flowers. These spots typically occur after heavy rain fall, or if you habitually water the plant from the top rather than watering them at the root.
Susceptible Plants: Rose plants are the most susceptible. Plants can become vulnerable as early as 9–18 hours after a rainfall.
Treatment: You should practice a blend of proactive treatments and prevention in order to preserve your rose plants. While it is possible to salvage a rose plant that is hit hard with black spots, it can be difficult if they lose all their leaves. If you notice black spots on a stem or a few of the leaves, immediately remove them and spray your bush with a fungicidal spray. Continue doing this for the next few days or as directed.
Impact: Black spots are notorious for killing rose bushes. Basically, they infect the plant and can be very difficult to kill once its taken root. Personally, I recommend purchasing a variety of black spot resistent roses to ensure your plants are safe. However, if you’re consistent and vigilant at applying anti-fungal spray, your plants should be fine!
It’s super important that you remember to spray your roses on a regular basis, especially if you live in a humid climate. Just remember to be proactive with your roses so they give you lots of flowers and rose hips.
Rust
Plant rust is actually another common plant infection that is usually pretty benign, but that doesn’t mean you should ignore it. Rust can be caused by a number of fungi varieties. The color of the rust is indicative of the fungal variety, but it tends to appear either grey or brown on the surface of a leaf or, in rare cases, the stem.
While this rusty-looking fungus can be harmless, it is best to treat it as soon as you spot it. If it is aggressive enough, it can harm your plant’s vitality and potentially kill it.
Causes: Various types of fungi infect the leaves and stems of plants and utilize it as a host to reproduce. The species Puccinia triticina Eriks typically infects the leaves while the fungus Puccinia graminis f. usually attacks the stem.
Susceptible Plants: Plant rust can impact pretty much affect any plant, including trees, shrubbery, and grasses. However, you may spot it spreading across your tomatoes, potatoes, flowers, or berry bushes.
Treatment: You can treat rust by applying anti-fungal sprays to the leaves and removing all of the infected areas of the plant. If you’re afraid of the rust spreading to your other plants, consider removing the infected plant and either burning it or throwing it away in the trash. Proper spacing between plants is the best way to prevent rust from developing and spreading.
Impact: Rust is not known for killing plants. However, it can impact the plant’s health and quality of produce. Its best to take it seriously and spray your plants with an anti-fungal spray to be on the safe side. In rare cases, rust can kill a plant.
Many people mistakingly believe that rust on plants is the same type which corrodes your faucet. It's not actual rust. This is a type of fungi that can, in extreme cases, kill a plant.
Blossom Rot
Have you ever noticed the ends of your tomatoes turning brown or black? This spot usually forms on the base of the tomato fruit itself rather than impacting or hurting the plant itself. This is known as blossom rot, and it most commonly affects tomatoes. It is caused by a lack of calcium, despite looking like a fungal infection caused by too much watering.
That’s actually one of the biggest mistakes you can make when dealing with blossom rot!
Causes: The main cause of calcium deficiency or blossom rot in plants is a lack of water and nutrients. This can occur if you have heavy, clay-like soil, or are experiencing a draught.
Susceptible Plants: Blossom rot can occur in many plants but tomatoes are the most susceptible. It usually appears as a small to medium size black or brown spot at the base of a ripe or near ripe tomato.
Treatment: Proper fertilization, watering, and organic matter are all important parts of preventing blossom end rot. Crop rotation can also help ensure you don’t lose your tomato harvest to this disease. If you notice blossom end rot impacting your tomatoes, than giving them an extra drink of water for a few days could fix the issue.
Impact: Blossom rot can destroy a tomato harvest. Unfortunately, the tomato fruits that get impacted by the spotting aren’t very tasty and you’ll probably end up throwing them away. It may be best to pluck off any young tomatoes or blossoms if you spot this on your ripe fruits and give the next batch extra water. This could prevent the rot from occuring on your next batch.
The best way to treat blossom rot is to ensure proper fertilization and watering of your tomato crops. Water and certain fertilizers carry much-needed calcium and other nutrients through the plant's stem and into the fruits.
Squash Vine Borers
Unlike the other infections and diseases on our list, this one is actually an infestation. Squash vine borers are some of the most annoying insects since they can literally wipe out a whole field of zucchini, pumpkins, and other squash.
Oftentimes, people don’t even realize they have an infestation until it's too late. These little worms enter the stock of the squash plant when their mothers lay them as eggs. The eggs are typically laid along the base of the squash plant, and when they hatch, they bore into the stem and continue to grow. They cause the stem and leaves to lose their moisture and integrity and are well known as a menace to anyone growing some squash, especially in the summer months.
Causes: Squash borer worms are the larvae of the clearwing moth. You’ve probably seen these odd looking bugs flying clumsily around your vegetable patch. They appear somewhat like orange and black wasps, although they don’t bite, so you won’t have to worry about that. But, you may have to worry about them laying their eggs near your crops, the eggs hatching, and the little worms eating your plants from the inside out.
Susceptible Plants: These worms usually attack soft-stemmed plants, like squash and cucumbers. You will likely start to notice your plant leaves wilting and the bases of your crops by the root beginning to turn yellow or brown. If you notice that most of the stem is a mushy brown color, then the infestation is probably out of control.
Treatment: Starting your crop early is a great way to avoid losing your harvest to squash vine borers. This will likely allow you to get a good harvest before the worms begin to hatch. Unfortunately, it can be very difficult to heal your plant after the infestation, especially if it is in the late stages. You can also prevent the moths from laying their eggs in your field by attempting to control the population. Some recommend using parasitic wasps to address the issue, but you can also try leaving a bowl or two of yellow colored water near your plants. The moths tend to get drawn to the color and will likely drawn.
Impact: Unfortunately, squash vine borers are very effective at killing off your squash supply. And its tricky to get rid of them once they’ve taken up residence. Practice proper disposal of infected plants as well as annual crop rotation to hwlp prevent the issue from ever occuring!
Certain types of squash plants are more resistant to these pests than others. If you’re really struggling to save your harvest, try switching your zucchini for cucuzzi and butternut squash.
Why Do Plants Get Sick?
There are several main causes of plant sickness, including mold, fungi, bacteria, and pest infestation. These diseases can impact almost any part of a plant, although they’re usually most obvious in the stems and leaves. While most of these ailments are treatable, it's best to practice healthy crop rotation and fertilization to ensure your plants grow healthy and strong.
If you’re wondering how you can practice crop rotation in small spaces, you’re not alone. It sounds counter intuitive! However, you can actually ensure your plants receive adequate nutrients and prevent diseases by following some basic practices.
If you’re growing your crops in a garden patch, section it off if some chicken wire fence. Label each portion with a sign or some other indicator so you remember what you planted where. At the end of the year, keep track of where you grew your tomatoes, cucumbers, squash, and other veggies the previous year and try to mix it up as best you can.
You may also want to consider adding new, mineral-rich soil to your garden every year or two. Or, gather leaves to guarantee the earth is full or nutrients for your plants.
We will be releasing a whole article on this topic very soon, so stay tuned!
How Do You Treat Plant Diseases?
Prevention is key when it comes to treating plant diseases. Rotate your crops, fertilize them adequately, and add organic material to the ground to ensure proper drainage. And, if you think something looks a little off about your plant, don’t hesitate. Take action right away to treat the issue and nip it in the bud.
Is Malnutrition the Same as Plant Disease?
Malnutrition is technically slightly different from an infestation or disease. Malnutrition occurs when your plants aren’t receiving enough minerals from the soil and typically occurs when the ground has not been properly tilled at the start of the year, nor has enough organic matter been added. This causes the plants to look sickly, produce sub-par produce, and potentially die if left unaddressed.
Closing Thoughts: Just What the Doctor Ordered!
It's ironic, really, that we eat vegetables to stay healthy, and yet veggies can get sick, too! We rely on vegetables and fruits to give our bodies the nutrients and vitamins they need to function for us every day. The least we can do it be proactive in ensuring they are as healthy as can be!
In a way, you could argue that caring for your sickly crops is a form of self-care. By addressing their ailments and giving them lots of nutrients, we guarantee the fruits and veggies we consume are full of vitamins and minerals rather than weak and frail.
So the next time you're pursuing your corn field or simply checking out your little tomato patch, make sure you look out for the smallest signs of poor health. When the plants are healthy, so are we!
