|Spring dead spot of bermudagrass|
We're also seeing an unusually high number of spring dead spot outbreaks on zoysiagrasses across the southeastern US. Samples, photos, and reports of spring dead spot on zoysiagrass fairways, tees, lawns, and landscapes have been rolling in all spring.
Spring dead spot of zoysiagrass?
Yes, this is not a new thing. Spring dead spot was first documented in zoysiagrass by Green et al. in 1993 as part of the zoysia patch complex, which turned out to be mostly large patch and a little bit of spring dead spot. The Color Atlas of Turfgrass Diseases by Tani and Beard also lists spring dead spot as a disease of zoysiagrasses in Japan.
In North Carolina, we've seen spring dead spot on zoysiagrass every year since 2002 and documented that it is caused by Ophiosphaerella korrae, the same species that infects bermudagrass in this part of the country.
|Spring dead spot of 'El Toro' zoysiagrass|
Overall, zoysiagrass seems to be more resistant or tolerant to spring dead spot compared to bermudagrass. The patches are typically smaller and not as widespread. Given the superior cold tolerance of zoysiagrass, this makes sense. The problem is that zoysiagrass is even slower to recover from spring dead spot than bermudagrass. Although the symptoms may not be as severe, they can linger for extended periods of time.
Not all zoysiagrass varieties seem to be susceptible to spring dead spot. In Kansas the disease was observed on 'Meyer'. In North Carolina, most cases have been observed on Zoysia japonica varieties like 'El Toro' and 'Empire'.
|Spring dead spot of 'Diamond' zoysiagrass|
This year is a little different in that we're seeing spring dead spot on more varieties. Most notably, we've confirmed the disease on golf course fairways and tees established with the Zoysia matrella cultivar 'Diamond'. To our knowledge this is the first confirmation of spring dead spot occurring on Zoyisa matrella.
Spring dead spot management on zoysiagrass is identical to that on bermudagrass. We've seen very good results from preventive application of fenarimol (Rubigan) in the fall. Regular cultivation during the summer also helps to reduce spring dead spot development and speeds up the recovery process. We're continuing to research the effects of nitrogen sources and other fertilization practices on spring dead spot development, but I don't have time to open that can of worms this week. Stay tuned for details on that in next week's post!