Common Plant Diseases and how to treat them

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Healthy plants are always likely to resist disease. It would be best if you spaced plants to have good air circulation around them to prevent disease development. The plant disease control products available in the market are all protectants. Consequently, they must be applied before the occurrence of the problem. You need to follow the label directions on the label of all fungicides.

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Here, we present some common plant diseases and how you can prevent and treat them.

How to Identify Common Plant Diseases

Recognizing the symptoms to practice prevention and protect your plants from debilitating diseases is essential. You need to follow a holistic approach. You need first to identify the pathogen. In the next step, you need to decide on a treatment method that is effective, safe, and responsible. 

Common Plant Disease – Black Spot

Black spot is regarded as one of the most common plant diseases. It is predominantly found on roses but can also occur on other ornamental and garden plants. This fungal disease causes black, round spots on the leave’s upper sides. Usually, lower leaves get infected first.

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In severe infestations, the infected leaves turn yellow and fall off the plant. Black spot is a problem during wet weather or when leaves are soaked for more than 6 hours. Black spot spores overwinter on the fallen leaves. 

Tips for Controlling Black Spots on Leaves

  • You must sow the plant in well-draining soil. It would be best if you kept your plants healthy by providing regular feedings of organic fertilizer. Organic fertilizer helps in preventing fungal diseases in plants.
  • The fungus spores overwinter in plant debris. Thus, you need to remove dead leaves and infected canes from around the plants and discard them in the trash. Ensure that you do not add them to the compost pile; else, you will have a bigger problem on your hands.
  • You must disinfect your pruners with a household disinfectant after every use. You can use ethanol or isopropyl alcohol directly from the bottle.  
  • Since water (not wind) spreads the fungal spores, avoid applying water to the leaves. So, when you are watering the plant, apply water directly to the roots of the plant. A soaker hose to water plants prone to the disease would be best.

Other Leaf Spots

Fungal leaf spot disease can be found outdoors in the landscape and indoors on houseplants. It occurs during warm and wet conditions. As the infection spreads and progresses, the fungal spots grow large enough to touch each other. The leaf surface appears similar to blotches than spots. The leaf spots may result in the defoliation of a plant. To treat this, you follow the same tips as the ones to control the black spot.

Common Plant Disease – Powdery Mildew  

Powdery mildew is a common plant disease caused by fungus and it affects many landscape plants, fruits, flowers, and vegetables. Powdery mildew is easy to identify. Infected plants display a white powdery substance which is most visible on upper leaf surfaces.

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Additionally, it can appear anywhere on the plant, including flower buds, stems and the fruit of the plant. Tje fungus thrives during low soil moisture conditions and levels of high humidity on the upper section of the plant surface. It tends to affect plants that are kept in shady areas more than those in direct sun.

Tips for Controlling Powdery Mildew

  • It would be best if you inspected plants, the ones you buy from a greenhouse, before purchasing for insects and mildew. 
  • If you think that wiping off the leaves is an effective powdery mildew treatment, then you are gravely mistaken. If you do this, it will return within days of cleaning.
  • Because spores overwinter in debris, You should remove all infected debris. You need to trim and remove infected parts of the plant. 
  • Make sure that you do not till the debris into the soil or use it in the compost pile. 
  • Space the plants far enough apart . This would increase air circulation and thereby reduce the humidity.

Common Plant Disease – Downy Mildew

It is essential to understand the difference between downy mildews differ from powdery mildews. Powdery mildews are true fungal pathogens which display a white powdery substance on the upper leaves.

On the other hand, Downy mildews are more related to algae and produce grayish fuzzy-looking spores on the lower surfaces of leaves. You need to look for pale green or yellow spots on the upper surfaces of older leaves to identify downy mildew.

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The fungus will display a grayish to white, cotton-like Downy substance on the lower surfaces. Downy mildew occurs during cool and moist weather, such as in late fall or early spring. Spore production is favored by temperatures less than 65°F and with high levels of relative humidity. 

Tips for Downy Mildew Treatment

  • Downy mildew needs water to spread and survive. If there is no water on the leaves, the disease will not be able to spread. You need to keep water off the leaves as much as possible.
  • As the disease overwinters on dead plant debris, ensure the area around your plants in the fall are clean so as to help prevent the disease in the following spring.

Some fungicides used to control powdery mildew will not prevent downy mildew.

Common Plant Disease – Blight

Plant blight is a common disease. It caused the potato famine in 1840 and about one million people died. Besides potatoes, blight affects other plants like tomatoes. It is a fungal disease which spreads around through windborne spores.

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Hence, spores can cover large areas and rapidly spread the infection. It can only spread under warm and humid conditions, especially with two consecutive days of temperature above 50°F and humidity above 90% for eleven hours or more. No cure exists. Prevention is the only option.

Tips for Preventing Blight

  • If growing potatoes, grow early varieties because blight occurs during mid-summer, and you can harvest your crop before the blight.
  • Plant resistant varieties: Sarpo Mira and Sarpo Axona are two varieties that show good resistance. Practice good garden hygiene. 
  • Destroy any blight-infected plant parts. Keep the area clean of fallen debris from your diseased plants and discard it in the trash. Do not add to your compost pile.

Common Plant Disease – Canker

You can identify Canker by an open wound infected by fungal or bacterial pathogens. Some cankers are not severe, while others can be lethal. Canker occurs primarily on woody landscape plants. Its symptoms include sunken, swollen, cracked, or dead areas on stems, limbs, or trunks.

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Cankers can girdle branches and kill the foliage. Cankers are most common on stressed plants that have become weak by cold, insects, drought conditions, nutritional imbalances, or root rot. Rodents can also spread the pathogens.

Tips for Controlling Canker in Plants

  • Avoid overwatering and overcrowding.
  • Remove diseased parts in dry weather.
  • Avoid mechanical wounds likes damage from lawn mowers.
  • Grow resistant varieties whenever possible.
  • You need to keep the plants healthy by planting in healthy soils and maintaining nutritional requirements.
  • Wrap young, newly planted trees to prevent sunscalding. Sunscald creates dead patches on the trunk and limbs of young trees if the trunks have been shaded, then transplanted to sunny areas.

Tips to Control Plant Fungus and Diseases

First and foremost, build well-drained soil with plenty of organic matter before planting. You may try raising the bed if necessary. Moreover, fill the beds with a commercial potting mix as the mixture will drains well.

You need to understand that soils hold too much water can cause rotting. there, avoid getting water on leaves. You must hand water at the root zone or use a soaker hose. Fertilize as and when necessary to keep plants in peak condition. 

  • Prune or stake plants
  • Do not crowd plants, and remove tall weeds to improve air circulation.
  • Choose resistant varieties whenever possible.
  • You can place plants in containers away from areas which do not receive proper air circulation.
  • Remove any infected debris so as to prevent the disease from spreading.
  • Remove and place severely infected plants in the trash (not in the compost bin).
  • Water during early morning hours so the plants can dry out and avoid getting water on the leaves. You can water later in the day if downy mildew is present as it favors morning moisture. Ireespective of the watering time, avoid getting water on the leaves. A soaker hose will keep water at the root zone and it will help prevent the spores from spreading.
  • You must inspect all plants before purchasing them from your local greenhouse for pests and disease symptoms.
  • After cutting diseased plant parts, you must disinfect pruners. 
  • A 10x hand lens is very helpful in detecting insect problems and diseases.

Final Thoughts

You must keep all parts of the plant protected by using a fungicide for plants. Earth-friendly fungicide spray are very helpful for use on houseplants and in organic gardens. Formulated with food-grade citric acid, the spray is highly effective at treating and preventing the common plant diseases outlined.

These steps will build a healthy immune system and help avoid disease and pest problems. Diseases and pests tend to attack weak, stressed plants. Simply compare with immune system. A better immune system , the better it will fight illness.

Related other topics English garden, hydrangea flower, hydroponic farming and more.

3 thoughts on “Common Plant Diseases and how to treat them

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