Black mold on tomatoes

How to Treat Powdery Mildew on Plants

Though the weather across much of the country may indicate otherwise, spring is on the horizon. That means it’s time to at least start thinking about what to plant in your garden this year and which types of diseases your plants may be susceptible to. Powdery mildew is a relatively common fungus that many plants can contract. If you find powdery mildew on your plants, it’s not necessarily fatal, but you don’t want it hanging around. Fortunately, there are many options for powdery mildew treatment.

What Is Powdery Mildew?

Powdery mildew thrives in conditions opposite those where you would find ordinary mildew. Instead of liking wet and damp conditions, powdery mildew actually prefers warm and dry environments. When it shows up, it’s often first thought to be dust or dirt and can be swept away with your finger – then it returns. It appears as light white or gray spots on the tops and bottoms of the leaves, stems, new growth, flowers and even fruit or vegetables.

What Causes Powdery Mildew on Plants?

Powdery mildew forms when plant foliage is dry, lighting is low, temperatures are moderate and there is high humidity. Ideal conditions for powdery mildew growth is often during the late spring or early summer when evenings are still cool and somewhat humid, but the days are beginning to get warm.

Is Powdery Mildew Dangerous?

In many cases, powdery mildew is not fatal to the plant; instead, it’s more of an aesthetic issue. However, if left untreated, powdery mildew can leech nutrients from the plant, eventually causing leaves to wither and yellow. This can make blooms unsightly and leave vegetables and fruits particularly vulnerable to sunburn. Powdery mildew can eventually reduce the plant’s producing capacity and affect the flavors of fruits and vegetables.

Which Plants and Vegetables Are Most Susceptible?

There is a variety of powdery mildew species and they can affect different types of plants. While no plant is 100% immune, here are some plants that tend to be particularly susceptible.

Here are some fruits and vegetables where you would be most likely to find powdery mildew.

Note that this is not an all-inclusive list, so always keep a vigilant eye on your plants for signs of powdery mildew development.

Can Powdery Mildew Spread to Other Plants?

Powdery mildew spores are spread by the wind and can survive the winter in debris piles or on plants. The good news is that just because you find it on one plant, it doesn’t mean all others nearby will be contaminated. If you catch powdery mildew on zucchinis, roses or other plants, employ preventative measures, like the ones listed below, to ensure your other plants are not in conditions favorable to its development.

How Can I Prevent Powdery Mildew?

One way to prevent powdery mildew is to plant mildew-resistant plant varieties. If that isn’t an option, though, here are some other steps to take:

  • Ensure there is enough spacing between your plants to provide enough airflow around all parts of the plant.
  • Don’t over fertilize your plants. New growth tends to be very susceptible to powdery mildew development.
  • Put plants where they will get enough light and avoid overly shady locations.
  • Make sure the soil can drain properly. Inadequate drainage can make soil a breeding ground for disease-causing organisms.
  • Use compost to boost the nutrient levels in the soil, which will in turn increase beneficial microorganism populations.
  • Keep plants properly maintained by removing any dead or diseased foliage and stems.
  • Use preventative treatment options, like a sulfur fungicide, before powdery mildew even forms.

How to Treat Powdery Mildew

If your plants do develop powdery mildew despite your best efforts, don’t worry. There are many environmentally friendly options for eliminating the disease, including:

Baking Soda. Baking soda itself isn’t normally effective as a powdery mildew treatment, but when it’s combined with liquid soap and water, it can be a powerful weapon. It’s normally most beneficial if used as a preventative measure rather than a treatment. Combine one tablespoon baking soda and one-half teaspoon of liquid, non-detergent soap with one gallon of water, and spray the mixture liberally on the plants.

Mouthwash. The mouthwash you may use on a daily basis for killing the germs in your mouth can also be effective at killing powdery mildew spores. Since its function is to kill germs, the powdery mildew spores can’t withstand it. Using three parts water to one part mouthwash has been found to be a good ratio, but new growth can be damaged since mouthwash is potent, so use with caution.

Milk. Milk is making its way onto the scene as a viable means to control powdery mildew. Not all the science is known, but the compounds in milk may be able to act as an antiseptic and fungicide as well as potentially increase the plant’s overall immunity. It tends to be effective as a method of preventing powdery mildew on zucchini and other types of squash, as well as cucumbers. An effective mixture ratio is about one part milk to two or three parts water.

Organic Fungicide Treatments. If you don’t want a do-it-yourself solution, there is a variety of commercial treatment options that are just as environmentally friendly and approved for organic gardening. By going this route, you also know exactly what types of pests the treatment will kill and which types of plants it’s most helpful for.

Water. Since dry conditions coupled with high humidity are often the culprits behind powdery mildew growth, watering your plants overhead and getting the entire plant wet can help. However, it’s important to use this method somewhat sparingly as overwatering can cause other issues for your plants.

Why Choose Safer® Brand?

Sometimes with a do-it-yourself option, it can be difficult to ensure the ratios of ingredients are correct, and if they aren’t just so, the treatment may not work how you were anticipating. You may also need to use caution on which parts of the plants you apply homemade remedies. When trusting your plant’s health to the experts at Safer® Brand, you know for sure what you’re getting in each bottle and that it’s safe and effective for all parts of the plant.

Safer® Brand’s powdery mildew treatments are OMRI certified, which means it’s approved for use in organic gardening. It works by utilizing the power of sulfur compounds, which ultimately alter the plant’s pH. It’s not harmful to the plant, but powdery mildew and other fungi cannot survive.

Another benefit of using a fungicide that’s formulated for organic gardening like those Safer® Brand offers is that it doesn’t harm the soil. Millions of tiny microbes reside in the soil, providing your plant with nutrients and protecting it from pathogens. Using organic disease-control methods can help keep beneficial microorganism populations where they should be and your soil and plants healthy.

So, whether it’s powdery mildew on squash or powdery mildew on roses, Safer® Brand’s line of organic gardening treatments can help your plants, and the environment, stay disease-free and beautiful.

What is this white mold infesting my tomato plants?

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How to Prevent Black Spots & Blossom End Rots on Tomatoes

Are black spots appearing on your tomatoes? Learn what causes black spots to appear. Find out what steps you can take to prevent them from appearing on your tomatoes again.

Cause of Black Spots on Tomatoes

If you see black spots on your tomatoes then you are most likely dealing with a condition called blossom end rots. This is a fairly common problem that tomato gardeners may experience.

Blossom end rots tend to occur when the tomato growing season starts out wet. You will start to notice the rot when the fruits are about half their full size. Vegetable and fruits like tomatoes need a health intake of calcium in order to develop. The blossom end of the tomato will start to break down when there’s a lack of calcium.

The shortage of calcium can be caused by a number of factors such as moisture fluctuation, low-pH soil, or the presence of too much fertilizer. While pests don’t directly contribute to blossom end rots, you may want to take the appropriate steps to keep them at bay. Common tomato pests may include flies, slugs, and caterpillars.

Tomato Blossom End Rot Prevention Tips

It’s most likely too late to salvage tomatoes affected by bottom end rots. Here are a few steps you could take to prevent blossom end rots for future tomato crops.

Soil pH Level
The soil pH should not be too acidic or too alkaline. The optimal pH level for tomatoes is between 6.2 and 6.8. This soil condition will enable the tomato plant to take in more calcium.

Fertilizer Usage
Don’t over-do the fertilizer. Too much nitrogen, especially during the early fruiting stage, may tie up the calcium to the soil chemistry.

Moisture Stress
The soil should be kept evenly moist. One way of maintaining an even level of moisture is to apply mulch on top of the soil. Mulch can minimize evaporation from the soil.

Calcium Spray
You can apply calcium spray to tomato plants as a temporary measure. Calcium sprays can be made at home using calcium nitrate or calcium chloride. Combine four tablespoons of either powder with a gallon of water. Pour the solution into a spray bottle and shake well.

When ready, spray the calcium solution on the leaves and stems when the first bloom starts to appear on the tomato plants.

Sam Choan is the Founder of Organic Lesson. He started this site to share tips on using natural remedies at home when such options are available.

Gray Mold Of Tomatoes: How To Treat Gray Mold In Tomato Plants

A disease of tomatoes that occurs both in greenhouse produced and garden grown tomatoes is called tomato gray mold. Gray mold in tomato plants is caused by a fungus with a host range of over 200. Gray mold of tomatoes also causes postharvest rot at harvest and in storage and can cause a variety of other diseases, including damping off and blight. Given the seriousness of the disease, what are the symptoms of tomato gray mold and how is it managed?

Symptoms of Gray Mold in Tomato Plants

Gray mold, or Botrytis blight, affects not just tomatoes, but other vegetables such as:

  • Beans
  • Cabbage
  • Endive
  • Lettuce
  • Muskmelon
  • Peas
  • Peppers
  • Potatoes

Caused by the fungus Botrytis cinerea, these one-celled spores are borne on multiple branches which gives the fungus its name from the Greek ‘botrys,’ meaning bunch of grapes.

Gray mold of tomatoes appears on seedlings and young plants and appears as a grayish-brown mold that covers stems or leaves. Blossoms and the blossom end of the fruit are covered in dark gray spores. The infection spreads from the blossoms or the fruit back toward the stem. The infected stem turns white and develops a canker that may girdle it which may result in wilting above the infected region.

Tomatoes infected with gray mold turn light brown to gray when they come into contact with other infected plant parts or develop white rings called “ghost spots” if they are infected directly by airborne spores. Fruit that is infected and stored becomes covered with a gray coating of spores and may also show white mycelium on the surface of the fruit.

Managing Gray Mold of Tomatoes

Gray mold is more prominent when there is rain, heavy dew or fog prior to harvesting. The fungus also infiltrates inured plant tissues. Spores of this fungal disease reside in the residue of host plants such as tomatoes, peppers and weeds and are then spread via wind. The spores then land on the plants and create an infection when there is water available. The disease progresses most rapidly when temperatures are 65-75 F. (18-24 C.).

To combat the incidence of gray mold, irrigation needs to be carefully managed. Tomato fruit that is allowed to come into contact with water are more likely to become infected. Water at the base of the plants and allow the topsoil to dry between waterings.

Handle plants and fruit carefully to avoid injury, which may lead to a portal for disease. Remove and destroy infected plants.

Fungicides may be used to prevent infection but will not suppress the disease in plants that are already infected.

Black Stems On Tomatoes: Treating Tomato Stem Diseases In The Garden

One day your tomato plants are hale and hearty and the next day they’re riddled with black spots on the stems of the tomato plants. What causes black stems on tomatoes? If your tomato plant has black stems, don’t panic, it’s more than likely the result of a fungal tomato stem disease that can easily be treated with a fungicide.

Help, the Stem is Turning Black on My Tomatoes!

There are a number of fungal diseases that result in a stem turning black on tomatoes. Amongst these is Alternaria stem canker, which is caused by the fungus Alternaria alternata. This fungus either already lives in the soil or spores have landed on the tomato plant when infected old tomato debris has been disturbed. Brown to black lesions develop at the soil line. These cankers eventually enlarge, resulting in the death of the plant. In the case of Alternaria stem canker, unfortunately, there is no treatment. However, Alternaria resistant varieties of tomatoes are available.

Bacterial canker is another tomato stem disease that causes black spots on stems of tomato plants. It is readily apparent on older plants

as brown streaking and dark lesions. The lesions can appear anywhere on the plant. The bacteria Clavibacter michiganensis is the culprit here and it survives indefinitely in plant tissue. To prevent infection, sanitize equipment with a bleach solution and soak seeds in 130 degree F. (54 C.) water for 25 minutes prior to planting. Till areas of the garden where tomatoes have been grown thoroughly to break up and hasten the decaying of old plants.

Black stems on tomatoes may also be the result of Early blight. Alternaria solani is the fungus responsible for this disease and is spread in cool, humid weather, often after a period of rain. This fungus thrives in soil where infected tomatoes, potatoes or nightshades have grown. Symptoms include small black to brown spots under a half inch wide. They can be on leaves or fruit, but more commonly on stems. In this case, a topical application of copper fungicide or Bacillus subtilis should clear the infection up and in the future practice crop rotation.

Late blight is another fungal disease that thrives in humid climates. It usually appears in the early summer when humidity is up, with a humidity of 90% and temps around 60-78 degrees F. (15-25 C.). Within 10 hours of these conditions, purple-brown to black lesions begin to dot leaves and spread down into the stems. Fungicides are helpful to manage the spread of this disease and use resistant plants whenever possible.

Preventing Tomato Stem Diseases

If your tomato plant has black stems, it may be too late or a simple fungal application may remedy the issue. Ideally, the best plan is to plant resistant tomatoes, practice crop rotation, sanitize all equipment, and avoid overcrowding to prevent disease from infiltrating your tomatoes.

Also, removing the lower branches and leaving the stem bare up to the first set of flowers can be helpful, then mulch around the plant after removing the foliage to this point. Mulching can act as a barrier as can removing the lower leaves so rain splashed spores cannot infect the plant. Additionally, water in the morning to give the foliage time to dry and remove any diseased leaves immediately.

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