Battling Mold on Your Alfalfa Plants

As an alfalfa grower, that fuzzy white or gray mold you notice on your plants can be alarming. But don’t panic. Mold is a common issue that can be managed with some adjustments to your practices. With the right prevention and treatment, you can keep mold at bay and keep your alfalfa thriving.

Understanding Alfalfa Mold

Several species of fungus can cause mold on alfalfa. The main culprits include:

• Downy mildew – Causes yellowing leaves and white mold on undersides.

• Powdery mildew – Forms a white or gray powdery coating on leaves

• Gray mold (Botrytis) – Fluffy gray mold that spreads rapidly.

While unsightly, mild mold damage is not detrimental. But heavy infestations can weaken and kill plants. Hot, humid weather tends to spur outbreaks.

Cultural Prevention

Promoting vigorous growth and proper moisture levels will make your alfalfa less mold-prone:

• Avoid overcrowding plants which reduces airflow and creates humidity.

• Water early in the day so leaves dry fully before nightfall. Drip irrigation is ideal.

• Apply 1-2 inches of mulch around plants to prevent spores from splashing up from soil.

• Prune away any dead branches and leaves which can harbor fungal spores.

• Scout for mold frequently and remove affected leaves immediately before it spreads.

Growing Resistant Varieties

Plant mold-resistant alfalfa varieties suitable for your climate:

• ‘Bulwark V’ has tolerance for multiple types of mildew.

• ‘Saranac AR’ resists anthracnose, leaf spot, and other diseases.

• ‘Team’ has good overall disease resistance and vigor.

• Check with local agriculture extension office for best regional options.

Fungicide Application

When conditions favor heavy mold growth, fungicide sprays can protect plants:

• Apply at first sign of disease and repeat per label instructions, typically every 7-14 days.

• Use a broad spectrum fungicide containing chlorothalonil, mancozeb or copper sulfate.

• Cover both top and undersides of leaves thoroughly but avoid excessive runoff.

• Always follow safety precautions when mixing and applying fungicides.

Post-Harvest Mold Prevention

Proper curing and storage of harvested alfalfa is key to prevent mold:

• Allow cut alfalfa to wilt in the field briefly before gathering and drying.

• Turn cuttings regularly as they dry to speed drying and retain nutrients.

• Dry baled alfalfa to 15% moisture content or lower before storage. Use a moisture meter.

• Ensure drying area and storage location have ample airflow and low humidity.

• Check bales frequently for hot spots and mold. Discard severely affected ones.

Treating Moldy Hay

If hay becomes molded after baling, some remediation can salvage it:

• Separate out obviously rotten bales to discard. They are not safe for feed.

• For lightly affected bales, spread out in sun to dry further before re-baling.

• Mixing in mold inhibitors can make somewhat moldy hay safe for consumption. Consult your vet.

• Always feed moldy hay with caution and watch for animal sensitivity. Don’t feed moldy hay to pregnant animals.

When to Take Action

• Early stage mold can often be managed with diligent prevention alone.

• If mold persists despite cultural practices, apply fungicides.

• Discard badly molded hay that can pose toxicity risk if fed to livestock.

• Seek expert guidance if mold severely impacts plant health and survival.

With attentive crop management and quick response when needed, mold doesn’t have to plague your alfalfa production. A proactive but measured approach will keep this nuisance at bay and let your alfalfa thrive. Stay vigilant for signs of mold and be prepared to take action before it gets out of hand.