It’s asparagus season, and we are enjoying spears from our own plants, though not as many as we’d like.

We moved crowns from our old house to the new, and have had rather mixed luck. Some didn’t survive transplant. Others grew poorly last year, and did not show their faces this year. Still others sprouted this year, but have been succumbing to phytophthora infection—a new challenge for us.

Phytophthora asparagi is an oomycete. Its long-lived spores overwinter in the soil and infect asparagus roots and spears. Phytophthora infection interferes with water transport in the stem, causing shrivelling and a ‘shepherd’s crook’ curl to the spears.

Oomycetes were once thought to be fungi, because their growth forms can be similar. They are, however, genetically distinct and are now known to be more closely related to kelp than fungi. Many oomycetes are plant pathogens, and some, like late potato blight, sudden oak disease, and Phytophthora asparagi are of economic importance.

We never had trouble with phytophthora at the old place—our well-drained soil with excellent nutrient levels kept it at bay. But at the new property, the heavy clay soil devoid of nutrients provides perfect conditions for phytophthora growth. 

Two months ago, before we’d identified phytophthora, I planted a packet of asparagus seed. I wanted to fill in the gaps in the asparagus bed, where our transplanted plants had died. Now, with 38 beautiful asparagus seedlings in the greenhouse, I’ve got a different plan for them.

Michigan State Extension recommends fungicide and careful selection of planting site to control phytophthora. I’d like to avoid the fungicide, but I can manage the soil, at least a little.

My little seedlings will need about 18 months in pots before I can plant them out. That’s plenty of time to prepare a special raised bed for them, filled with compost, sand, and soil for high-nutrient, well-drained growing conditions. In the meantime, we’ll enjoy the asparagus we are getting, and do our best to keep the old plant alive until the new ones can be harvested.

And, just so you know, the plural of asparagus is asparagus.