It never fails, around April or May each year the UF/IFAS Extension Service gets inundated with calls from distressed homeowners and landscapers about dying lawns. This year has proven no different. Multiple grass samples have been analyzed by the Extension Service in the past weeks and the most common culprit have been fungal diseases, notably large patch and root rots.
Large patch, also known as brown patch, is an insidious fungal disease. The symptoms don’t make themselves really known until spring when the grass should be greening up. In actuality, the disease began infecting the lawns in winter. So by the time the large brown patches of dead or dying grass are seen, the disease is well established and therefore much more difficult to eradicate.
The other fungal diseases we are seeing a lot of right now are root rots, such as Pythium root rot and take-all. Although diagnosis from the UF Plant Diagnostic Center is needed to confirm which fungal pathogen is causing it, root rots are evidenced by dark roots with very few if any fine root hairs. A healthy grass root should be white and covered in many fine root hairs. Nematodes can also be to blame for black, stunted, rotted roots and oftentimes infect lawns weakened by fungal diseases.
Confirmation is Key
So what should you do if your lawn has large patches of brown, stunted dying lawn? First, call or visit your local Extension Service office. Photos are helpful to start but the best way to confirm the presence of diseases or pest issues is to bring in fresh samples of lawns. A 4” x 4” square of lawn with roots and dirt intact will usually suffice, although a larger sample with more soil may be needed if testing for nematodes.
If large patch and/or root rot are confirmed in your lawn, a fungicide will need to be regularly and repeatedly applied according to the label instructions. Fungicides work as preventatives, not cures, so the areas of grass that are infected will stay infected. In other words, your lawn may look worse before it begins looking better. The repeated application of fungicide and use of best lawn management practices will, with time and patience, allow healthy grass to fill in the dead patches.
Although we can’t do anything about the weather, whether it’s excessive rain like we had this past winter or the extreme heat we’re experiencing now, the best method to prevent large patch and root rot is to maintain a healthy lawn. For more information about lawn best management practices, such as proper irrigation, mowing and fertilizing, contact your UF/IFAS Extension Service Marion County.