What Is Stemphylium Blight: Recognizing And Treating Stemphylium Blight Of Onions

If you are thinking that only onions get onion Stemphylium blight, think again. What is Stemphylium blight? It’s a disease caused by the fungus Stemphylium vesicarium that attacks onions and many other veggies, including asparagus and leeks. For more information about Stemphylium blight of onions, read on.

What is Stemphylium Blight?

Not everyone knows or has even heard of Stemphylium leaf blight. Exactly what is it? This serious fungal disease attacks onions and other crops. It’s fairly easy to detect onions with Stemphylium blight. The plants develop yellowish, wet lesions on foliage. These lesions grow larger and change color, turning light brown at the center, then dark brown or black as the spores of the pathogen develop. Look for the yellow lesions on the side of the leaves facing the prevailing wind. They are most likely to occur when the weather is very wet and warm. Stemphylium blight of onions is initially seen in leaf tips and leaves, and the infection usually does not extend into the bulb scales. In addition to onions, this fungal disease attacks:

Preventing Onion Stemphyliuim Blight

You can take efforts to prevent onion Stemphyliuim blight by following these cultural steps: Remove all plant debris at the end of the growing season. Carefully clean the entire garden bed of foliage and stems. It also helps to make plant your onion rows following the direction of the prevailing wind. This both limits the amount of time the foliage is wet and encourages good airflow between plants. For the same reasons, it is best to keep plant density down. You are much less likely to have onions with Stemphylium blight if you keep a good distance between plants. In addition, be sure that the soil where you plant onions offers excellent drainage. If onions with Stemphylium blight have appeared in your garden, it pays to check into blight resistant selections. In India, VL1 X Arka Kaylan produces high-quality, resistant bulbs. Welsh onion (Allium fistulosum) is also resistant to Stemphylium leaf blight. Ask at your garden store or order blight resistant strains online.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.