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Downy mildew

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**1. Symptoms of Downy Mildew:**
– Initial symptoms include large, angular or blocky, yellow areas on the upper surface of leaves.
– Lesions rapidly expand and turn brown as they mature.
– The under surface of infected leaves appears watersoaked.
– Purple-brown mold becomes visible on closer inspection.
– Yellowing and mottling of leaves, fuzzy white or gray growth on the underside, stunted growth, distorted or discolored plant parts, and premature leaf drop are common signs.

**2. Management and Control of Downy Mildew:**
– Cultural options like crop rotations and tillage practices do not affect disease development.
– Planting early season varieties may reduce the threat posed by downy mildew.
– Removal and destruction of symptomatic plants is recommended.
– Fungicides like chlorothalonil and mancozeb are effective against downy mildew.
– Organic control methods include improving air circulation and reducing humidity.
– Proper sanitation measures, integrated pest management strategies, and selecting resistant cultivars are key in combating downy mildew.

**3. Host-specific and Plant-specific Mildews:**
– Basil downy mildew, Cucurbitaceae downy mildew, Grapevine downy mildew, Hop Downy Mildew, and Impatiens downy mildew are specific types affecting different plants.
– Soybeans, spinach, sunflowers, roses, Rubus species, and cucurbits like cantaloupe and watermelon are prone to specific downy mildew pathogens.
– Each host plant faces unique challenges with downy mildew, impacting yield and quality.

**4. Causes and Impact of Downy Mildew:**
– Fungal pathogens are responsible for downy mildew.
– Environmental conditions conducive to disease development play a significant role.
Plant species susceptibility influences outbreaks.
– Poor air circulation aids in the spread of downy mildew.
– Early detection and prevention strategies are crucial in managing the disease.
Downy mildew leads to reduced crop yield and quality, increased production costs, loss of market value, and negative economic impacts on agricultural regions.

**5. Research and Development Efforts in Downy Mildew:**
– Studies focus on spore germination, infection mechanisms, disease cycle, and management strategies.
– Efforts are made to identify genetic markers for resistance.
– Collaborative research aims to improve crop quality and production.
– Resources and guidelines are developed for prevention and control.
– Ongoing research is essential for advancing understanding and management of downy mildew.

Downy mildew (Wikipedia)

Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to the Peronosporaceae family. In commercial agriculture, they are a particular problem for growers of crucifers, grapes and vegetables that grow on vines. The prime example is Peronospora farinosa featured in NCBI-Taxonomy and HYP3. This pathogen does not produce survival structures in the northern states of the United States, and overwinters as live mildew colonies in Gulf Coast states. It progresses northward with cucurbit production each spring. Yield loss associated with downy mildew is most likely related to soft rots that occur after plant canopies collapse and sunburn occurs on fruit. Cucurbit downy mildew only affects leaves of cucurbit plants.

Downy mildew
Example of downy mildew (left) along with powdery mildew on a grape leaf
Causal agentsoomycetes
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