Downy mildew
Peronospora destructor
What is Downy mildew (Peronospora destructor)?
Downy mildew (Peronospora destructor) is a plant disease caused by a fungus-like organism. The disease is widespread and can be found in various regions where these crops are cultivated. It affects plants belonging to the Allium genus, such as garlic, onion, shallot, chives, and leek. In addition it thrives in cool temperatures (50-77°F) and high humidity. Symptoms include circular clumps of yellowed plants in the field, pale green to brown or yellow collapsed leaf tissue, and grayish-white fuzzy growths on older leaves.
How does Downy mildew (Peronospora destructor) occur?
Downy mildew (Peronospora destructor) reproduces through the production and dispersal of spores. It requires live hosts but survives in debris and soil. It thrives in cool, humid conditions (≥95% relative humidity), with spore production declining above 75°F and ceasing above 82-84°F. Airborne spores land on plants and need leaf wetness for infection. Infection occurs in 2-3 hours at 43-61°F and 5 hours at 61-68°F. Sporulation happens 8-16 days after infection, facilitating rapid disease progression under favorable conditions.
Symptoms
1 - Effects on Plants
• Downy mildew (Peronospora destructor) significantly affects plants by causing leaf loss, reducing photosynthesis, stunting growth, and lowering yield. This makes plants more susceptible to other pathogens and stress factors. • Moreover, the presence of discolored and distorted leaves diminishes the market value of the affected plants.
2 - Environmental Implications
Outbreaks of downy mildew disrupt natural and agricultural systems, resulting in reduced biodiversity. Crop losses and increased production costs have a significant impact on farmers and industry.
Solutions
1 - Crop Rotation and Planting Practices
• Implement a 3-year rotation away from Allium and other crops in fields where the disease has occurred. • Use disease-free bulbs, sets, and seeds for planting. • Remove and destroy any infected plant material, including residue, volunteer plants, and culls. • Avoid entering fields when leaves are wet to minimize the spread of spores. • Take care to prevent crop injuries caused by herbicides and other materials.
2 - Minimize Canopy Leaf Wetness
• Avoid sprinkler irrigation, especially as the canopy fills. • Adjust the irrigation schedule to promote leaf drying and prevent prolonged leaf wetness. • Choose fields with good air movement and proper drainage. • Align rows with prevailing winds to enhance air circulation. • Adjust planting dates to avoid a full canopy during conditions favoring downy mildew.
5 - Fungicides for Treatment
• Oxathiapiprolin/Mandipropamid: Brand name - Orondis Ultra. • Fenamidone: Brand name - Reason 500 SC. • Mefenoxam/Mancozeb: Brand name - Ridomil Gold MZ WG. • Mefenoxam/Chlorothalonil: Brand name - Ridomil Gold Bravo SC. • Dimethomorph: Brand name - Forum. • Mancozeb: Brand name - Dithane F-45 Rainshield. • Fluazinam: Brand name - Omega 500F. • Chlorothalonil: Brand names - Bravo Weatherstik, Echo 720. • Copper Sulfate: Brand name - Basic Copper 53. Note: The use of fungicides should be in accordance with label instructions and resistance management practices. Thorough foliage coverage is essential for effective control of downy mildew.
Susceptible Species
FAQ
Do shade growing plants need any Sunlight?
Shade growing plants do need sunlight, although they require less than other plants. They need some direct sunlight each morning to help them photosynthesize and grow properly. Also, indirect sunlight throughout the day helps them stay healthy. Shade growing plants will benefit from the sunshine, but if they get too much or too little, then they can suffer the consequences. It's important to pay attention to the needs of your plants so that you can provide them with the proper light for optimal growth.
How often should you water indoor plants?
Indoor plants should be watered when the soil feels dry to a depth of about two inches, usually about once a week. A helpful technique to determine your plants' watering needs is to feel the soil before and after watering to get a sense of how long it takes to dry out. An important note to remember is that some plants require less water than others, and it's best to research the specific needs of your individual plants. Likewise, if your home is very dry, you might need to water more often as the lack of moisture can stress the plants and lead to problems like brown leaves and wilted stems.
Can my monstera plant get root rot?
Yes, a plant can get root rot. Root rot is a fungal disease that can be caused by over-watering, poor soil drainage, or high humidity levels in the air. Signs of root rot include yellowing leaves, wilting and stunted growth, and damaged or browning root systems. Sometimes it is difficult to detect root rot until the plant is removed from the soil, as the problems are mainly below the soil surface. Treating root rot usually involves removing the affected parts of the plant and replanting the unaffected ones.
Can I put my Monstera outside in summer?
No, you should not put your Monstera outside in summer. Monstera plants need warm, humid air to thrive, and direct sunlight can scorch their leaves. Instead, put your Monstera in a bright, sunny spot with indirect light, making sure the sun never directly hits the leaves. During the summer, keep your Monstera's soil damp and mist it occasionally to keep the leaves hydrated. At nighttime, keep the temperature around 16 - 21°C (60 - 70°F). You can definitely take your Monstera outdoors for short periods of time, just make sure to bring it back in if it starts to get too hot.
What happens if my monstera plant gets too cold?
If your monstera plant gets too cold, it will become vulnerable to pests, disease, or other damage. Cold temperatures can damage the leaves of the plant, causing them to become spotted or limp. The roots of monstera plants may also suffer in cold temperatures, leading to root rot or other diseases. Belonging to the tropical family, monsteras are used to warm environments and do not do well in cold temperatures, so it is important to ensure your plant is kept in conditions that suit their needs.
Is it possible to grow a vegetable garden in a small space?
Yes, it is possible to grow a vegetable garden in a small space. Gardening in a small space can be as simple as growing a few containerized plants in pots and raised beds, or as elaborate as vertically stacking planters, hanging pouches, and hanging baskets on a wall, railing, or fence. Regardless of the size of the space you are working with, some simple techniques such as companion planting, organic fertilizers, and water conservation can help you get the most out of your small vegetable garden.
Is peppermint herb green good for digestion?
Peppermint herb is indeed beneficial for digestion. The flavonoids in the herb support digestion by reducing inflammation in the digestive track, aiding in digestion and relieving indigestion, heartburn, and even the symptoms of irritable bowel syndrome. Additionally, peppermint is naturally rich in menthol, which helps to relax the muscles of the stomach, aiding in the digestion of food. Peppermint herb can be consumed in a variety of forms, such as teas, tinctures and capsules, as well as by adding the herb to food or directly to water or tea.
Should peppermint herb green be consumed daily?
No, peppermint herb green should not be consumed daily. This is because it contains high levels of menthol, which can be toxic if taken in large doses. Additionally, consuming large amounts of peppermint herb green could interfere with the absorption of essential minerals and vitamins, potentially causing vitamin deficiencies. For these reasons, it is best to consult with a doctor before incorporating peppermint herb green into your daily diet.
