How to Get Rid of Fungus on Alfalfa Plant: A Comprehensive Guide

Alfalfa, also known as lucerne, is a popular forage crop grown around the world to feed livestock. However, various fungal diseases can infect alfalfa and severely reduce yields. If you notice fungus on your alfalfa plants, taking prompt action is crucial to save your crop. In this comprehensive guide, we will cover how to identify, treat, and prevent fungal diseases in alfalfa.

Common Fungal Diseases in Alfalfa

Several different fungi can cause disease in alfalfa plants Here are some of the most common fungal infections to look out for

• Anthracnose – Caused by the fungus Colletotrichum trifolii, anthracnose leads to dark, sunken lesions on stems and leaves. It thrives in warm, humid conditions.

• Spring Black Stem – This fungal disease emerges in cool, wet spring weather. Look for black streaking on stems along with leaf spotting.

• Powdery Mildew – A white, powdery fungal growth on leaves and stems indicates powdery mildew. It spreads rapidly in crowded plantings.

• Downy Mildew – Light green patches that eventually turn brown on the upper leaf surface characterize downy mildew. The lower leaf surface may have gray fungal growth.

• Phytophthora Root Rot – Waterlogged soils favor this root rot disease Infected plants wilt and have reddish roots with dark lesions

• Verticillium Wilt – Caused by a soil-borne fungus, verticillium wilt makes leaves scorch and curl. Discoloration occurs in the stems and roots.

• Sclerotinia Crown and Stem Rot – White, cottony fungal growth appears on stems near the soil line. Entire plants rapidly wilt and die.

How to Identify Fungal Diseases

Carefully inspect your alfalfa plants to spot early disease symptoms. Look for:

• Discolored spots or lesions on leaves

• White or gray powdery coating on leaves

• Black streaking on stems

• Wilting, yellowing, or scorched leaves

• Stunted growth

• Rapid plant death

• Fungal fruiting structures on infected tissue

Comparison pictures of common alfalfa fungal diseases can help accurately identify the specific pathogen involved. Contact your local agricultural extension office if you need assistance with diagnosis.

Effective Treatment Methods

Once fungal disease is identified in your alfalfa, swift treatment is key to limiting damage. Here are proven methods to get rid of fungus on alfalfa plants:

1. Apply Fungicides

Several effective fungicides are available that control alfalfa fungal diseases. Targeted application is important – choose a product that lists your specific fungal problem on the label. Proper timing of fungicide sprays when the pathogen is active but before major damage occurs is also crucial.

A spring application of fungicide is generally the best time to treat alfalfa, as spring is when we face the most disease pressure with cool, wet conditions in the field. Fungicides can also tank mix with Roundup® herbicide and insecticides.

2. Improve Air Circulation

Poor air circulation creates the humid environment fungi need to thrive. Ensure alfalfa plants are not overcrowded. Avoid planting rows too close together. Proper spacing allows airflow which keeps foliage dry.

3. Follow Good Sanitation Practices

Remove any infected debris from the field after harvest. This prevents fungal spores from overwintering and reinfecting your next alfalfa crop. Clean equipment thoroughly between cuttings to prevent spreading diseases.

4. Rotate Crops

Many alfalfa fungi persist well in the soil. Rotating to non-legume crops like corn or small grains for 3-4 years substantially reduces inoculum levels. This gives alfalfa planted later a “clean slate” with lower fungal populations to combat.

5. Plant Resistant Varieties

Choose alfalfa varieties with resistance to specific diseases prevalent in your area. For example, varieties with resistance to anthracnose, spring black stem, and Phytophthora root rot are advisable in many regions. Check with local experts on the best fungus-resistant varieties to plant.

6. Improve Soil Drainage

Excess soil moisture encourages many root and crown fungal rots. Installing drainage tile or planting alfalfa on raised beds improves drainage. This creates unfavorable conditions for water-loving fungal pathogens to infect plants.

7. Reduce Leaf Wetness

Avoid overhead irrigation that wets alfalfa foliage for long periods. Instead, use drip irrigation or irrigate early in the day so leaves dry quickly. Dense plantings and low-lying fields with poor air drainage tend to have prolonged leaf wetness ideal for fungal diseases.

Prevention Tips to Avoid Fungus Issues

While treatment of existing fungal infections is important, prevention of new problems is ideal. Here are proactive measures to keep fungus at bay in your alfalfa fields:

• Start with certified, disease-free seed to avoid introducing pathogens.

• Test soil and maintain optimal pH and fertility to support strong plant health.

• Control irrigation carefully – don’t overwater. Let soil partially dry between waterings.

• Monitor fields frequently and treat diseased plants promptly before fungi spread.

• Reduce plant stress from insects, weeds, compaction, or other factors that increase susceptibility.

• Avoid working in fields when plants are wet to limit potential spread of fungal spores.

• Allow proper regrowth intervals between cuttings so plants store adequate energy reserves.

• Plant alfalfa in well-drained fields and improve drainage in overly wet spots if possible.

Left unchecked, fungal diseases can devastate an alfalfa crop, causing substantial yield and quality losses. However, armed with the knowledge to recognize common alfalfa fungi, implement timely treatment, and adopt preventive practices, you can successfully manage these plant pathogens. Following an integrated disease management approach tailored to the specific fungal problems in your area offers the best protection and peace of mind for alfalfa growers dealing with this threat. With proper fungal disease control, your alfalfa fields will thrive, providing abundant high-quality forage to support your livestock operation.