Tech Notes Issue 10

Large Patch

Large Patch is a mid - to early spring disease of warm season turfgrasses. Initially reported on zoysiagrass, the disease was originally called Zoysia patch. Subsequently the disease was diagnosed on multiple warm season turfgrass, and for consistency purposes the
name "Large Patch" evolved. The pathogen Rhizoctonia solani is similar to the pathogen that causes brown patch on cool season turfgrasses, except the large patch pathogen belongs to a different anastomosis group (AG-2-2(LP). The optimal temperature for infection is 25- 28C but can infect at temperatures ranging from 10 to 30 C. Generally, large patch is most severe under moist or wet conditions. Large patch is increasingly becoming more of a problem on seashore paspalum during the winter months.

Spring Coring and Verticutting of Couchgrass

Coming out of winter couchgrass can be in a semidormant or dormant stage. As the couchgrass greens up it is often common to core to relieve compaction from winter play and verticut to stimulate growth.

Coring should be delayed until soil temperatures reach an average of 22 C per day. The reason for this is that by coring early you may actually slow couchgrass growth. The core hole actually will help keep the soil temperatures cooler as a result of the cooler nighttime temperature affect on the holes, which will actually delay soil warming. Coring to reduce compaction when soil temperatures are adequate to promote growth is the ideal time.

Vertical mowing is popular to remove  thatch and is often done in spring. The ideal time is again when couchgrass is actively growing in mid- to late spring. At this time couchgrass will be sending stolons out and by cutting these stolons via verticutting you can stimulate more dense upright growth. Additionally the removal of thatch can help promote surface warming and growth.